I’m using this program as something of a testbed for some engineering work that I’ll talk about in future posts, including supporting pixel-perfect bitmap images at multiple DPI settings in WPF and using the Visual Styles APIs to draw native-looking controls (with animation). I’ve also taken the opportunity to learn a bit about localising programs, and v3.1.0 contains three user interface languages: English (Australia), English (United States) and Japanese (Japan) – thanks to Miho Inaba (稲葉美穂) for help with the latter.
The following is based on the Windows Developer Preview and might not accurately represent the final version of Windows 8.
A significant change in Windows 8 is the removal of support for Windows classic theming. In the Windows Developer Preview, there is no Windows Classic theme, and all themes (including Windows Basic and the four high contrast themes) use the Desktop Window Manager (DWM) for desktop composition (in Windows Vista and Windows 7, it was only enabled for Aero themes).
While some users may miss the Windows Classic theme (it might return in later builds, of course), this is definitely a positive development. All themes will receive the benefits of hardware acceleration, and there will no longer be the need to maintain a separate code path for when the DWM is disabled (as long as the program targets only Windows 8 or later).
In order to maintain compatibility with earlier versions of Windows, when a high contrast theme is selected, Windows 8 will simulate the Windows classic theming model unless an application specifies Windows 8 as a supported OS in its application manifest. The sample program I made for the previous post did not include such a manifest, so it doesn’t work correctly in the Windows Developer Preview with high contrast themes:
Compare this to a task dialog:
(The button in the WPF window is also drawn incorrectly, but presumably that will be fixed in .NET 4.5.)
Adding the appropriate manifest to the application causes it to work as it should:
I’ve updated the sample code in the previous post to include the manifest file.
In a post earlier this year, I investigated how to retrieve information about theme fonts in Windows. Briefly, the Visual Styles APIs can be used when visual styles are enabled, but values need to be hard-coded (to some extent) otherwise.
Andrew Powell commented on my previous post noting difficulties in implementing the GetThemeFont function in managed code. In this post, I’ll demonstrate how to implement the relevant functions in a simple WPF project. In particular, I’ll focus on displaying information about the ‘main instruction’ text style as seen in Task Dialogs.
Read on for details.
Update: See this post for a sample implementation in WPF.
Have you ever wondered how to access the various font colours and styles found throughout Windows, such as that of the ‘Main Instruction’ text in the Task Dialog shown above?
If you are using WPF, the SystemFonts class might sound promising at first. However, this class only exposes the following: the icon font, caption font, small caption font, menu font, message font and status font. These aren’t very exciting – in fact, they are all simply 9pt Segoe UI in Windows Vista/7 Aero. (Aside: early Windows 8 builds use 11pt Segoe UI Semilight as the caption (and small caption) font.) For those using Win32 directly, the SystemFonts class wraps around
the SystemParametersInfo function (specifically with the messages SPI_GETNONCLIENTMETRICS and SPI_GETICONTITLELOGFONT) the GetThemeSysFont function.
MSDN offers some guidance on default fonts and colours in Windows Vista/7: apparently ‘Main Instruction’ text is 12pt #003399 Segoe UI. This table, while helpful, is not comprehensive, and in general it’s not a good idea to hard-code this kind of thing, as themes/visual styles are liable to change.
The keys lie in the Visual Styles APIs, introduced in Windows XP. In particular, the GetThemeFont function and GetThemeColor function (with the TMT_TEXTCOLOR property identifier), both found in UxTheme.dll. We simply need to specify the ‘part and state’ of the control in question (these are defined in Vsstyle.h and Vssym32.h). ‘Main Instruction’ text, for example, is referenced by the TEXT_MAININSTRUCTION part in the TEXTSTYLE class.
Regrettably, visual styles APIs only work when visual styles are enabled (who’d have thought it?). That is to say, we can’t rely on them with classic themes (Windows Classic and the High Contrast themes).
I emailed the very knowledgeable Larry Osterman about this, and he was kind enough to respond:
AeroStyle.xml tells which metrics to ask for which theme parts (for the OS that matches the version of the SDK it’s in), but there’s no theme API support for classic modes.
Basically they get the metric they’re looking for from the AeroStyle.xml file.
AeroStyle.xml is included in the latest versions of the Windows SDK. It contains the same classes and parts and states mentioned earlier in an XML format. The ‘MainInstruction’ part in the ‘TextStyle’ class looks like this, for instance:
<TextColor>0 51 153</TextColor>
<Font>Segoe UI, 12, Quality:ClearType</Font>
Of interest are the ‘ClassicValue’ elements. When visual styles are disabled, it seems that ‘Main Instruction’ text uses the caption font (8pt bold Microsoft Sans Serif, as it happens).