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1 /* ----------------------------------------------------------------------------
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2 * Double buffering code
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3 * ----------------------------------------------------------------------------
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4 */
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5
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6
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7 #include "dbl.h"
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8
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9 struct {
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10 unsigned short red;
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11 unsigned short green;
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12 unsigned short blue;
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13 } color[] = {
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14 { 65280, 65280, 65280 }, /* white */
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15 { 0, 0, 65280 }, /* blue */
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16 { 0, 65280, 0 }, /* green */
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17 { 65280, 0, 0 }, /* red */
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18 { 42240, 10752, 10752 }, /* brown */
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19 { 65280, 32512, 0 }, /* orange */
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20 { 32512, 32512, 32512 }, /* gray */
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21 { 0, 0, 0 } /* black */
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22 };
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23
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24 /* ------------------------------------------------------------------------- */
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25
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26 DoubleBuffer *
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27 DBLcreate_double_buffer (display, window, backing_store, colors, num_colors)
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28 Display *display;
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29 Window window;
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30 int backing_store;
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31 XColor *colors;
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32 int num_colors;
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33 {
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34 int i, j, k, l, m, offset, mask, size;
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35 int max_planes;
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36
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37 char *string;
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38 Surface *surface;
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39 DoubleBuffer *db;
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40 XGCValues xgcv;
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41 unsigned long xgcvmask;
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42
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43 /* allocate the double buffer structure, and then open the display */
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44
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45 if ((db = (DoubleBuffer *)calloc(1, sizeof(DoubleBuffer))) == 0) {
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46 printf("DBLopen_double_buffer : memory allocation error\n");
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47 return (NULL);
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48 }
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49
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50 /* note the display */
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51
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52 db->display = display;
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53
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54 /* first some information about our display */
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55
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56 db->screen = DefaultScreenOfDisplay(db->display);
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57 db->window = window;
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58
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59 /* now get some information on color resources */
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60
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61 db->visual = DefaultVisualOfScreen(db->screen);
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62 db->depth = DefaultDepthOfScreen(db->screen);
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63 db->colormap = DefaultColormapOfScreen(db->screen);
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64
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65 /* set up colors */
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66
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67 for (i = 0 ; i < num_colors; i++) {
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68 color[i].red = colors[i].red;
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69 color[i].green = colors[i].green;
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70 color[i].blue = colors[i].blue;
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71 }
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72
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73 /* see if the user wanted to limit the number of planes used
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74 then see how many are available, make it a multiple of 2 */
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75
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76 if ((string = getenv("DBL_MAX_PLANES")) == NULL)
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77 max_planes = DBL_MAX_PLANES;
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78 else {
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79 max_planes = atoi(string);
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80 }
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81
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82 if ((db->num_planes = PlanesOfScreen(db->screen)) > max_planes) {
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83 db->num_planes = max_planes;
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84 }
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85
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86 db->num_planes = (db->num_planes >> 1) << 1;
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87
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88
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89 /* otherwise allocate contiguous planes to do double buffering */
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90
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91 while (db->num_planes >= DBL_MIN_PLANES) {
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92 if (XAllocColorCells (db->display, db->colormap, 1, db->planes,
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93 db->num_planes, db->pixels, 1)) {
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94 break;
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95 }
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96
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97 db->num_planes -= 2;
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98 }
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99
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100 /* if we have at least minimum planes, then we can do double
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101 buffering and we want to setup our surfaces and colormaps */
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102
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103 if (db->num_planes < DBL_MIN_PLANES)
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104 db->num_surfaces = 0;
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105 else {
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106 db->num_colors = 1 << (db->num_planes >> 1);
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107 db->num_surfaces = DBL_MAX_SURFACES;
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108
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109 /* if the number of colors is less than DBL_MAX_COLORS,
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110 then we want to make sure black is the last color */
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111
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112 for (i = db->num_colors - 1; i < DBL_MAX_COLORS; i++) {
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113 color[i].red = color[DBL_MAX_COLORS - 1].red;
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114 color[i].green = color[DBL_MAX_COLORS - 1].green;
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115 color[i].blue = color[DBL_MAX_COLORS - 1].blue;
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116 }
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117
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118 /* we have a set of contiguous planes. compute a mask for
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119 the planes, and figure out the offset in the hardware */
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120
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121 for (i = 0; i < db->num_planes; i++) {
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122 db->mask |= db->planes[i];
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123 }
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124
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125 mask = db->mask;
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126 offset = 0;
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127
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128 while ((mask & 1) == 0) {
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129 mask = mask >> 1;
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130 offset = offset + 1;
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131 }
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132
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133 mask = (1 << (db->num_planes >> 1)) - 1;
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134
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135 /* now create the surfaces that will contain plane mask and
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136 colormap information that we use to do double buffering */
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137
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138 for (i = 0; i < db->num_surfaces; i++) {
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139 size = sizeof(Surface) + sizeof(XColor) * (1 << db->num_planes);
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140
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141 if ((surface = (Surface *)malloc(size)) != NULL)
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142 db->surface[i] = surface;
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143 else {
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144 printf("DBLcreate_double_buffer : memory allocation error\n");
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145 DBLdelete_double_buffer(db);
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146 return(NULL);
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147 }
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148
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149 surface->offset = offset + i * (db->num_planes >> 1);
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150 surface->mask = mask << surface->offset;
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151 surface->num_colors = 1 << db->num_planes;
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152
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153 /* compute our pixel values by taking every permutation
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154 of the pixel and planes returned by XAllocColorCells */
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155
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156 for (j = 0; j < (surface->num_colors); j++) {
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157 surface->color[j].pixel = db->pixels[0];
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158 }
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159
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160 for (j = 0; j < db->num_planes; j++) {
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161 for (k = (1 << j); k < (surface->num_colors); k += (2 << j)) {
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162 for (l = k; l < (k + (1 << j)); l++) {
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163 surface->color[l].pixel |= db->planes[j];
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164 }
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165 }
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166 }
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167
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168 /* now populate those pixels with the proper colors so
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169 that we can do animation by banging in a new colormap */
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170
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171 for (j = 0; j < surface->num_colors; j++) {
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172 k = (j & surface->mask) >> surface->offset;
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173
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174 surface->color[j].red = color[k].red;
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175 surface->color[j].green = color[k].green;
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176 surface->color[j].blue = color[k].blue;
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177
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178 surface->color[j].flags = DoRed | DoGreen | DoBlue;
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179 }
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180 }
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181
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182 db->current_surface = 0;
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183 }
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184
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185
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186 /* now figure out what pixel values we will use to draw with
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187 and store them in the double buffer structure */
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188
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189 if (db->num_surfaces == 0) {
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190 db->num_colors = DBL_MAX_COLORS;
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191 db->colors[0] = WhitePixelOfScreen(db->screen);
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192
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193 for (i = 1; i < db->num_colors; i++) {
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194 db->colors[i] = BlackPixelOfScreen(db->screen);
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195 }
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196 }
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197 else {
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198 for (i = 0; i < db->num_colors; i++) {
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199 j = (i << (db->num_planes >> 1)) + i;
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200 db->colors[i] = db->surface[0]->color[j].pixel;
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201 }
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202 }
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203
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204 /* fill out the remaining colors with the last color */
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205
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206 for (; i < DBL_MAX_COLORS; i++) {
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207 db->colors[i] = db->colors[db->num_colors - 1];
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208 }
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209
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210 db->width = WidthOfScreen(db->screen);
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211 db->height = HeightOfScreen(db->screen);
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212
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213 /* if there are no surfaces then we are doing animation with
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214 a frame buffer, so create a pixmap as our frame buffer */
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215
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216 if (db->num_surfaces > 0)
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217 db->drawable = db->window;
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218 else {
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219 db->frame = XCreatePixmap(db->display, db->window,
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220 db->width, db->height, db->depth);
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221 db->drawable = db->frame;
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222 }
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223
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224 /* if they have requested backing store, then create an extra
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225 pixmap which we can use as backing store to handle exposures */
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226
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227 if (backing_store) {
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228 db->backing = XCreatePixmap(db->display, db->window,
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229 db->width, db->height, db->depth);
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230 }
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231
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232 /* use the 0 pixel from one of the surfaces for the background */
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233
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234 xgcv.background = DBLinq_background(db);
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235 xgcv.line_style = LineSolid;
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236 xgcv.line_width = 0;
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237 xgcv.cap_style = CapButt;
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238 xgcv.join_style = JoinRound;
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239 xgcvmask = GCBackground | GCLineStyle | GCLineWidth | GCCapStyle |
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240 GCJoinStyle;
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241
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242 db->gc = XCreateGC(db->display, db->drawable, xgcvmask, &xgcv);
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243
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244 /* do an initial frame to setup the colormap, and return */
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245
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246 DBLbegin_frame(db);
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247 DBLend_frame(db, 1);
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248 return (db);
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249 }
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250
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251 /* ------------------------------------------------------------------------- */
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252
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253 void
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254 DBLdelete_double_buffer (db)
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255 DoubleBuffer *db;
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256 {
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257 int i;
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258
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259 /* remove and and all surfaces that are out there */
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260
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261 for (i = 0; i < DBL_MAX_SURFACES; i++) {
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262 if (db->surface[i] != 0) {
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263 free(db->surface[i]);
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264 }
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265 }
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266
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267 /* now clean up the various resources used for this double buffer */
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268
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269 if (db->frame != 0) {
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270 XFreePixmap(db->display, db->frame);
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271 }
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272
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273 if (db->backing != 0) {
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274 XFreePixmap(db->display, db->backing);
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275 }
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276
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277 /* if we created our own private colormap, then free the colormap */
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278
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279 if (db->colormap != DefaultColormapOfScreen(db->screen)) {
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280 XFreeColormap(db->display, db->colormap);
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281 }
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282
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283 free (db);
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284 }
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285
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286 /* ------------------------------------------------------------------------- */
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287
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288 unsigned long
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289 DBLinq_background(db)
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290 DoubleBuffer *db;
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291 {
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292 if (db->num_surfaces > 0)
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293 return(db->surface[0]->color[0].pixel);
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294 else
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295 return(WhitePixelOfScreen(db->screen));
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296 }
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297
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298 /* ------------------------------------------------------------------------- */
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299
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300 DBLbegin_frame(db)
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301 DoubleBuffer *db;
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302 {
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303 Surface *surface;
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304
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305 /* there will be at most two surfaces optimize with "&"*/
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306
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307 if (db->num_surfaces > 0) {
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308 db->current_surface = (db->current_surface + 1) & 1;
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309 surface = db->surface[db->current_surface];
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310 }
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311
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312 /* clear the back surface of the window which may actually be a pixmap */
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313
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314 if (db->num_surfaces > 0)
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315 XSetPlaneMask (db->display, db->gc, surface->mask);
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316
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317 /* clear out the back surface or frame buffer as appropriate */
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318
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319 XSetFunction(db->display, db->gc, GXclear);
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320 XFillRectangle(db->display, db->drawable, db->gc,
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321 0, 0, db->width, db->height);
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322
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323 /* set writing mode back to copy */
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324 XSetFunction (db->display, db->gc, GXcopy);
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325
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326 XSync(db->display, False);
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327 }
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328
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329
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330 /* ------------------------------------------------------------------------- */
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331
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332
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333 DBLend_frame(db, init)
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334 DoubleBuffer *db;
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335 short init;
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336 {
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337 Surface *surface;
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338
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339 /* if there are no drawing surfaces, then we are doing animation
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340 with a frame buffer, copy the frame buffers to their viewports */
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341
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342 if (db->num_surfaces == 0) {
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343 if (! init)
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344 XCopyArea (db->display, db->frame, db->window,
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345 db->gc, 0,0, db->width, db->height, 0,0);
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346 } else {
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347
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348 /* otherwise, we can flip the surface by banging in the new colormap */
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349
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350 XSync(db->display, False);
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351 surface = db->surface[db->current_surface];
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352 XStoreColors (db->display, db->colormap,
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353 surface->color, surface->num_colors);
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354 }
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355
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356 if (db->backing != 0) {
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357 XCopyArea (db->display, db->window, db->backing,
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358 db->gc, 0,0, db->width, db->height, 0,0);
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359 }
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360
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361 /* make sure this all goes off to the server, right away */
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362
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363 XSync(db->display, False);
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364 }
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365
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366
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367
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368
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369
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370
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371
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372
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373
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374
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375
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376
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377
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