This change allows:
* Engines to update their target rendering surface/size and pixel
format with the backend multiple times during gameplay;
* Users to resize the ScummVM window without having it reset
size/position every time an engine updates its target surface
format;
* Conversions/scaling to continue to run efficiently in hardware,
instead of requiring engines to pick their maximum possible
output format once and upscale inefficiently in software;
* The window to reset size once when an engine calls to set its
initial output size, and to reset again once ScummVM returns to
the launcher.
This is relevant for at least SCI32 and DreamWeb engines, which
perform graphics mode switches during games.
Destroying and recreating the SDL window whenever the video mode
changes in SDL2 is not necessary and causes several problems:
1. In windowed mode, the game window shifts position;
2. In fullscreen mode in macOS, every time the window is
recreated, it causes the OS to play its switch-to-fullscreen
animation again and emit system alert noises;
3. The window content flickers; and
4. The engine loses events from the old destroyed window.
This patch changes the SDL backend code to avoid destroying and
recreating the SDL window when using SDL2, except when switching
OpenGL modes, since there is no way to change the OpenGL feature
of a window.
There are still some outstanding issues with OpenGL where window
size ends up getting reset even though the user has resized it;
this will probably need to be addressed at some point in another
patch.
Thanks to @bgK and @criezy for their feedback which made this
patch much better.
Co-Authored-By: Bastien Bouclet <bastien.bouclet@gmail.com>
Crtl-Alt-f now enables/disables filtering instead of changing the
graphics mode. Since there is only one graphics mode now, a hotkey
to change it is a bit useless.
Those outdated resize events are sent from SDL_DestroyWindow when the
window is fullscreen and doesn't have the SDL_WINDOW_FULLSCREEN_DESKTOP
flag (thus Surface SDL is not affected). Switching resolutions in fullscreen, or
switching from fullscreen to windowed will therefore cause a resize event to
be received with the former fullscreen resolution after we have already setup
the window to use the new resolution. If we don't ignore this event we end up
with a texture size and a window size that are not consistent and for example
see only a part of the texture (if the old resolution is bigger than the new one.
This mode should *not* be used by any new engines/code. If someone is going
to use it and says it works with the OpenGL output, please make them wear a
red uniform and beam them onto a remote planet.
Formerly, we required that the OpenGL mode was fixed at compile time. Now we
allow the code to work with whatever it is given at runtime.
It is still possible to force a context type on compile time.
This used to be used by Sword25. Since it is not supported by GLES and no
engine code uses it we drop support. Hopefully, this helps people to realize
they should not use that format in their engine.
Formerly we did not initialize the mouse emulation from SdlEventSource
properly. Now hopefully joysticks etc. should work fine with the SDL OpenGL
output too.
Subclasses of OpenGLGraphicsManager are now supposed to supply a refreshScreen
function which handles actual screen updating (for example, buffer swapping).
Sadly this also requires us to extend GraphicsManager for this SDL specific
feature. However, since that's only used in the SDL backend and Tizen it
should be fine for now...
