video: Add a warning to the docs about using SDL_GetDisplayDPI.

Fixes #5647.
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Ryan C. Gordon 2022-08-02 10:50:51 -04:00
parent f1390780ca
commit 307b0b7813
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@ -444,6 +444,15 @@ extern DECLSPEC int SDLCALL SDL_GetDisplayUsableBounds(int displayIndex, SDL_Rec
* A failure of this function usually means that either no DPI information is
* available or the `displayIndex` is out of range.
*
* **WARNING**: This reports the DPI that the hardware reports, and it is not
* always reliable! It is almost always better to use SDL_GetWindowSize() to
* find the window size, which might be in logical points instead of pixels,
* and then SDL_GL_GetDrawableSize(), SDL_Vulkan_GetDrawableSize(),
* SDL_Metal_GetDrawableSize(), or SDL_GetRendererOutputSize(), and compare
* the two values to get an actual scaling value between the two. We will
* be rethinking how high-dpi details should be managed in SDL3 to make
* things more consistent, reliable, and clear.
*
* \param displayIndex the index of the display from which DPI information
* should be queried
* \param ddpi a pointer filled in with the diagonal DPI of the display; may