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comparison: gfx/cairo/libpixman/src/pixman-dither.h
gfx/cairo/libpixman/src/pixman-dither.h
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
equal
deleted
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| -1:000000000000 | 0:24b3ea95bb4a |
|---|---|
| 1 #define R16_BITS 5 | |
| 2 #define G16_BITS 6 | |
| 3 #define B16_BITS 5 | |
| 4 | |
| 5 #define R16_SHIFT (B16_BITS + G16_BITS) | |
| 6 #define G16_SHIFT (B16_BITS) | |
| 7 #define B16_SHIFT 0 | |
| 8 | |
| 9 #define MASK 0xff | |
| 10 #define ONE_HALF 0x80 | |
| 11 | |
| 12 #define A_SHIFT 8 * 3 | |
| 13 #define R_SHIFT 8 * 2 | |
| 14 #define G_SHIFT 8 | |
| 15 #define A_MASK 0xff000000 | |
| 16 #define R_MASK 0xff0000 | |
| 17 #define G_MASK 0xff00 | |
| 18 | |
| 19 #define RB_MASK 0xff00ff | |
| 20 #define AG_MASK 0xff00ff00 | |
| 21 #define RB_ONE_HALF 0x800080 | |
| 22 #define RB_MASK_PLUS_ONE 0x10000100 | |
| 23 | |
| 24 #define ALPHA_8(x) ((x) >> A_SHIFT) | |
| 25 #define RED_8(x) (((x) >> R_SHIFT) & MASK) | |
| 26 #define GREEN_8(x) (((x) >> G_SHIFT) & MASK) | |
| 27 #define BLUE_8(x) ((x) & MASK) | |
| 28 | |
| 29 // This uses the same dithering technique that Skia does. | |
| 30 // It is essentially preturbing the lower bit based on the | |
| 31 // high bit | |
| 32 static inline uint16_t dither_32_to_16(uint32_t c) | |
| 33 { | |
| 34 uint8_t b = BLUE_8(c); | |
| 35 uint8_t g = GREEN_8(c); | |
| 36 uint8_t r = RED_8(c); | |
| 37 r = ((r << 1) - ((r >> (8 - R16_BITS) << (8 - R16_BITS)) | (r >> R16_BITS))) >> (8 - R16_BITS); | |
| 38 g = ((g << 1) - ((g >> (8 - G16_BITS) << (8 - G16_BITS)) | (g >> G16_BITS))) >> (8 - G16_BITS); | |
| 39 b = ((b << 1) - ((b >> (8 - B16_BITS) << (8 - B16_BITS)) | (b >> B16_BITS))) >> (8 - B16_BITS); | |
| 40 return ((r << R16_SHIFT) | (g << G16_SHIFT) | (b << B16_SHIFT)); | |
| 41 } | |
| 42 | |
| 43 static inline uint16_t dither_8888_to_0565(uint32_t color, pixman_bool_t toggle) | |
| 44 { | |
| 45 // alternate between a preturbed truncation and a regular truncation | |
| 46 if (toggle) { | |
| 47 return dither_32_to_16(color); | |
| 48 } else { | |
| 49 return convert_8888_to_0565(color); | |
| 50 } | |
| 51 } |
