pixelShuffle/pngReadWrite.h at master · Eppie/pixelShuffle · GitHub

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#include <png.h>

#ifdef ENABLE_PROFILING
#include "profiler.h"
#endif

int sWidth;
int sHeight;
int dWidth;
int dHeight;

void readPNGFile( char* filename, png_bytep* rowPointers, int* width, int* height ) {
	PROFILE_SCOPE(readPNGFile);
	png_byte bit_depth;
	png_byte color_type;
	FILE* fp = fopen( filename, "rb" );

	png_structp png = png_create_read_struct( PNG_LIBPNG_VER_STRING, NULL, NULL, NULL );

	if( !png ) {
		abort();
	}

	png_infop info = png_create_info_struct( png );

	if( !info ) {
		abort();
	}

	if( setjmp( png_jmpbuf( png ) ) ) {
		abort();
	}

	png_init_io( png, fp );

	png_read_info( png, info );

	*width = png_get_image_width( png, info );
	*height = png_get_image_height( png, info );
	color_type = png_get_color_type( png, info );
	bit_depth = png_get_bit_depth( png, info );

	if( bit_depth == 16 ) {
		png_set_strip_16( png );
	}

	if( color_type == PNG_COLOR_TYPE_PALETTE ) {
		png_set_palette_to_rgb( png );
	}

	if( color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8 ) {
		png_set_expand_gray_1_2_4_to_8( png );
	}

	if( png_get_valid( png, info, PNG_INFO_tRNS ) ) {
		png_set_tRNS_to_alpha( png );
	}

	if( color_type == PNG_COLOR_TYPE_RGB || color_type == PNG_COLOR_TYPE_GRAY || color_type == PNG_COLOR_TYPE_PALETTE ) {
		png_set_filler( png, 0xFF, PNG_FILLER_AFTER );
	}

	if( color_type == PNG_COLOR_TYPE_GRAY || color_type == PNG_COLOR_TYPE_GRAY_ALPHA ) {
		png_set_gray_to_rgb( png );
	}

	png_read_update_info( png, info );

	rowPointers = ( png_bytep* ) realloc( rowPointers, sizeof( png_bytep ) * *height );

	for( int y = 0; y < *height; y++ ) {
		rowPointers[y] = ( png_byte* ) malloc( png_get_rowbytes( png, info ) );
	}

	png_read_image( png, rowPointers );

	fclose( fp );
}

void writePNGFile( const char* filename, png_bytep* rowPointers, bool done = false ) {
	PROFILE_SCOPE(writePNGFile);
	FILE* fp = fopen( filename, "wb" );

	if( !fp ) {
		abort();
	}

	png_structp png = png_create_write_struct( PNG_LIBPNG_VER_STRING, NULL, NULL, NULL );

	if( !png ) {
		abort();
	}

#ifdef ANIMATION
	// Compression is ~1/3 of the total running time of the program. If we are writing a bunch of files,
	// disable compression at the expense of ~50% greater file sizes. If we are only writing the result file,
	// compress as per normal.
	png_set_compression_level( png, 0 );
#endif // ANIMATION

	png_infop info = png_create_info_struct( png );

	if( !info ) {
		abort();
	}

	if( setjmp( png_jmpbuf( png ) ) ) {
		abort();
	}

	png_init_io( png, fp );

	png_set_IHDR( png, info, dWidth, dHeight, 8, PNG_COLOR_TYPE_RGBA, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT );

	png_write_info( png, info );

	png_write_image( png, rowPointers );
	png_write_end( png, NULL );

	if( done ) {
		for( int y = 0; y < dHeight; y++ ) {
			free( rowPointers[y] );
		}

		free( rowPointers );
	}

	fclose( fp );
	png_destroy_write_struct( &png, ( png_infopp ) NULL );
	png_free_data( png, info, PNG_FREE_ALL, -1 );
}