- 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, png_voidp_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,
- png_infopp_NULL, png_infopp_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,
- png_infopp_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_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
- // http://zerowing.idsoftware.com/bugzilla/show_bug.cgi?id=491
- *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, png_infopp_NULL);
-
- free(row_pointers);
- g_FileSystemTable.m_pfnFreeFile (fbuffer);