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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <png.h>
#include <unistd.h>
#include "pngcp.h"
int writeimage(char *filename, unsigned long width, unsigned long height,
int bitdepth, int channels, char *raster){
FILE *image;
png_structp png;
png_infop info;
png_bytepp row_pointers = NULL;
int i, rowbytes;
if((image = fopen(filename, "wb")) == NULL){
fprintf(stderr, "Could not open the output image\n");
return -1;
}
// Determine how many bytes each row will consume
rowbytes = bitdepth / 8;
if(bitdepth % 8 != 0)
rowbytes++;
rowbytes *= channels;
rowbytes *= width;
// Convert the raster into a series of row pointers
if((row_pointers = malloc (height * sizeof (png_bytep))) == NULL){
fprintf(stderr, "Could not allocate memory\n");
return -1;
}
for (i = 0; i < height; ++i)
row_pointers[i] = raster + (i * rowbytes);
// Get ready for writing
if ((png =
png_create_write_struct (PNG_LIBPNG_VER_STRING, NULL, NULL,
NULL)) == NULL){
fprintf(stderr, "Could not create write structure for PNG (out of memory?)\n");
return -1;
}
// The pixels are expanded to the nearest byte
png_set_expand (png);
// Get ready to specify important stuff about the image
if ((info = png_create_info_struct (png)) == NULL){
fprintf(stderr,
"Could not create PNG info structure for writing (out of memory?)\n");
return -1;
}
if (setjmp (png_jmpbuf (png))){
fprintf(stderr, "Could not set the PNG jump value for writing\n");
return -1;
}
// This is needed before IO will work (unless you define callbacks)
png_init_io(png, image);
// We need to derive a PNG color type from the number of channels and bitdepth
// Define important stuff about the image
png_set_IHDR (png, info, width, height, bitdepth, PNG_COLOR_TYPE_RGB,
PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT,
PNG_FILTER_TYPE_DEFAULT);
png_write_info (png, info);
// Write the image out
png_write_image (png, row_pointers);
// Cleanup
png_write_end (png, info);
png_destroy_write_struct (&png, &info);
fclose(image);
return 0;
}
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