[Scummvm-tracker] [ScummVM :: Bugs] #12646: PORTS: MACOS: Mac OS loss of mouse focus with OpenGL

[ScummVM :: Bugs]

#12646: PORTS: MACOS: Mac OS loss of mouse focus with OpenGL
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Reporter:  aculotarpa               |       Owner:  (none)
    Type:  defect                   |      Status:  new
Priority:  normal                   |   Component:  Port: Mac OS X
 Version:                           |  Resolution:
Keywords:  Mac OS X, OpenGL, Mouse  |        Game:
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Comment (by kalkie):

 I've submitted a PR for fixing this issue:
 https://github.com/scummvm/scummvm/pull/3699

 There was an off-by-one kind of error in clipping the mouse coordinates to
 the game's viewport in scaled HiDPI mode. At least MacOS is affected, but
 based on comments in https://github.com/libsdl-org/SDL/issues/2119, also
 iOS and Wayland have similar scaled HiDPI support.

 If the mouse gets out of the game's viewport on right/bottom side, the
 off-by-one error causes the cursor to be set on the outside edge of the
 viewport, not inside of it. This leads into a loop, where the mouse is
 again detected to be outside of the viewport, reset on the edge again,
 etc., making the game freeze.

 This only happens with the OpenGL graphics mode, because the SDL Surface
 mode doesn't support HiDPI mode. There are quite a few workarounds for the
 issue, in addition to changing the graphics mode. One could disable mouse
 capture (Ctrl+m) or change to one of the stretch modes filling the entire
 screen with the game. If the game's viewport fills the whole window, the
 cursor cannot get outside of the allowed area, thus avoiding the issue.
-- 
Ticket URL: <https://bugs.scummvm.org/ticket/12646#comment:7>
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