init opened the ticket and wrote:

When playing the game using SDL for video and input, some mouse events are lost. This applies to fast clicks with a mouse button, such as when clicking a button. The click is simply not detected by the program, and is quite irritating. I have to apply this patch to play, otherwise the game is nearly unplayable (although that might just be my personal preference).

The problem is that the program does not ensure that mouse button events are received properly by those UI elements that may receive them. A mouse press simply sets a global flag for the corresponding button to true, and clears it when the button is released. In the game main loop, each round the input queue is (completely) processed once. If both the button press and the button release events appears in the event queue while the queue is being processed, the flag will be set and cleared before the rest of the code have any chance of reacting to this information (since this happens outside the processing of the input queue).

I have written a patch that solves this problem. It adds code on the receiving end that flags the input processor when the input events have been seen, and updates the input processor to act accordingly. Thus, the button flags cannot be cleared before the receiving end has seen the new state.

There is also a related drag problem, mostly seen when dragging signals along a track. If you click and drag quickly from the starting point, the game will detect the drag as beginning not where you clicked but one tile along the dragged path. This means that if you click on a one-way signal, the game will think that you clicked on the next tile, that hasn't got any signals, and therefore create two-way signals at the perceived starting point and onwards. This problem is not fixed in the patch though, since I have not yet figured out how dragging works.

The patch works for SVN revision 5388.

Attachments

• sdl-lost-mouse-events-r5388.patch (7.87 KiB)

Reported version: trunk
Operating system: Linux

This issue was imported from FlySpray: https://bugs.openttd.org/task/221