[PATCH] dix: force a minimum of 0 for screen coordinates.

[Peter Hutterer]

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 at who-t.net>
Acked-by: Simon Thum <simon.thum at gmx.de>
---
 dix/getevents.c |   13 +++++++++++++
 1 files changed, 13 insertions(+), 0 deletions(-)

diff --git a/dix/getevents.c b/dix/getevents.c
index 5224d31..2df32e8 100644
--- a/dix/getevents.c
+++ b/dix/getevents.c
@@ -781,6 +781,19 @@ positionSprite(DeviceIntPtr dev, int *x, int *y, float x_frac, float y_frac,
         *screeny_frac = dev->last.remainder[1];
     }
 
+    /* Hit the left screen edge? */
+    if (*screenx <= 0 && *screenx_frac < 0.0f)
+    {
+        *screenx_frac = 0.0f;
+        x_frac = 0.0f;
+    }
+    if (*screeny <= 0 && *screeny_frac < 0.0f)
+    {
+        *screeny_frac = 0.0f;
+        y_frac = 0.0f;
+    }
+
+
     old_screenx = *screenx;
     old_screeny = *screeny;
     /* This takes care of crossing screens for us, as well as clipping
-- 
1.6.3.rc1.2.g0164.dirty