uxa: Simplify BLT solid acceleration for spans filling by only clipping once.

We were clipping each span against the bounds of the clip, throwing
out the span early if it was all clipped, and then walked the clip box
clipping against each of the cliprects.  We would expect spans to
typically be clipped against one box, and not thrown out, so we were
not saving any work there.  For multiple cliprects, we were adding
work.  Only for many spans clipped entirely out of a complicated clip
region would it have saved work, and it clearly didn't save bugs as
evidenced by the many fix attempts here.

Reviewed-by: Keith Packard <keithp@keithp.com>
(cherry picked from commit ace324e4aa27effdd621156eec03f3f87b610732)

Signed-off-by: Owain G. Ainsworth <oga@openbsd.org>

1 files changed, 21 insertions, 44 deletions

diff --git a/uxa/uxa-accel.c b/uxa/uxa-accel.c
index 339144bc..18131127 100644
--- a/uxa/uxa-accel.c
+++ b/uxa/uxa-accel.c
@@ -1,3 +1,4 @@
+
 /*
  * Copyright ® 2001 Keith Packard
  *
@@ -63,7 +64,7 @@ uxa_fill_spans(DrawablePtr pDrawable, GCPtr pGC, int n,
 	BoxPtr pextent, pbox;
 	int nbox;
 	int extentX1, extentX2, extentY1, extentY2;
-	int fullX1, fullX2, fullY1;
+	int x1, x2, y, fullX1, fullX2, fullY1;
 	int partX1, partX2;
 	int off_x, off_y;
 	xRenderColor color;
@@ -214,58 +215,34 @@ solid:
 						 pGC->fgPixel))
 		goto fallback;
 
-	pextent = REGION_EXTENTS(pGC->screen, pClip);
-	extentX1 = pextent->x1;
-	extentY1 = pextent->y1;
-	extentX2 = pextent->x2;
-	extentY2 = pextent->y2;
 	while (n--) {
-		fullX1 = ppt->x;
-		fullY1 = ppt->y;
-		fullX2 = fullX1 + (int)*pwidth;
+		x1 = ppt->x;
+		y = ppt->y;
+		x2 = x1 + (int)*pwidth;
 		ppt++;
 		pwidth++;
 
-		if (fullY1 < extentY1 || extentY2 <= fullY1)
-			continue;
+		nbox = REGION_NUM_RECTS(pClip);
+		pbox = REGION_RECTS(pClip);
+		while (nbox--) {
+			if (pbox->y1 > y || pbox->y2 <= y)
+				continue;
 
-		if (fullX1 < extentX1)
-			fullX1 = extentX1;
+			if (x1 < pbox->x1)
+				x1 = pbox->x1;
 
-		if (fullX2 > extentX2)
-			fullX2 = extentX2;
+			if (x2 > pbox->x2)
+				x2 = pbox->x2;
 
-		if (fullX1 >= fullX2)
-			continue;
+			if (x2 <= x1)
+				continue;
 
-		nbox = REGION_NUM_RECTS(pClip);
-		if (nbox == 1) {
 			(*uxa_screen->info->solid) (dst_pixmap,
-						    fullX1 + off_x,
-						    fullY1 + off_y,
-						    fullX2 + off_x,
-						    fullY1 + 1 + off_y);
-		} else {
-			pbox = REGION_RECTS(pClip);
-			while (nbox--) {
-				if (pbox->y1 <= fullY1 && fullY1 < pbox->y2) {
-					partX1 = pbox->x1;
-					if (partX1 < fullX1)
-						partX1 = fullX1;
-					partX2 = pbox->x2;
-					if (partX2 > fullX2)
-						partX2 = fullX2;
-					if (partX2 > partX1) {
-						(*uxa_screen->info->
-						 solid) (dst_pixmap,
-							 partX1 + off_x,
-							 fullY1 + off_y,
-							 partX2 + off_x,
-							 fullY1 + 1 + off_y);
-					}
-				}
-				pbox++;
-			}
+						    x1 + off_x,
+						    y + off_y,
+						    x2 + off_x,
+						    y + 1 + off_y);
+			pbox++;
 		}
 	}
 	(*uxa_screen->info->done_solid) (dst_pixmap);