re: New PAG book & tool to help learn VB6 to VB.NET migration approaches (by PaulYuk)

Robert Conley — Thu, 17 Nov 2005 16:57:31 GMT

Great guide if you are converting a database front end. But any other type of vb application it is useless particulary graphics intensive programs like CAD/CAM software.

What is needed are compatibility object that mimic VB6 objects. Plus GDI+ needs to be a lot quicker than it is now.
VB6
Dim I As Double
Const H As Double = 500
Const W As Double = 500
' ' Init
Me.ForeColor = vbBlack
Me.DrawWidth = 1

'
For I = 0 To W Step 5
Call Me.Line(I, 0)-(I, H)
Next
'
For I = 0 To H Step 5
Call C.DrawLine(0, I)-( W, I)
Next

GDI+

Dim I As Int32
Dim G As Graphics
P As Pen
Const H As Int32 = 500
Const W As Int32 = 500

' Init
G = Me.CreateGraphics
P = New Pen(Color.Black)

For I = 0 To W Step 5
G.DrawLine(P, I, 0, I, H)
Next

For I = 0 To H Step 5
G.DrawLine(P, 0, I, W, I)
Next

' Cleanup
Set P = Nothing
Set G = Nothing

VB6 Flat GDI+ Api

Dim Graphics As Long, Pen As Long
Dim I As Long
Const H As Long = 500
Const W As Long = 500

' Init
Call GdipCreateFromHDC(Me.hDC, Graphics)
Call GdipCreatePen1(Black, 1, UnitPixel, Pen)

For I = 0 To W Step 5
Call GdipDrawLineI(Graphics, Pen, I, 0, I, H)
Next

For I = 0 To H Step 5
Call GdipDrawLineI(Graphics, Pen, 0, I, W, I)
Next

' Cleanup
Call GdipDeletePen(Pen)
Call GdipDeleteGraphics(Graphics)

VB6 GDI

Dim hDC As Long
Dim I As Long
Dim pt As POINTAPI
Const H As Long = 500
Const W As Long = 500

hDC = GetDC(Me.hwnd)
For I = 0 To W Step 5
Call MoveToEx(hDC, I, 0, pt)
Call LineTo(hDC, I, H)
Next
'
For I = 0 To H Step 5
Call MoveToEx(hDC, 0, I, pt)
Call LineTo(hDC, W, I)
Next

Call ReleaseDC(hwnd, hDC)

The VB6 native graphics and GDI run about 20 times faster (a 100 loops averaging 40 milliseconds on my machine)

The VB6 flat GDI+ Api and VB.NET 8 (2005) both in a 100 loops ran about 800 milliseconds on average. I tested on several other machine as well.

This and nearly two dozen other issues is why so many of us VB6 developers are not migrating to VB.NET.

Nearly all the migration examples I have seen offered are squared toward big corporate needs of web sites and database front end. Those of us who are consultants, VARs, and independent software developers has have their upgrade path throughly trashed by Microsoft decisions regarding VB.NET.

The justifications for these decisions are increasing losing their value as technologies such as LINQ are being demonstrated.

If you can add LINQ syntax to the Visual Basic langauge there is no reason you can't support the VB6 syntax.

Rob Conley
Head Programmer
Plasma Automation