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kichikuou
5e80c96587
A typical event loop in System4 game looks like this:
while (true) {
SACT2.Mouse_GetPos(x, y);
// Update the screen according to the mouse position (x, y)
...
SACT2.Update();
if (SACT2.Key_IsDown(VK_LBUTTON)) {
// A button was pressed at (x, y)
...
}
}
This works poorly with touch devices. Assume that a touch event occured
during SACT2.Update(). It updates internal mouse position and button
status. After SACT2.Update(), the game calls SACT2.Key_IsDown(VK_LBUTTON).
It returns true, but the game has not yet called SACT2.Mouse_GetPos()
after the touch event, so it assumes that the button was pressed where
the mouse pointer was before the touch.
In order to avoid this situation, this defers mouse button events
synthesized (by SDL) from touch. Such deferred events are processed when
SACT2.Mouse_GetPos() is called or after 50ms.