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Writing libpng template
#include <stdio.h>
#include <stdlib.h>
#include <png.h>
int width, height;
int main(){
width = 1500; height = 1000;
char filename[] = "t.png";
/*open stream */
FILE *fp = fopen(filename, "wb");
if (fp==NULL){
perror(filename);
exit(1);
}
png_structp png = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
if (!png) {fprintf(stderr, "png_structp_png at line %d: failed\n", __LINE__); return 1;}
png_infop info = png_create_info_struct(png);
if (!info) {fprintf(stderr, "png_infop at line %d: failed\n", __LINE__); return 1;}
if (setjmp(png_jmpbuf(png))) {fprintf(stderr, "setjump at line %d: abort\n", __LINE__); return 1;}
png_init_io(png, fp);
png_set_IHDR(
png,
info,
width, height,
8,
PNG_COLOR_TYPE_RGBA,
PNG_INTERLACE_NONE,
PNG_COMPRESSION_TYPE_DEFAULT,
PNG_FILTER_TYPE_DEFAULT);
png_write_info(png, info);
png_bytep *row = NULL;
row = (png_bytep*) malloc(sizeof(png_bytep)*height);
if (row == NULL) {fprintf(stderr, "malloc at line %d: failed\n", __LINE__); return 1;}
for (int y = 0; y < height; y++) {
row[y] = malloc(sizeof(png_bytep)*width);
if (row[y] == NULL) {fprintf(stderr, "allocating row failed: memory leak occured!! \n");return 1;}
png_bytep line = row[y];
png_byte val0 = 0x00;
for (int x = 0; x < width; x++){
png_bytep px = (line+(x*4));
px[0] =val0;val0++;val0%=0xFF;
px[1] = px[0];
px[2] = px[0]
px[3] = 0xFF;
}
}
png_write_image(png, row);
png_write_end(png, NULL);
for (int y = 0; y < height; y++) free(row[y]);
free(row);
fclose(fp);
png_destroy_write_struct(&png, &info);
return 0;
}
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