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Bug 2321

Summary: SDL_MouseMotionEvent coordinates out of bounds in FULLSCREEN_DESKTOP
Product: SDL Reporter: microvirus.multiplying
Component: eventsAssignee: Sam Lantinga <slouken>
Status: RESOLVED ABANDONED QA Contact: Sam Lantinga <slouken>
Severity: major    
Priority: P2    
Version: 2.0.1   
Hardware: x86_64   
OS: Windows 7   

Description microvirus.multiplying 2013-12-20 21:18:49 UTC 
When receiving mouse events via SDL_PeepEvents(..SDL_GETEVENT) the following problem occurs when the window is fullscreen:
When moving the mouse to the far left of the screen the event for SDL_MOUSEMOTION gives a negative value  for 'event.motion.x', effectively making the mouse disappear off-screen.

Application uses SDL_RenderSetLogicalSize and the fullscreen used is SDL_WINDOW_FULLSCREEN_DESKTOP.

This effectively means, for the user, that the mouse is 'stuck' outside of the screen and has to be pulled back (how much depends on how fast the user moves the mouse off-screen) before it can be used again.

I'd like to emphasize that this only happens when fullscreen is enabled: when running windowed with mouse grabbed via SDL_SetWindowGrab this does not occur.
Comment 1 microvirus.multiplying 2013-12-20 21:23:44 UTC 
The effect seems most prominent near the corners of the screen. Though I have observed, via the debugger, negative x values for event.motion.x, the effect is particularly noticeable to the user when the mouse is sent to one of the corners of the screen.
Comment 2 Sam Lantinga 2013-12-23 23:52:09 UTC 
Does this happen if you don't use SDL_RenderSetLogicalSize()?  It may be that the aspect ratio of your desired resolution doesn't match the actual resolution.
Comment 3 microvirus.multiplying 2013-12-24 15:13:26 UTC 
Yes, the aspect ratio's definitely differ between the 'logical size' of the game and the fullscreen ratio.
When running fullscreen, letterboxes are displayed left and right.

I did some further testing and if I enable the system cursor (the game draws its own cursor, usually) then one sees that the system cursor is allowed into the black area of the screen. But, this is outside the game limits, so the SDL_MouseMotionEvent contains negative coordinates.
To get back into game-limits, the user then has to move the cursor back into the non-blacked out portions.

Is this behaviour by design? I would have expected that in fullscreen the mouse would be confined to the logical part of the screen, as that's what you'd normally expect from fullscreen.
Comment 4 Ryan C. Gordon 2018-08-06 21:20:20 UTC 
Hello, and sorry if you're getting dozens of copies of this message by email.

We are closing out bugs that appear to be abandoned in some form. This can happen for lots of reasons: we couldn't reproduce it, conversation faded out, the bug was noted as fixed in a comment but we forgot to mark it resolved, the report is good but the fix is impractical, we fixed it a long time ago without realizing there was an associated report, etc.

Individually, any of these bugs might have a better resolution (such as WONTFIX or WORKSFORME or INVALID) but we've added a new resolution of ABANDONED to make this easily searchable and make it clear that it's not necessarily unreasonable to revive a given bug report.

So if this bug is still a going concern and you feel it should still be open: please feel free to reopen it! But unless you respond, we'd like to consider these bugs closed, as many of them are several years old and overwhelming our ability to prioritize recent issues.

(please note that hundred of bug reports were sorted through here, so we apologize for any human error. Just reopen the bug in that case!)

Thanks,
--ryan.