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Bug 1908 - Mac: cmd-tab doesn't work in fullscreen mode
Summary: Mac: cmd-tab doesn't work in fullscreen mode
Status: RESOLVED WONTFIX
Alias: None
Product: SDL
Classification: Unclassified
Component: video (show other bugs)
Version: HG 2.0
Hardware: x86_64 Mac OS X 10.8
: P2 minor
Assignee: (disabled) Jørgen Tjernø
QA Contact: Sam Lantinga
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2013-06-10 20:49 UTC by Alex Szpakowski
Modified: 2013-08-13 01:27 UTC (History)
1 user (show)

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Description Alex Szpakowski 2013-06-10 20:49:43 UTC 
When an SDL window is in Fullscreen mode in OS X, the cmd-tab (program switching) and window minimization hotkeys don't function.

This is a long-standing issue which is present in both SDL 2.0 and 1.2. I'm not sure whether it's a fundamental limitation of OSX' old fullscreen API or not, however both Mac OS 10.6 and 10.7 introduced new methods of going fullscreen while retaining the ability to easily switch to another program.

SDL 2.0's minimum OS X target version is 10.5, so always using the new fullscreen methods introduced in later versions probably isn't desired.

It's also possible to use SDL_WINDOW_FULLSCREEN_DESKTOP in SDL 2.0, but then the developer using SDL has to manually scale graphics and input coordinates to emulate different resolutions, which is kind of a pain.
Comment 1 Sam Lantinga 2013-06-13 01:10:57 UTC 
Hey Jorgen, what was the result of your Mac fullscreen investigation?
Comment 2 Alex Szpakowski 2013-06-14 22:36:15 UTC 
I did a bit of investigating myself. Some of my findings:

• I don't believe there is a way to nicely have command-tab/minimization/exposé support with the old <= 10.5 fullscreen Mode API.

• The new recommended way is to create a borderless fullscreen window and set the OpenGL context backbuffer dimensions to the requested screen size - it will be automatically scaled up when the backbuffer is drawn to the screen. It appears to actually be supported down to OS 10.3, but the Apple docs imply it only gets the performance benefit of normal fullscreen in >= 10.6.

• The new recommended way has some implications:

   - The resolution cannot be larger than the current desktop mode resolution. This isn't necessarily a bad thing, but it's a change from the current API.

   - Because the backbuffer is automatically scaled up to the full window size, it will always stretch to completely fill the screen instead of maintaining its aspect ratio with black borders, unless code is written to explicitly do that. This is another change from the current API, and personally I'd much rather the black borders than stretching.

   - Mouse coordinates (etc.) would need to be scaled from the window dimensions to the requested screen size and vice versa, when going between Cocoa and the program using SDL. This would get a bit more complicated if black borders were added for non-native aspect ratios.

   - I don't have a Retina Mac so I don't know how the retina scaling would be dealt with (if at all) using this technique. Probably worth further investigation.

• Because this method is just creating a standard window without borders, the new fullscreen mechanisms added in 10.7 compliment this method rather than replace it. Having the new method automatically use 10.7's fullscreen when supported seems to be rather simple to implement, which is nice. Mac OS 10.9 is significantly improving the fullscreen experience added in 10.7, so this seems like the way forward.
Comment 3 Alex Szpakowski 2013-06-14 22:40:40 UTC 
Also, I am not sure how this would all work out for SDL programs *not* using OpenGL - I haven't looked into that at all. Does SDL in OS X already always use an OpenGL context internally? If not, two separate code paths might be needed if the new fullscreen method does end up being used for OpenGL.
Comment 4 buckyballreaction 2013-07-13 01:32:46 UTC 
I think this issue might be the same as the bugs I've encountered, and mentioned on the mailing list:

http://lists.libsdl.org/pipermail/sdl-libsdl.org/2013-July/089121.html

If not, I can open a different bug
Comment 5 buckyballreaction 2013-08-13 00:21:00 UTC 
I had my hopes that resolution of bug #1996, which was fixed recently, might solve this bug.  Sadly it didn't.  CMD + H in an OpenGL fullscreen window still produces a black screen (on OSX 10.6) and fails to minimize it.

.
Comment 6 Alex Szpakowski 2013-08-13 00:24:46 UTC 
It's not really a bug in SDL's code - it's just the way the old OS X display capture method works.
You should probably either always use SDL_WINDOW_FULLSCREEN_DESKTOP or detect command-M, command-H, and command-tab keypresses and un-fullscreen the window manually (Awesomenauts does this and it works ok.)
Comment 7 buckyballreaction 2013-08-13 00:43:38 UTC 
My goodness, you're right!  SDL_WINDOW_FULLSCREEN_DESKTOP works like a charm.  How did I miss this?

We already do graphic scaling, etc., so this was perfect.

Thanks!