GRASS Programmer's Manual
6.4.2(2012)
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00001 #include "cairodriver.h" 00002 00003 void write_ppm(void) 00004 { 00005 char *mask_name = G_store(file_name); 00006 FILE *output, *mask; 00007 int x, y; 00008 00009 output = fopen(file_name, "wb"); 00010 if (!output) 00011 G_fatal_error("cairo: couldn't open output file %s", file_name); 00012 00013 mask_name[strlen(mask_name) - 2] = 'g'; 00014 00015 mask = fopen(mask_name, "wb"); 00016 if (!mask) 00017 G_fatal_error("cairo: couldn't open mask file %s", mask_name); 00018 00019 G_free(mask_name); 00020 00021 fprintf(output, "P6\n%d %d\n255\n", width, height); 00022 fprintf(mask, "P5\n%d %d\n255\n", width, height); 00023 00024 for (y = 0; y < height; y++) { 00025 const unsigned int *row = (const unsigned int *)(grid + y * stride); 00026 00027 for (x = 0; x < width; x++) { 00028 unsigned int c = row[x]; 00029 int a = (c >> 24) & 0xFF; 00030 int r = (c >> 16) & 0xFF; 00031 int g = (c >> 8) & 0xFF; 00032 int b = (c >> 0) & 0xFF; 00033 00034 if (a > 0 && a < 0xFF) { 00035 r = r * 0xFF / a; 00036 g = g * 0xFF / a; 00037 b = b * 0xFF / a; 00038 } 00039 00040 fputc((unsigned char)r, output); 00041 fputc((unsigned char)g, output); 00042 fputc((unsigned char)b, output); 00043 fputc((unsigned char)a, mask); 00044 } 00045 } 00046 00047 fclose(output); 00048 fclose(mask); 00049 }