1 /* 2 * Copyright 2005, Stephan Aßmus <superstippi@gmx.de>. All rights reserved. 3 * Distributed under the terms of the MIT License. 4 * 5 * Base class for different drawing modes. 6 * 7 */ 8 9 #ifndef DRAWING_MODE_H 10 #define DRAWING_MODE_H 11 12 #include "PatternHandler.h" 13 #include "PixelFormat.h" 14 15 class PatternHandler; 16 17 typedef PixelFormat::color_type color_type; 18 typedef PixelFormat::agg_buffer agg_buffer; 19 20 union pixel32 { 21 uint32 data32; 22 uint8 data8[4]; 23 }; 24 25 // BLEND 26 // 27 // This macro assumes source alpha in range 0..255 and 28 // ignores dest alpha (is assumed to equal 255). 29 // TODO: We need the assignment of alpha only when drawing into bitmaps! 30 #define BLEND(d, r, g, b, a) \ 31 { \ 32 pixel32 _p; \ 33 _p.data32 = *(uint32*)d; \ 34 d[0] = (((((b) - _p.data8[0]) * (a)) + (_p.data8[0] << 8)) >> 8); \ 35 d[1] = (((((g) - _p.data8[1]) * (a)) + (_p.data8[1] << 8)) >> 8); \ 36 d[2] = (((((r) - _p.data8[2]) * (a)) + (_p.data8[2] << 8)) >> 8); \ 37 } 38 39 // BLEND_FROM 40 // 41 // This macro assumes source alpha in range 0..255 and 42 // ignores dest alpha (is assumed to equal 255). 43 // It uses two colors for the blending (f and s) and writes 44 // the result into a third color (d). 45 // TODO: We need the assignment of alpha only when drawing into bitmaps! 46 #define BLEND_FROM(d, r1, g1, b1, r2, g2, b2, a) \ 47 { \ 48 d[0] = (((((b2) - (b1)) * (a)) + ((b1) << 8)) >> 8); \ 49 d[1] = (((((g2) - (g1)) * (a)) + ((g1) << 8)) >> 8); \ 50 d[2] = (((((r2) - (r1)) * (a)) + ((r1) << 8)) >> 8); \ 51 } 52 53 // BLEND16 54 // 55 // This macro assumes source alpha in range 0..65025 and 56 // ignores dest alpha (is assumed to equal 255). 57 // TODO: We need the assignment of alpha only when drawing into bitmaps! 58 // BLEND16 59 #define BLEND16(d, r, g, b, a) \ 60 { \ 61 pixel32 _p; \ 62 _p.data32 = *(uint32*)d; \ 63 d[0] = (((((b) - _p.data8[0]) * (a)) + (_p.data8[0] << 16)) >> 16); \ 64 d[1] = (((((g) - _p.data8[1]) * (a)) + (_p.data8[1] << 16)) >> 16); \ 65 d[2] = (((((r) - _p.data8[2]) * (a)) + (_p.data8[2] << 16)) >> 16); \ 66 } 67 68 69 70 // BLEND_COMPOSITE 71 // 72 // This macro assumes source alpha in range 0..255 and 73 // composes the source color over a possibly semi-transparent background. 74 #define BLEND_COMPOSITE(d, r, g, b, a) \ 75 { \ 76 pixel32 _p; \ 77 _p.data32 = *(uint32*)d; \ 78 if (_p.data8[3] == 255) { \ 79 BLEND(d, r, g, b, a); \ 80 } else { \ 81 uint8 alphaRest = 255 - (a); \ 82 uint32 alphaTemp = (65025 - alphaRest * (255 - _p.data8[3])); \ 83 uint32 alphaDest = _p.data8[3] * alphaRest; \ 84 uint32 alphaSrc = 255 * (a); \ 85 d[0] = (_p.data8[0] * alphaDest + (b) * alphaSrc) / alphaTemp; \ 86 d[1] = (_p.data8[1] * alphaDest + (g) * alphaSrc) / alphaTemp; \ 87 d[2] = (_p.data8[2] * alphaDest + (r) * alphaSrc) / alphaTemp; \ 88 d[3] = alphaTemp >> 8; \ 89 } \ 90 } 91 92 // BLEND_COMPOSITE16 93 // 94 // This macro assumes source alpha in range 0..65025 and 95 // composes the source color over a possibly semi-transparent background. 96 // TODO: implement a faster version 97 #define BLEND_COMPOSITE16(d, r, g, b, a) \ 98 { \ 99 BLEND_COMPOSITE(d, r, g, b, (a) >> 8); \ 100 } 101 102 103 #endif // DRAWING_MODE_H 104 105