[PATCH] SDL2: Can't set resolution in fullscreen mode

[historic_bruno]

With SDL1, we could set the fullscreen resolution, but not with SDL2, because we create the window with ​SDL_WINDOW_FULLSCREEN_DESKTOP to work around some issues with true fullscreen mode. Fullscreen desktop is a "fake" fullscreen which is only a borderless window that fills the screen, so it runs at native resolution.

Currently I know of issues on Windows and OS X using SDL_WINDOW_FULLSCREEN (see #2041). Once they are fixed, we can change the flag and fix this regression.

[historic_bruno]

I think we should add a config option to toggle between SDL_WINDOW_FULLSCREEN and ​SDL_WINDOW_FULLSCREEN_DESKTOP. SDL_WINDOW_FULLSCREEN would always be preferable but it's still too buggy to be the default, and sometimes SDL_WINDOW_FULLSCREEN_DESKTOP could be preferred for those who want the desktop resolution in fullscreen mode.

[historic_bruno]

Tested the latest SDL Hg version on Windows 7 and the fullscreen transitions are much improved, I didn't find any obvious bugs on my system.

[SuperTux95]

I'd like to be able to use the super key or alt+tab to temporarily minimize 0ad on Debian. Currently it is only possible in windowed mode with the added performance impact. Other games like Xonotic allow to be minimized with super/alt+tab in fullscreen when paused.

[fcxSanya]

Added a patch according to Ben's suggestion here:

I think we should add a config option to toggle between SDL_WINDOW_FULLSCREEN and ​SDL_WINDOW_FULLSCREEN_DESKTOP.

By default it preserves the current implementation (SDL_WINDOW_FULLSCREEN_DESKTOP).

Tested on Linux, looks working.

To test: change xres/yres to something different from the current screen resolution, set windowed = false and make sure that:

1. with fakefullscreen = true (default) the game window is created with the desktop resolution
2. with fakefullscreen = false the game window is created with xres/yres

[fcxSanya]

I suddenly realized that it doesn't make sense to pass fakeFullscreen around as method arguments like fullscreen as I do in fake_fullscreen_option.diff​, so I made the second version of the patch (fake_fullscreen_option_v2.diff​) which doesn't add fakeFullscreen params to methods.

[wraitii]

Patch does what it says, but that doesn't play nice with OSX. Also seems to fail with #2349: hold the screen gets mangled (probably an SDL issue)

If the point is to allow running at a reduced resolution in fullscreen to speed up the game, I would advise instead, as I did on #2349, to decouple the renderer resolution from the real resolution.

Removing rfc in the meantime.

[elexis]

Moving to the Work In Progress milestone, since there is a patch asking for feedback, but since it is not strictly bound to a specific release.

[wraitii]

Perhaps after ​https://code.wildfiregames.com/D1925 we could add support for SDL_WINDOW_FULLSCREEN.

[Stan]

So I tried replacing

	if (fullscreen)
		flags |= SDL_WINDOW_FULLSCREEN_DESKTOP;

by

	if (fullscreen)
		flags |= SDL_WINDOW_FULLSCREEN;

On Windows 10 and there is still at least one issue.

If you open the game in Windowed mode, then going into full screen forces 1024x768. If you open the game in FullScreen mode, resolution is Desktop's but if you switch to windowed then back to full screen it's now 1024x768

[Vladislav Belov]

Refs r26148.

[Stan]

Backlogging due to lack of progress, lack of review, or users going MIA.