Fix alpha map computation in miComputeCompositeRegion()

According to the RENDER spec, the origin of the alpha map is
interpreted relative to the origin of the drawable of the image, not
the origin of the drawable of the alpha map.

This commit fixes that and adds an alpha-test.c test program.

The only use of alpha maps I have been able to find is in Qt and they
don't use a non-zero alpha origin.
This commit is contained in:
Søren Sandmann Pedersen 2009-05-27 15:51:19 -04:00
parent ebfd6688d1
commit 6e69272473

View File

@ -459,8 +459,8 @@ miComputeCompositeRegion (RegionPtr pRegion,
if (pSrc->alphaMap)
{
if (!miClipPictureSrc (pRegion, pSrc->alphaMap,
xDst - (xSrc + pSrc->alphaOrigin.x),
yDst - (ySrc + pSrc->alphaOrigin.y)))
xDst - (xSrc - pSrc->alphaOrigin.x),
yDst - (ySrc - pSrc->alphaOrigin.y)))
{
pixman_region_fini (pRegion);
return FALSE;
@ -477,8 +477,8 @@ miComputeCompositeRegion (RegionPtr pRegion,
if (pMask->alphaMap)
{
if (!miClipPictureSrc (pRegion, pMask->alphaMap,
xDst - (xMask + pMask->alphaOrigin.x),
yDst - (yMask + pMask->alphaOrigin.y)))
xDst - (xMask - pMask->alphaOrigin.x),
yDst - (yMask - pMask->alphaOrigin.y)))
{
pixman_region_fini (pRegion);
return FALSE;