-void LoadImage( const char *filename, unsigned char **pic, int *width, int *height ){
- png_byte** row_pointers;
- unsigned char *fbuffer = NULL;
- png_bytep p_fbuffer;
-
- int nLen = g_FileSystemTable.m_pfnLoadFile( (char *)filename, (void **)&fbuffer, 0 );
- if ( nLen == -1 ) {
- return;
- }
-
- p_fbuffer = fbuffer;
-
- // the reading glue
- // http://www.libpng.org/pub/png/libpng-manual.html
-
- png_structp png_ptr = png_create_read_struct
- ( PNG_LIBPNG_VER_STRING, NULL,
- user_error_fn, user_warning_fn );
- if ( !png_ptr ) {
- g_FuncTable.m_pfnSysPrintf( "libpng error: png_create_read_struct\n" );
- return;
- }
-
- png_infop info_ptr = png_create_info_struct( png_ptr );
- if ( !info_ptr ) {
- png_destroy_read_struct( &png_ptr,
- NULL, NULL );
- g_FuncTable.m_pfnSysPrintf( "libpng error: png_create_info_struct (info_ptr)\n" );
- return;
- }
-
- png_infop end_info = png_create_info_struct( png_ptr );
- if ( !end_info ) {
- png_destroy_read_struct( &png_ptr, &info_ptr,
- NULL );
- g_FuncTable.m_pfnSysPrintf( "libpng error: png_create_info_struct (end_info)\n" );
- return;
- }
-
- // configure the read function
- png_set_read_fn( png_ptr, ( voidp ) & p_fbuffer, ( png_rw_ptr ) & user_read_data );
-
- if ( setjmp( png_ptr->jmpbuf ) ) {
- png_destroy_read_struct( &png_ptr, &info_ptr,
- &end_info );
- if ( *pic ) {
- g_free( *pic );
- free( row_pointers );
- }
- return;
- }
-
- png_read_info( png_ptr, info_ptr );
-
- int bit_depth = png_get_bit_depth( png_ptr, info_ptr );
- int color_type = png_get_color_type( png_ptr, info_ptr );
-
- // we want to treat all images the same way
- // The following code transforms grayscale images of less than 8 to 8 bits,
- // changes paletted images to RGB, and adds a full alpha channel if there is
- // transparency information in a tRNS chunk.
- if ( color_type == PNG_COLOR_TYPE_PALETTE ) {
- png_set_palette_to_rgb( png_ptr );
- }
-
- if ( color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8 ) {
- png_set_expand_gray_1_2_4_to_8( png_ptr );
- }
-
- if ( png_get_valid( png_ptr, info_ptr, PNG_INFO_tRNS ) ) {
- png_set_tRNS_to_alpha( png_ptr );
- }
-
- if ( !( color_type & PNG_COLOR_MASK_ALPHA ) ) {
- // Set the background color to draw transparent and alpha images over.
- png_color_16 my_background, *image_background;
-
- if ( png_get_bKGD( png_ptr, info_ptr, &image_background ) ) {
- png_set_background( png_ptr, image_background,
- PNG_BACKGROUND_GAMMA_FILE, 1, 1.0 );
- }
- else{
- png_set_background( png_ptr, &my_background,
- PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0 );
- }
-
- // Add alpha byte after each RGB triplet
- png_set_filler( png_ptr, 0xff, PNG_FILLER_AFTER );
- }
-
- // read the sucker in one chunk
- png_read_update_info( png_ptr, info_ptr );
-
- color_type = png_get_color_type( png_ptr, info_ptr );
- bit_depth = png_get_bit_depth( png_ptr, info_ptr );
-
- *width = png_get_image_width( png_ptr, info_ptr );
- *height = png_get_image_height( png_ptr, info_ptr );
-
- // allocate the pixel buffer, and the row pointers
- int size = ( *width ) * ( *height ) * 4;
- // still have to use that g_malloc heresy
- *pic = (unsigned char *)g_malloc( size );
- row_pointers = (png_byte**) malloc( ( *height ) * sizeof( png_byte* ) );
-
- int i;
- for ( i = 0; i < ( *height ); i++ )
- row_pointers[i] = (png_byte*)( *pic ) + i * 4 * ( *width );
-
- // actual read
- png_read_image( png_ptr, row_pointers );
-
- /* read rest of file, and get additional chunks in info_ptr - REQUIRED */
- png_read_end( png_ptr, info_ptr );
-
- /* free up the memory structure */
- png_destroy_read_struct( &png_ptr, &info_ptr, NULL );
-
- free( row_pointers );
- g_FileSystemTable.m_pfnFreeFile( fbuffer );