I'm working on a per-monitor DPI aware application with multi-monitor capability. It's necessary to know the design-time PixelsPerInch of the Form to scale it according to the current monitor DPI if the Form is moved across monitors. The problem is that I don't get PixelsPerInch consistently. While debugging, in the form's overridden Loaded method I get the correct 120 value. When running standalone, I get 96 (and so the form scales bigger). I use Scaled property as false and rescale manually in DoShow with ChangeScale (also setting monitor index/boundsrect if necessary). Then on WM_DPICHANGED, if ever, rescale again (anyway it's not sent while debugging, probably because of the IDE). All looks fine, just on standalone run it's larger.
Why do I get different numbers for PixelsPerInch? Or at which point should I request the design-time value of it?
I'm using XE7 at the moment. With a standard (?) win 10 manifest, and call SetProcessDPIAwareness at the very beginning of unit initializations. I prefer it this way, so a "/no_dpi_aware" run is also possible with the blurry windows scaling. Of course I can just hardcode "120", but I wouldn't like it.
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0">
<assemblyIdentity type="win32" name="xxxx" version="3.1.0.0" processorArchitecture="*"/>
<dependency>
<dependentAssembly>
<assemblyIdentity type="win32" name="Microsoft.Windows.Common-Controls" version="6.0.0.0" publicKeyToken="6595b64144ccf1df" language="*" processorArchitecture="*"/>
</dependentAssembly>
</dependency>
<trustInfo xmlns="urn:schemas-microsoft-com:asm.v3">
<security>
<requestedPrivileges>
<requestedExecutionLevel level="asInvoker"/>
</requestedPrivileges>
</security>
</trustInfo>
<compatibility xmlns="urn:schemas-microsoft-com:compatibility.v1">
<application>
<!--The ID below indicates application support for Windows 10 -->
<supportedOS Id="{8e0f7a12-bfb3-4fe8-b9a5-48fd50a15a9a}"/>
<!--The ID below indicates application support for Windows 8.1 -->
<supportedOS Id="{1f676c76-80e1-4239-95bb-83d0f6d0da78}"/>
<!--The ID below indicates application support for Windows 8 -->
<supportedOS Id="{4a2f28e3-53b9-4441-ba9c-d69d4a4a6e38}"/>
<!--The ID below indicates application support for Windows 7 -->
<supportedOS Id="{35138b9a-5d96-4fbd-8e2d-a2440225f93a}"/>
<!--The ID below indicates application support for Windows Vista -->
<supportedOS Id="{e2011457-1546-43c5-a5fe-008deee3d3f0}"/>
</application>
</compatibility>
</assembly>
