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trunk/third/libart_lgpl/art_rgb_rgba_affine.c
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1 | /* Libart_LGPL - library of basic graphic primitives |

2 | * Copyright (C) 1998 Raph Levien |

3 | * |

4 | * This library is free software; you can redistribute it and/or |

5 | * modify it under the terms of the GNU Library General Public |

6 | * License as published by the Free Software Foundation; either |

7 | * version 2 of the License, or (at your option) any later version. |

8 | * |

9 | * This library is distributed in the hope that it will be useful, |

10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |

11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |

12 | * Library General Public License for more details. |

13 | * |

14 | * You should have received a copy of the GNU Library General Public |

15 | * License along with this library; if not, write to the |

16 | * Free Software Foundation, Inc., 59 Temple Place - Suite 330, |

17 | * Boston, MA 02111-1307, USA. |

18 | */ |

19 | |

20 | #include "config.h" |

21 | #include "art_rgb_rgba_affine.h" |

22 | |

23 | #include <math.h> |

24 | #include "art_misc.h" |

25 | #include "art_point.h" |

26 | #include "art_affine.h" |

27 | #include "art_rgb_affine_private.h" |

28 | |

29 | /* This module handles compositing of affine-transformed rgba images |

30 | over rgb pixel buffers. */ |

31 | |

32 | /* Composite the source image over the destination image, applying the |

33 | affine transform. */ |

34 | |

35 | /** |

36 | * art_rgb_rgba_affine: Affine transform source RGBA image and composite. |

37 | * @dst: Destination image RGB buffer. |

38 | * @x0: Left coordinate of destination rectangle. |

39 | * @y0: Top coordinate of destination rectangle. |

40 | * @x1: Right coordinate of destination rectangle. |

41 | * @y1: Bottom coordinate of destination rectangle. |

42 | * @dst_rowstride: Rowstride of @dst buffer. |

43 | * @src: Source image RGBA buffer. |

44 | * @src_width: Width of source image. |

45 | * @src_height: Height of source image. |

46 | * @src_rowstride: Rowstride of @src buffer. |

47 | * @affine: Affine transform. |

48 | * @level: Filter level. |

49 | * @alphagamma: #ArtAlphaGamma for gamma-correcting the compositing. |

50 | * |

51 | * Affine transform the source image stored in @src, compositing over |

52 | * the area of destination image @dst specified by the rectangle |

53 | * (@x0, @y0) - (@x1, @y1). As usual in libart, the left and top edges |

54 | * of this rectangle are included, and the right and bottom edges are |

55 | * excluded. |

56 | * |

57 | * The @alphagamma parameter specifies that the alpha compositing be |

58 | * done in a gamma-corrected color space. In the current |

59 | * implementation, it is ignored. |

60 | * |

61 | * The @level parameter specifies the speed/quality tradeoff of the |

62 | * image interpolation. Currently, only ART_FILTER_NEAREST is |

63 | * implemented. |

64 | **/ |

65 | void |

66 | art_rgb_rgba_affine (art_u8 *dst, |

67 | int x0, int y0, int x1, int y1, int dst_rowstride, |

68 | const art_u8 *src, |

69 | int src_width, int src_height, int src_rowstride, |

70 | const double affine[6], |

71 | ArtFilterLevel level, |

72 | ArtAlphaGamma *alphagamma) |

73 | { |

74 | /* Note: this is a slow implementation, and is missing all filter |

75 | levels other than NEAREST. It is here for clarity of presentation |

76 | and to establish the interface. */ |

77 | int x, y; |

78 | double inv[6]; |

79 | art_u8 *dst_p, *dst_linestart; |

80 | const art_u8 *src_p; |

81 | ArtPoint pt, src_pt; |

82 | int src_x, src_y; |

83 | int alpha; |

84 | art_u8 bg_r, bg_g, bg_b; |

85 | art_u8 fg_r, fg_g, fg_b; |

86 | int tmp; |

87 | int run_x0, run_x1; |

88 | |

89 | dst_linestart = dst; |

90 | art_affine_invert (inv, affine); |

91 | for (y = y0; y < y1; y++) |

92 | { |

93 | pt.y = y + 0.5; |

94 | run_x0 = x0; |

95 | run_x1 = x1; |

96 | art_rgb_affine_run (&run_x0, &run_x1, y, src_width, src_height, |

97 | inv); |

98 | dst_p = dst_linestart + (run_x0 - x0) * 3; |

99 | for (x = run_x0; x < run_x1; x++) |

100 | { |

101 | pt.x = x + 0.5; |

102 | art_affine_point (&src_pt, &pt, inv); |

103 | src_x = floor (src_pt.x); |

104 | src_y = floor (src_pt.y); |

105 | src_p = src + (src_y * src_rowstride) + src_x * 4; |

106 | if (src_x >= 0 && src_x < src_width && |

107 | src_y >= 0 && src_y < src_height) |

108 | { |

109 | |

110 | alpha = src_p[3]; |

111 | if (alpha) |

112 | { |

113 | if (alpha == 255) |

114 | { |

115 | dst_p[0] = src_p[0]; |

116 | dst_p[1] = src_p[1]; |

117 | dst_p[2] = src_p[2]; |

118 | } |

119 | else |

120 | { |

121 | bg_r = dst_p[0]; |

122 | bg_g = dst_p[1]; |

123 | bg_b = dst_p[2]; |

124 | |

125 | tmp = (src_p[0] - bg_r) * alpha; |

126 | fg_r = bg_r + ((tmp + (tmp >> 8) + 0x80) >> 8); |

127 | tmp = (src_p[1] - bg_g) * alpha; |

128 | fg_g = bg_g + ((tmp + (tmp >> 8) + 0x80) >> 8); |

129 | tmp = (src_p[2] - bg_b) * alpha; |

130 | fg_b = bg_b + ((tmp + (tmp >> 8) + 0x80) >> 8); |

131 | |

132 | dst_p[0] = fg_r; |

133 | dst_p[1] = fg_g; |

134 | dst_p[2] = fg_b; |

135 | } |

136 | } |

137 | } else { dst_p[0] = 255; dst_p[1] = 0; dst_p[2] = 0; } |

138 | dst_p += 3; |

139 | } |

140 | dst_linestart += dst_rowstride; |

141 | } |

142 | } |

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