Optional Windows application manifest file to enable DPI awareness

[Demonese]

Version/Branch of Dear ImGui:

Version: any
Branch: any

Back-end/Renderer/Compiler/OS

Back-ends: imgui_impl_win32.cpp + imgui_impl_win32.cpp
Compiler: MSVC
Operating System: Windows

My Issue/Question:

I think we can provide a sample application manifest file in misc directory:

• common.manifest

<?xml version="1.0" encoding="utf-8"?>
<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0" xmlns:asmv3="urn:schemas-microsoft-com:asm.v3">
    <assemblyIdentity type="win32" name="Application" version="1.0.0.0"/>
    <trustInfo xmlns="urn:schemas-microsoft-com:asm.v3">
        <security>
            <requestedPrivileges>
                <requestedExecutionLevel level="asInvoker" uiAccess="false"/>
            </requestedPrivileges>
        </security>
    </trustInfo>
    <compatibility xmlns="urn:schemas-microsoft-com:compatibility.v1">
        <application>
            <!-- Windows 10 -->
            <supportedOS Id="{8e0f7a12-bfb3-4fe8-b9a5-48fd50a15a9a}"/>
            <!-- Windows 8.1 -->
            <supportedOS Id="{1f676c76-80e1-4239-95bb-83d0f6d0da78}"/>
            <!-- Windows 8 -->
            <supportedOS Id="{4a2f28e3-53b9-4441-ba9c-d69d4a4a6e38}"/>
            <!-- Windows 7 -->
            <supportedOS Id="{35138b9a-5d96-4fbd-8e2d-a2440225f93a}"/>
            <!-- Windows Vista -->
            <supportedOS Id="{e2011457-1546-43c5-a5fe-008deee3d3f0}"/>
        </application>
    </compatibility>
    <asmv3:application>
        <asmv3:windowsSettings>
            <dpiAware xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">true/pm</dpiAware>
            <dpiAwareness xmlns="http://schemas.microsoft.com/SMI/2016/WindowsSettings">PerMonitorV2</dpiAwareness>
        </asmv3:windowsSettings>
    </asmv3:application>
</assembly>

• your cmake file

target_sources(foo PRIVATE
    common.manifest
)

This manifest file can replace the complex loading DLL/function call. If anyone needs it.

[ocornut]

We already provide a helper function that does the same without the need for manifest, and work with old Windows and compile with old SDK. So I don’t think the manifest is ever needed.

[ocornut]

FYI the function we provide is ImGui_ImplWin32_EnableDpiAwareness().
Hopefully the manifest can be useful too, with other or custom backends.
I believe GLFW always enable this, and SDL has a flag on the window for it.
Closing it as there's no specific action required but this thread is now nicely findable and labeled :) Thank you!

[ocornut]

As pointed by #4200 there is indeed an issue with our function, which is that it seems to requires a manifest to "upgrade" DPI handling from 8.1-era support to 10-era support (varying DPI), so there are ways we can improve that.

[ocornut]

PS: See improvement done in #4200 (comment)