Capture the mouse and to track input outside an SDL window.
int SDL_CaptureMouse(SDL_bool enabled);
|SDL_TRUE to enable capturing, SDL_FALSE to disable.
Returns 0 on success or -1 if not supported; call SDL_GetError() for more information.
Capturing enables your app to obtain mouse events globally, instead of just within your window. Not all video targets support this function. When capturing is enabled, the current window will get all mouse events, but unlike relative mode, no change is made to the cursor and it is not restrained to your window.
This function may also deny mouse input to other windows--both those in your application and others on the system--so you should use this function sparingly, and in small bursts. For example, you might want to track the mouse while the user is dragging something, until the user releases a mouse button. It is not recommended that you capture the mouse for long periods of time, such as the entire time your app is running. For that, you should probably use SDL_SetRelativeMouseMode() or SDL_SetWindowGrab(), depending on your goals.
While captured, mouse events still report coordinates relative to the current (foreground) window, but those coordinates may be outside the bounds of the window (including negative values). Capturing is only allowed for the foreground window. If the window loses focus while capturing, the capture will be disabled automatically.
While capturing is enabled, the current window will have the
SDL_WINDOW_MOUSE_CAPTURE flag set.
Please note that as of SDL 2.0.22, SDL will attempt to "auto capture" the mouse while the user is pressing a button; this is to try and make mouse behavior more consistent between platforms, and deal with the common case of a user dragging the mouse outside of the window. This means that if you are calling SDL_CaptureMouse() only to deal with this situation, you no longer have to (although it is safe to do so). If this causes problems for your app, you can disable auto capture by setting the
SDL_HINT_MOUSE_AUTO_CAPTURE hint to zero.
This function is available since SDL 2.0.4.