From: Søren Sandmann Pedersen <s...@redhat.com>
Introduce a new ITER_LOCALIZED_ALPHA flag that indicates that the
alpha value computed is used only for the alpha channel of the output;
it doesn't affect the RGB channels.
Then in pixman-bits-image.c, if a destination is either a8r8g8b8 or
x8r8g8b8 with localized alpha, the iterator will return a pointer
directly into the image.
---
pixman/pixman-bits-image.c | 31 +++++++++++++++++++++++++++++--
pixman/pixman-general.c | 19 +++++++++++++++++--
pixman/pixman-private.h | 19 +++++++++++++++++--
3 files changed, 63 insertions(+), 6 deletions(-)
diff --git a/pixman/pixman-bits-image.c b/pixman/pixman-bits-image.c
index 9cd8b5a..df8d56e 100644
--- a/pixman/pixman-bits-image.c
+++ b/pixman/pixman-bits-image.c
@@ -1410,6 +1410,18 @@ next_line_write_wide (pixman_iter_t *iter)
iter->y++;
}
+static uint32_t *
+get_scanline_direct_write (pixman_iter_t *iter, const uint32_t *mask)
+{
+ return iter->buffer;
+}
+
+static void
+next_line_direct_write (pixman_iter_t *iter)
+{
+ iter->buffer += iter->image->bits.rowstride;
+}
+
void
_pixman_bits_image_iter_init (pixman_image_t *image,
pixman_iter_t *iter,
@@ -1418,8 +1430,23 @@ _pixman_bits_image_iter_init (pixman_image_t *image,
{
if ((flags & (ITER_NARROW | ITER_WRITE)) == (ITER_NARROW | ITER_WRITE))
{
- iter->get_scanline = get_scanline_narrow;
- iter->next_line = next_line_write_narrow;
+ if (((image->common.flags &
+ (FAST_PATH_NO_ALPHA_MAP | FAST_PATH_NO_ACCESSORS)) ==
+ (FAST_PATH_NO_ALPHA_MAP | FAST_PATH_NO_ACCESSORS)) &&
+ (image->bits.format == PIXMAN_a8r8g8b8 ||
+ (image->bits.format == PIXMAN_x8r8g8b8 &&
+ (flags & ITER_LOCALIZED_ALPHA))))
+ {
+ iter->buffer = image->bits.bits + y * image->bits.rowstride + x;
+
+ iter->get_scanline = get_scanline_direct_write;
+ iter->next_line = next_line_direct_write;
+ }
+ else
+ {
+ iter->get_scanline = get_scanline_narrow;
+ iter->next_line = next_line_write_narrow;
+ }
}
else if (flags & ITER_WRITE)
{
diff --git a/pixman/pixman-general.c b/pixman/pixman-general.c
index 4f73331..84b52c2 100644
--- a/pixman/pixman-general.c
+++ b/pixman/pixman-general.c
@@ -106,7 +106,7 @@ general_composite_rect (pixman_implementation_t *imp,
pixman_iter_t src_iter, mask_iter, dest_iter;
pixman_combine_32_func_t compose;
pixman_bool_t component_alpha;
- iter_flags_t narrow;
+ iter_flags_t narrow, dest_flags;
int Bpp;
int i;
@@ -143,9 +143,24 @@ general_composite_rect (pixman_implementation_t *imp,
mask_x, mask_y, width, height,
mask_buffer, narrow);
+ if (op == PIXMAN_OP_CLEAR ||
+ op == PIXMAN_OP_SRC ||
+ op == PIXMAN_OP_DST ||
+ op == PIXMAN_OP_OVER ||
+ op == PIXMAN_OP_IN_REVERSE ||
+ op == PIXMAN_OP_OUT_REVERSE ||
+ op == PIXMAN_OP_ADD)
+ {
+ dest_flags = narrow | ITER_WRITE | ITER_LOCALIZED_ALPHA;
+ }
+ else
+ {
+ dest_flags = narrow | ITER_WRITE;
+ }
+
_pixman_implementation_iter_init (imp->toplevel, &dest_iter, dest,
dest_x, dest_y, width, height,
- dest_buffer, narrow | ITER_WRITE);
+ dest_buffer, dest_flags);
component_alpha =
mask &&
diff --git a/pixman/pixman-private.h b/pixman/pixman-private.h
index 8d3a604..8532b98 100644
--- a/pixman/pixman-private.h
+++ b/pixman/pixman-private.h
@@ -185,8 +185,23 @@ union pixman_image
typedef struct pixman_iter_t pixman_iter_t;
typedef enum
{
- ITER_NARROW = (1 << 0),
- ITER_WRITE = (1 << 1)
+ ITER_NARROW = (1 << 0),
+ ITER_WRITE = (1 << 1),
+
+ /* "Localized alpha" is when the alpha channel is used only to compute the
+ * alpha value of the destination and doesn't influence the RGB part.
+ *
+ * For example, the OVER operator has localized alpha for the destination,
+ * because the destination alpha doesn't affect the results in the RGB
+ * channels. Similarly, ADD has localized alpha for both source and
+ * destination because the alpha values never 'leak' into the resulting
+ * RGB values.
+ *
+ * When he destination is xRGB, this is useful knowledge, because then
+ * we can treat it as ARGB, which means in some cases we can avoid copying
+ * it to a temporary buffer.
+ */
+ ITER_LOCALIZED_ALPHA = (1 << 2)
} iter_flags_t;
struct pixman_iter_t
--
1.6.0.6
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