WPF Text Blog : wpf

WPF Text Measurement Units

text — Fri, 11 Dec 2009 23:48:00 GMT

The WPF text team has seen some people get confused about what units WPF uses when measuring text. Samer, a developer on the WPF text team, and I have created this post to try and shed some light on this subject. The first part of this post is very straight forward, whereas the end will only be useful for those of you who are extensively using WPF text APIs.

General Units

WPF supports multiple units for text measurement. The units that can be used are “px” (device independent pixels), “in" (inches), "cm" (centimeters), "pt" (points). If you do not specify the unit of measurement, WPF defaults to px.

<TextBlock FontSize="24">Hello World</TextBlock>

To force WPF to use a different unit of measurement, just append the unit abbreviation to the FontSize.

<TextBlock FontSize="24pt">Hello World</TextBlock>

Device Independent Pixels & Physical Pixels

In accordance with WPF’s resolution independence, the framework measures objects in device independent pixels. These device independent pixels can have different sizes than physical pixels.

1 device independent pixel = 1/96 inch.

1 physical pixel = 1/DPI (dependent on the system DPI)

Default system settings usually choose a DPI of 96 so these two types of pixels come out to be the same size. If this is not the case, it is easy to convert between the two types of pixels.

physical pixels = DPI/96 * device independent pixels

device independent pixels = 96/DPI * physical pixels

Notice that as the DPI increases, so does the number of physical pixels which compose one device independent pixel. Hence, objects that have their sizes specified in device independent pixels get larger as the system DPI increases.

Points

A point (pt) is also a common unit of measurement for fonts.

1pt = 1/72 inches

Converting between points and device independent pixels is also easy.

pt = 72/96 device independent pixels

device independent pixels = 96/72 pt

Remember objects which are measured in device independent pixels get larger as system DPI increases? This is true for text. Since there is a constant ratio between point sizes/device independent pixels, if the point size of text is held constant while the system DPI is increased, the size of the rendered text will grow.

Uses For Font Units

Aside from knowing how to correctly set FontSize, the above knowledge could be helpful in understanding the values that WPF text APIs, such as FormattedText or TextFormatter, use and return for the different text measurements. The metrics returned from these APIs are in device independent pixel (eg. some properties of GlyphTypeface including Baseline, CapsHeight, XHeight). When interacting with these APIs make sure that you convert to device independent pixels from whatever unit your font is measured in, or visa versa.

- Samer and Chipalo

WPF TypeCon Workshop Material

text — Mon, 06 Aug 2007 23:34:00 GMT

Thanks to all who attended TypeCon's Fonts and Typography in WPF workshop. We had a great time chatting with you all Thursday morning. In the below zip file you can find some of the material we went over in the lab. This includes:

1. The extremely useful WPF Layout and Font Quick Reference which lists and describes common typography and text layout related properties.

2. The completed version of the reflective textbox lab

3. Mikhail Leonov's presentation on WPF font model.

Also here are a couple links that may be helpful:

WPF Typography SDK page:http://msdn2.microsoft.com/en-us/library/ms742190.aspx

The Sample OpenType Font Pack: http://msdn2.microsoft.com/en-us/library/ms746705.aspx

WPF forums: http://forums.microsoft.com/msdn/showforum.aspx?forumid=119&siteid=1

-Christine Ahonen, Chris Han, Mikhail Leonov, and Simon Daniels

Microsoft Surface

text — Wed, 30 May 2007 19:22:00 GMT

Unrelated to text, but extremely cool...

Microsoft Chairman Bill Gates once talked about putting a PC on every desk. Now Gates is talking about turning the desk itself — or a tabletop — into a computer. Microsoft is set to announce an ambitious new computing category today called "surface computing" to try to make it happen.

The initiative, several years in the making, transforms an ordinary tabletop into a translucent, interactive façade. The surface can recognize cellphones, digital cameras, special ID-coded digital dominoes and other physical objects.

And it can respond to human touch. Kids can finger-paint digitally. Business travelers can dive into maps and surf the Web without a mouse or keyboard, by using simple touch gestures across the screen. In restaurant settings, you'll be able to order meals and play digital board games. At home, there may be no more fussing with the half-dozen remote controls sitting on your coffee table. That's because the table becomes the remote control.

http://www.microsoft.com/surface/

http://www.usatoday.com/tech/products/2007-05-29-microsoft-surface_N.htm

Dot Net Solution's WPF Wikipedia Explorer

text — Tue, 09 Jan 2007 00:59:00 GMT

Dot Net Solutions created a fun Wikipedia explorer app that takes Wikipedia content and displays it in a WPF FlowDocument and also adds in a 3D topic explorer. Fun app that ou can install through click-once here: http://www.dotnetsolutions.ltd.uk/casestudies/wikipediaexplorer/.