xserver: Branch 'master'

[GitLab Mirror]

 mi/mipointer.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

New commits:
commit 0ee4ed286ea238e2ba2ca57227c3e66aca11f56b
Author: Willem Jan Palenstijn <wjp at usecode.org>
Date:   Sun Mar 31 14:56:58 2024 +0200

    mi: fix rounding issues around zero in miPointerSetPosition
    
    Fixes: https://gitlab.freedesktop.org/xorg/xserver/-/issues/577
    
    This patch replaces the instances of trunc in miPointerSetPosition by
    floor, thereby removing the incorrect behaviour with subpixel pointer
    locations between -1 and 0.
    
    This is the relevant code fragment:
    
        /* In the event we actually change screen or we get confined, we just
         * drop the float component on the floor
         * FIXME: only drop remainder for ConstrainCursorHarder, not for screen
         * crossings */
        if (x != trunc(*screenx))
            *screenx = x;
        if (y != trunc(*screeny))
            *screeny = y;
    
    The behaviour of this code does not match its comment for subpixel
    coordinates between -1 and 0. For example, if *screenx is -0.5, the
    preceding code would (correctly) clamp x to 0, but this would not be
    detected by this condition, since 0 == trunc(-0.5), leaving *screenx
    at -0.5, out of bounds.
    
    This causes undesirable behaviour in GTK3 code using xi2, where negative
    subpixel coordinates like this would (to all appearances randomly)
    remove the focus from windows aligned with the zero boundary when the
    mouse hits the left or top screen boundaries.
    
    The other occurences of trunc in miPointerSetPosition have a more subtle
    effect which would prevent proper clamping if there is a pointer limit
    at a negative integer rather than at 0. This patch changes these to
    floor for consistency.
    
    Signed-off-by: Willem Jan Palenstijn <wjp at usecode.org>
    Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1451>

diff --git a/mi/mipointer.c b/mi/mipointer.c
index 613c225a9..652726f3b 100644
--- a/mi/mipointer.c
+++ b/mi/mipointer.c
@@ -622,8 +622,8 @@ miPointerSetPosition(DeviceIntPtr pDev, int mode, double *screenx,
     pPointer = MIPOINTER(pDev);
     pScreen = pPointer->pScreen;
 
-    x = trunc(*screenx);
-    y = trunc(*screeny);
+    x = floor(*screenx);
+    y = floor(*screeny);
 
     switch_screen = !point_on_screen(pScreen, x, y);
 
@@ -701,9 +701,9 @@ miPointerSetPosition(DeviceIntPtr pDev, int mode, double *screenx,
      * drop the float component on the floor
      * FIXME: only drop remainder for ConstrainCursorHarder, not for screen
      * crossings */
-    if (x != trunc(*screenx))
+    if (x != floor(*screenx))
         *screenx = x;
-    if (y != trunc(*screeny))
+    if (y != floor(*screeny))
         *screeny = y;
 
     return pScreen;