1 | /* Libart_LGPL - library of basic graphic primitives |
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2 | * Copyright (C) 1998-2000 Raph Levien |
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3 | * |
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4 | * This library is free software; you can redistribute it and/or |
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5 | * modify it under the terms of the GNU Library General Public |
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6 | * License as published by the Free Software Foundation; either |
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7 | * version 2 of the License, or (at your option) any later version. |
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8 | * |
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9 | * This library is distributed in the hope that it will be useful, |
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10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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12 | * Library General Public License for more details. |
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13 | * |
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14 | * You should have received a copy of the GNU Library General Public |
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15 | * License along with this library; if not, write to the |
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16 | * Free Software Foundation, Inc., 59 Temple Place - Suite 330, |
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17 | * Boston, MA 02111-1307, USA. |
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18 | */ |
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19 | |
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20 | #include "config.h" |
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21 | #include "art_uta_vpath.h" |
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22 | |
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23 | #include <math.h> |
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24 | |
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25 | #include "art_misc.h" |
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26 | #include "art_vpath.h" |
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27 | #include "art_uta.h" |
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28 | |
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29 | #ifndef MAX |
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30 | #define MAX(a, b) (((a) > (b)) ? (a) : (b)) |
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31 | #endif /* MAX */ |
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32 | |
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33 | #ifndef MIN |
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34 | #define MIN(a, b) (((a) < (b)) ? (a) : (b)) |
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35 | #endif /* MIN */ |
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36 | |
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37 | /** |
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38 | * art_uta_add_line: Add a line to the uta. |
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39 | * @uta: The uta to modify. |
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40 | * @x0: X coordinate of line start point. |
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41 | * @y0: Y coordinate of line start point. |
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42 | * @x1: X coordinate of line end point. |
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43 | * @y1: Y coordinate of line end point. |
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44 | * @rbuf: Buffer containing first difference of winding number. |
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45 | * @rbuf_rowstride: Rowstride of @rbuf. |
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46 | * |
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47 | * Add the line (@x0, @y0) - (@x1, @y1) to @uta, and also update the |
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48 | * winding number buffer used for rendering the interior. @rbuf |
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49 | * contains the first partial difference (in the X direction) of the |
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50 | * winding number, measured in grid cells. Thus, each time that a line |
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51 | * crosses a horizontal uta grid line, an entry of @rbuf is |
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52 | * incremented if @y1 > @y0, decremented otherwise. |
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53 | * |
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54 | * Note that edge handling is fairly delicate. Please rtfs for |
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55 | * details. |
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56 | **/ |
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57 | void |
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58 | art_uta_add_line (ArtUta *uta, double x0, double y0, double x1, double y1, |
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59 | int *rbuf, int rbuf_rowstride) |
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60 | { |
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61 | int xmin, ymin; |
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62 | double xmax, ymax; |
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63 | int xmaxf, ymaxf; |
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64 | int xmaxc, ymaxc; |
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65 | int xt0, yt0; |
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66 | int xt1, yt1; |
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67 | int xf0, yf0; |
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68 | int xf1, yf1; |
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69 | int ix, ix1; |
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70 | ArtUtaBbox bb; |
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71 | |
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72 | xmin = floor (MIN(x0, x1)); |
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73 | xmax = MAX(x0, x1); |
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74 | xmaxf = floor (xmax); |
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75 | xmaxc = ceil (xmax); |
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76 | ymin = floor (MIN(y0, y1)); |
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77 | ymax = MAX(y0, y1); |
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78 | ymaxf = floor (ymax); |
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79 | ymaxc = ceil (ymax); |
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80 | xt0 = (xmin >> ART_UTILE_SHIFT) - uta->x0; |
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81 | yt0 = (ymin >> ART_UTILE_SHIFT) - uta->y0; |
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82 | xt1 = (xmaxf >> ART_UTILE_SHIFT) - uta->x0; |
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83 | yt1 = (ymaxf >> ART_UTILE_SHIFT) - uta->y0; |
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84 | if (xt0 == xt1 && yt0 == yt1) |
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85 | { |
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86 | /* entirely inside a microtile, this is easy! */ |
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87 | xf0 = xmin & (ART_UTILE_SIZE - 1); |
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88 | yf0 = ymin & (ART_UTILE_SIZE - 1); |
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89 | xf1 = (xmaxf & (ART_UTILE_SIZE - 1)) + xmaxc - xmaxf; |
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90 | yf1 = (ymaxf & (ART_UTILE_SIZE - 1)) + ymaxc - ymaxf; |
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91 | |
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92 | ix = yt0 * uta->width + xt0; |
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93 | bb = uta->utiles[ix]; |
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94 | if (bb == 0) |
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95 | bb = ART_UTA_BBOX_CONS(xf0, yf0, xf1, yf1); |
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96 | else |
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97 | bb = ART_UTA_BBOX_CONS(MIN(ART_UTA_BBOX_X0(bb), xf0), |
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98 | MIN(ART_UTA_BBOX_Y0(bb), yf0), |
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99 | MAX(ART_UTA_BBOX_X1(bb), xf1), |
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100 | MAX(ART_UTA_BBOX_Y1(bb), yf1)); |
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101 | uta->utiles[ix] = bb; |
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102 | } |
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103 | else |
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104 | { |
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105 | double dx, dy; |
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106 | int sx, sy; |
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107 | |
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108 | dx = x1 - x0; |
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109 | dy = y1 - y0; |
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110 | sx = dx > 0 ? 1 : dx < 0 ? -1 : 0; |
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111 | sy = dy > 0 ? 1 : dy < 0 ? -1 : 0; |
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112 | if (ymin == ymaxf) |
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113 | { |
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114 | /* special case horizontal (dx/dy slope would be infinite) */ |
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115 | xf0 = xmin & (ART_UTILE_SIZE - 1); |
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116 | yf0 = ymin & (ART_UTILE_SIZE - 1); |
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117 | xf1 = (xmaxf & (ART_UTILE_SIZE - 1)) + xmaxc - xmaxf; |
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118 | yf1 = (ymaxf & (ART_UTILE_SIZE - 1)) + ymaxc - ymaxf; |
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119 | |
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120 | ix = yt0 * uta->width + xt0; |
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121 | ix1 = yt0 * uta->width + xt1; |
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122 | while (ix != ix1) |
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123 | { |
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124 | bb = uta->utiles[ix]; |
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125 | if (bb == 0) |
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126 | bb = ART_UTA_BBOX_CONS(xf0, yf0, ART_UTILE_SIZE, yf1); |
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127 | else |
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128 | bb = ART_UTA_BBOX_CONS(MIN(ART_UTA_BBOX_X0(bb), xf0), |
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129 | MIN(ART_UTA_BBOX_Y0(bb), yf0), |
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130 | ART_UTILE_SIZE, |
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131 | MAX(ART_UTA_BBOX_Y1(bb), yf1)); |
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132 | uta->utiles[ix] = bb; |
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133 | xf0 = 0; |
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134 | ix++; |
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135 | } |
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136 | bb = uta->utiles[ix]; |
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137 | if (bb == 0) |
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138 | bb = ART_UTA_BBOX_CONS(0, yf0, xf1, yf1); |
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139 | else |
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140 | bb = ART_UTA_BBOX_CONS(0, |
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141 | MIN(ART_UTA_BBOX_Y0(bb), yf0), |
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142 | MAX(ART_UTA_BBOX_X1(bb), xf1), |
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143 | MAX(ART_UTA_BBOX_Y1(bb), yf1)); |
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144 | uta->utiles[ix] = bb; |
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145 | } |
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146 | else |
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147 | { |
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148 | /* Do a Bresenham-style traversal of the line */ |
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149 | double dx_dy; |
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150 | double x, y; |
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151 | double xn, yn; |
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152 | |
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153 | /* normalize coordinates to uta origin */ |
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154 | x0 -= uta->x0 << ART_UTILE_SHIFT; |
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155 | y0 -= uta->y0 << ART_UTILE_SHIFT; |
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156 | x1 -= uta->x0 << ART_UTILE_SHIFT; |
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157 | y1 -= uta->y0 << ART_UTILE_SHIFT; |
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158 | if (dy < 0) |
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159 | { |
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160 | double tmp; |
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161 | |
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162 | tmp = x0; |
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163 | x0 = x1; |
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164 | x1 = tmp; |
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165 | |
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166 | tmp = y0; |
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167 | y0 = y1; |
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168 | y1 = tmp; |
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169 | |
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170 | dx = -dx; |
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171 | sx = -sx; |
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172 | dy = -dy; |
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173 | /* we leave sy alone, because it would always be 1, |
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174 | and we need it for the rbuf stuff. */ |
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175 | } |
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176 | xt0 = ((int)floor (x0) >> ART_UTILE_SHIFT); |
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177 | xt1 = ((int)floor (x1) >> ART_UTILE_SHIFT); |
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178 | /* now [xy]0 is above [xy]1 */ |
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179 | |
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180 | ix = yt0 * uta->width + xt0; |
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181 | ix1 = yt1 * uta->width + xt1; |
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182 | #ifdef VERBOSE |
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183 | printf ("%% ix = %d,%d; ix1 = %d,%d\n", xt0, yt0, xt1, yt1); |
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184 | #endif |
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185 | |
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186 | dx_dy = dx / dy; |
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187 | x = x0; |
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188 | y = y0; |
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189 | while (ix != ix1) |
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190 | { |
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191 | int dix; |
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192 | |
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193 | /* figure out whether next crossing is horizontal or vertical */ |
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194 | #ifdef VERBOSE |
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195 | printf ("%% %d,%d\n", xt0, yt0); |
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196 | #endif |
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197 | yn = (yt0 + 1) << ART_UTILE_SHIFT; |
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198 | |
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199 | /* xn is the intercept with bottom edge of this tile. The |
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200 | following expression is careful to result in exactly |
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201 | x1 when yn = y1. */ |
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202 | xn = x1 + dx_dy * (yn - y1); |
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203 | |
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204 | if (xt0 != (int)floor (xn) >> ART_UTILE_SHIFT) |
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205 | { |
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206 | /* horizontal crossing */ |
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207 | xt0 += sx; |
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208 | dix = sx; |
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209 | if (dx > 0) |
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210 | { |
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211 | xn = xt0 << ART_UTILE_SHIFT; |
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212 | yn = y0 + (xn - x0) / dx_dy; |
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213 | |
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214 | xf0 = (int)floor (x) & (ART_UTILE_SIZE - 1); |
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215 | xf1 = ART_UTILE_SIZE; |
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216 | } |
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217 | else |
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218 | { |
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219 | xn = (xt0 + 1) << ART_UTILE_SHIFT; |
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220 | yn = y0 + (xn - x0) / dx_dy; |
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221 | |
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222 | xf0 = 0; |
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223 | xmaxc = (int)ceil (x); |
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224 | xf1 = xmaxc - ((xt0 + 1) << ART_UTILE_SHIFT); |
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225 | } |
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226 | ymaxf = (int)floor (yn); |
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227 | ymaxc = (int)ceil (yn); |
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228 | yf1 = (ymaxf & (ART_UTILE_SIZE - 1)) + ymaxc - ymaxf; |
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229 | } |
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230 | else |
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231 | { |
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232 | /* vertical crossing */ |
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233 | dix = uta->width; |
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234 | xf0 = (int)floor (MIN(x, xn)) & (ART_UTILE_SIZE - 1); |
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235 | xmax = MAX(x, xn); |
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236 | xmaxc = (int)ceil (xmax); |
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237 | xf1 = xmaxc - (xt0 << ART_UTILE_SHIFT); |
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238 | yf1 = ART_UTILE_SIZE; |
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239 | |
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240 | if (rbuf != NULL) |
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241 | rbuf[yt0 * rbuf_rowstride + xt0] += sy; |
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242 | |
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243 | yt0++; |
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244 | } |
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245 | yf0 = (int)floor (y) & (ART_UTILE_SIZE - 1); |
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246 | bb = uta->utiles[ix]; |
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247 | if (bb == 0) |
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248 | bb = ART_UTA_BBOX_CONS(xf0, yf0, xf1, yf1); |
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249 | else |
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250 | bb = ART_UTA_BBOX_CONS(MIN(ART_UTA_BBOX_X0(bb), xf0), |
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251 | MIN(ART_UTA_BBOX_Y0(bb), yf0), |
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252 | MAX(ART_UTA_BBOX_X1(bb), xf1), |
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253 | MAX(ART_UTA_BBOX_Y1(bb), yf1)); |
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254 | uta->utiles[ix] = bb; |
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255 | |
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256 | x = xn; |
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257 | y = yn; |
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258 | ix += dix; |
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259 | } |
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260 | xmax = MAX(x, x1); |
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261 | xmaxc = ceil (xmax); |
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262 | ymaxc = ceil (y1); |
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263 | xf0 = (int)floor (MIN(x1, x)) & (ART_UTILE_SIZE - 1); |
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264 | yf0 = (int)floor (y) & (ART_UTILE_SIZE - 1); |
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265 | xf1 = xmaxc - (xt0 << ART_UTILE_SHIFT); |
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266 | yf1 = ymaxc - (yt0 << ART_UTILE_SHIFT); |
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267 | bb = uta->utiles[ix]; |
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268 | if (bb == 0) |
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269 | bb = ART_UTA_BBOX_CONS(xf0, yf0, xf1, yf1); |
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270 | else |
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271 | bb = ART_UTA_BBOX_CONS(MIN(ART_UTA_BBOX_X0(bb), xf0), |
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272 | MIN(ART_UTA_BBOX_Y0(bb), yf0), |
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273 | MAX(ART_UTA_BBOX_X1(bb), xf1), |
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274 | MAX(ART_UTA_BBOX_Y1(bb), yf1)); |
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275 | uta->utiles[ix] = bb; |
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276 | } |
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277 | } |
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278 | } |
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279 | |
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280 | /** |
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281 | * art_uta_from_vpath: Generate uta covering a vpath. |
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282 | * @vec: The source vpath. |
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283 | * |
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284 | * Generates a uta covering @vec. The resulting uta is of course |
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285 | * approximate, ie it may cover more pixels than covered by @vec. |
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286 | * |
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287 | * Return value: the new uta. |
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288 | **/ |
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289 | ArtUta * |
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290 | art_uta_from_vpath (const ArtVpath *vec) |
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291 | { |
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292 | ArtUta *uta; |
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293 | ArtIRect bbox; |
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294 | int *rbuf; |
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295 | int i; |
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296 | double x, y; |
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297 | int sum; |
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298 | int xt, yt; |
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299 | ArtUtaBbox *utiles; |
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300 | ArtUtaBbox bb; |
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301 | int width; |
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302 | int height; |
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303 | int ix; |
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304 | |
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305 | art_vpath_bbox_irect (vec, &bbox); |
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306 | |
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307 | uta = art_uta_new_coords (bbox.x0, bbox.y0, bbox.x1, bbox.y1); |
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308 | |
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309 | width = uta->width; |
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310 | height = uta->height; |
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311 | utiles = uta->utiles; |
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312 | |
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313 | rbuf = art_new (int, width * height); |
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314 | for (i = 0; i < width * height; i++) |
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315 | rbuf[i] = 0; |
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316 | |
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317 | x = 0; |
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318 | y = 0; |
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319 | for (i = 0; vec[i].code != ART_END; i++) |
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320 | { |
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321 | switch (vec[i].code) |
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322 | { |
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323 | case ART_MOVETO: |
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324 | x = vec[i].x; |
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325 | y = vec[i].y; |
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326 | break; |
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327 | case ART_LINETO: |
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328 | art_uta_add_line (uta, vec[i].x, vec[i].y, x, y, rbuf, width); |
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329 | x = vec[i].x; |
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330 | y = vec[i].y; |
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331 | break; |
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332 | default: |
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333 | /* this shouldn't happen */ |
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334 | break; |
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335 | } |
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336 | } |
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337 | |
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338 | /* now add in the filling from rbuf */ |
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339 | ix = 0; |
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340 | for (yt = 0; yt < height; yt++) |
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341 | { |
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342 | sum = 0; |
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343 | for (xt = 0; xt < width; xt++) |
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344 | { |
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345 | sum += rbuf[ix]; |
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346 | /* Nonzero winding rule - others are possible, but hardly |
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347 | worth it. */ |
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348 | if (sum != 0) |
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349 | { |
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350 | bb = utiles[ix]; |
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351 | bb &= 0xffff0000; |
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352 | bb |= (ART_UTILE_SIZE << 8) | ART_UTILE_SIZE; |
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353 | utiles[ix] = bb; |
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354 | if (xt != width - 1) |
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355 | { |
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356 | bb = utiles[ix + 1]; |
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357 | bb &= 0xffff00; |
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358 | bb |= ART_UTILE_SIZE; |
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359 | utiles[ix + 1] = bb; |
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360 | } |
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361 | if (yt != height - 1) |
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362 | { |
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363 | bb = utiles[ix + width]; |
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364 | bb &= 0xff0000ff; |
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365 | bb |= ART_UTILE_SIZE << 8; |
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366 | utiles[ix + width] = bb; |
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367 | if (xt != width - 1) |
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368 | { |
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369 | utiles[ix + width + 1] &= 0xffff; |
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370 | } |
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371 | } |
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372 | } |
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373 | ix++; |
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374 | } |
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375 | } |
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376 | |
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377 | art_free (rbuf); |
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378 | |
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379 | return uta; |
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380 | } |
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