/*! \file lib/cairodriver/read_ppm.c \brief GRASS cairo display driver - read PPM image (lower level functions) (C) 2007-2008, 2011 by Lars Ahlzen and the GRASS Development Team This program is free software under the GNU General Public License (>=v2). Read the file COPYING that comes with GRASS for details. \author Lars Ahlzen (original contibutor) \author Glynn Clements */ #include #include "cairodriver.h" void cairo_read_ppm(void) { char *mask_name = G_store(ca.file_name); FILE *input, *mask; int x, y; int i_width, i_height, maxval; input = fopen(ca.file_name, "rb"); if (!input) G_fatal_error(_("Cairo: unable to open input file <%s>"), ca.file_name); if (fscanf(input, "P6 %d %d %d", &i_width, &i_height, &maxval) != 3) G_fatal_error(_("Cairo: invalid input file <%s>"), ca.file_name); fgetc(input); if (i_width != ca.width || i_height != ca.height) G_fatal_error(_("Cairo: input file has incorrect dimensions: " "expected: %dx%d got: %dx%d"), ca.width, ca.height, i_width, i_height); mask_name[strlen(mask_name) - 2] = 'g'; mask = fopen(mask_name, "rb"); if (!mask) G_fatal_error(_("Cairo: unable to open input mask file <%s>"), mask_name); if (fscanf(mask, "P5 %d %d %d", &i_width, &i_height, &maxval) != 3) G_fatal_error(_("Cairo: invalid input mask file <%s>"), mask_name); fgetc(mask); if (i_width != ca.width || i_height != ca.height) G_fatal_error(_("Cairo: input mask file has incorrect dimensions: " "expected: %dx%d got: %dx%d"), ca.width, ca.height, i_width, i_height); G_free(mask_name); for (y = 0; y < ca.height; y++) { unsigned int *row = (unsigned int *)(ca.grid + y * ca.stride); for (x = 0; x < ca.width; x++) { int r = fgetc(input); int g = fgetc(input); int b = fgetc(input); int a = fgetc(mask); r = r * 255 / maxval; g = g * 255 / maxval; b = b * 255 / maxval; a = a * 255 / maxval; if (a > 0 && a < 0xFF) { r = r * a / 0xFF; g = g * a / 0xFF; b = b * a / 0xFF; } row[x] = (a << 24) | (r << 16) | (g << 8) | (b << 0); } } fclose(input); fclose(mask); }