SDL window size, state, and position functions have been considered immediate, with their effects assuming to have taken effect upon successful return of the function. However, several windowing systems handle these requests asynchronously, resulting in the functions blocking until the changes have taken effect, potentially for long periods of time. Additionally, some windowing systems treat these as requests, and can potentially deny or fulfill the request in a manner differently than the application expects, such as not allowing a window to be positioned or sized beyond desktop borders, prohibiting fullscreen, and so on.
With these changes, applications can make requests of the window manager that do not block, with the understanding that an associated event will be sent if the request is fulfilled. Currently, size, position, maximize, minimize, and fullscreen calls are handled as asynchronous requests, with events being returned if the request is honored. If the application requires that the change take effect immediately, it can call the new SDL_SyncWindow function, which will attempt to block until the request is fulfilled, or some arbitrary timeout period elapses, the duration of which depends not only on the windowing system, but on the operation requested as well (e.g. a 100ms timeout is fine for most X11 events, but maximizing a window can take considerably longer for some reason). There is also a new hint 'SDL_VIDEO_SYNC_ALL_WINDOW_OPS' that will mimic the old behavior by synchronizing after every window operation with, again, the understanding that using this may result in the associated calls blocking for a relatively long period.
The deferred model also results in the window size and position getters not reporting false coordinates anymore, as they only forward what the window manager reports vs allowing applications to set arbitrary values, and fullscreen enter/leave events that were initiated via the window manager update the window state appropriately, where they didn't before.
Care was taken to ensure that order of operations is maintained, and that requests are not ignored or dropped. This does require some implicit internal synchronization in the various backends if many requests are made in a short period, as some state and behavior depends on other bits of state that need to be known at that particular point in time, but this isn't something that typical applications will hit, unless they are sending a lot of window state in a short time as the tests do.
The automated tests developed to test the previous behavior also resulted in previously undefined behavior being defined and normalized across platforms, particularly when it comes to the sizing and positioning of windows when they are in a fixed-size state, such as maximized or fullscreen. Size and position requests made when the window is not in a movable or resizable state will be deferred until it can be applied, so no requests are lost. These changes fix another long-standing issue with renderers recreating maximized windows, where the original non-maximized size was lost, resulting in the window being restored to the wrong size. All automated video tests pass across all platforms.
Overall, the "make a request/get an event" model better reflects how most windowing systems work, and some backends avoid spending significant time blocking while waiting for operations to complete.
The following objects now have properties that can be user modified:
* SDL_AudioStream
* SDL_Gamepad
* SDL_Joystick
* SDL_RWops
* SDL_Renderer
* SDL_Sensor
* SDL_Surface
* SDL_Texture
* SDL_Window
SDL considers a hidden window to be unmapped and blocks or defers certain operations until the window is shown again, however, the X11 and Cocoa backends would set the hidden flag when the window was minimized, which blocked the functionality of SDL_RestoreWindow().
Specify that a window with the hidden flag set is unmapped and not visible on the desktop or in the dock/taskbar without a call to SDL_ShowWindow(), and don't set the hidden flag in the X11 and Cocoa backends when the window is in the minimized state, but still mapped to the desktop.
Add SDL_ShowWindowSystemMenu() to display the system-level menu for windows. Typically, this is done by right-clicking on the system provided window decorations, however, if an application is rendering its own client-side decorations, there is currently no way to display it. This menu is provided by the system and can provide privileged desktop functionality such as moving or pinning a window to a specific workspace or display, setting the always-on-top property, or taking screenshots. In many cases, there are no APIs which allow applications to perform these actions manually.
Implemented for Wayland via functionality provided by the xdg_toplevel protocol, Win32 via the undocumented message 0x313 (typically called WM_POPUPSYSTEMMENU), and X11 via the "_GTK_SHOW_WINDOW_MENU" atom (supported in GNOME and KDE).
Adds the SDL_EVENT_WINDOW_OCCLUDED events and the window flag SDL_WINDOW_OCCLUDED to report when the window occlusion state has changed, so that the application can take appropriate measures, as it may wish to suspend drawing, throttle, or otherwise behave in a more energy efficient manner when the window is not visible. When the window is no longer occluded, the SDL_EVENT_WINDOW_EXPOSED event is sent and the occlusion flag is cleared.
This is handled on macOS via the window occlusion state event (available as of 10.9), and via the xdg-shell protocol on Wayland (version 6, wayland-protocols 1.32, passed through in libdecor 0.1.2).
Also renamed SDL_GetDisplayOrientation() SDL_GetDisplayCurrentOrientation()
The natural orientation of the primary display is the frame of reference for accelerometer and gyro sensor readings.
We have gotten feedback that abstracting the coordinate system based on the display scale is unexpected and it is difficult to adapt existing applications to the proposed API.
The new approach is to provide the coordinate systems that people expect, but provide additional information that will help applications properly handle high DPI situations.
The concepts needed for high DPI support are documented in README-highdpi.md. An example of automatically adapting the content to display scale changes can be found in SDL_test_common.c, where auto_scale_content is checked.
Also, the SDL_WINDOW_ALLOW_HIGHDPI window flag has been replaced by the SDL_HINT_VIDEO_ENABLE_HIGH_PIXEL_DENSITY hint.
Fixes https://github.com/libsdl-org/SDL/issues/7709
It turns out there's a race condition on X11 where the window could be placed by the window manager while being placed by the application, so we need to have the initial position available at window creation.
Ryan C. Gordon
SDL Wiki Bot
Sam Lantinga
Frank Praznik
Sylvain