OS DPI scale not applied to UI

[chrismile]

Windows (and similarly also Linux) has an option to specify an OS DPI scale that apps should apply to their content such that text is readable also on high-DPI displays (see below).

gvk-pipeline-explorer seems to ignore this scale for now, which causes the UI to be almost unreadable on such high-DPI displays without either lowering the screen resolution or going very close to the monitor.

If a reference for how to achieve this with ImGui is helpful, I have previously added such code in my own graphics library sgl (see links below). The code is unfortunately not very well cleaned up.

• Windows gets told the app is DPI aware at https://github.com/chrismile/sgl/blob/master/src/Utils/AppSettings.cpp#L167 (but I assume gvk may already be doing something like that via GLFW, as otherwise the app should usually just be zommed in). Here, I use DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2 if possible to tell it the app is able to adapt the DPI scale per monitor.
• The OS DPI scale is computed in a system-dependent way in https://github.com/chrismile/sgl/blob/master/src/Graphics/Utils/HiDPI.cpp. I have a custom code path using GetDpiForWindow on Windows, but glfwGetMonitorContentScale in GLFW might be sufficient. I have this as a fallback in the code, but so far it always uses the primary monitor (so the app in this case wouldn't be per-monitor DPI aware).
• The OS DPI scale is incorporated in font sizes and the ImGui style object in https://github.com/chrismile/sgl/blob/master/src/ImGui/ImGuiWrapper.cpp. When the DPI scale changes (e.g., because the window was moved to another monitor), the fonts are freed and reloaded (though not from disk, just from memory; I load them to disk only once).
• glfwSetFramebufferSizeCallback and glfwSetWindowContentScaleCallback are used to trigger the font reloading when the DPI scale changed.