Bug 24187

Summary: Negative root window coordinates
Product: xorg Reporter: Peter Hutterer <peter.hutterer>
Component: Server/Input/CoreAssignee: Peter Hutterer <peter.hutterer>
Status: RESOLVED FIXED QA Contact: Xorg Project Team <xorg-team>
Severity: normal    
Priority: medium    
Version: 7.4 (2008.09)   
Hardware: Other   
OS: All   
Whiteboard:
i915 platform: i915 features:
Bug Depends on:    
Bug Blocks: 23613    

Description Peter Hutterer 2009-09-27 19:58:28 UTC 
Clipping on subpixels is broken in GetPointerEvents and friends. Moving into the upper left corner it is possible to get negative (-1..0) root window coordinates.
Comment 1 Peter Hutterer 2009-10-01 19:20:15 UTC 
commit 45f447dafded5adfe11b7df3325c2d8f6ae0639b
Author: Peter Hutterer <peter.hutterer@who-t.net>
Date:   Thu Oct 1 21:19:11 2009 +1000

    dix: force a minimum of 0 for screen coordinates.
    
    Currently the root coordinates may fall into ]-1..0] if the subpixel
    remainder is less than 0. Screen coordinates mustn't go below 0, so use
    miPointerSetPosition to cap off the remainder if the coordinates are below
    0.
    
    This is cheating a bit, a more comprehensive solution to deal with subpixels
    correctly when crossing screens is needed. For now, this'll do.
    
    Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
    Acked-by: Simon Thum <simon.thum@gmx.de>

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