diff options
| -rw-r--r-- | lerp-notes | 42 | ||||
| -rw-r--r-- | pixman/pixman.h | 92 |
2 files changed, 90 insertions, 44 deletions
diff --git a/lerp-notes b/lerp-notes new file mode 100644 index 00000000..883c6e93 --- /dev/null +++ b/lerp-notes @@ -0,0 +1,42 @@ +PIXMAN_TYPE_A means the A channel is at the bottom of the pixel. Ie., +x4a4 is xxxxaaaa and not aaaaxxxx. + +PIXMAN_TYPE_W means the W channel is at the top of the pixel. Ie., +x4w4 would be meaningless. However, w8x24 means + + wwwwwwwwxxxxxxxxxxxxxxxxxxxxxxxx + + +The interpretation of TYPE_W formats is that they are shades of +white. Basically, the alpha channel is replicated in the r, g, and b +channels so that the result is white with an alpha of w. + +The interpretation for TYPE_A formats is that the rgb channels are +0. Ie., TYPE_A pixels are black with an alpha of a. + +The TYPE_W interpretation is convenient because in conjunction with +the LERP operators it means component alpha becomes completely +regular. + +LERP is always interpreted across all channels, so if you use a TYPE_W +format, the result is that all channels are modulated with the alpha +value. Component alpha then is just a matter of using an RGB mask for +the LERP. + +We need to be careful with strength reducing. Basically, the OVER_LERP +operator can be reduced from + + OVER_LERP with TYPE_W mask + +to + + OVER with TYPE_A mask + +For regular OVER TYPE_A and TYPE_W masks are the same. + +However, OVER_LERP with TYPE_A mask is something entirely different +that cannot be implemented in terms of regular OVER. (That one simply +throws away the RGB channels of the operation). + +For completeness, we should probably specify what happens if you ask +for component alpha with an A mask. diff --git a/pixman/pixman.h b/pixman/pixman.h index ec95fcc2..75969a2d 100644 --- a/pixman/pixman.h +++ b/pixman/pixman.h @@ -664,6 +664,7 @@ struct pixman_indexed #define PIXMAN_TYPE_YUY2 6 #define PIXMAN_TYPE_YV12 7 #define PIXMAN_TYPE_BGRA 8 +#define PIXMAN_TYPE_W 9 #define PIXMAN_FORMAT_COLOR(f) \ (PIXMAN_FORMAT_TYPE(f) == PIXMAN_TYPE_ARGB || \ @@ -672,67 +673,70 @@ struct pixman_indexed /* 32bpp formats */ typedef enum { - PIXMAN_a8r8g8b8 = PIXMAN_FORMAT(32,PIXMAN_TYPE_ARGB,8,8,8,8), - PIXMAN_x8r8g8b8 = PIXMAN_FORMAT(32,PIXMAN_TYPE_ARGB,0,8,8,8), - PIXMAN_a8b8g8r8 = PIXMAN_FORMAT(32,PIXMAN_TYPE_ABGR,8,8,8,8), - PIXMAN_x8b8g8r8 = PIXMAN_FORMAT(32,PIXMAN_TYPE_ABGR,0,8,8,8), - PIXMAN_b8g8r8a8 = PIXMAN_FORMAT(32,PIXMAN_TYPE_BGRA,8,8,8,8), - PIXMAN_b8g8r8x8 = PIXMAN_FORMAT(32,PIXMAN_TYPE_BGRA,0,8,8,8), - PIXMAN_x2r10g10b10 = PIXMAN_FORMAT(32,PIXMAN_TYPE_ARGB,0,10,10,10), - PIXMAN_a2r10g10b10 = PIXMAN_FORMAT(32,PIXMAN_TYPE_ARGB,2,10,10,10), - PIXMAN_x2b10g10r10 = PIXMAN_FORMAT(32,PIXMAN_TYPE_ABGR,0,10,10,10), - PIXMAN_a2b10g10r10 = PIXMAN_FORMAT(32,PIXMAN_TYPE_ABGR,2,10,10,10), + PIXMAN_a8r8g8b8 = PIXMAN_FORMAT(32,PIXMAN_TYPE_ARGB,8,8,8,8), + PIXMAN_x8r8g8b8 = PIXMAN_FORMAT(32,PIXMAN_TYPE_ARGB,0,8,8,8), + PIXMAN_a8b8g8r8 = PIXMAN_FORMAT(32,PIXMAN_TYPE_ABGR,8,8,8,8), + PIXMAN_x8b8g8r8 = PIXMAN_FORMAT(32,PIXMAN_TYPE_ABGR,0,8,8,8), + PIXMAN_b8g8r8a8 = PIXMAN_FORMAT(32,PIXMAN_TYPE_BGRA,8,8,8,8), + PIXMAN_b8g8r8x8 = PIXMAN_FORMAT(32,PIXMAN_TYPE_BGRA,0,8,8,8), + PIXMAN_x2r10g10b10 = PIXMAN_FORMAT(32,PIXMAN_TYPE_ARGB,0,10,10,10), + PIXMAN_a2r10g10b10 = PIXMAN_FORMAT(32,PIXMAN_TYPE_ARGB,2,10,10,10), + PIXMAN_x2b10g10r10 = PIXMAN_FORMAT(32,PIXMAN_TYPE_ABGR,0,10,10,10), + PIXMAN_a2b10g10r10 = PIXMAN_FORMAT(32,PIXMAN_TYPE_ABGR,2,10,10,10), + PIXMAN_w8x24 = PIXMAN_FORMAT(32,PIXMAN_TYPE_W,8,0,0,0), /* 24bpp formats */ - PIXMAN_r8g8b8 = PIXMAN_FORMAT(24,PIXMAN_TYPE_ARGB,0,8,8,8), - PIXMAN_b8g8r8 = PIXMAN_FORMAT(24,PIXMAN_TYPE_ABGR,0,8,8,8), + PIXMAN_r8g8b8 = PIXMAN_FORMAT(24,PIXMAN_TYPE_ARGB,0,8,8,8), + PIXMAN_b8g8r8 = PIXMAN_FORMAT(24,PIXMAN_TYPE_ABGR,0,8,8,8), /* 16bpp formats */ - PIXMAN_r5g6b5 = PIXMAN_FORMAT(16,PIXMAN_TYPE_ARGB,0,5,6,5), - PIXMAN_b5g6r5 = PIXMAN_FORMAT(16,PIXMAN_TYPE_ABGR,0,5,6,5), - - PIXMAN_a1r5g5b5 = PIXMAN_FORMAT(16,PIXMAN_TYPE_ARGB,1,5,5,5), - PIXMAN_x1r5g5b5 = PIXMAN_FORMAT(16,PIXMAN_TYPE_ARGB,0,5,5,5), - PIXMAN_a1b5g5r5 = PIXMAN_FORMAT(16,PIXMAN_TYPE_ABGR,1,5,5,5), - PIXMAN_x1b5g5r5 = PIXMAN_FORMAT(16,PIXMAN_TYPE_ABGR,0,5,5,5), - PIXMAN_a4r4g4b4 = PIXMAN_FORMAT(16,PIXMAN_TYPE_ARGB,4,4,4,4), - PIXMAN_x4r4g4b4 = PIXMAN_FORMAT(16,PIXMAN_TYPE_ARGB,0,4,4,4), - PIXMAN_a4b4g4r4 = PIXMAN_FORMAT(16,PIXMAN_TYPE_ABGR,4,4,4,4), - PIXMAN_x4b4g4r4 = PIXMAN_FORMAT(16,PIXMAN_TYPE_ABGR,0,4,4,4), + PIXMAN_r5g6b5 = PIXMAN_FORMAT(16,PIXMAN_TYPE_ARGB,0,5,6,5), + PIXMAN_b5g6r5 = PIXMAN_FORMAT(16,PIXMAN_TYPE_ABGR,0,5,6,5), + + PIXMAN_a1r5g5b5 = PIXMAN_FORMAT(16,PIXMAN_TYPE_ARGB,1,5,5,5), + PIXMAN_x1r5g5b5 = PIXMAN_FORMAT(16,PIXMAN_TYPE_ARGB,0,5,5,5), + PIXMAN_a1b5g5r5 = PIXMAN_FORMAT(16,PIXMAN_TYPE_ABGR,1,5,5,5), + PIXMAN_x1b5g5r5 = PIXMAN_FORMAT(16,PIXMAN_TYPE_ABGR,0,5,5,5), + PIXMAN_a4r4g4b4 = PIXMAN_FORMAT(16,PIXMAN_TYPE_ARGB,4,4,4,4), + PIXMAN_x4r4g4b4 = PIXMAN_FORMAT(16,PIXMAN_TYPE_ARGB,0,4,4,4), + PIXMAN_a4b4g4r4 = PIXMAN_FORMAT(16,PIXMAN_TYPE_ABGR,4,4,4,4), + PIXMAN_x4b4g4r4 = PIXMAN_FORMAT(16,PIXMAN_TYPE_ABGR,0,4,4,4), /* 8bpp formats */ - PIXMAN_a8 = PIXMAN_FORMAT(8,PIXMAN_TYPE_A,8,0,0,0), - PIXMAN_r3g3b2 = PIXMAN_FORMAT(8,PIXMAN_TYPE_ARGB,0,3,3,2), - PIXMAN_b2g3r3 = PIXMAN_FORMAT(8,PIXMAN_TYPE_ABGR,0,3,3,2), - PIXMAN_a2r2g2b2 = PIXMAN_FORMAT(8,PIXMAN_TYPE_ARGB,2,2,2,2), - PIXMAN_a2b2g2r2 = PIXMAN_FORMAT(8,PIXMAN_TYPE_ABGR,2,2,2,2), + PIXMAN_a8 = PIXMAN_FORMAT(8,PIXMAN_TYPE_A,8,0,0,0), + PIXMAN_w8 = PIXMAN_FORMAT(8,PIXMAN_TYPE_W,8,0,0,0), + PIXMAN_r3g3b2 = PIXMAN_FORMAT(8,PIXMAN_TYPE_ARGB,0,3,3,2), + PIXMAN_b2g3r3 = PIXMAN_FORMAT(8,PIXMAN_TYPE_ABGR,0,3,3,2), + PIXMAN_a2r2g2b2 = PIXMAN_FORMAT(8,PIXMAN_TYPE_ARGB,2,2,2,2), + PIXMAN_a2b2g2r2 = PIXMAN_FORMAT(8,PIXMAN_TYPE_ABGR,2,2,2,2), - PIXMAN_c8 = PIXMAN_FORMAT(8,PIXMAN_TYPE_COLOR,0,0,0,0), - PIXMAN_g8 = PIXMAN_FORMAT(8,PIXMAN_TYPE_GRAY,0,0,0,0), + PIXMAN_c8 = PIXMAN_FORMAT(8,PIXMAN_TYPE_COLOR,0,0,0,0), + PIXMAN_g8 = PIXMAN_FORMAT(8,PIXMAN_TYPE_GRAY,0,0,0,0), - PIXMAN_x4a4 = PIXMAN_FORMAT(8,PIXMAN_TYPE_A,4,0,0,0), + PIXMAN_x4a4 = PIXMAN_FORMAT(8,PIXMAN_TYPE_A,4,0,0,0), - PIXMAN_x4c4 = PIXMAN_FORMAT(8,PIXMAN_TYPE_COLOR,0,0,0,0), - PIXMAN_x4g4 = PIXMAN_FORMAT(8,PIXMAN_TYPE_GRAY,0,0,0,0), + PIXMAN_x4c4 = PIXMAN_FORMAT(8,PIXMAN_TYPE_COLOR,0,0,0,0), + PIXMAN_x4g4 = PIXMAN_FORMAT(8,PIXMAN_TYPE_GRAY,0,0,0,0), /* 4bpp formats */ - PIXMAN_a4 = PIXMAN_FORMAT(4,PIXMAN_TYPE_A,4,0,0,0), - PIXMAN_r1g2b1 = PIXMAN_FORMAT(4,PIXMAN_TYPE_ARGB,0,1,2,1), - PIXMAN_b1g2r1 = PIXMAN_FORMAT(4,PIXMAN_TYPE_ABGR,0,1,2,1), - PIXMAN_a1r1g1b1 = PIXMAN_FORMAT(4,PIXMAN_TYPE_ARGB,1,1,1,1), - PIXMAN_a1b1g1r1 = PIXMAN_FORMAT(4,PIXMAN_TYPE_ABGR,1,1,1,1), + PIXMAN_a4 = PIXMAN_FORMAT(4,PIXMAN_TYPE_A,4,0,0,0), + PIXMAN_r1g2b1 = PIXMAN_FORMAT(4,PIXMAN_TYPE_ARGB,0,1,2,1), + PIXMAN_b1g2r1 = PIXMAN_FORMAT(4,PIXMAN_TYPE_ABGR,0,1,2,1), + PIXMAN_a1r1g1b1 = PIXMAN_FORMAT(4,PIXMAN_TYPE_ARGB,1,1,1,1), + PIXMAN_a1b1g1r1 = PIXMAN_FORMAT(4,PIXMAN_TYPE_ABGR,1,1,1,1), - PIXMAN_c4 = PIXMAN_FORMAT(4,PIXMAN_TYPE_COLOR,0,0,0,0), - PIXMAN_g4 = PIXMAN_FORMAT(4,PIXMAN_TYPE_GRAY,0,0,0,0), + PIXMAN_c4 = PIXMAN_FORMAT(4,PIXMAN_TYPE_COLOR,0,0,0,0), + PIXMAN_g4 = PIXMAN_FORMAT(4,PIXMAN_TYPE_GRAY,0,0,0,0), /* 1bpp formats */ - PIXMAN_a1 = PIXMAN_FORMAT(1,PIXMAN_TYPE_A,1,0,0,0), + PIXMAN_a1 = PIXMAN_FORMAT(1,PIXMAN_TYPE_A,1,0,0,0), + PIXMAN_w1 = PIXMAN_FORMAT(1,PIXMAN_TYPE_W,1,0,0,0), - PIXMAN_g1 = PIXMAN_FORMAT(1,PIXMAN_TYPE_GRAY,0,0,0,0), + PIXMAN_g1 = PIXMAN_FORMAT(1,PIXMAN_TYPE_GRAY,0,0,0,0), /* YUV formats */ - PIXMAN_yuy2 = PIXMAN_FORMAT(16,PIXMAN_TYPE_YUY2,0,0,0,0), - PIXMAN_yv12 = PIXMAN_FORMAT(12,PIXMAN_TYPE_YV12,0,0,0,0) + PIXMAN_yuy2 = PIXMAN_FORMAT(16,PIXMAN_TYPE_YUY2,0,0,0,0), + PIXMAN_yv12 = PIXMAN_FORMAT(12,PIXMAN_TYPE_YV12,0,0,0,0) } pixman_format_code_t; /* Querying supported format values. */ |