[Pixman] [PATCH] Introduce new FAST_PATH_SAMPLES_OPAQUE flag

[Søren Sandmann Pedersen]

From: Søren Sandmann Pedersen <ssp at redhat.com>

This flag is set whenever the pixels of a bits image don't have an
alpha channel. Together with FAST_PATH_SAMPLES_COVER_CLIP it implies
that the image effectively is opaque, so we can do operator reductions
such as OVER->SRC.
---
 pixman/pixman-image.c   |   10 ++++++----
 pixman/pixman-private.h |    1 +
 pixman/pixman.c         |   11 +++++++++++
 3 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/pixman/pixman-image.c b/pixman/pixman-image.c
index 0b8bb3c..0e3601f 100644
--- a/pixman/pixman-image.c
+++ b/pixman/pixman-image.c
@@ -406,12 +406,14 @@ compute_image_info (pixman_image_t *image)
 	    }
 	}
 
-	if (image->common.repeat != PIXMAN_REPEAT_NONE				&&
-	    !PIXMAN_FORMAT_A (image->bits.format)				&&
+	if (!PIXMAN_FORMAT_A (image->bits.format)				&&
 	    PIXMAN_FORMAT_TYPE (image->bits.format) != PIXMAN_TYPE_GRAY		&&
 	    PIXMAN_FORMAT_TYPE (image->bits.format) != PIXMAN_TYPE_COLOR)
 	{
-	    flags |= FAST_PATH_IS_OPAQUE;
+	    flags |= FAST_PATH_SAMPLES_OPAQUE;
+
+	    if (image->common.repeat != PIXMAN_REPEAT_NONE)
+		flags |= FAST_PATH_IS_OPAQUE;
 	}
 
 	if (source_image_needs_out_of_bounds_workaround (&image->bits))
@@ -459,7 +461,7 @@ compute_image_info (pixman_image_t *image)
 	image->common.filter == PIXMAN_FILTER_CONVOLUTION	||
 	image->common.component_alpha)
     {
-	flags &= ~FAST_PATH_IS_OPAQUE;
+	flags &= ~(FAST_PATH_IS_OPAQUE | FAST_PATH_SAMPLES_OPAQUE);
     }
 
     image->common.flags = flags;
diff --git a/pixman/pixman-private.h b/pixman/pixman-private.h
index c4e6bb8..dedea0b 100644
--- a/pixman/pixman-private.h
+++ b/pixman/pixman-private.h
@@ -571,6 +571,7 @@ _pixman_choose_implementation (void);
 #define FAST_PATH_BILINEAR_FILTER		(1 << 20)
 #define FAST_PATH_NO_NORMAL_REPEAT		(1 << 21)
 #define FAST_PATH_HAS_TRANSFORM			(1 << 22)
+#define FAST_PATH_SAMPLES_OPAQUE		(1 << 23)
 
 #define FAST_PATH_PAD_REPEAT						\
     (FAST_PATH_NO_NONE_REPEAT		|				\
diff --git a/pixman/pixman.c b/pixman/pixman.c
index e79e135..55c5981 100644
--- a/pixman/pixman.c
+++ b/pixman/pixman.c
@@ -884,6 +884,17 @@ do_composite (pixman_op_t	       op,
     if (!analyze_extent (mask, dest_x - mask_x, dest_y - mask_y, extents, &mask_flags))
 	goto out;
 
+    /* If the clip is within the source samples, and the samples are opaque,
+     * then the source is effectively opaque.
+     */
+#define BOTH (FAST_PATH_SAMPLES_OPAQUE | FAST_PATH_SAMPLES_COVER_CLIP)
+
+    if ((src_flags & BOTH) == BOTH)
+	src_flags |= FAST_PATH_IS_OPAQUE;
+    
+    if ((mask_flags & BOTH) == BOTH)
+	mask_flags |= FAST_PATH_IS_OPAQUE;
+    
     /*
      * Check if we can replace our operator by a simpler one
      * if the src or dest are opaque. The output operator should be
-- 
1.7.1.1