sna: Do not use color corrected pixel values for comparing against gc

Dashed zero-width lines devolve into two passes (first to draw the
foreground dashes, and then to draw the gaps). The code was using the
pixel value to decide which phase was being drawn -- however the color
on the gc is not always bit exact (e.g. alpha channel) with the pixel
value. As a result, we would oft miss drawing anything when rendering
into the scanout.

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1059152
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 24 insertions, 26 deletions

diff --git a/src/sna/sna_accel.c b/src/sna/sna_accel.c
index b1744ae2..36ad9b32 100644
--- a/src/sna/sna_accel.c
+++ b/src/sna/sna_accel.c
@@ -6457,6 +6457,7 @@ struct sna_fill_spans {
 	PixmapPtr pixmap;
 	RegionRec region;
 	unsigned flags;
+	uint32_t phase;
 	struct kgem_bo *bo;
 	struct sna_damage **damage;
 	int16_t dx, dy;
@@ -6630,9 +6631,7 @@ sna_poly_point__dash(DrawablePtr drawable, GCPtr gc,
 		     int mode, int n, DDXPointPtr pt)
 {
 	struct sna_fill_spans *data = sna_gc(gc)->priv;
-	struct sna_fill_op *op = data->op;
-
-	if (op->base.u.blt.pixel == gc->fgPixel)
+	if (data->phase == gc->fgPixel)
 		sna_poly_point__fill(drawable, gc, mode, n, pt);
 }
 
@@ -6641,9 +6640,7 @@ sna_poly_point__dash_clip_extents(DrawablePtr drawable, GCPtr gc,
 				  int mode, int n, DDXPointPtr pt)
 {
 	struct sna_fill_spans *data = sna_gc(gc)->priv;
-	struct sna_fill_op *op = data->op;
-
-	if (op->base.u.blt.pixel == gc->fgPixel)
+	if (data->phase == gc->fgPixel)
 		sna_poly_point__fill_clip_extents(drawable, gc, mode, n, pt);
 }
 
@@ -6652,9 +6649,7 @@ sna_poly_point__dash_clip_boxes(DrawablePtr drawable, GCPtr gc,
 				  int mode, int n, DDXPointPtr pt)
 {
 	struct sna_fill_spans *data = sna_gc(gc)->priv;
-	struct sna_fill_op *op = data->op;
-
-	if (op->base.u.blt.pixel == gc->fgPixel)
+	if (data->phase == gc->fgPixel)
 		sna_poly_point__fill_clip_boxes(drawable, gc, mode, n, pt);
 }
 
@@ -6707,9 +6702,7 @@ sna_fill_spans__dash(DrawablePtr drawable,
 		     DDXPointPtr pt, int *width, int sorted)
 {
 	struct sna_fill_spans *data = sna_gc(gc)->priv;
-	struct sna_fill_op *op = data->op;
-
-	if (op->base.u.blt.pixel == gc->fgPixel)
+	if (data->phase == gc->fgPixel)
 		sna_fill_spans__fill(drawable, gc, n, pt, width, sorted);
 }
 
@@ -6750,9 +6743,7 @@ sna_fill_spans__dash_offset(DrawablePtr drawable,
 			    DDXPointPtr pt, int *width, int sorted)
 {
 	struct sna_fill_spans *data = sna_gc(gc)->priv;
-	struct sna_fill_op *op = data->op;
-
-	if (op->base.u.blt.pixel == gc->fgPixel)
+	if (data->phase == gc->fgPixel)
 		sna_fill_spans__fill_offset(drawable, gc, n, pt, width, sorted);
 }
 
@@ -6805,9 +6796,7 @@ sna_fill_spans__dash_clip_extents(DrawablePtr drawable,
 				  DDXPointPtr pt, int *width, int sorted)
 {
 	struct sna_fill_spans *data = sna_gc(gc)->priv;
-	struct sna_fill_op *op = data->op;
-
-	if (op->base.u.blt.pixel == gc->fgPixel)
+	if (data->phase == gc->fgPixel)
 		sna_fill_spans__fill_clip_extents(drawable, gc, n, pt, width, sorted);
 }
 
@@ -6889,9 +6878,7 @@ sna_fill_spans__dash_clip_boxes(DrawablePtr drawable,
 				DDXPointPtr pt, int *width, int sorted)
 {
 	struct sna_fill_spans *data = sna_gc(gc)->priv;
-	struct sna_fill_op *op = data->op;
-
-	if (op->base.u.blt.pixel == gc->fgPixel)
+	if (data->phase == gc->fgPixel)
 		sna_fill_spans__fill_clip_boxes(drawable, gc, n, pt, width, sorted);
 }
 
@@ -9206,7 +9193,11 @@ spans_fallback:
 				}
 				assert(gc->miTranslate);
 
-				DBG(("%s: miZeroLine (solid dash)\n", __FUNCTION__));
+				DBG(("%s: miZeroLine (solid dash, clipped? %d (complex? %d)), fg pass [%08x]\n",
+				     __FUNCTION__,
+				     !!(data.flags & 2), data.flags & 2 && !region_is_singular(&data.region),
+				     gc->fgPixel));
+
 				if (!sna_fill_init_blt(&fill,
 						       data.sna, data.pixmap,
 						       data.bo, gc->alu, color,
@@ -9214,14 +9205,21 @@ spans_fallback:
 					goto fallback;
 
 				gc->ops = &sna_gc_ops__tmp;
+				data.phase = gc->fgPixel;
 				miZeroDashLine(drawable, gc, mode, n, pt);
 				fill.done(data.sna, &fill);
 
+				DBG(("%s: miZeroLine (solid dash, clipped? %d (complex? %d)), bg pass [%08x]\n",
+				     __FUNCTION__,
+				     !!(data.flags & 2), data.flags & 2 && !region_is_singular(&data.region),
+				     gc->bgPixel));
+
 				if (sna_fill_init_blt(&fill,
-						       data.sna, data.pixmap,
-						       data.bo, gc->alu,
-						       gc->bgPixel,
-						       FILL_POINTS | FILL_SPANS)) {
+						      data.sna, data.pixmap,
+						      data.bo, gc->alu,
+						      gc->bgPixel,
+						      FILL_POINTS | FILL_SPANS)) {
+					data.phase = gc->bgPixel;
 					miZeroDashLine(drawable, gc, mode, n, pt);
 					fill.done(data.sna, &fill);
 				}