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Diffstat (limited to 'docs')
-rw-r--r-- | docs/pixman.txt | 47 |
1 files changed, 0 insertions, 47 deletions
diff --git a/docs/pixman.txt b/docs/pixman.txt deleted file mode 100644 index e42e9d1..0000000 --- a/docs/pixman.txt +++ /dev/null @@ -1,47 +0,0 @@ -= Pixman accelerated Rendering = - -Several people recommended using pixman for 2D blitting to improve performance -as pixman has assembler-accelerated backends. However, pixman does not provide -the functions we need. -Most rendering operations we need, do alpha compositing with a foreground and -background color. With pixman we would have to do something like: - - pixman_image_t *pdst = pixman_image_create_bits( - PIXMAN_x8r8g8b8, - width, - height, - (uint32_t*)dst, - rb->stride); - pixman_image_t *pmsk = pixman_image_create_bits( - PIXMAN_a8, - width, - height, - (uint32_t*)src, - req->buf->stride); - - pixman_color_t fcol = { 0xffff, 0xffff, 0xffff, 0xffff }; - pixman_image_t *psrc = pixman_image_create_solid_fill( - &fcol); - - uint32_t bcol = (req->br << 16) | (req->bg << 8) | req->bb; - pixman_fill((void*)dst, rb->stride / 4, 32, 0, 0, - width, height, bcol); - - pixman_image_composite(PIXMAN_OP_OVER, - psrc, pmsk, pdst, - 0, 0, 0, 0, 0, 0, - width, height); - -That is, we create pixman-images for the destination and the mask. We could -save them in the video-display and glyph objects so there is actually no need -to allocate them dynamically. However, the solid color object can be any RGB -value and thus it must be allocated for every blit. This is way too heavy and -pixman should really provide a way to create solid images easier. Preferably -without any function call. -But the bigger problem is actually that we have to copy data twice. We need to -first call pixman_fill() and then pixman_image_composite() to get the -behavior we want. This totally kills performance. - -Profiling pixman_image_composite(), we see that it definitely is better than -our unoptimized blitters, but we need to add a function which does both -operations at once to pixman to get a decent performance. |