Calvin Hsia's WebLog : History

Make your Task Switcher Window bigger

Calvin_Hsia — Sat, 22 Aug 2009 00:51:00 GMT

One of the best features of Windows is the ability to Cut and Paste data within an application or from one application to another.

You can alt-tab or click on the task bar to switch between actively running applications, like Word and Visual Studio. When you hit Alt-Tab, a window comes up.

This Task switcher window, by default has 3 rows of 7 icons. If you have more than 21 top level windows open, that dialog gets confusing.

Without tabbed browsing a few years ago (the ability of Internet Explorer to open multiple Tabs to view multiple web pages in a single top level IE Window), I had tons of these windows. (Try Window Key Tab to switch applications on any machine with Aero enabled!)

In fact, sometimes I run so many I get confused when I Alt-Tab and see the behavior of the default 21 (3 row by 7 column) icon display. So, I just modify this to be 5 rows by 9 columns.

Open RegEdit and change these keys:

HKEY_CURRENT_USER\Control Panel\Desktop\CoolSwitchRows

HKEY_CURRENT_USER\Control Panel\Desktop\CoolSwitchColumns

See also CoolSwitchRows: http://technet.microsoft.com/en-us/library/cc978607.aspx

In the old days (the late 70's to early 80's, when a 5 Meg hard disk was cool!), you could only run one application on your computer at a time. To transfer data from one program to another, you would open one application, save the information temporarily to a file on (floppy) disk, then open the other application, import the temporary file.

Then along came Borland's Sidekick and AutoDesq DesqView. I think Sidekick had a way of storing text data: it was a TSR: a Terminate and Stay Resident program. That means it was always available even if you were running another application. Once you start it, it would “terminate” but still be running. It would always be in memory, reducing the memory available to other programs.

I remember writing various TSRs. One was a simple program that could flash on the screen any message at any time interval and duration:

Flashmsg /m:"You're getting hungry" /t:200 /d:1

Another would monitor key strokes. Every 100^th keystroke it could double a keystroke, substitute another, record, or suppress one. I didn't circulate these evil programs. (do you believe me? J)

A more useful one came about because a fellow ice hockey teammate and client heard I knew something about computers and wanted his business's Contact List to be instantly available at any time. So I wrote a TSR that would display a simple database of names and phone numbers around 1982. Over the years, I migrated the database maintenance to FoxBase and eventually FoxPro (1990?). So while the client was using WordPerfect, he could hit a key combination to bring up his Contact List instantly.

A TSR can monitor various interrupts, such as the keyboard, by just replacing the interrupt vector with its own. The interrupt vector was just a pointer to the code to run if the keyboard is hit. My TSR would just forward most requests to the original ISR (Interrupt Service Routine). Back in those DOS days, it was easy to replace system memory. “Protected mode” was unheard of.

DesqView was another TSR, but it allowed you to run multiple applications "simultaneously". If I remember right, it "paged" out one app for another, writing to disk the 256K that one was using for the other. This was an immense boost in productivity.

In those days, I was using a really great text editor called PC-Write (one of the first "shareware" programs) from Bob Wallace (Microsoft Employee #9). (It was around this time that dBase, FoxBase were born.)

When Windows 3.1 came out around the early 90's, you could use OLE (Object Linking and Embedding, which sort of got renamed to ActiveX later) and DDE (Dynamic Data Exchange) to have applications communicate with each other. The big demo was a Word Document or Fox database embedding an Excel spreadsheet or a photograph.

You can still embed a photo or spreadsheet in Foxpro using a General field (on XP, Vista and Windows Server08 R2(which is Win7 under the hood)):

CREATE CURSOR temp (name c(10), gen g)

INSERT INTO temp (name) VALUES ("Photo")

APPEND GENERAL gen FROM d:\kids.jpg

MODIFY GENERAL gen

INSERT INTO temp (name) VALUES ("Excel")

APPEND GENERAL gen FROM d:\2008.07.xlsx

BROWSE

You can double click the image or Excel spreadsheet to see or edit it within Fox. You can also use the Edit->Insert Special menu to insert other kinds of objects.

For fun, try this:

x=DDEINITIATE("visualfoxpro","")

_cliptext="This text goes on the clipboard"

Or notice the intellisense when you try this from the Fox Command window

x=CREATEOBJECT("Excel.Application")

x.Visible=1

x.Workbooks.Add

x.Cells(1,1).Value="Hi"

Try starting Visual Studio and choose File->Open->File-> navigate to a photo or spreadsheet!

Create or open an existing VB project which has no build errors and then

Dim x=CREATEOBJECT("Excel.Application")

Stop

F5 to hit the breakpoint, Debug->Window->Immediate to open the immediate window.

Then resize VS so you can see Excel, type

x.Visible=1

x.Workbooks.Add

x.Cells(1,1).Value="Hi"

Try something similar in C# (add a reference to Microsoft.VisualBasic.Dll)

Object x = Microsoft.VisualBasic.Interaction.CreateObject("excel.application","");

var z = "Put a bpt here";

Which pixels do you turn on when you draw a line?

Calvin_Hsia — Mon, 30 Mar 2009 21:46:00 GMT

When I wrote my cartoon animation program almost 30 years ago (see Cartoon animation program) I needed to know how to draw a line.

Of course, nowadays, we just call a library function that will draw a line given two points.

If you think about it, the problem is quite complex. Imagine a rectangular array of pixels. Which ones do you paint in order to “see” a straight line?

If the desired line is horizontal, or vertical, the problem is simple. However, choosing which pixels to draw for an oblique line is an interesting mathematical problem: see Bresenham's line algorithm - Wikipedia, the free encyclopedia

Even back then, I found Bresenham’s algorithm in a book and implemented it for my cartoon program.

Suppose you want to create a simple drawing program. When you move the mouse, you can handle the MouseMove event, and light up the pixel at the position of the mouse.

However, this will only create a dotted line, with fewer dots if the mouse moved quickly.

Let’s see if we can use Bresenham’s algorithm to light up the pixels between successive mouse events.

This sample uses larger “pixels”, so you can actually see them as squares. In the code I called them cells (mainly because I stole a lot of the code from my game of Life (see Cellular Automata: The Game of Life )

The actual mouse down causes a red pixel to be drawn, and the generated ones are black.

Below are C# and VB versions.

Start Visual Studio 2008

Choose File->New->Project->C# or VB->Windows Forms Application.

Choose View->Code

Paste in the VB or C# version of the code below, hit F5 to run it.

Move the mouse slowly and you’ll see more red pixels. Quickly, and you’ll see more black generated pixels.

Note how the code needs to distinguish between 2 sets of x-y coordinates: actual pixels, and cell coordinates.

Try adjusting the Cell size.

Think about what a right click would do.

Remove double spaces from pasted code samples in blog

<C#Sample>

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Windows.Forms;

namespace WindowsFormsApplication1

{

public partial class Form1 : System.Windows.Forms.Form

{

Size m_numCells = new Size(350, 200);// we'll use an array of Cells

Boolean[,] m_cells; // the array of cells: whether they've been drawn or not

Size m_cellSize = new Size(8, 8); // cell height & width

Size m_Offset = new Size(0, 0);

bool m_MouseDown = false;

Button btnErase;

Point? m_PtOld;

SolidBrush m_brushMouse = new SolidBrush(Color.Red);

SolidBrush m_brushGenerated = new SolidBrush(Color.Black);

delegate bool DrawCellDelegate(Point ptcell, Brush br);

Graphics m_oGraphics;

public Form1()

{

this.Load += new EventHandler(this.Loaded);

}

void Loaded(Object o, EventArgs e)

{

this.Width = 600;

this.Height = 400;

this.btnErase = new Button();

this.btnErase.Text = "&Erase";

this.btnErase.Click += new EventHandler(this.btnErase_Click);

this.Controls.Add(this.btnErase);

this.BackColor = Color.White;

btnErase_Click(null, null);

}

void btnErase_Click(object sender, System.EventArgs e)

{

m_oGraphics = Graphics.FromHwnd(this.Handle);

m_numCells.Width = this.Width / m_cellSize.Width;

m_numCells.Height = this.Height / m_cellSize.Height;

m_cells = new Boolean[m_numCells.Width, m_numCells.Height];

m_oGraphics.FillRectangle(Brushes.White, new Rectangle(0, 0, this.Width, this.Height));

}

Point PointToCell(Point p1)

{

Point ptcell = new Point(

(p1.X - m_Offset.Width) / m_cellSize.Width,

(p1.Y - m_Offset.Height) / m_cellSize.Height);

return ptcell;

}

protected override void OnMouseDown(MouseEventArgs e)

{

if (e.Button == MouseButtons.Left)

{

m_MouseDown = true;

m_PtOld = new Point(e.X, e.Y);

CheckMouseDown(e);

}

#if AREA

else

{

AreaFill(PointToCell(new Point(e.X, e.Y)));

}

#endif

}

protected override void OnMouseMove(MouseEventArgs e)

{

if (m_MouseDown)

{

CheckMouseDown(e);

}

protected override void OnMouseUp(MouseEventArgs e)

{

m_MouseDown = false;

}

void CheckMouseDown(MouseEventArgs e)

{

Point ptMouse = new Point(e.X, e.Y);

Point ptcell = PointToCell(ptMouse);

if (ptcell.X >= 0 && ptcell.X < m_numCells.Width &&

ptcell.Y >= 0 && ptcell.Y < m_numCells.Height)

{

DrawLineOfCells(PointToCell(m_PtOld.Value), ptcell, new DrawCellDelegate(DrawACell));

m_PtOld = ptMouse;

}

bool DrawACell(Point ptcell, Brush br)

{

bool fDidDraw = false;

if (!m_cells[ptcell.X, ptcell.Y]) // if not drawn already

{

m_cells[ptcell.X, ptcell.Y] = true;

//*

m_oGraphics.FillRectangle(br,

m_Offset.Width + ptcell.X * m_cellSize.Width,

m_Offset.Height + ptcell.Y * m_cellSize.Height,

m_cellSize.Width,

m_cellSize.Height);

/*/

g.DrawRectangle(new Pen(Color.Blue,1),

m_Offset.Width + ptcell.X * m_cellSize.Width,

m_Offset.Height + ptcell.Y * m_cellSize.Height,

m_cellSize.Width,

m_cellSize.Height);

//*/

fDidDraw = true;

}

return fDidDraw;

}

void DrawLineOfCells(Point p1, Point p2, DrawCellDelegate drawit)

{

// http://en.wikipedia.org/wiki/Bresenham%27s_line_algorithm

Brush br = m_brushMouse;

int x0 = p1.X;

int y0 = p1.Y;

int x1 = p2.X;

int y1 = p2.Y;

int x, cx, deltax, xstep,

y, cy, deltay, ystep,

error;

bool st;

// find largest delta for pixel steps

st = (Math.Abs(y1 - y0) > Math.Abs(x1 - x0));

// if deltay > deltax then swap x,y

if (st)

{

x0 ^= y0; y0 ^= x0; x0 ^= y0; // swap(x0, y0);

x1 ^= y1; y1 ^= x1; x1 ^= y1; // swap(x1, y1);

}

deltax = Math.Abs(x1 - x0);

deltay = Math.Abs(y1 - y0);

error = (deltax / 2);

y = y0;

if (x0 > x1) { xstep = -1; }

else { xstep = 1; }

if (y0 > y1) { ystep = -1; }

else { ystep = 1; }

for (x = x0; (x != (x1 + xstep)); x += xstep)

{

cx = x; cy = y; // copy of x, copy of y

// if x,y swapped above, swap them back now

if (st)

{

cx ^= cy; cy ^= cx; cx ^= cy;

}

if (drawit(new Point(cx, cy), br))

{

br = m_brushGenerated;

}

error -= deltay; // converge toward end of line

if (error < 0)

{ // not done yet

y += ystep;

error += deltax;

}

</C#Sample>

Public Class Form1

Dim m_numCells = New Size(350, 300) ' we'll use an array of cells

Dim m_cells(,) As Boolean ' the array of cells: whether they've been drawn or not

Dim m_cellSize = New Size(8, 8) ' cell size & width

Dim m_Offset = New Size(0, 0)

Dim m_MouseDown = False

Dim WithEvents btnErase As Button

Dim m_PtOld As Point?

Dim m_brushGenerated = New SolidBrush(Color.Black)

Dim m_brushMouse = New SolidBrush(Color.Red)

Dim m_oGraphics As Graphics

Delegate Function DrawCellDelegate(ByVal ptCell As Point, ByVal br As Brush) As Boolean

Sub Form_Load() Handles Me.Load

Me.Width = 600

Me.Height = 400

Me.btnErase = New Button()

Me.btnErase.Text = "&Erase"

Me.Controls.Add(Me.btnErase)

Me.BackColor = Color.White

btnErase_Click()

End Sub

Sub btnErase_Click() Handles btnErase.Click

m_oGraphics = Graphics.FromHwnd(Me.Handle)

m_numCells.Width = Me.Width / m_cellSize.Width

m_numCells.Height = Me.Height / m_cellSize.Height

ReDim m_cells(m_numCells.Width, m_numCells.Height)

m_oGraphics.FillRectangle(Brushes.White, New Rectangle(0, 0, Me.Width, Me.Height))

End Sub

Function PointToCell(ByVal p1 As Point) As Point

Dim ptcell = New Point( _

(p1.X - m_Offset.Width) / m_cellSize.Width, _

(p1.Y - m_Offset.Height) / m_cellSize.Height)

Return ptcell

End Function

Protected Overrides Sub OnMouseDown(ByVal e As System.Windows.Forms.MouseEventArgs)

If e.Button = Windows.Forms.MouseButtons.Left Then

m_MouseDown = True

m_PtOld = New Point(e.X, e.Y)

CheckMouseDown(e)

#If AREA Then

Else

AreaFill(PointToCell(New Point(e.X, e.Y)))

#End If

End If

End Sub

Protected Overrides Sub OnMouseMove(ByVal e As System.Windows.Forms.MouseEventArgs)

If m_MouseDown Then

CheckMouseDown(e)

End If

End Sub

Protected Overrides Sub OnMouseUp(ByVal e As System.Windows.Forms.MouseEventArgs)

m_MouseDown = False

End Sub

Sub CheckMouseDown(ByVal e As MouseEventArgs)

Dim ptMouse = New Point(e.X, e.Y)

Dim ptcell = PointToCell(ptMouse)

If (ptcell.X >= 0 And ptcell.X < m_numCells.Width And _

ptcell.Y >= 0 And ptcell.Y < m_numCells.Height) Then

DrawLineOfCells(PointToCell(m_PtOld.Value), ptcell, New DrawCellDelegate(AddressOf DrawACell))

m_PtOld = ptMouse

End If

End Sub

Function DrawACell(ByVal ptCell As Point, ByVal br As Brush) As Boolean

Dim fDidDraw = False

If Not m_cells(ptCell.X, ptCell.Y) Then

m_cells(ptCell.X, ptCell.Y) = True

m_oGraphics.FillRectangle(br, _

m_Offset.Width + ptCell.X * m_cellSize.Width, _

m_Offset.Height + ptCell.Y * m_cellSize.Height, _

m_cellSize.Width, _

m_cellSize.Height)

fDidDraw = True

End If

Return fDidDraw

End Function

Sub DrawLineOfCells(ByVal p0 As Point, ByVal p1 As Point, ByVal drawit As DrawCellDelegate)

Dim br = m_brushMouse

Dim x0 = p0.X

Dim y0 = p0.Y

Dim x1 = p1.X

Dim y1 = p1.Y

Dim fSwapped = False

Dim dx = Math.Abs(x1 - x0)

Dim dy = Math.Abs(y1 - y0)

If dy > dx Then

fSwapped = True ' swap x0<=>y0, x1<->y1

x0 = p0.Y

y0 = p0.X

x1 = p1.Y

y1 = p1.X

dx = Math.Abs(x1 - x0)

dy = Math.Abs(y1 - y0)

End If

Dim err = CInt(dx / 2)

Dim y = y0

Dim xstep = 1

If x0 > x1 Then

xstep = -1

End If

Dim ystep = 1

If y0 > y1 Then

ystep = -1

End If

Dim x = x0

While x <> x1 + xstep

Dim cx = x, cy = y ' copy of x,y

If fSwapped Then

cx = y

cy = x

End If

If drawit(New Point(cx, cy), br) Then ' if it wasn't already drawn

br = m_brushGenerated

End If

err -= dy

If err < 0 Then

y += ystep

err += dx

End If

x += xstep

End While

End Sub

End Class

</VBSample>

Cartoon animation program

Calvin_Hsia — Thu, 29 Jan 2009 23:16:00 GMT

A cartoon can be thought of as a series of drawings. To simulate movement, the drawings can be slightly different from each other.

Remember drawing simple cartoons using a pad of paper? Simply flipping through the pages made the drawings come to life.

This was tedious work: a computer can help.

Just after first IBM PC came out in Aug 81, I wrote a cartoon animation program in C++ and assembly code. The concept was very simple: just use the mouse (I had to write my own mouse driver for a RS-232 serial mouse and had to hijack the COM1 port for my DOS program) to let the user draw some lines on the screen. Then the user could save those lines as a cartoon frame, and then draw another frame. The program could then calculate multiple frames in between the user created frames, creating smooth animation.

That early 80's version of cartoon still runs on XP (although it writes directly to the video memory so it requires full screen mode.

It doesn't run on Vista (I think you can download a DOS compatible window to make it work.)

A zip file of the 80's version is available here. Unzip the contents to a folder (check out the date stamps!), then run cartoon.exe and hit Shift-A.

It includes some stored samples, like flying birds, alphabet, basketball. Because this was written before Windows, it won't work with your mouse. You can see the main menu bar at the top. The only thing you can do with this program is run the stored samples by hitting Shift-A. Q will Quit. Try typing other chars to invoke various commands.

If you get it to run on Vista, please let me know the details.

About 10 years ago, I wrote another version of Cartoon in Foxpro and it was modified and published as a Solution Sample.

Start Visual Foxpro, Task Pane, Solution Samples. In the "Search for sample" text, box, type in Animation. "Display line animation in a form"

You can run the form, or click on the button on the right of the task pane that opens the form in the Form Designer, so you can see the source code.

You can also open the form in the Class Browser, then export the code into a single file using the "View Class Code" button.

Foxpro excerpt of the inbetween algorithm (notice how cursors (in-memory data tables) are used)

SELECT (lcTable)

DO WHILE !EOF("shadow")

mr = recno()

mr2 = recno("shadow")

FOR nb = 0 TO nBetween

THISFORMSET.frmAnimation.cls

GO mr

IF mr2 < RECCOUNT("shadow")

GO mr2 IN shadow

ENDIF

nFrames1 = &lcTable..frameno

nFrames2 = shadow.frameno

SCAN WHILE &lcTable..frameno = nFrames1

nx1 = &lcTable..x1 + nb * (shadow.x1 - &lcTable..x1) / nBetween

ny1 = &lcTable..y1 + nb * (shadow.y1 - &lcTable..y1) / nBetween

nx2 = &lcTable..x2 + nb * (shadow.x2 - &lcTable..x2) / nBetween

ny2 = &lcTable..y2 + nb * (shadow.y2 - &lcTable..y2) / nBetween

THISFORMSET.frmAnimation.line(nx1,ny1,nx2,ny2)

IF !EOF("shadow")

SKIP IN shadow

IF shadow.frameno # nFrames2

SKIP -1 IN shadow

ENDIF

ENDSCAN

SELECT shadow

IF !EOF()

SKIP

LOCATE REST FOR shadow.Frameno # nFrames2

ENDIF

SELECT (lcTable)

wait wind "" time .05

ENDFOR

ENDDO

USE IN shadow

SCAN REST

THISFORMSET.frmAnimation.line(x1,y1,x2,y2)

ENDSCAN

THISFORMSET.frmAnimation.frameno = nFrames1 + 1

Below is a more up to date example using WPF. The equivalent animation code is in tmr_tick().

Try running it, hitting the Demo button.

Start Visual Studio 2008.

Choose File->New Project->Visual Basic->WPF Application.

(This also works with Temporary projects)

Open Window1.xaml.vb. Paste in the code below, then hit F5 to run.

I had my wife and kids playing with it for quite a while!

Try adding a frame or MouseWheel while a cartoon is playing.

Try right click and then draw: it changes the way you draw.

Experiment with using a touchpad and a mouse for drawing.

Try using variable frame rates. Add a feature to save/restore the current cartoon.

Try drawing your name, or the letters of the alphabet.

My original had features like copy/paste from frames, color fill

See also:

My toys over the years

Why was the original IBM PC 4.77 Megahertz?

Class Window1

Private WithEvents btnNewFrame As Button

Private WithEvents btnErase As Button

Private WithEvents btnPlay As Button

Private WithEvents btnDemo As Button

Private WithEvents btnReset As Button

Private txtStatus As TextBlock

Private _AnimControl As AnimControl

Sub Load() Handles MyBase.Loaded

Me.Width = 800

Me.Height = 600

Dim xaml = _

<DockPanel

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" LastChildFill="True">

<TextBlock>Draw to create lines for a cartoon frame. Add a new frame, hit play</TextBlock>

<TextBlock>Rebirth of Calvin's cartoon program circa 1982

<Hyperlink>http://blogs.msdn.com/calvin_hsia</Hyperlink>

</TextBlock>

</StackPanel>

<Button Name="btnNewFrame" ToolTip="Add current drawing to cartoon, so you can create a new one">_New Frame</Button>

<Button Name="btnErase">_Erase</Button>

<Button Name="btnReset" ToolTip="Erase all frames">_Reset</Button>

</StackPanel>

</Border>

</DockPanel>

Dim dPanel = CType(System.Windows.Markup.XamlReader.Load(xaml.CreateReader), DockPanel)

Dim MyCtrl = CType(dPanel.FindName("MyCtrl"), UserControl)

_AnimControl = New AnimControl(Me)

MyCtrl.Content = _AnimControl

btnPlay = CType(dPanel.FindName("btnPlay"), Button)

btnNewFrame = CType(dPanel.FindName("btnNewFrame"), Button)

btnPlay = CType(dPanel.FindName("btnPlay"), Button)

btnDemo = CType(dPanel.FindName("btnDemo"), Button)

btnErase = CType(dPanel.FindName("btnErase"), Button)

btnReset = CType(dPanel.FindName("btnReset"), Button)

txtStatus = CType(dPanel.FindName("txtStatus"), TextBlock)

Me.Content = dPanel

End Sub

Sub btnNewFrame_Click() Handles btnNewFrame.Click

_AnimControl.NewFrame()

RefreshStatus()

End Sub

Sub btnPlay_Click() Handles btnPlay.Click

btnNewFrame_Click() ' save any currently drawn changes first

_AnimControl.Play()

End Sub

Sub btnDemo_Click() Handles btnDemo.Click

_AnimControl.Demo()

End Sub

Sub btnErase_Click() Handles btnErase.Click

_AnimControl.EraseBtn()

End Sub

Sub btnReset_Click() Handles btnReset.Click

_AnimControl.Reset()

End Sub

Friend Sub RefreshStatus()

Me.txtStatus.Text = String.Format("Frame count = {0} CurLineCnt = {1} CurFrame= {2} Between = {3}", _

_AnimControl._UserFrameList.Count, _AnimControl._CurLineList.Count, _

_AnimControl._ndxUserFrame, _AnimControl._nBetween)

End Sub

End Class

Public Class AnimControl

Inherits FrameworkElement

Private WithEvents _timer As New System.Windows.Threading.DispatcherTimer

Private _Window1 As Window1

Friend _nBetween As Integer = 10 ' # of frames being calc'd between user frames

Friend _ndxUserFrame As Integer ' index into user created frames.

Private _ndxBetween As Integer ' from 0 to nBetween

Friend _nBetweenDyn As Integer = 0 ' # to add to _nBetween for next animation: adjustable by mousewheel

Private _ptCurrent As Point?

Private _ptOld As Point?

Private _fPenDown As Boolean

Private _oPen = New Pen(Brushes.Black, 2)

Private _PenModeDrag As Boolean = True ' Click to create line segs, or continuous drag to create multiple segs

' lines to draw for current image: could be while composing, or playing. Could be real frame or calc'd frame

Friend _CurLineList As New List(Of cFrameLine)

'Frames stored by user

Friend _UserFrameList As New List(Of cCartoonFrame)

Sub New(ByVal w As Window1)

_Window1 = w

End Sub

Sub Reset()

Me._timer.IsEnabled = False 'stop playback, if any

Me._UserFrameList.Clear() ' erase all user data

Me._nBetweenDyn = 0

EraseBtn()

End Sub

Sub EraseBtn() ' erase current frame

_CurLineList.Clear()

Me._ptOld = Nothing

Me._fPenDown = False

Me.InvalidateVisual()

End Sub

Sub Demo()

Reset()

Me._CurLineList.Add(New cFrameLine(New Point(10, 10), New Point(10, 300)))

Me._CurLineList.Add(New cFrameLine(New Point(10, 300), New Point(300, 300)))

Me._CurLineList.Add(New cFrameLine(New Point(300, 300), New Point(300, 10)))

Me._CurLineList.Add(New cFrameLine(New Point(300, 10), New Point(10, 10)))

Me._UserFrameList.Add(New cCartoonFrame(Me._CurLineList, 30))

Me._CurLineList.Clear() ' reset for next frame

Me._CurLineList.Add(New cFrameLine(New Point(10, 10), New Point(300, 10)))

Me._CurLineList.Add(New cFrameLine(New Point(300, 10), New Point(300, 300)))

Me._CurLineList.Add(New cFrameLine(New Point(300, 300), New Point(10, 300)))

Me._CurLineList.Add(New cFrameLine(New Point(10, 300), New Point(10, 10)))

Me._UserFrameList.Add(New cCartoonFrame(Me._CurLineList, 50))

Me._CurLineList.Clear() ' reset for next frame

Me._CurLineList.Add(New cFrameLine(New Point(10, 10), New Point(300, 10)))

Me._UserFrameList.Add(New cCartoonFrame(Me._CurLineList, 10))

Play()

End Sub

Sub NewFrame()

If _CurLineList.Count > 0 Then

Dim curFrame = New cCartoonFrame(_CurLineList, 10)

_UserFrameList.Add(curFrame)

EraseBtn()

End If

End Sub

Friend Sub Play()

If _UserFrameList.Count < 2 Then

MsgBox("Need at least 2 frames to animate")

Return

End If

If _timer.IsEnabled Then ' if we're already playing, stop

_timer.IsEnabled = False

Else

_timer.Interval = New TimeSpan(0, 0, 0, 0, 50) ' days,hrs,mins,secs,msecs

_timer.IsEnabled = True

End If

Me._fPenDown = False

Me._ndxUserFrame = 0

Me._ndxBetween = 1 ' 1st is drawn now, next by timer tick

Me._CurLineList.Clear()

Me._CurLineList.AddRange(Me._UserFrameList(0)._Lines) 'get the 1st frame

Me.InvalidateVisual() ' show it

End Sub

Sub tmr_tick() Handles _timer.Tick ' let's do the animating

If _ndxUserFrame = Me._UserFrameList.Count - 1 Then ' we've reached the end: let's restart

Me._ndxUserFrame = 0

Me._ndxBetween = 0

End If

Me._CurLineList.Clear()

Dim frmLeft = Me._UserFrameList(Me._ndxUserFrame) ' the frame on the left

Dim frmRight = Me._UserFrameList(Me._ndxUserFrame + 1) ' the frame on the right

_nBetween = Math.Max(0, frmLeft._nBetween + Me._nBetweenDyn) ' recorded value plus mousewheel adjustment

Dim nLinesToDraw = Math.Max(frmLeft._Lines.Count, frmRight._Lines.Count) - 1

For ndx = 0 To nLinesToDraw ' calc the lines to draw

Dim lineLeft = frmLeft._Lines(Math.Min(ndx, frmLeft._Lines.Count - 1))

Dim lineRight = frmRight._Lines(Math.Min(ndx, frmRight._Lines.Count - 1))

Dim pt0 As New Point With _

{.X = lineLeft.pt0.X + Me._ndxBetween * (lineRight.pt0.X - lineLeft.pt0.X) / (_nBetween + 1), _

.Y = lineLeft.pt0.Y + Me._ndxBetween * (lineRight.pt0.Y - lineLeft.pt0.Y) / (_nBetween + 1)}

Dim pt1 As New Point With _

{.X = lineLeft.pt1.X + Me._ndxBetween * (lineRight.pt1.X - lineLeft.pt1.X) / (_nBetween + 1), _

.Y = lineLeft.pt1.Y + Me._ndxBetween * (lineRight.pt1.Y - lineLeft.pt1.Y) / (_nBetween + 1)}

Dim newLine = New cFrameLine(pt0, pt1)

Me._CurLineList.Add(newLine)

If Me._ndxBetween > Me._nBetween Then ' we've reached the right

Me._ndxUserFrame += 1 ' advance to next user frame

Me._ndxBetween = 0 ' we don't want to redraw frmRight when it becomes frmLeft

End If

Me._ndxBetween += 1 ' advance to next frame

Me.InvalidateVisual()

End Sub

Protected Overrides Sub OnRender(ByVal drawingContext As System.Windows.Media.DrawingContext)

drawingContext.DrawRectangle(Brushes.AliceBlue, New Pen(Brushes.Purple, 1), New Rect(0, 0, Me.RenderSize.Width, Me.RenderSize.Height))

For Each fr In Me._CurLineList ' draw the lines in the current frame

drawingContext.DrawLine(_oPen, fr.pt0, fr.pt1)

If Me._fPenDown Then

If Me._ptOld.HasValue Then

drawingContext.DrawLine(_oPen, Me._ptOld, Me._ptCurrent)

Else

drawingContext.DrawLine(_oPen, Me._ptOld, Me._ptCurrent)

End If

_Window1.RefreshStatus()

End Sub

Protected Overrides Sub OnMouseDown(ByVal e As System.Windows.Input.MouseButtonEventArgs)

If e.RightButton = MouseButtonState.Pressed Then

Me._PenModeDrag = Not Me._PenModeDrag ' toggle modes on right click

Else

If Me._PenModeDrag Then

Me._ptOld = e.GetPosition(Me)

Else

If e.RightButton = MouseButtonState.Pressed Then

Me._fPenDown = False

Me._ptOld = Nothing

Else

Me._fPenDown = True

Me._ptCurrent = e.GetPosition(Me) ' get cur pos rel to self

If Not Me._ptOld.HasValue Then

Me._ptOld = Me._ptCurrent ' same

End If

Me.InvalidateVisual()

End If

End Sub

Protected Overrides Sub OnMouseMove(ByVal e As System.Windows.Input.MouseEventArgs)

If Me._PenModeDrag Then

If e.LeftButton = MouseButtonState.Pressed Then

If Me._ptOld.HasValue Then

Me._ptCurrent = e.GetPosition(Me)

Dim newFrameLine = New cFrameLine(Me._ptOld, Me._ptCurrent)

Me._CurLineList.Add(newFrameLine)

Me._ptOld = Me._ptCurrent

Me.InvalidateVisual()

End If

Else

If Me._fPenDown Then

If Me._ptOld.HasValue Then

Me._ptCurrent = e.GetPosition(Me)

End If

Me.InvalidateVisual()

End If

End Sub

Protected Overrides Sub OnMouseUp(ByVal e As System.Windows.Input.MouseButtonEventArgs)

If Me._fPenDown Then

Me._ptCurrent = e.GetPosition(Me) ' get cur pos rel to self

Dim newFrameLine = New cFrameLine(Me._ptOld, Me._ptCurrent)

Me._CurLineList.Add(newFrameLine)

Me._ptOld = Me._ptCurrent

Me._fPenDown = False

Me.InvalidateVisual()

End If

End Sub

Protected Overrides Sub OnMouseWheel(ByVal e As System.Windows.Input.MouseWheelEventArgs)

If Me._timer.IsEnabled Then ' only when playing

Me._nBetweenDyn += If(e.Delta > 0, 2, -2)

End If

End Sub

<DebuggerDisplay("{ToString()}")> _

Public Class cCartoonFrame ' User created cartoon frame

Public ReadOnly _Lines As New List(Of cFrameLine) ' a frame is a list of lines

' # of frames to gen between real user frames

Public ReadOnly _nBetween As Integer

Sub New(ByVal lst As List(Of cFrameLine), ByVal nBetween As Integer)

_Lines.AddRange(lst)

_nBetween = nBetween

End Sub

Public Overrides Function ToString() As String

Return String.Format("LineCount = {0}", _Lines.Count)

End Function

End Class

'A line to be animated. Could belong to a real or gen'd user frame, or while user is actively drawing

<DebuggerDisplay("{ToString()}")> _

Public Class cFrameLine ' User created cartoon line. It's just 2 points.

Friend ReadOnly pt0 As Point

Friend ReadOnly pt1 As Point

Sub New(ByVal pt0 As Point, ByVal pt1 As Point)

Me.pt0 = pt0

Me.pt1 = pt1

End Sub

Public Overrides Function ToString() As String

Return String.Format("Line = ({0}) - ({1})", pt0.ToString, pt1.ToString)

End Function

End Class

</Cartoon Code>

Cellular Automata: The Game of Life

Calvin_Hsia — Mon, 14 Jul 2008 21:57:00 GMT

I remember my dad getting a copy of Scientific American magazine every month when I was a kid. He kept back issues on a shelf in our living room. I remember being fascinated by the issue (Oct 1970) which described John Conway’s Game of Life.

A few decades later, in the mid 80’s I wrote my own version using the DeSmet C compiler on an original IBM PC (see Why was the original IBM PC 4.77 Megahertz?). I remember playing with gliders, glider guns and other formations.

A couple decades after that, I wrote one in C# (the date is 2003). Below is my original version from 2003, with one line of code added to make it run with more recent versions of VS.

(A subsequent article in Scientific American (Dec 84) described a cellular automata that simulated the Predator Prey ecosystem called Wator by Alexander Dewdney. This inspired me to write my own version of Wator in C++.)

Start VS 2008. File->New->Project->C#->Windows Forms

Edit the Program.cs code and replace it with the code below, then hit F5. Try moving the mouse around. Button1 results in an error.

The one line I had to add to get it to work was:

Form.CheckForIllegalCrossThreadCalls = false;

Without that line, an exception would occur:

System.InvalidOperationException was unhandled

Message="Cross-thread operation not valid: Control 'Form1' accessed from a thread other than the thread it was created on."

Source="System.Windows.Forms"

StackTrace:

at System.Windows.Forms.Control.get_Handle()

at Life.Form1.DrawCells(Boolean fDrawAll) in C:\Users\calvinh\AppData\Local\Temporary Projects\WindowsFormsApplication1\Program.cs:line 47

at Life.Form1.Shuffle() in C:\Users\calvinh\AppData\Local\Temporary Projects\WindowsFormsApplication1\Program.cs:line 90

at Life.Form1.Generations() in C:\Users\calvinh\AppData\Local\Temporary Projects\WindowsFormsApplication1\Program.cs:line 184

at Life.Form1.MyThread() in C:\Users\calvinh\AppData\Local\Temporary Projects\WindowsFormsApplication1\Program.cs:line 304

at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)

at System.Threading.ThreadHelper.ThreadStart()

InnerException:

Looking at the code, I see that indeed I wrote code that created a background thread that drew to the hWnd directly. So I added the code to set CheckForIllegalCrossThreadCalls false.

using System;

using System.Drawing;

using System.Collections;

using System.ComponentModel;

using System.Windows.Forms;

using System.Data;

using System.Threading;

using System.Runtime.InteropServices;

namespace Life

{

/// <summary>

/// Summary description for Form1.

/// </summary>

public class Form1 : System.Windows.Forms.Form

{

/// <summary>

/// Required designer variable.

/// </summary>

[DllImport("kernel32.dll")]

public static extern bool Beep(int freq, int dura);

private System.ComponentModel.Container components = null;

private TextBox m_box;

private Button m_button;

private Thread m_Thread = null;

bool m_nReset = false;

static int m_numx = 200;

static int m_numy = 200;

static int m_cellx = 5;

static int m_celly = 5;

static int m_Offx = 10;

static int m_Offy = 10;

static int MAXCOLOR = 8;

static int COLORDIV = 16; // # of gens before color changes

bool m_fDrawAll = false;

SolidBrush m_brushBlack = new SolidBrush(Color.Black);

SolidBrush m_brushWhite = new SolidBrush(Color.White);

SolidBrush[] m_brushArray = new SolidBrush[MAXCOLOR];

Queue m_queue = new Queue();

int[,] m_cells = new int[m_numx, m_numy];

private System.Windows.Forms.Button button1;

int[,] m_diff = new int[m_numx, m_numy];

private int DrawCells(bool fDrawAll)

{

int nTotal = 0;

Graphics g = Graphics.FromHwnd(this.Handle);

int x, y;

if (fDrawAll)

{

System.Diagnostics.Debug.Write("\nDraw");

}

for (x = 0; x < m_numx; x++)

{

for (y = 0; y < m_numy; y++)

{

if (fDrawAll || m_diff[x, y] == 1)

{

if (m_cells[x, y] == 0)

{

g.FillRectangle(m_brushWhite, m_Offx + x * m_cellx, m_Offy + y * m_celly, m_cellx - 1, m_celly - 1);

}

else

{

nTotal++;

g.FillRectangle(m_brushArray[m_cells[x, y] / COLORDIV], m_Offx + x * m_cellx, m_Offy + y * m_celly, m_cellx - 1, m_celly - 1);

}

return nTotal;

}

private void Shuffle()

{

int x, y;

Random myrandom = new Random();

for (x = 0; x < m_numx; x++)

{

for (y = 0; y < m_numy; y++)

{

m_diff[x, y] = m_cells[x, y] = myrandom.Next(100) < 50 ? 1 : 0;

}

DrawCells(false);

}

private int CountNeighbors(int x, int y)

{

if (x >= 0 && x < m_numx && y >= 0 && y < m_numy)

{

return m_cells[x, y] > 0 ? 1 : 0;

}

return 0;

}

private int Generation()

{

int[,] tmp = new int[m_numx, m_numy];

int x, y;

for (x = 0; x < m_numx; x++)

{

for (y = 0; y < m_numy; y++)

{

tmp[x, y] = CountNeighbors(x - 1, y - 1) +

CountNeighbors(x - 1, y) +

CountNeighbors(x - 1, y + 1) +

CountNeighbors(x, y - 1) +

CountNeighbors(x, y + 1) +

CountNeighbors(x + 1, y - 1) +

CountNeighbors(x + 1, y) +

CountNeighbors(x + 1, y + 1);

}

for (x = 0; x < m_numx; x++)

{

for (y = 0; y < m_numy; y++)

{

if (tmp[x, y] == 3 && m_cells[x, y] == 0) // an empty cell with exactly 3 neighbors: 1 is born

{

m_diff[x, y] = m_cells[x, y] = 1;

}

else if (tmp[x, y] >= 2 && tmp[x, y] <= 3 && m_cells[x, y] > 0) // a live cell with 2 or more neighbors lives

{

if (m_cells[x, y] == COLORDIV * MAXCOLOR - 1)

{

m_diff[x, y] = 0; // no change

}

else

{

m_cells[x, y]++;

m_diff[x, y] = 1;

}

else

{ // loneliness

if (m_cells[x, y] == 0) // already empty

{

m_diff[x, y] = 0; // no change

}

else

{

m_cells[x, y] = 0;

m_diff[x, y] = 1;

}

if (m_queue.Count > 0)

{

lock (m_queue.SyncRoot)

{

foreach (Point pt in m_queue)

{

m_diff[pt.X, pt.Y] = 1;

if (m_cells[pt.X, pt.Y] == 0)

{

m_cells[pt.X, pt.Y] = 1;

}

else

{

m_cells[pt.X, pt.Y] = 0;

}

m_queue.Clear();

}

int nResult = DrawCells(m_fDrawAll);

m_fDrawAll = false;

return nResult;

}

private void Generations()

{

int nTotal;

while (true)

{

Shuffle();

for (int i = 0; i < 100000; i++)

{

nTotal = Generation();

this.Text = i.ToString() + " : " + nTotal.ToString();

if (m_nReset)

{

m_nReset = false;

break;

}

private void handlethebutton(object sender, EventArgs e)

{

m_nReset = true;

}

private void OnClick(object sender, EventArgs e)

{

}

private void Onmmove(object sender, MouseEventArgs e)

{

Point pt = this.PointToClient(Cursor.Position);

Point ptcell = new Point();

ptcell.X = (pt.X - m_Offx) / m_cellx;

ptcell.Y = (pt.Y - m_Offy) / m_celly;

if (ptcell.X >= 0 && ptcell.X < m_numx && ptcell.Y >= 0 && ptcell.Y < m_numy)

{

lock (m_queue.SyncRoot)

{

m_queue.Enqueue(ptcell);

}

private void OnActivated(object sender, EventArgs e)

{

// Generations();

if (m_Thread == null)

{

m_Thread = new Thread(new ThreadStart(MyThread));

m_Thread.Start();

while (!m_Thread.IsAlive)

{

m_Thread.Abort();

}

else

{

m_fDrawAll = true;

}

private void FormPaint(object sender, PaintEventArgs e)

{

m_fDrawAll = true;

}

/// <summary>

/// Clean up any resources being used.

/// </summary>

protected override void Dispose(bool disposing)

{

if (m_Thread != null && m_Thread.IsAlive)

{

m_Thread.Abort();

}

if (disposing)

{

if (components != null)

{

components.Dispose();

}

base.Dispose(disposing);

}

#region Windows Form Designer generated code

/// <summary>

/// Required method for Designer support - do not modify

/// the contents of this method with the code editor.

/// </summary>

private void InitializeComponent()

{

this.button1 = new System.Windows.Forms.Button();

this.SuspendLayout();

// button1

this.button1.Location = new System.Drawing.Point(392, 0);

this.button1.Name = "button1";

this.button1.TabIndex = 0;

this.button1.Text = "button1";

this.button1.Click += new System.EventHandler(this.button1_Click);

// Form1

this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);

this.ClientSize = new System.Drawing.Size(800, 558);

this.Controls.AddRange(new System.Windows.Forms.Control[] {

this.button1});

this.Name = "Form1";

this.Text = "Life";

this.Click += new System.EventHandler(this.Form1_Click);

this.Load += new System.EventHandler(this.Form1_Load);

this.ResumeLayout(false);

}

#endregion

/// <summary>

/// The main entry point for the application.

/// </summary>

[STAThread]

static void Main()

{

Application.Run(new Form1());

}

private void MyThread()

{

Generations();

}

public Form1()

{

// Required for Windows Form Designer support

InitializeComponent();

this.Height = m_Offy + m_numy * m_celly;

this.Width = m_Offx + m_numx * m_cellx;

this.Left = 00;

this.Top = 0;

this.BackColor = Color.White;

m_box = new TextBox();

m_box.BackColor = Color.Cyan;

m_box.Text = "Hi";

m_box.Size = new Size(100, 100);

m_button = new Button();

m_button.BackColor = Color.Red;

m_button.Location = new Point(150, 00);

m_button.Text = "&Reset";

Controls.Add(m_button);

m_button.Click += new EventHandler(this.handlethebutton);

Controls.Add(m_box);

// this.Paint += new PaintEventHandler(this.FormPaint);

this.Activated += new EventHandler(this.OnActivated);

this.Click += new EventHandler(this.OnClick);

this.MouseMove += new MouseEventHandler(this.Onmmove);

this.Paint += new PaintEventHandler(this.FormPaint);

for (int i = 0; i < MAXCOLOR; i++)

{

Color clr = Color.FromArgb(255, (MAXCOLOR - i - 1) * 32, 0, 0);

m_brushArray[i] = new SolidBrush(clr);

}

private void Form1_Load(object sender, System.EventArgs e)

{

Form.CheckForIllegalCrossThreadCalls = false;

// Beep(1000,1000);

}

private void Form1_Click(object sender, System.EventArgs e)

{

}

private void button1_Click(object sender, System.EventArgs e)

{

Generation();

}

</code sample>

Examine .Net Memory Leaks

Calvin_Hsia — Fri, 11 Apr 2008 22:54:00 GMT

Writing programs using .Net is very productive. One reason is because much of memory management is “managed” for you. In C, C++ and other “native” languages, if you allocate memory, you’re responsible for freeing it. There were stopgap measures, like destructors, SmartPointers and reference counting, which helped, but were still cumbersome.

Foxpro manages memory for you, and has used garbage collection for decades: Heartbeat: Garbage collection in VFP and .NET are similar

However, you can still have memory leaks in .Net.

Try this in VS 2008: (I think it will work in 2005 too, can somebody verify? Thanks)

1. File->New->Project->VB Windows Console Application.

2. Paste the sample code below.

3. Project->Properties->Debug->Enable Unmanaged Code debugging

If you’re running 64 bit, you can force 32 bit targeting: Project->Properties->Compile->Advanced Compile Settings->Target CPU->x86 (see this for more about x64)

The sample code has a loop that creates and releases an instance of a class MyWatcher that uses the FileSystemWatcher class that reacts to events, such as files being created in a directory.

The class has a member (Dim MyLargeMemoryEater(100000) As String) which eats up 4 bytes (8 bytes on x64) per array element. At the end of each loop, the garbage collector is called to release everything. The class has a Finalize method that will be called when the garbage collector collects.

When you run the code, you see the increase in memory use in each loop. The increase per iteration is just a little more than the amount of memory used by MyLargeMemoryEater . Also, the Finalizers don’t run until the application is shutting down.

If you uncomment the “UnSubscribe” line, then the finalizer fires (on a different thread) and you can see the leak is gone.

Now let’s examine the leak by looking at the heap.

Make it leak, then put a breakpoint on the “Done” line after the loop. At this point, we suspect there are 100 instances of MyWatcher in the managed heap.

Wouldn’t it be great to see them? Let’s use SOS:

Open the Immediate window: Debug Menu->Windows-> Immediate window

Type in the lines in red

!load sos.dll

extension C:\Windows\Microsoft.NET\Framework\v2.0.50727\sos.dll loaded

!dumpheap -type MyWatcher

PDB symbol for mscorwks.dll not loaded

Address MT Size

02b7431c 000d313c 16

<…>

02bdc3f0 000d313c 16

02bdc550 000d313c 16

total 100 objects

Statistics:

MT Count TotalSize Class Name

000d313c 100 1600 ConsoleApplication1.MyWatcher

Total 100 objects

So now we know that there are 100 instances still around. Why were they not garbage collected? Because somebody has a reference to them. Choose one of the instances (02bdc550), and use the gcroot command:

!gcroot 02bdc550

Note: Roots found on stacks may be false positives. Run "!help gcroot" for

more info.

Error during command: Warning. Extension is using a callback which Visual Studio does not implement.

Scan Thread 6948 OSTHread 1b24

Scan Thread 536 OSTHread 218

Scan Thread 6448 OSTHread 1930

DOMAIN(00601068):HANDLE(AsyncPinned):b15b4:Root:02bdda44(System.Threading.OverlappedData)->

02bddf38(System.Threading.IOCompletionCallback)->

02bdcfc4(System.IO.FileSystemWatcher)->

02b8b14c(System.IO.FileSystemEventHandler)->

02bdc550(ConsoleApplication1.MyWatcher)

Now we see that the FileSystemWatcher is referencing us via an eventhandler.

(The “!dumpheap -stat” command is also very useful to see what’s on the heap)

See also:

Collecting garbage at the wrong time

SOS Debugging Extension (SOS.dll)

http://www.codeproject.com/KB/dotnet/Memory_Leak_Detection.aspx

http://www.julmar.com/blog/mark/PermaLink,guid,643649fc-0467-4f0d-9a95-323ed7ce4298.aspx

Debugging a memory leak in managed code: Ping - SendAsync

Module Module1

Friend g_cnt As Integer

Sub Main()

'uncomment these 2 lines to test the event watcher

'Dim oFileWatcher = New MyWatcher

'MsgBox("Wait in msgbox. FSW events still fire: copy a file into d:\")

Dim oldPeak = 0L

For i = 1 To 100

Dim oWatcher = New MyWatcher

' oWatcher.UnSubscribe() ' uncomment this line to remove handler

oWatcher = Nothing

GC.Collect() ' collect garbage

GC.WaitForPendingFinalizers() ' allow finalizers

GC.Collect() ' collect again for any objects that had finalizers

Dim newpeak = Process.GetCurrentProcess.PeakWorkingSet64

Debug.WriteLine("All released? " + i.ToString + " " + _

" WorkingSet =" + Process.GetCurrentProcess.WorkingSet64.ToString("n0") + _

" Peak=" + newpeak.ToString("n0") + _

" delta =" + (newpeak - oldPeak).ToString)

oldPeak = newpeak

GC.Collect() ' collect garbage

GC.WaitForPendingFinalizers() ' allow finalizers

GC.Collect() ' collect again for any objects that had finalizers

Debug.WriteLine("Done")

End Sub

End Module

Class MyWatcher

Dim MyLargeMemoryEater(100000) As String ' make the instance bigger to magnify issue: 4 bytes per array item on x86

Dim fsw As IO.FileSystemWatcher

Sub New()

fsw = New IO.FileSystemWatcher

fsw.Path = "d:\"

fsw.Filter = "*.*"

AddHandler fsw.Created, AddressOf OnWatcherFileCreated

fsw.EnableRaisingEvents = True

End Sub

Sub UnSubscribe()

RemoveHandler fsw.Created, AddressOf OnWatcherFileCreated

End Sub

Sub OnWatcherFileCreated(ByVal sender As Object, ByVal args As System.IO.FileSystemEventArgs)

Debug.WriteLine((New StackTrace).GetFrames(0).GetMethod.Name + " " + args.FullPath)

End Sub

Protected Overrides Sub Finalize() ' called when garbage collector collects on the GC Finalizer thread.

MyBase.Finalize()

Debug.WriteLine((New StackTrace).GetFrames(0).GetMethod.Name + g_cnt.ToString + " Thread= " + System.Threading.Thread.CurrentThread.ManagedThreadId.ToString)

End Sub

End Class

</Code Sample>

Uninstall VB6 causes error message: You do not have a license to use this control

Calvin_Hsia — Tue, 08 Jan 2008 00:35:00 GMT

I was running out of disk space on one of my machines, so I used my TreeMap program to see where I could delete files to save space.

I saw that I still had VB6 on the machine, and I didn’t need it on that machine any more, so I uninstalled it.

It's amazing how little disk space VB6 occupied, compared to VB.Net! I remember when FoxPro came on floppy disks, and Turbo Pascal came on a single (360k ?) floppy disk!

The next year (actually only several days later <g>), I tried running my trusty picture viewer which allows me to query and show my pictures and movies to show them or thumbnails. I received an error message: "You do not have a license to use this control".

I thought that it must have been the movie player ActiveX control that was giving me the problem.

I started Visual Studio and attached to the process, and found that the error occurred when MSCOMCTL.OCX was being loaded. That triggered a memory that I had removed VB6 a while ago. I think the MSCommon controls, such as the TreeView, ListView, Slider, etc originated from VB5, and Visual FoxPro and other products repackage them.

Upon further debugging, I found that it was actually the Slider control (which allows me to slide through almost 30,000 pictures/movies) that was giving the error.

thisform.AddObject("oSlider","cSlider")

WITH thisform.oSlider

.left=350

.width = 350

.visible=1

.min=1

.borderstyle=1

.largechange=1

ENDWITH

DEFINE CLASS cSlider as olecontrol

oleclass="mscomctllib.slider.2"

PROCEDURE keypress(p1)

thisform.keypress(p1)

PROCEDURE change

thisform.txtNum.value=this.value

thisform.txtNum.valid

ENDDEFINE

I just needed to find what registry keys needed to be added back, so the application would work again. I found this link, which worked perfectly:

You receive an error message "You do not have a license to use this control" when you use Visual Basic 6.0 controls in Visual Studio 2005 or in Visual Studio .NET

Run your application forms on the web

Calvin_Hsia — Fri, 14 Sep 2007 03:43:00 GMT

I received a customer question:

I have looked all over the web and still searching, and found your blog. I have a very specific issue and I need to ask whether this is doable first of all and how to do it after.

First of all, I need to make a foxPro app that wll also run as a web application. Can this be done? And if so how? I have looked into creating an ASP.NET page and calling a COM from there. However, is this equivalent to calling the actual .exe, is it like running the program from within ASP.NET or is it simply calling some methods and functionality? Basically, can foxpro be used as a web DB/app?

Can you give me some guidelines on how to go about this? Or direct me to some additional info?

According to my Ship It award (an award given to employees for shipping a Microsoft product), Visual FoxPro 5.0 shipped in August 96. VFP5 ships with a sample called FoxIsapi, which I created (at the prompting of Melissa Dunn) to demonstrate creating a Fox Form in the Fox form designer, showing Employee information, their photos and their sales in a grid.

For further information about FoxIsapi and how it worked, see this article: http://msdn.microsoft.com/archive/default.asp?url=/archive/en-us/dnarfoxgen/html/msdn_custole.asp

Quote from article:

the same form can be deployed in four different ways: as a normal Visual FoxPro form, as a Visual FoxPro run time, as an OLE Automation server from an OLE Automation client, and over the Internet using any Web browser!

Over a decade ago, I used to demonstrate this sample, changing the FoxIsapi form in the designer, saving it, and showing how easily that one change propagates to all 4 deployment scenarios.

I've copied/pasted the article below because it's marked Archive Content, and might be deleted any day..

FoxIsapi is a sample using ISAPI extensions, just as ASP pages do.

Designing an application that can run on the web and as a rich Windows application requires careful architecture. You'll need to separate the application into multiple tiers: you might have heard of presentation layer (the User Interface), the business rules layer, the data layer. You’ll have to deal with saving application state to know that a particular user is, for example, editing record #5 when hitting Save, while another might be editing record #4. FoxIsapi uses a cookie to save application state.

My personal digital photo/video collection application runs on both the web and as a rich windows client. I can query for any photos just with a string search, including from my cell phone My rich windows client can page through dozens of photos at a time, and Enable crop and zooming in on your digital photograph display form

It’s actually 2 separate applications talking to the same data, sharing some code.

Try viewing the FoxIsapi code (samples->servers->Foxisapi->FoxIs.pjx)

Try running the code (this shows the form in 2 ways: as a Fox Form and in the browser)

SET SAFETY OFF

CD HOME(2)+"\servers\foxisapi\foxis"

PUBLIC x

x=NEWOBJECT("employee","employee")

x.Visible=1

?x.startup() && shows the generated HTML

STRTOFILE(x.startup(),"d:\t.htm")

! d:\t.htm

You might have to Alt-Tab to the form because it’s a top-level window.

There are a lot more wrinkles to getting the web form to work under IIS.

You’ll have to set the employee.vcx cdatapath property to point to the data (change the cgraphicspath while you’re at it), build the project as an MTDLL, then see if this code works:

x=CREATEOBJECT("foxis.employee")

?x.startup() && shows the generated HTML

These paths are currently like HOME(1)+"\Samples\Data"), and HOME(1) (the VFP install directory) in a COM server has a different value

You’ll have to deal with IIS security. On Windows XP (after you install IIS), copy tools\foxisapi\foxisapi.dll to c:\inetpub\wwwroot\scripts\foxisapi.dll (You might need to make the scripts directory)
Disable anonymous access for now, and use “Integrated Windows Authentication” (Control Panel->Admin Tools->IIS->Web Sites->Default Web Site->Right click on Scripts->Directory Security->Anon Access and Authentication
On the Directory tab of the same dialog, change “Execute Permissions” to “Scripts and Executables”.
Try this http://localhost/scripts/foxisapi.dll in a browser. If you get an error message that FoxIsapi failed, it means you’re doing well. Foxisapi.dll loaded and working. If you get a dialog asking what you want to do with foxisapi.dll, then you don’t have execute permissions working.
Open a browser, this URL: http://localhost/scripts/foxisapi.dll/foxis.employee.startup will display the form, with the grid and photo. Try View->Source to see that the HTML is that from the Startup method.

Hints:

You can stop/start IIS with “Net stop w3svc”, “Net start w3svc”, or IISRESET
On Windows Server 2008 (Vista Server) I installed VFP to a folder “d:\VFP” because Program Files folder is locked down for security reasons. Start VFP as an Admin because Admin rights are required to register a COM server in the registry. In Server Manager, select Roles->Web Server (IIS) to see what Role Services are installed. Install Application development, which includes ISAPI Extensions. You'll also need to go to Scripts->Handler Mappings and edit the script map for ISAPI-dll, and point it to scripts\Foxisapi.dll
See the source code for foxisapi for more info (Samples\Servers\Foxisapi\CSource\Foxisapi.cpp)
Using ‘Integrated Windows Authentication” means the web request will come in as the same user that started the browser. That means if you have rights to read/write the files/data, then through the browser you'll have the same rights. Allowing anonymous access means you'll have to grant the anonymous user rights
Try this http://localhost/scripts/foxisapi.dll/status
Try this http://localhost/scripts/foxisapi.dll/reset
Try creating FOXISAPI.INI file with these 2 lines in the scripts dir (will be read upon reset)

[foxisapi]

busytimeout=4

User designed forms, like Employee.scx, inherit from the Isapi.Isform class, which has a GenHTML method. This method loops through all the controls contained on the form and generates HTML for them.

Keep in mind FoxIsapi is just a sample, from almost a dozen years ago, when the internet was very young. Newer web architectures abound.

For an article on using ASP to serve up web pages with Fox (which doesn’t require shutting down the server), see Blogs get 300 hits per hour: Visual FoxPro can count.

You can also run foxis.employee out of process using COM+ applications: Control Panel->Admin Tools->Component Services->Computer->My Computer->COM+ Applications. Create a New empty application called FOXIS, then under FOXIS->Components, Install New Component, and navigate to the MTDLL you built: foxis.dll. Now when you instantiate foxis.employee, the ball will spin and it will be out of the IIS process (inetinfo.exe).

Also, there are numerous Fox web applications using Rick Strahl's Web Connection (www.west-wind.com)

Note: because this is an old sample, there is no guarantee of support if it doesn't work for you. I did get it to work on Windows Server 2008 and XP.

Visual FoxPro Technical Articles

Custom OLE Servers

Calvin Hsia
Microsoft Corporation

October 1996

Introduction

Think back to the early computer systems available only ten or twenty years ago. In these early days of computing, users could only run a single application at a time. There was no concept of multitasking. Sharing information between applications was very cumbersome. If one application processed the output of another application, then some sort of information sharing strategy had to be devised. Along came multitasking environments, such as Microsoft® Windows®, that allowed multiple applications to run simultaneously. Users felt more powerful because they could run a spreadsheet and their accounting program simultaneously, perhaps cutting/pasting data from one to the other. Sharing data between applications became easier.

As computer operating systems evolved, OLE 1.0 was introduced, in which users could actually "embed" data objects created by other applications right into their main application. When a user opens a Word document and double-clicks on the embedded Microsoft Excel object, Excel starts up and allows the user to interact with the data. However, this implementation meant that Excel would start as its own separate application, and the user would see both Excel and Word on the screen at the same time. Furthermore, the Word document’s representation of the Excel spreadsheet would be marked with hash marks, indicating that it was being edited by Excel via OLE. This early attempt at allowing users to create "compound documents" was effective, but ungainly.

Along came OLE 2.0, which allows OLE In-Place Activation. This made the Excel embedded object come alive in the same Application Window as the Word object, with the menus and toolbars being "merged." The concept of the "compound document" is being further propagated because the document has a single "merged" editing environment.

These evolutionary steps in compound document architecture really help the interactive user to be more productive with the operating environment. Users can run multiple applications simultaneously and hence realize productivity gains. However, application developers also have seen an evolution in application programmability, allowing application writers the ability to programmatically control other applications.

With Windows, a technology called DDE, or Dynamic Data Exchange was introduced. This allowed programmers to write programs in a particular programming language that could communicate and command some other applications to do their bidding. This concept of a programmer writing a Controller or Client that uses the services of a Server was cumbersome with DDE. The programmer would have to know the programming languages of both objects, would have to create a DDE callback routine, and would have to have intimate knowledge of the server applications.

Another feature of OLE 2, OLE Automation, addresses the shortcomings of DDE and introduces a new level of inter-application communication. OLE Automation allows the application developer to allow other applications to "talk" to it programmatically in a standard way. The programmer designs an "interface” through which an OLE Automation controller can invoke routines and change properties on the OLE Automation server.

An application that can be an OLE Automation Server multiplies its usefulness to the modern computer environment. A standalone application like Excel has many graphing, mathematical, statistical, and financial functions. Other applications can take advantage of these functions simply by programmatically calling Excel. The end user of the application doesn't even need to know that Excel is being used.

Of course, in order to use an OLE server object, an application must be able to talk to it as an OLE Automation controller. Visual FoxPro™ version 3.x, Microsoft Excel, and Visual Basic® are all OLE Automation controller capable.

Calling Other Automation Objects

Several examples follow using Visual FoxPro as an OLE Automation controller. Most of these will work with Visual FoxPro 3.0 and Visual FoxPro 5.0.

An example using Microsoft Excel

PUBLIC ox

ox=CreateObject("Excel.application")

ox.visible=.t.

ox.windowstate=1

ox.left = 10

ox.application.top = 10

ox.workbooks.add

FOR i = 1 TO 3

    FOR j= 1 to 5

        ox.cells[i,j].value = I * 10 + j

    ENDFOR

ENDFOR

An example using Microsoft Word

ox=CreateObject("word.basic")

ox.appshow

ox.filenew

ox.insert("test")

ox.filesaveas("c:\t.txt")

An example using MAPI

If you're feeling lonely, you can send mail to yourself using this code:

ox= createobject("mapi.session")

?ox.logon("calvinh")

?ox.name,ox.class,ox.operatingsystem,ox.version

msg = ox.outbox.messages.add

msg.subject = "testsubject"

msg.text = "Don't be lonely"

recip = msg.recipients.add

recip.name = "calvinh"

?recip.resolve

msg.send(.t.,.f.)

?ox.logoff()

You can also create automatic message readers and generators via OLE Automation, and you can publish mail messages and folders over the intranet so that a client using a Web browser can view them.

An example using the Internet

ox=CreateObject("InternetExplorer.Application")

ox.visible=.t.

ox.navigate("http://www.msn.com")

If you don't like Internet Explorer or Netscape Browser, create your own in a Visual FoxPro form with just a few lines of code:

PUBLIC ox

ox = CreateObject("MyInternetExplorer")

ox.visible = .t.

ox.oWeb.navigate(GETENV("computername"))  && insert your URL here

DEFINE CLASS MyInternetExplorer AS form

    ADD OBJECT oWeb AS CWeb

    caption = "My Internet Explorer"

    PROCEDURE init

        THISFORM.LEFT = 0

        THISFORM.WIDTH = SYSMETRIC(1) * 3/4

        THISFORM.height = SYSMETRIC(2)*3/4

        THIS.Resize

    PROCEDURE resize

        This.oWeb.resize

ENDDEFINE

DEFINE CLASS CWeb AS olecontrol

    oleclass = "Shell.Explorer.1"

    PROCEDURE Resize

        THIS.Width = THISFORM.Width - 10

        THIS.Height = THISFORM.Height - 10

    PROCEDURE Refresh

        nodefault

ENDDEFINE

Then you can just click on any hyperlinks and get lost on the Web. Or you can type in a command:

ox.oweb.navigate("www.msn.com")

to go to a particular URL.

Calling Visual FoxPro from Another Application

Visual FoxPro 5.0 itself is an OLE automation server. This means that from any other application that can be an OLE automation controller, you can CreateObject("VisualFoxPro.application") to get an object reference to Visual FoxPro 5.0, and change properties and invoke methods.

From Another Application that Is Not OLE Automation Controller Capable

Some applications are not capable of being an OLE automation controller, and thus are incapable of using Visual FoxPro as an OLE automation server. However, the capability to call into the Visual FoxPro automation server is in a DLL called fpole.dll, which ships with Visual FoxPro 5.0. If these applications can call 32-bit DLLs, and then they can load this DLL and control Visual FoxPro. For example, a Windows Help file or Microsoft Word can declare and use DLLs and thus use Visual FoxPro as an automation server.

As an example of using this DLL, here's some code that you can run from Visual FoxPro 3.0 (even though Visual FoxPro 3.0 is an automation controller, it also can call into 32-bit DLLs) that calls Visual FoxPro 5.0 as an automation server.

From Visual FoxPro 3.0

MYDLL = "fpole.dll"

clear

DECLARE integer SetOleObject in (MYDLL) string

DECLARE integer FoxDoCmd in (MYDLL) string,string

DECLARE integer FoxEval in (MYDLL) string, string @,integer

buff="this is the initial value of buffer"+space(100)

*=SetOleObject("visualfoxpro.application")

i = 1

do while !chrsaw()

    mt = "?'FoxDoCmd" +str(i)+"'"

    =FoxDoCmd(mt,"")

?mt

    i = i + 1

enddo

=inkey(.1)

clea dlls

From Microsoft Word

From Microsoft Word, you can create a WordBasic program that starts Visual FoxPro 5.0 as an automation server, opens a database, and retrieves a specific record:

Declare Sub FoxDoCmd Lib "fpole.dll"(cCommand As String, cBringToFront As String)

Sub main

FoxDoCmd "USE c:\fox40\samples\data\customer", ""

FoxDoCmd "LOCATE FOR cust_id = 'CENTC'", ""

FoxDoCmd "_CLIPTEXT = customer.company + CHR(9) + customer.contact", ""

EditPaste

End Sub

From a Windows Help file

1. In the [CONFIG] section of a help project, register the .dll:

2.                      RegisterRoutine("fpole.dll","FoxDoCmd","SS")

3. In your .rtf file, call the function the same way you would call a native Help macro:

4.                      HotSpotText!FoxDoCmd("DO (HOME() + 'myprg')","a")

5. Compile and run the Help file.

You can see a sample of this in the main Visual FoxPro Help file. From the Visual FoxPro Help menu choose Sample Applications. When the Sample Applications topic appears, click on the RUN or OPEN buttons. This invokes fpole.dll to start Visual FoxPro and runs the program hlp2fox.prg in the main Visual FoxPro directory.

From Visual Test

From Visual Test, you can write a Visual Test Basic Script that calls into Visual FoxPro to get object references and mnemonic names of Visual FoxPro objects.

Viewport Clear

DECLARE FUNCTION MessageBox LIB "user32.dll" ALIAS "MessageBoxA" (h&,m$,c$,f&) as long

DECLARE FUNCTION FoxDoCmd cdecl LIB " fpole.dll" (h$,j$) as long

DECLARE FUNCTION FoxEval cdecl LIB " fpole.dll" (h$,j$, leng&) as long

sub DoClick (x&,y&)

    dim buff$,cmd$,flag%

    flag% = 0

    buff$ =  string$(132,32)

    cmd$ = "oref = sys(1270," + str$(x&) + "," + str$(y&)+")"

    'print cmd$

    FoxDocmd(cmd$,"")

    IF DoEval$("type('oref')") = "O" then

        IF DoEval$("oref.name") <> "Screen" then

            FoxDoCmd("kk = sys(1272,oref)","")

            IF instr(DoEval$("kk"),".") > 0 then

                FoxDoCmd("kk2 = LEFT(kk,AT('.',kk)-1)","")

                FoxDoCmd("AINSTANCE(mm,kk2)","")

                IF DoEval$("IIF(ALEN(mm,1) > 0,'A','B')") = "A" THEN

                'IF DoEval$("AINSTANCE(mm,kk2) > 0") THEN

                    FoxDoCmd("kk = mm[1] + SUBSTR(kk,AT('.',kk))","")

                    cmd$ = DoEval("kk") +".click"

                    print #1,cmd$

                    print Cmd$

                    FoxDoCmd(cmd$,"")

                ENDIF

            endif

            flag% = 1

        ENDIF

    endif

    IF flag% = 0 then

        'Play "{Click 723, 356, Left}"

        cmd$ = "{Click " + str$(x&) + "," + str$(y&)+", Left}"

        print #1,"play " + CHR$(34) + cmd$ + chr$(34)

        play cmd$

    ENDIF

end sub

function DoEval$ ( s$)

    dim buff$,cmd$,k&

    buff$ =  string$(132,32)

    k& = FoxEval(s$,buff$,len(buff$))

    if k& <= 0 then

        MessageBox(0,buff$,"Eval error",0)

    endif

    DoEval = buff$

end function

The Visual FoxPro Help file has more information on how to use fpole.dll.

In-Process and Out-of-Process Servers

An in-process OLE server is simply a DLL that lives in the same process address space as the OLE client. An out-of-process server lives in its own process space, and thus is typically an .exe.

An in-process server is faster than an EXE server when passing parameters back and forth, but it also can crash the host if it crashes. There is very little protection from an errant DLL server for the host. An EXE server can crash and not necessarily crash the host. Also, an EXE server can be run on a remote machine using remote automation or COM in a distributed environment (DCOM).

Because an EXE server runs in its own process, the processor gives it processor time slices to execute whatever it wants, which is typically an event loop. A DLL server depends on the OLE client to give it process time. This implies that when an EXE server presents a user interface (UI) element, such as a form, to the user, the user can navigate the form as expected. The DLL server, however, can present the form, but cannot interact with it.

Generally, this is not a problem because OLE servers are typically designed to perform some sort of server task, which has no UI elements. For example, running an OLE server that serves Web pages typically means the server lives on an unattended Web server machine.

In-Process and Out-of-Process Servers in VFP 6

The new apartment model threading support requires that in-process .dll Automation servers not have user-interfaces. In Visual FoxPro 5.0, one could create (although it was not recommended) an in-process .dll Automation server that had a user-interface such as a form. The form could be used only for display because the form events are not supported. In Visual FoxPro 6.0, any attempts to create a user-interface in an in-process .dll Automation generates an error.

An out-of-process .exe Automation server can have a user-interface. A new Visual FoxPro 6.0 function, SYS(2335), has been added so you can disable modal events for an out-of-process .exe Automation server, which may be deployed remotely without intervention from a user. Modal events are created by user-defined modal forms, system dialogs, the MESSAGEBOX( ) function and the WAIT command, and so on.

Your First Custom OLE Automation Object

Create a new Visual FoxPro 5.0 project called FIRST. Add a new file first.prg with the following lines:

DEFINE CLASS myfirst AS custom OLEPUBLIC

    PROCEDURE INIT

        MessageBox(program(),"Here in my first OLE server")

ENDDEFINE

Note that there is nothing about this program that's new except the "OLEPUBLIC" keyword. (You can also make Visual Classes OLEPUBLIC from the Class Info dialog box.) What does this do? Absolutely nothing, until you Build an .exe or .dll from the project. If you watch carefully during the build process, you'll see the message "Creating Type Library and Registering OLE Server."

The build process creates a first.tlb, first.vbr, along with your OLE Server (either first.exe or first.dll). The TLB is an OLE Typelibrary, which can be browsed using any OLE Type Library browser, such as the ones that come with the Visual FoxPro Class Browser, Microsoft Excel, Visual Basic, and Visual C++®. The .VBR file is a text file of registry entries. These are almost identical to those that were created and entered into your registry. The only difference is that file names are prepended with their full path names. This .VBR file is useful for the Setup wizard and when you want to deploy your OLE server on another machine, which might use different paths.

Now try the following from the Command window:

    ox = CreateObject("first.myfirst")

    *wait a few secs till the server comes up with the msgbox

    * (you might have to alt-tab to the msgbox)

    ?ox.application.name

    ?ox.application.visible

    ?ox.

    ?ox.application.docmd("messagebox(home())")

    ?ox.application.docmd("_cliptext=home() + sys(2003) + sys(2004)")

You can add the line OX = CreateObject("myfirst") to the PRG as the first line, and then the .exe file will run just like any normal .exe. (Note: the string inside this CreateObject is the Visual FoxPro class name and not an OLE ProgID.) If it were a visual class library, you can add a Main program that does a SET CLASSLIB to the appropriate VCX and then CreateObject the object (not the OLE ProgID).

Determining the Initial Directory

Note the last line in the sample. On my machine, it copies "C:\WINNT\SYSTEM32" to the Clipboard three times. This means that even though the OLE server is in a particular directory, OLE starts it with the WINNT\SYSTEM32 directory. This brings up an interesting problem. How does the OLE server find its component pieces, such as .DBFs, reports, and so on?

We need to determine the directory in which the OLE Server lives, because that's typically where the parts are. Then we can SET DEFAULT TO that directory, or we can SET PATH TO it. One solution is to make the INIT or LOAD method of the OLE Public class change to the right directory, with the directory name either hard coded or as a custom property on the class. This works fine on one machine, until the server is moved or installed on a different machine with a different path.

Fortunately, there are a couple WIN32 API functions available to help. For an EXE server, we can call the GetModuleFileName( ) function, which returns the full path name to the main .exe of the current process if null is passed as the first parameter. For a DLL server, we use the GetModuleHandle( ) function with the name of the DLL as the parameter to retrieve a handle to the server. We pass this handle to the GetModuleFileName( ) function to get the full path name of the DLL.

Note the use of the _VFP.StartMode property. The Help file shows the various values of this property, which indicate in which mode Visual FoxPro was started: normal, as an OLE server, or as a custom DLL or EXE OLE server:

CLOSE DATA ALL

SET TALK OFF

SET SAFETY OFF

SET EXCLUSIVE OFF

SET DELETED ON

DECLARE INTEGER GetPrivateProfileString in win32api String,String,String,;

      String @, integer,string

if _vfp.startmode>1    &&  automation server

    LOCAL buf,nlen

    buf=space(400)

    DECLARE INTEGER GetModuleFileName in win32api Integer,String @,Integer

    * As an EXE or DLL, we need to find the home directory, not the curdir() and not

    * the dir of the runtime. The classlibrary property shows this for PRGs, but not VCXs

    IF _vfp.startmode = 3 && inproc dll

        DECLARE INTEGER GetModuleHandle in win32api String

        nlen=Getmodulefilename(GetModuleHandle(this.srvname+".dll"),@buf,len(buf))

    ELSE

        nlen=Getmodulefilename(0,@buf,len(buf))

    ENDIF

    buf = LEFTC(buf,nlen)

    this.cdir = LEFTC(buf,RATC('\',buf)-1)

    this.csrvname = SUBSTRC(buf,RATC('\',buf)+1)

    this.csrvname = LEFTC(this.csrvname,AT_C(".",this.csrvname)-1)

endif

IF !EMPTY(this.cDir)

    SET DEFAULT TO (this.cDir)

ENDIF

SET PATH TO (this.cDatapath)

use employee

Add the SAMPLES\DATA\TESTDATA.DBC to your FIRST.PJX. Add a new class to the project called MYFORM based on FORM and store it in first.vcx. Make the class OLE Public in the Class Info dialog box, and add three custom properties: cDir, cSrvName, and cDataPath. Initialize cDatapath to the directory where your testdata.dbc is, and cSrvName to FIRST. The cDir property will be initialized with the above code added to the LOAD event of the form class. Drag a couple of EMPLOYEE fields from the Project onto the class. Add the VCR class from the SAMPLES\CLASSES directory to your project, and drag an instance of the VCR button onto your form. Save the class and BUILD EXE first FROM first.

Now you've built an OLE server with the employee form. This server can be instantiated from any other OLE controller, but let’s test it from Visual FoxPro because it’s easy and familiar. In the Command window, type OX = CreateObject("myfirst.myclass"), then type OX.Application.visible=.t. This will make the Visual FoxPro run-time frame visible. OX.SHOW will make your form visible, and you can navigate around the form with the VCR buttons.

RELEASE OX or CLEAR ALL will release the server. If you had changed the ShowWindow property to 2, then the server form would be a Top Level form and the run-time Visual FoxPro desktop would not need to be shown. You can also add the line THISFORM.VISIBLE = .T. in the INIT event of the form class.

Now try BUILD DLL rather than BUILD EXE, and experiment. Note that you cannot interact with the server: when you bring the mouse over the server, you just get an hourglass. If the DLL server had the ability to interact with the user, then it would be more like an OLE or ActiveX Control. Even though you can't interact with the form, you can still give it commands from the Client: ox.application.docmd("skip") and ox.refresh will skip to the next record. ?ox.application.eval("recno()") will return the current record number, as expected.

Registry Issues

Below is my sample .vbr file. You'll notice the presence of long strings of numbers. These are GUIDs or Globally Unique Identifiers (sometimes called UUIDs, or Universally Unique Identifiers). These are automatically generated by your computer and are guaranteed to be virtually unique, based upon the time stamp and your machine's network card, among other things.

When an OLE client application does a CreateObject, the parameter is called the ProgID or Programmatic ID. The registry is searched for the ProcID to find the ClassID, which is just a GUID. Then that ClassID is located in the registry to find more information about the server.

Visual FoxPro Custom OLE servers are self-registering. To register an EXE server, just run the .exe with the /regserver option. The /unregserver unregisters the server. For a DLL server, run the utility Regsvr32.exe with the name of the DLL as the first parameter. This will register the DLL. To unregister it, add a second parameter.

Visual FoxPro OLE automation servers require the presence of the Visual FoxPro run time on the target machine. This is vfp500.dll and vfp5enu.dll (for the English U.S. platform).

VB4SERVERINFO

HKEY_CLASSES_ROOT\first.myfirst = myfirst

HKEY_CLASSES_ROOT\first.myfirst\NotInsertable

HKEY_CLASSES_ROOT\first.myfirst\CLSID = {3DB63101-0FED-11D0-9A44-0080C70FB085}

HKEY_CLASSES_ROOT\CLSID\{3DB63101-0FED-11D0-9A44-0080C70FB085} = myfirst

HKEY_CLASSES_ROOT\CLSID\{3DB63101-0FED-11D0-9A44-0080C70FB085}\ProgId = first.myfirst

HKEY_CLASSES_ROOT\CLSID\{3DB63101-0FED-11D0-9A44-0080C70FB085}\VersionIndependentProgId = first.myfirst

HKEY_CLASSES_ROOT\CLSID\{3DB63101-0FED-11D0-9A44-0080C70FB085}\LocalServer32 = first.exe /automation

HKEY_CLASSES_ROOT\CLSID\{3DB63101-0FED-11D0-9A44-0080C70FB085}\TypeLib = {3DB63102-0FED-11D0-9A44-0080C70FB085}

; TypeLibrary registration

HKEY_CLASSES_ROOT\TypeLib\{3DB63102-0FED-11D0-9A44-0080C70FB085}

HKEY_CLASSES_ROOT\TypeLib\{3DB63102-0FED-11D0-9A44-0080C70FB085}\1.0 = first Type Library

HKEY_CLASSES_ROOT\TypeLib\{3DB63102-0FED-11D0-9A44-0080C70FB085}\1.0\0\win32 = first.tlb

OLE Server Instancing

If from the Project menu you choose Project Info for the FIRST project, you'll see that there are three panes of information. The third is called Servers, from which you can view or change the information relating to each OLE Public in your project. Note that this information will only appear after you've built your project into an EXE or DLL, because only then is the OLEPUBLIC keyword meaningful.

The Instancing drop-down allows you to specify how an out-of-process server will behave. If this is set at "Single Use" and builds an EXE, then each OLE Automation client that instantiates this server will get its own private instance of the server. For example, if you type OX = CreateObject("first.myform ") and then OY = CreateObject("first.myform"), you'll actually get two running processes. (Note the SET EXCLUSIVE OFF line in the LOAD event; this is important!) You can use tools like Task Manager to see two first.exes running. This will also be the case if there were two different clients, say, Visual Basic and Visual FoxPro.

If you change the instancing on "Myform" to "Multiple Use" (which means this class can be used multiple times, or can have multiple "Masters"), then instantiate both OX and OY as above, TaskManager shows only a single Server instance serving multiple "Masters." You'll also note that moving the record pointer in one instance will change it in the other. You can change the DataSession property to 2—PRIVATE to avoid this.

The third option on Instancing is "Not Creatable." Why would you want this? Suppose you have a Class library with at least one OLE Public in it for one project. Now suppose you want to use some of the classes in that class library for another project, but you didn't want to use that OLE Public class. Using this instancing option means that the OLE Public will be ignored to solve this problem.

Automating a FoxPro 2.x Application

With just a few lines of code, you can take a FoxPro 2.x program and make it an OLE server. For example, the Laser sample that ships with FoxPro 2.6 is a laser disk library manager program. The main program is Laser.SPR. To turn this into an OLE object callable from Visual Basic or Excel, create a new project and add a new main program:

ox = create("laser")

define class laser as custom olepublic

    proc init

        cd d:\fpw26\sample\laser    && change dir to the right place

        set path to data

        this.application.visible = .t.  && make us visible.

    proc doit

        do laser.spr

enddefine

Add laser.spr and rebuild the project. You'll need to manually add a couple of Laser files. Now, you can try OX = Createobject("laser.laser"), and then OX.Doit. The laser application is now running as an OLE Automation server! If you modify the LASER.SPR program so that it doesn't close the LASER table when the READ (remember this command?) is finished, then you can query what laser disc title was chosen: ?ox.application.eval("title")

Your First Dynamic Web Page

Your FIRST.PJX project contained a simple OLE server that just put up a message box. This is not very useful, especially since most OLE servers should be able to run on an unattended server machine. Let's modify this sample to generate HTML strings. Add to your FIRST.PRG the class definition for dbpub:

DEFINE CLASS dbpub AS custom OLEPUBLIC

    cDataPath = "c:\vfp\samples\data"

        && change this to point to the dir where your TESTDATA.DBC is

    cDir = ""

    cSrvName = "first"

    PROCEDURE INIT

        CLOSE DATA ALL

        SET TALK OFF

        SET SAFETY OFF

        SET EXCLUSIVE OFF

        SET DELETED ON

        DECLARE INTEGER GetPrivateProfileString in win32api String,String,String,;

              String @, integer,string

        if _vfp.startmode>1    &&  automation server

            LOCAL buf,nlen

            buf=space(400)

            DECLARE INTEGER GetModuleFileName in win32api Integer,String @,Integer

            * As an EXE or DLL, we need to find the home directory, not the curdir() and not

            * the dir of the runtime. The classlibrary property

            * shows this for PRGs, but not VCXs

            IF _vfp.startmode = 3 && inproc dll

                DECLARE INTEGER GetModuleHandle in win32api String

                nlen=Getmodulefilename(GetModuleHandle(this.csrvname+".dll"),@buf,len(buf))

            ELSE

                nlen=Getmodulefilename(0,@buf,len(buf))

            ENDIF

            buf = LEFTC(buf,nlen)

            this.cdir = LEFTC(buf,RATC('\',buf)-1)

            this.csrvname = SUBSTRC(buf,RATC('\',buf)+1)

            this.csrvname = LEFTC(this.csrvname,AT_C(".",this.csrvname)-1)

        endif

        IF !EMPTY(this.cDir)

            SET DEFAULT TO (this.cDir)

        ENDIF

        SET PATH TO (this.cDatapath)

    PROCEDURE dbpub(parms,inifile,relflag)

        LOCAL rv

        rv = "HTTP/1.0 200 OK"+CHR(13)+CHR(10)

        rv = m.rv + "Content-Type: text/html"+CHR(13)+CHR(10)+CHR(13)+CHR(10)

        rv = m.rv + "<HTML>"

        rv = m.rv + "Parm1 =" + m.parms + "<p>"

        rv = m.rv + "Parm2 =" + m.inifile

        RETURN m.rv

ENDDEFINE

Note that the INIT method here is almost identical to the LOAD event for the form above. I've just removed the USE EMPLOYEE line. The DBPUB method takes three parameters and returns an HTML string. Test it out with ox=CreateObject('first.dbpub') then ?ox.dbpub("parm1","parm2",1234).

Now we need to find an Internet Web server. You can use Windows NT® 4.0 Server, which comes with Microsoft Internet Information Server (IIS), or NT3.51, Service Pack 4 with IIS. Windows 95 and Windows NT 4.0 Workstation will also work with Personal Web server. Other ISAPI compatible servers have been rumored to work. Take the file VFP\SAMPLES\SERVERSFOXISAPI\FOXISAPI.DLL (note that the latest copy of this can be found on the Microsoft Visual FoxPro Web site) and place it in the SCRIPTS directory of your IIS.

Suppose the Web site is named "myweb." Start up a Web browser, and type in the URL: http://myweb/scripts/foxisapi.dll. You should get a Foxisapi error page, indicating that the DLL is working correctly. Try adding arguments, such as http://myweb/scripts/foxisapi.dll/arg1.arg2.method?test. The first and second arguments are interpreted as the ProgID of an OLE Automation server. The third parameter is interpreted as the method name, and whatever is after the "?" is interpreted as a parameter to pass.

Before we run your FIRST server from the web, we need to tend to some security issues if you're running on Windows NT 4.0. IIS runs as a service on NT, which means it can run with no user logged in. It also has very limited rights to various parts of the operating system. Services normally do not have a desktop, so a MessageBox from a service won't even show up on the screen and will just hang the service.

Windows NT 3.51 will allow any service rights to read the registry and launch an OLE server. This means you have little control over somebody attaching to your machine and using it to run tasks. If you run the IIS service manager, and look at the WWW service properties, you'll notice that the anonymous user logs in as IUSR_MYWEB. From the Visual FoxPro command window, type !/n DCOMCNFG. This is an Windows NT 4.0 utility that you must run after registering an OLE server. Add "IUSR_MYWEB" to the three button dialogs on the DCOMCNFG Default Security page. Look for "myfirst" in the list of applications on the Applications Page. Choose Properties> Identity, and run as the Interactive User. Your particular machine/network setup might vary from these procedures.

Because Visual FoxPro registers the server each time after a build, you may have to run DCOMCNFG after each build. You can just run it and exit without changing anything. An alternative is to connect to the server machine from another machine and just copy the new server EXE or DLL over the old one (assuming it's already registered on the server machine).

Now that we've got security, lets hit our Web site with "myweb/scripts/foxisapi.dll/myfirst.dbpub.dbpub?test" The returned HTML string shows the parameters. The first parameter is just whatever is after the "?". The second parameter is the name of a .INI file that contains information about the Web hit. You can see this information get parsed out if you do the following:

MODIFY CLASS isform OF HOME()+"samples\servers\foxisapi\isapi" METHOD genhtml

Here's a sample .INI file:

The INI file looks like this:

[FOXISAPI]

Request Method=GET

Query String=

Logical Path=/foxis.employee.startup

Physical Path=d:\inetsrv\wwwroot\foxis.employee.startup

FoxISAPI Version=FoxISAPI v1.0

Request Protocol=HTTP/1.0

Referer=/scripts/foxisapi.dll

Server Software=Microsoft-Internet-Information-Server/1.0

Server Name=127.0.0.1

Server Port=80

Remote Host=127.0.0.1

Remote Address=127.0.0.1

[All_HTTP]

HTTP_ACCEPT=*/*, q=0.300,audio/x-aiff,audio/basic,image/jpeg,image/gif,text/plain,text/html

HTTP_USER_AGENT=Mozilla/1.22 (compatible; MSIE 1.5; Windows NT)

HTTP_CONNECTION=Keep-Alive

HTTP_EXTENSION=Security/Digest

[Accept]

*/*=Yes

q=0.300=Yes

audio/x-aiff=Yes

audio/basic=Yes

image/jpeg=Yes

image/gif=Yes

text/plain=Yes

text/html=Yes

[SYSTEM]

GMT Offset=-28800

The third parameter is just a number passed in by reference. It's actually meaningless to the server. Each time a Web hit occurs, foxisapi.dll will instantiate the ProgID, invoke the method passing the parms, return the generated HTML to the Web site, and then release the OLE server. It's pretty inefficient to start and stop the OLE server each time. However, if the server changes the value to 0, then the server won't be released and will be already running and ready for the next Web hit. To release the server, it need only not alter the value.

To release all Visual FoxPro servers on a single server, you can use the URL: "/scripts/foxisapi.dll/reset". This will call all cached existing instances of Visual FoxPro servers and tell them to release.

Database Publishing on the Web

Now that we know how to have Visual FoxPro OLE servers generate HTML, let's get a little fancier and publish a .dbf on the Web. Change the DBPUB method to the code below:

    PROCEDURE dbpub(parms,inifile,relflag)

        LOCAL rv,m.ii,mt

        rv = "HTTP/1.0 200 OK"+CHR(13)+CHR(10)

        rv = m.rv + "Content-Type: text/html"+CHR(13)+CHR(10)+CHR(13)+CHR(10)

        rv = m.rv + "<HTML>" + '<table border = "10">' + chr(13)

        USE (m.parms) SHARED    && Open the table

        for ii = 1 to FCOUNT()

            IF type("EVAL(FIELD(m.ii))") = 'G'

                loop    && don't proc general fields

            ENDIF

            rv = rv + "<th>" + PROPER(field(m.ii)) + "</th>" + chr(13)

        endfor

        rv = rv + "</tr>" + chr(13)

        SCAN

            rv = rv + "<tr>"

            for ii = 1 TO FCOUNT()

                IF type("EVAL(FIELD(m.ii))") = 'G'

                    loop    && don't proc general fields

                ENDIF

                mt = eval(field(m.ii))

                do case

                case type("mt") = 'C'

                    rv = rv + "<td>" + mt + "</td>"

                case type("mt") = 'T'

                    rv = rv + "<td>" + TTOC(mt) + "</td>"

                case type("mt") $ 'NY'

                    rv = rv + "<td align=right>" + str(mt,8) + "</td>"

                case type("mt") = 'D'

                    rv = rv + "<td>" + DTOC(mt) + "</td>"

                endcase

                rv = rv + chr(13)

            endfor

            rv = rv + "</tr>"

        ENDSCAN

        rv = rv +"</table>"

        return rv

The first parameter specifies the name of the table. All this does is loop through all the columns and rows in a DBF and returns an HTML Table string. Try it with a few URLs: "HTTP://myweb/scripts/foxisapi.dll/first.dbpub.dbpub?customer", "HTTP://myweb/scripts/foxisapi.dll/first.dbpub.dbpub?employee".

By just putting the name of a table in a URL, it is published on the Web. Pretty powerful stuff!

Deploying Your Visual FoxPro Applications Over the Internet

In your Visual FoxPro SAMPLES\SERVERS directory is a directory called FOXISAPI. This is a sample form class that just allows the user to edit/view the EMPLOYEE data in TESTDATA.DBC. However, the same form can be deployed in four different ways: as a normal Visual FoxPro form, as a Visual FoxPro run time, as an OLE Automation server from an OLE Automation client, and over the Internet using any Web browser!

This sample requires only that end users have a machine capable of running any Internet browser, which means it will allow you to deploy Visual FoxPro applications on 286s, Macs, Unix boxes, and maybe even personal digital assistants! Any changes made to the application only need to be done once. The changes will be automatically propagated to the other deployment platforms.

The readme.txt file in that directory explains how to install and configure the sample. For the latest version of this sample, go to the Visual FoxPro home page at http://www.microsoft.com/vfoxpro/. Also be sure to read the comments in foxisapi.cpp and isapi.vcx for tips.

The FOXISAPI sample takes advantage of the third parameter to do smart instancing of the server. The CMD method allows the user to execute DOS commands or evaluate FoxPro expressions on the server. If RESET is passed as a DOS command, the server will not change the third parameter to 0, and thus the server instance gets released.

Most of the work in the FOXISAPI sample is done by the GENHTML method. The result is a two column HTML table with labels for the field names and text box controls for the field values. It does an AMEMBERS( ) function call to determine dynamically what objects are on the form and to place the objects into an array. It then does a two-dimensional bubble sort to sort the objects into x,y order. HTML is stream based, whereas Visual FoxPro is pixel based.

The method then loops through each form member in the array elements and tries to generate HTML for them. If the object has its own GENHTML method, then it is invoked to return an HTML string. The class of the object is examined to determine what kind of object it is, and the appropriate HTML is generated. If there's a text box, then an associated label is searched for. Both of these get entered into the HTML table for the form.

After the form is generated, GENHTML then looks at the .INI file and appends the data to a table and the returned HTML.

Web servers can be hit multiple times by multiple clients. If client A clicks NEXT and client B clicks NEXT, it's important that the server knows which record was current for each client. This is handled with a cookie, which is just a unique ID assigned to the client. Subsequently served Web pages to that client include the same cookie hardcoded in its HTML.

Error Handling is extremely important from an OLE server, especially one that serves up Web pages. The server is typically unattended, and often doesn't even have a desktop to which error dialogs can be displayed. If there's an error in the FOXISAPI sample, the error method generates an Error HTML page and the GENHTML method returns that error page.

The LOG method in the FOXISAPI sample is useful: it just adds a line to a text file. The file can be examined to see what the server is doing. Use this liberally when debugging your applications. Microsoft Visual Studio™, which comes with Visual C++, has an option to automatically reload externally modified files, so you can just watch the log as the file changes.

Some parameters are passed via URLs, and thus some characters are not legal. For example, the chars "<>()" are not legal. They are converted by the Web browser to their hexadecimal equivalents prepended by a "%". The FIXURL method reverses the conversion.

Who Hit You?

When your Web server is hit from a Web site, how do you know who hit you? There are three new functions added to Foxtools that will help determine this. It also depends on whether you're on an intranet or the Internet. These functions call the Win Sockets API to resolve a remote IP Address to a host name.

I've added three functions to Foxtools that will resolve IP addresses.

    {"_WSOCKSTARTUP",    (FPFI) WSockStartup, 7,  "I,R,R,R,R,R,R"},

    {"_WSOCKCLEANUP",    (FPFI) WSockCleanup, 0,  ""},

    {"_WSOCKGETHOSTBYADDR",    (FPFI) WSockGetHostByAddr, 2,  "C,R"},

Call _WSOCKSTARTUP and _WSOCKCLEANUP to initialize/uninitialize the Winsock library. The _WSOCKGETHOSTBYADDR function takes an IP address string like "123.123.123.123" and resolves it into the name of the machine.

// store 0 to buff1,buff2,buff3,buff4,buff5,buff6

//?_wsockstartup(256 * 1 + 1,@buff1,@buff2,@buff3,@buff4,@buff5,@buff6)

// integer version, wVersion,wHighVersion,szDescription,szSystemStatus,iMaxSockets,iMaxUdpDg

//?    _wsockgethostbyaddr("123.123.123.123",@buff1)      &&returns 1 on success, 0 on failure

//        ?buff1                && returns the host name

// Note: if the target machine is not available, this call can take a long time.

Active Server Pages

Using Internet Information Server 3.0 with Active Server Framework (with the code name Denali) you can have your Web server send Active Server Pages (ASP). These ASP files are HTML files with special tags enclosed in the delimiters "<%" and "%>". These tags delimit both client-side and server-side scripts. Those that are server side will be executed on the server and will not show up on the client side (when the client Internet browser does a View>Source, for example).

The server-side scripting can be in any scripting language, but defaults to VBScript. You can create an ASP file that has a few lines of script that will return HTML for your ISAPI form:

<% set ox = server.CreateObject("foxis.employee")%>

<% = ox.Startup()%>

Here, a server script variable called ox is assigned an object reference to the Visual FoxPro automation server "foxis.employee". The second line invokes the startup method on the object, and returns the results as HTML.

In this case, the OLE server instancing model is handled by Denali. Because ox is a script variable, its lifetime is the lifetime of the script. That means the entire Visual FoxPro server instance is instantiated and released for each Web hit. Denali provides variables scoped to a session to allow the OLE server to have a longer lifetime:

<% set session("ox") = server.CreateObject("foxis.employee")%>

<% = session("ox").Startup()%>

Instead of using a script variable, we're using a session variable called ox.

Using this method of starting the OLE server, the server instance will exist until the session.timeout (default 20 minutes) expires.

The ISFORM class of ISAPI has a property called fASP which is either True or False, indicating whether or not the class was instantiated from an ASP page or from an HTML page (using the HREF /scripts/foxisapi.dll/foxis.employee.startup). If this flag is true, then the server can return generated HTML without an HTML Content header (there already is one in the ASP page. Also, an ASP page generates a cookie that can be used as the unique identifier for the session, and this is parsed out in the STARTUP method.

<% set session("ox") = server.CreateObject("foxis.employee")%>

<% = session("ox").Startup("ASP Cookie=" + Request.ServerVariable("http_cookie"),"",0)%>

Other Uses of OLE Servers

OLE was designed so that an out-of-process automation server does not have to live on the same machine as the client. It can be run on any other machine on the network. This remote automation capability means that OLE server applications don't care whether they're to be deployed on a local machine or a remote one. Also, because a single server can serve multiple clients, new classes of client/server application architectures are possible.

OLE servers allow application developers to deploy their applications as OLE clients or OLE servers, or both. That is, an application can have two or more components: one that acts as an OLE client, and one that acts as an OLE server. For example, a customer form might be a simple OLE client application running on dozens of machines, but it might talk to a single OLE server application that lives on a server machine somewhere that might enforce business rules, such as no new orders from a customer who has outstanding debts. The business rule enforcer might then talk to the actual data itself, which might be on Microsoft SQL Server or Visual FoxPro tables on yet another machine. If the customer form were to change, then only the front end needs to be updated. If the business rules change, then only the single business rule enforcer needs to be replaced. This "three-tier" client/server architecture also means that data processing loads get distributed to specialized applications/machines designed and optimized to do the job.

Another useful architecture is to have a client application spin off computationally- or resource-intensive tasks to other machines, so the client machine is free for other tasks such as printing, database updating, report generation, end-of-month processing, and so on.

The MVPs are coming!

Calvin_Hsia — Tue, 13 Mar 2007 04:34:00 GMT

I was quoted in this Computerworld article about the MVP summit, which is happening this week in Seattle.

The author says I compiled a “spreadsheet that ranked the most prolific posters on the FoxPro forum”.

That is slightly incorrect: obvious to Fox users, I used Fox to maintain a database for this job. I almost certainly used FoxBase because the list started way before FoxPro existed. In fact, those dial up days preceded the internet, and it cost lots of $ to connect to online bulletin boards like Compuserve (at 2400 Baud<g>)

Those were the days of TapCIS and OzCIS: two popular offline readers. They could be configured to go online to CIS (Compuserve Information Services), visit various fora (what’s the plural of forum?), download and upload messages, then log off. I could spend hours reading/posting messages with no connect time charges accumulating.

Reminds me of the days in junior high when our 4K ram computer had a sign that said “Think Offline!”

Original Compuserve magazine article on MVPs: Compuserve Magazine Microsoft MVP article

Another article on my MVP: http://www.calvinhsia.com/images/PacBusNews.jpg

A blog about my list: What is a Microsoft MVP? Calvin's List updated for the new century

My high school computer: Relaxen und watchen das blinkenlights. What lights?

Write your own hangman game

Calvin_Hsia — Tue, 10 Oct 2006 03:26:00 GMT

Many years ago (1985) I wrote a C program to play Hangman. I had decoded a word processor spelling dictionary for my word source.

More recently, I have encoded 2 spelling dictionaries for general purpose use: 1 with 171201 words, the other with 53869. There’s some pretty serious compression to get them both into a 679,936 byte dll. That’s an average of 3 bytes per word!

This hangman doesn’t have much graphically, but it does keep your average score.

Fox and VB versions below:

See also:

Click to download Dictionary.dll (you'll need to REGSVR32 this guy)

A word puzzle (also a link to download the dictionary): A Discounter Introduces Reductions: Multiple Anagrams

Another game: The Nametag Game

A program to convert your phone number into words: Phone Number Challenge update

Here’s the Fox version

PUBLIC ox as HangMan

ox=CREATEOBJECT("HangMan")

ox.play

DEFINE CLASS HangMan AS Form

oDict=0

nWordLen=0

cWord=""

cPriorWord=""

nSolved = 0 && #of letters solved for current word

nWrongLetters=0 && # of wrong letters for current word

nTotalWords = 0

nTotalWrong=0

AllowOutput=.f.

left=200

DIMENSION aLabels[26]

ADD OBJECT lblStatus as label WITH ;

top=this.Height/2+40,;

width = thisform.Width-10,;

Height=60,;

caption=""

PROCEDURE Init

this.oDict=CREATEOBJECT("dictionary.dict")

this.oDict.DictNum=2 && Small dictionary (53000 words)

nMinlen=5 && Minimum length of word

FOR i = 1 TO ALEN(this.aLabels)

this.AddObject("this.aLabels["+TRANSFORM(i)+"]","MyLabel")

ENDFOR

this.Visible= .T.

PROCEDURE Play

nMinlen=5 && Minimum length of word

this.nWordLen=0

this.cPriorWord = this.cWord

DO WHILE this.nWordLen < nMinLen

this.cWord=this.oDict.RandWord(1)

this.nWordLen=LEN(this.cWord)

ENDDO

FOR i = 1 TO ALEN(this.aLabels)

WITH this.aLabels[i] as Label

IF i <= this.nWordLen

.Visible= .T.

.Left=10 + i * 20

.Top=thisform.Height/2-20

.Width=20

.Caption="_"

ELSE

.Visible=.f.

ENDIF

ENDWITH

ENDFOR

this.nSolved = this.nWordLen && track # of solved letters

this.nWrongLetters = 0

this.ShowStatus

PROCEDURE ShowStatus

cStr=""

cStr=cStr+CHR(13)+" # of Wrong Letters = "+TRANSFORM(this.nWrongLetters)

* cStr=cStr+this.cWord+" " && Cheat!

IF !this.cPriorWord ==""

cStr=cStr+CHR(13)+"Prior word = '"+this.cPriorWord+"'"

cStr = cStr + CHR(13)+"Average # of wrong guesses is "+;

TRANSFORM(this.nTotalWrong/this.nTotalWords,"999.99")+" for "+;

TRANSFORM(this.nTotalWords)+" words"

ENDIF

this.lblStatus.Caption=cStr

PROCEDURE KeyPress(nKeyCode, nShiftAltCtrl)

DO CASE

CASE nKeyCode=27

thisform.Release

CASE ISALPHA(CHR(nKeyCode))

cchr = LOWER(CHR(nkeyCode))

fGotone = .f.

FOR i = 1 TO this.nWordLen

IF SUBSTR(this.cWord, i,1) = cchr AND ;

"_" = this.aLabels[i].caption

fGotOne=.t.

this.aLabels[i].Caption=cchr

this.nSolved = this.nSolved-1

IF this.nSolved = 0 && solved it!

this.nTotalWords = this.nTotalWords+1

this.nTotalWrong = this.nTotalWrong + this.nWrongLetters

this.Play

RETURN

ENDIF

ENDFOR

IF !fGotOne

this.nWrongLetters = this.nWrongLetters +1

ENDIF

this.ShowStatus

ENDCASE

ENDDEFINE

DEFINE CLASS MyLabel as Label

FontSize=14

FontBold=.t.

FontName="Courier New" && Monospace

width=20

height=30

ENDDEFINE

And the VB version:

Public Class Form1

Dim oDict As Object

Dim nWordLen = 0

Dim cWord As String = ""

Dim cPriorWord As String = ""

Dim nSolved = 0 '&& #of letters solved for current word

Dim nWrongLetters = 0 '&& # of wrong letters for current word

Dim nTotalWords = 0

Dim nTotalWrong = 0

Dim aLabels(26) As MyLabel

Dim oLblStatus As New Label

Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

oDict = CreateObject("Dictionary.Dict")

oDict.DictNum = 2 ' Small dictionary (53000 words)

Dim nMinlen = 5 ' Minimum length of word

Me.Width = 400

Dim i

For i = 0 To aLabels.Length - 1

aLabels(i) = New MyLabel

Me.Controls.Add(aLabels(i))

oLblStatus.Top = Me.Height / 2 + 20

oLblStatus.Height = 150

oLblStatus.Width = Me.Width

oLblStatus.Visible = True

Me.Controls.Add(oLblStatus)

End Sub

Sub Play()

Dim nMinlen = 5 ' Minimum length of word

Me.nWordLen = 0

Me.cPriorWord = Me.cWord

Do While Me.nWordLen < nMinlen

Me.cWord = Me.oDict.RandWord(1)

Me.nWordLen = Len(Me.cWord)

Loop

For i As Integer = 0 To Me.aLabels.Length - 1

With Me.aLabels(i)

If i < Me.nWordLen Then

.Visible = True

.Left = 10 + i * 20

.Top = Me.Height / 2 - 20

.Width = 20

.Text = "_"

Else

.Visible = False

End If

End With

Me.nSolved = Me.nWordLen ' track # of solved letters

Me.nWrongLetters = 0

Me.ShowStatus()

End Sub

Private Sub Form1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles Me.KeyPress

Select Case e.KeyChar

Case Chr(27)

End

Case Else

Dim cchr As Char = Char.ToLower(e.KeyChar)

If Char.IsLetter(cchr) Then

Dim fGotone As Boolean = False

For i As Integer = 0 To Me.nWordLen - 1

If Me.cWord.Substring(i, 1) = cchr And _

"_" = Me.aLabels(i).Text Then

fGotone = True

Me.aLabels(i).Text = cchr

Me.nSolved = Me.nSolved - 1

If Me.nSolved = 0 Then ' solved it!

Me.nTotalWords = Me.nTotalWords + 1

Me.nTotalWrong = Me.nTotalWrong + Me.nWrongLetters

Me.Play()

Return

End If

If Not fGotone Then

Me.nWrongLetters = Me.nWrongLetters + 1

End If

Me.ShowStatus()

End If

End Select

End Sub

Sub ShowStatus()

Dim cString As String = ""

cString = cString + Chr(13) + " # of Wrong Letters = " & Me.nWrongLetters

' cString=cString+Me.cWord+" " && Cheat!

If Not Me.cPriorWord = "" Then

cString = cString + Chr(13) + "Prior word = '" + Me.cPriorWord + "'"

cString = cString + Chr(13) + "Average # of wrong guesses is " & _

String.Format("{0:###.##}", Me.nTotalWrong / Me.nTotalWords) & " for " & _

Me.nTotalWords & " words"

End If

Me.oLblStatus.Text = cString

End Sub

Class MyLabel

Inherits Label

Sub New()

Me.Font = New Font("Courier New", 14, FontStyle.Bold)

Width = 20

Height = 30

End Sub

End Class

Private Sub Form1_Shown(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Shown

Me.Play()

End Sub

End Class