12 static png_struct *png_ptr;
13 static png_info *info_ptr;
22 png_create_write_struct(PNG_LIBPNG_VER_STRING, &jbuf,
NULL,
NULL);
26 info_ptr = png_create_info_struct(png_ptr);
30 if (setjmp(png_jmpbuf(png_ptr)))
37 png_init_io(png_ptr, output);
39 png_set_IHDR(png_ptr, info_ptr,
42 PNG_COLOR_TYPE_PALETTE, PNG_INTERLACE_NONE,
43 PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
46 png_set_invert_alpha(png_ptr);
48 png_color png_pal[256];
51 for (i = 0; i < 256; i++) {
57 png_set_PLTE(png_ptr, info_ptr, png_pal, 256);
60 png_byte
trans = (png_byte) 0;
62 png_set_tRNS(png_ptr, info_ptr, &trans, 1,
NULL);
66 str =
getenv(
"GRASS_PNG_COMPRESSION");
67 if (str && sscanf(str,
"%d", &compress) == 1)
68 png_set_compression_level(png_ptr, compress);
70 png_write_info(png_ptr, info_ptr);
72 line = G_malloc(
width * 4);
78 for (x = 0; x <
width; x++, p++) {
89 for (x = 0; x <
width; x++, p++, q++)
92 png_write_row(png_ptr, line);
97 png_write_end(png_ptr, info_ptr);
99 png_destroy_write_struct(&png_ptr, &info_ptr);
void G_free(void *buf)
Free allocated memory.
void get_pixel(unsigned int pixel, int *r, int *g, int *b, int *a)
unsigned char png_palette[256][4]
int G_fatal_error(const char *msg,...)
Print a fatal error message to stderr.
void output(const char *fmt,...)