dump_png.cpp

#ifdef __APPLE__
#include </usr/local/include/png.h>
#else
#include <png.h>
#endif
#include <cassert>
#include "minigl.h"

void Dump_png(MGLpixel* data,int width,int height,const char* filename)
{
    FILE* file=fopen(filename,"wb");
    assert(file);

    png_structp png_ptr=png_create_write_struct(PNG_LIBPNG_VER_STRING,0,0,0);
    assert(png_ptr);
    png_infop info_ptr=png_create_info_struct(png_ptr);
    assert(info_ptr);
    bool result=setjmp(png_jmpbuf(png_ptr));
    assert(!result);
    png_init_io(png_ptr,file);
    int color_type=PNG_COLOR_TYPE_RGBA;
    png_set_IHDR(png_ptr,info_ptr,width,height,8,color_type,PNG_INTERLACE_NONE,PNG_COMPRESSION_TYPE_DEFAULT,PNG_FILTER_TYPE_DEFAULT);

    MGLpixel** row_pointers=new MGLpixel*[height];
    for(int j=0;j<height;j++) row_pointers[j]=data+width*(height-j-1);
    png_set_rows(png_ptr,info_ptr,(png_byte**)row_pointers);
    png_write_png(png_ptr,info_ptr,PNG_TRANSFORM_IDENTITY,0);
    delete[] row_pointers;
    png_destroy_write_struct(&png_ptr,&info_ptr);
    fclose(file);
}