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Bug 4373 - SDL_WINDOW_ALLOW_HIGHDPI flag is not unset on failure
Summary: SDL_WINDOW_ALLOW_HIGHDPI flag is not unset on failure
Status: NEW
Alias: None
Product: SDL
Classification: Unclassified
Component: video (show other bugs)
Version: 2.0.9
Hardware: x86_64 Mac OS X (All)
: P2 normal
Assignee: Sam Lantinga
QA Contact: Sam Lantinga
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2018-11-09 02:58 UTC by Caleb Cornett
Modified: 2018-11-09 12:11 UTC (History)
2 users (show)

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Description Caleb Cornett 2018-11-09 02:58:31 UTC 
On macOS, if SDL cannot create a high-DPI window (e.g. because of an insufficient screen resolution), the SDL_WINDOW_ALLOW_HIGHDPI window flag is never turned off. This makes it difficult to determine at runtime if high-dpi window creation has been successful.

The snippet responsible for this behavior (or lack thereof) appears to be this:
https://hg.libsdl.org/SDL/file/a4d730631698/src/video/cocoa/SDL_cocoawindow.m#l1360

What's the best way to fix this? I suspect there's a simple solution, but I'm not familiar with Cocoa so I have no idea what it would be.
Comment 1 Alex Szpakowski 2018-11-09 12:11:21 UTC 
As the flag's name implies, it just makes SDL windows capable of being high-dpi, it isn't really meant to fail to create the window if it isn't high dpi - you can use SDL_GL_GetDrawableSize (if you're using OpenGL directly), or SDL_GetRendererOutputSize (if you're using SDL_Render) and compare that to SDL_GetWindowSize, to determine if the window is currently high dpi.