From 1cc9762b08a127a2475a44da71ca07cb294562f2 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Tue, 16 Sep 2014 12:14:31 +0100
Subject: [PATCH] uxa: Fix conversion of Segments into Rectangles

The trick is to make sure we consider the CapLast setting in the
direction the line is being drawn and adjust the inked pixels
accordingly.

Testcase: DrawSegments/hv0
Reported-by: Russell King
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 src/uxa/uxa-accel.c | 64 +++++++++++++++++++++++++++++----------------
 1 file changed, 42 insertions(+), 22 deletions(-)

diff --git a/src/uxa/uxa-accel.c b/src/uxa/uxa-accel.c
index 757b2761..9e7879bc 100644
--- a/src/uxa/uxa-accel.c
+++ b/src/uxa/uxa-accel.c
@@ -675,6 +675,43 @@ uxa_poly_lines(DrawablePtr pDrawable, GCPtr pGC, int mode, int npt,
 	free(prect);
 }
 
+static BoxRec box_from_seg(const xSegment *seg, GCPtr gc)
+{
+	BoxRec b;
+
+	if (seg->x1 == seg->x2) {
+		if (seg->y1 > seg->y2) {
+			b.y2 = seg->y1 + 1;
+			b.y1 = seg->y2 + 1;
+			if (gc->capStyle != CapNotLast)
+				b.y1--;
+		} else {
+			b.y1 = seg->y1;
+			b.y2 = seg->y2;
+			if (gc->capStyle != CapNotLast)
+				b.y2++;
+		}
+		b.x1 = seg->x1;
+		b.x2 = seg->x1 + 1;
+	} else {
+		if (seg->x1 > seg->x2) {
+			b.x2 = seg->x1 + 1;
+			b.x1 = seg->x2 + 1;
+			if (gc->capStyle != CapNotLast)
+				b.x1--;
+		} else {
+			b.x1 = seg->x1;
+			b.x2 = seg->x2;
+			if (gc->capStyle != CapNotLast)
+				b.x2++;
+		}
+		b.y1 = seg->y1;
+		b.y2 = seg->y1 + 1;
+	}
+
+	return b;
+}
+
 /**
  * uxa_poly_segment() checks if it can accelerate the lines as a group of
  * horizontal or vertical lines (rectangles), and uses existing rectangle fill
@@ -718,28 +755,11 @@ uxa_poly_segment(DrawablePtr pDrawable, GCPtr pGC, int nseg, xSegment * pSeg)
 	if (!prect)
 		return;
 	for (i = 0; i < nseg; i++) {
-		if (pSeg[i].x1 < pSeg[i].x2) {
-			prect[i].x = pSeg[i].x1;
-			prect[i].width = pSeg[i].x2 - pSeg[i].x1 + 1;
-		} else {
-			prect[i].x = pSeg[i].x2;
-			prect[i].width = pSeg[i].x1 - pSeg[i].x2 + 1;
-		}
-		if (pSeg[i].y1 < pSeg[i].y2) {
-			prect[i].y = pSeg[i].y1;
-			prect[i].height = pSeg[i].y2 - pSeg[i].y1 + 1;
-		} else {
-			prect[i].y = pSeg[i].y2;
-			prect[i].height = pSeg[i].y1 - pSeg[i].y2 + 1;
-		}
-
-		/* don't paint last pixel */
-		if (pGC->capStyle == CapNotLast) {
-			if (prect[i].width == 1)
-				prect[i].height--;
-			else
-				prect[i].width--;
-		}
+		BoxRec b = box_from_seg(&pSeg[i], pGC);
+		prect[i].x = b.x1;
+		prect[i].y = b.y1;
+		prect[i].width  = b.x2 - b.x1;
+		prect[i].height = b.y2 - b.y1;
 	}
 	pGC->ops->PolyFillRect(pDrawable, pGC, nseg, prect);
 	free(prect);