C++ png_set_filler函数代码示例

    void set_filler(uint_32 filler, filler_type type) const
    {
        TRACE_IO_TRANSFORM("png_set_filler: filler=%08x, type=%d\n",
                           filler, type);

        png_set_filler(m_png, filler, type);
    }

/* Since libpng forces us to use longjmp, this function shouldn't create any C++
 * objects, and needs to watch out for memleaks. */
static bool RageSurface_Save_PNG( RageFile &f, char szErrorbuf[1024], RageSurface *pImgIn )
{
	bool bAlpha = pImgIn->format->Amask != 0;
	RageSurface *pImg;
	bool bDeleteImg = RageSurfaceUtils::ConvertSurface( pImgIn, pImg, pImgIn->w, pImgIn->h, 32,
			Swap32BE( 0xFF000000 ),
			Swap32BE( 0x00FF0000 ),
			Swap32BE( 0x0000FF00 ),
			Swap32BE( 0x000000FF ) );
	if( !bDeleteImg )
		pImg = pImgIn;

	error_info error;
	error.szErr = szErrorbuf;

	png_struct *pPng = png_create_write_struct( PNG_LIBPNG_VER_STRING, &error, PNG_Error, PNG_Warning );
	if( pPng == NULL )
	{
		sprintf( szErrorbuf, "creating png_create_write_struct failed");
		return false;
	}

	png_info *pInfo = png_create_info_struct(pPng);
	if( pInfo == NULL )
	{
		png_destroy_read_struct( &pPng, NULL, NULL );
		if( bDeleteImg )
			delete pImg;
		sprintf( szErrorbuf, "creating png_create_info_struct failed");
		return false;
	}

	if( setjmp(png_jmpbuf(pPng)) )
	{
		png_destroy_read_struct( &pPng, &pInfo, NULL );
		return false;
	}

	png_set_write_fn( pPng, &f, RageFile_png_write, RageFile_png_flush );
	png_set_compression_level( pPng, 1 );

	png_set_IHDR( pPng, pInfo, pImg->w, pImg->h, 8, bAlpha? PNG_COLOR_TYPE_RGBA:PNG_COLOR_TYPE_RGB,
		PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE );

	png_write_info( pPng, pInfo );
	png_set_filler( pPng, 0, PNG_FILLER_AFTER );

	png_byte *pixels = (png_byte *) pImg->pixels;
	for( int y = 0; y < pImg->h; y++ )
		png_write_row( pPng, pixels + pImg->pitch*y );

	png_write_end( pPng, pInfo );
	png_destroy_write_struct( &pPng, &pInfo );

	/* Free the converted image. */
	if( bDeleteImg )
		delete pImg;

	return true;
}

/* Added to libpng-1.2.7 */
void PNGAPI
png_set_add_alpha(png_structp png_ptr, png_uint_32 filler, int filler_loc)
{
   png_debug(1, "in png_set_add_alpha\n");
   png_set_filler(png_ptr, filler, filler_loc);
   png_ptr->transformations |= PNG_ADD_ALPHA;
}

    void writePNG(const QImage& image)
    {
#ifndef QT_LSB
        // LSB disallows accessing the info_ptr directly. LSB's png_set_IHDR sets
        // the channels anyways, so just comment it out for LSB usage
        info_ptr->channels = 4;
#endif
        png_set_sig_bytes(png_ptr, 8); // Pretend we already wrote the sig
        png_set_IHDR(png_ptr, info_ptr, image.width(), image.height(),
                     8, image.hasAlphaChannel()
                     ? PNG_COLOR_TYPE_RGB_ALPHA : PNG_COLOR_TYPE_RGB,
                     0, 0, 0);
        png_write_info(png_ptr, info_ptr);
        if (!image.hasAlphaChannel())
            png_set_filler(png_ptr, 0,
                           QSysInfo::ByteOrder == QSysInfo::BigEndian ?
                           PNG_FILLER_BEFORE : PNG_FILLER_AFTER);
        //if ( QImage::systemByteOrder() == QImage::BigEndian ) {
        //png_set_swap_alpha(png_ptr);
        //}
        if (QSysInfo::ByteOrder == QSysInfo::LittleEndian) {
            png_set_bgr(png_ptr);
        }

        int height = image.height();
        png_bytep *row_pointers = new png_bytep[height];
        for (int i = 0; i < height; ++i)
            row_pointers[i] = (png_bytep)image.scanLine(i);
        png_write_image(png_ptr, row_pointers);
        delete [] row_pointers;
        png_write_end(png_ptr, info_ptr);
        end_png();
        begin_png();
    }

/**
 * \brief encode an image to RGB(A) PNG format
 * \private \memberof mapcache_image_format_png
 * \sa mapcache_image_format::write()
 */
mapcache_buffer* _mapcache_imageio_png_encode(mapcache_context *ctx, mapcache_image *img, mapcache_image_format *format) {
   png_infop info_ptr;
   int color_type;
   size_t row;
   mapcache_buffer *buffer = NULL;
   int compression = ((mapcache_image_format_png*)format)->compression_level;
   png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL,NULL,NULL);
   if (!png_ptr) {
      ctx->set_error(ctx, 500, "failed to allocate png_struct structure");
      return NULL;
   }

   info_ptr = png_create_info_struct(png_ptr);
   if (!info_ptr)
   {
      png_destroy_write_struct(&png_ptr,
            (png_infopp)NULL);
      ctx->set_error(ctx, 500, "failed to allocate png_info structure");
      return NULL;
   }

   if (setjmp(png_jmpbuf(png_ptr)))
   {
      ctx->set_error(ctx, 500, "failed to setjmp(png_jmpbuf(png_ptr))");
      png_destroy_write_struct(&png_ptr, &info_ptr);
      return NULL;
   }

   buffer = mapcache_buffer_create(5000,ctx->pool);

   png_set_write_fn(png_ptr, buffer, _mapcache_imageio_png_write_func, _mapcache_imageio_png_flush_func);

   if(mapcache_image_has_alpha(img))
      color_type = PNG_COLOR_TYPE_RGB_ALPHA;
   else
      color_type = PNG_COLOR_TYPE_RGB;
      
   png_set_IHDR(png_ptr, info_ptr, img->w, img->h,
         8, color_type, PNG_INTERLACE_NONE,
         PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
   if(compression == MAPCACHE_COMPRESSION_BEST)
      png_set_compression_level (png_ptr, Z_BEST_COMPRESSION);
   else if(compression == MAPCACHE_COMPRESSION_FAST)
      png_set_compression_level (png_ptr, Z_BEST_SPEED);

   png_write_info(png_ptr, info_ptr);
   if(color_type == PNG_COLOR_TYPE_RGB)
       png_set_filler(png_ptr, 255, PNG_FILLER_AFTER);

   png_bytep rowptr = img->data;
   for(row=0;row<img->h;row++) {
      png_write_row(png_ptr,rowptr);
      rowptr += img->stride;
   }
   png_write_end(png_ptr, info_ptr);
   png_destroy_write_struct(&png_ptr, &info_ptr);
   return buffer;
}

void read_png_file(char *filename) {
  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);

  // Read any color_type into 8bit depth, RGBA format.
  // See http://www.libpng.org/pub/png/libpng-manual.txt

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

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

  // PNG_COLOR_TYPE_GRAY_ALPHA is always 8 or 16bit depth.
  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);

  // These color_type don't have an alpha channel then fill it with 0xff.
  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);

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

  png_read_image(png, row_pointers);

  fclose(fp);
}

static void nspng_setup_transforms(png_structp png_ptr, png_infop info_ptr)
{
	int bit_depth, color_type;
#if 0
	int intent;
	double gamma;
#endif

	bit_depth = png_get_bit_depth(png_ptr, info_ptr);
	color_type = png_get_color_type(png_ptr, info_ptr);

	/* Set up our transformations */
	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 (bit_depth == 16) {
		png_set_strip_16(png_ptr);
	}

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

	if (!(color_type & PNG_COLOR_MASK_ALPHA)) {
		png_set_filler(png_ptr, 0xff, PNG_FILLER_AFTER);
	}

#if 0
	/* gamma correction - we use 2.2 as our screen gamma
	 * this appears to be correct (at least in respect to !Browse)
	 * see http://www.w3.org/Graphics/PNG/all_seven.html for a test case
	 */
	if (png_get_sRGB(png_ptr, info_ptr, &intent)) {
		png_set_gamma(png_ptr, 2.2, 0.45455);
	} else {
		if (png_get_gAMA(png_ptr, info_ptr, &gamma)) {
			png_set_gamma(png_ptr, 2.2, gamma);
		} else {
			png_set_gamma(png_ptr, 2.2, 0.45455);
		}
	}
#endif

	png_read_update_info(png_ptr, info_ptr);
}

static CogFrame *
cog_frame_new_from_png (void *data, int size)
{
  struct png_data_struct s = { 0 };
  png_structp png_ptr;
  png_infop info_ptr;
  png_bytep *rows;
  CogFrame *frame;
  guchar *frame_data;
  int j;
  int width, height;
  int color_type;

  png_ptr = png_create_read_struct (PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
  info_ptr = png_create_info_struct (png_ptr);

  s.data = data;
  s.size = size;
  png_set_read_fn (png_ptr, (void *) &s, read_data);

  png_read_info (png_ptr, info_ptr);

  width = png_get_image_width (png_ptr, info_ptr);
  height = png_get_image_height (png_ptr, info_ptr);
  color_type = png_get_color_type (png_ptr, info_ptr);
  GST_DEBUG ("PNG size %dx%d color_type %d", width, height, color_type);

  png_set_strip_16 (png_ptr);
  png_set_packing (png_ptr);
  if (color_type == PNG_COLOR_TYPE_RGB) {
    png_set_filler (png_ptr, 0xff, PNG_FILLER_BEFORE);
  }
  if (color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
    png_set_swap_alpha (png_ptr);
  }

  frame_data = g_malloc (width * height * 4);
  frame = cog_frame_new_from_data_ARGB (frame_data, width, height);
  frame->regions[0] = frame_data;

  rows = (png_bytep *) g_malloc (sizeof (png_bytep) * height);

  for (j = 0; j < height; j++) {
    rows[j] = COG_FRAME_DATA_GET_LINE (frame->components + 0, j);
  }
  png_read_image (png_ptr, rows);
  g_free (rows);

  png_destroy_read_struct (&png_ptr, &info_ptr, (png_infopp) NULL);

  return frame;
}

/**
 * @brief Initializes the npng.
 */
static int npng_info( npng_t *npng )
{
   png_uint_32 width, height;
   int bit_depth, color_type, interlace_type;
   /*double display_exponent, gamma;*/

   /* Read information. */
   png_read_info( npng->png_ptr, npng->info_ptr );

   /* Read header stuff. */
   png_get_IHDR( npng->png_ptr, npng->info_ptr, &width, &height,
         &bit_depth, &color_type, &interlace_type, NULL, NULL );

   /* Set Interlace handling if necessary. */
   if (interlace_type != PNG_INTERLACE_NONE)
      png_set_interlace_handling( npng->png_ptr );

   /* Strip down from 16 bit to 8 bit. */
   png_set_strip_16( npng->png_ptr );

   /* Extract small bits into separate bytes. */
   png_set_packing( npng->png_ptr );

   /* Expand palette to RGB. */
   if (color_type == PNG_COLOR_TYPE_PALETTE)
      png_set_expand( npng->png_ptr );
   /* Expand low bit grayscale to 8 bit. */
   if ((color_type == PNG_COLOR_TYPE_GRAY) && (bit_depth < 8))
      png_set_expand( npng->png_ptr );
   /* Expand tRNS data to alpha channel. */
   if (png_get_valid( npng->png_ptr, npng->info_ptr, PNG_INFO_tRNS) )
      png_set_expand( npng->png_ptr );

   /* Set grayscale to 8 bits. */
   if ((color_type == PNG_COLOR_TYPE_GRAY) ||
         (color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
      png_set_gray_to_rgb( npng->png_ptr );

   /* Set gamma. */
   /*if (png_get_gAMA( npng->png_ptr, info_ptr, &gamma) )
      png_set_gamma( npng->png_ptr, display_exponent, gamma );*/

   /* Fill alpha. */
   png_set_filler( npng->png_ptr, 0xff, PNG_FILLER_AFTER );

   /* Update information. */
   png_read_update_info( npng->png_ptr, npng->info_ptr );

   /* Success. */
   return 0;
}

/* Since libpng forces us to use longjmp, this function shouldn't create any C++
 * objects, and needs to watch out for memleaks. */
bool SavePNG( FILE *f, char szErrorbuf[1024], const Surface *pSurf )
{
/*	RageSurfaceUtils::ConvertSurface( pImgIn, pImg, pImgIn->w, pImgIn->h, 32,
			Swap32BE( 0xFF000000 ),
			Swap32BE( 0x00FF0000 ),
			Swap32BE( 0x0000FF00 ),
			Swap32BE( 0x000000FF ) );
*/
	error_info error;
	error.szErr = szErrorbuf;

	png_struct *pPng = png_create_write_struct( PNG_LIBPNG_VER_STRING, &error, PNG_Error, PNG_Warning );
	if( pPng == NULL )
	{
		sprintf( szErrorbuf, "creating png_create_write_struct failed");
		return false;
	}

	png_info *pInfo = png_create_info_struct(pPng);
	if( pInfo == NULL )
	{
		png_destroy_read_struct( &pPng, NULL, NULL );
		sprintf( szErrorbuf, "creating png_create_info_struct failed");
		return false;
	}

	if( setjmp(pPng->jmpbuf) )
	{
		png_destroy_read_struct( &pPng, &pInfo, png_infopp_NULL );
		return false;
	}

	png_set_write_fn( pPng, f, File_png_write, File_png_flush );
	png_set_compression_level( pPng, 1 );

	png_set_IHDR( pPng, pInfo, pSurf->iWidth, pSurf->iHeight, 8, PNG_COLOR_TYPE_RGBA,
		PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE );

	png_write_info( pPng, pInfo );
	png_set_filler( pPng, 0, PNG_FILLER_AFTER );

	png_byte *pixels = (png_byte *) pSurf->pRGBA;
	for( int y = 0; y < pSurf->iHeight; y++ )
		png_write_row( pPng, pixels + pSurf->iPitch*y );

	png_write_end( pPng, pInfo );
	png_destroy_write_struct( &pPng, &pInfo );

	return true;
}

static void
info_callback(png_structp png, png_infop info)
{
	int bit_depth, color_type, interlace, intent;
	double gamma;
	png_uint_32 width, height;
	
	/* Read the PNG details */
	png_get_IHDR(png, info, &width, &height, &bit_depth,
			&color_type, &interlace, 0, 0);
        
        /* Set up our transformations */
	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 (bit_depth == 16)
		png_set_strip_16(png);
	if (color_type == PNG_COLOR_TYPE_GRAY ||
			color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
		png_set_gray_to_rgb(png);
	if (!(color_type & PNG_COLOR_MASK_ALPHA))
		png_set_filler(png, 0xff, PNG_FILLER_AFTER);
	/* gamma correction - we use 2.2 as our screen gamma
	 * this appears to be correct (at least in respect to !Browse)
	 * see http://www.w3.org/Graphics/PNG/all_seven.html for a test case
	 */
	if (png_get_sRGB(png, info, &intent))
	        png_set_gamma(png, 2.2, 0.45455);
	else {
	        if (png_get_gAMA(png, info, &gamma))
	                png_set_gamma(png, 2.2, gamma);
	        else
	                png_set_gamma(png, 2.2, 0.45455);
	}


	png_read_update_info(png, info);

	rowbytes = png_get_rowbytes(png, info);
	interlace = (interlace == PNG_INTERLACE_ADAM7);
	raw_width = width;
	raw_height = height;
        
        rowstride = raw_width * 4;
        bitmap_data = malloc(rowstride * raw_height);
}

bool SkPngEncoderMgr::writeInfo(const SkImageInfo& srcInfo) {
    if (setjmp(png_jmpbuf(fPngPtr))) {
        return false;
    }

    png_write_info(fPngPtr, fInfoPtr);
    if (kRGBA_F16_SkColorType == srcInfo.colorType() &&
        kOpaque_SkAlphaType == srcInfo.alphaType())
    {
        // For kOpaque, kRGBA_F16, we will keep the row as RGBA and tell libpng
        // to skip the alpha channel.
        png_set_filler(fPngPtr, 0, PNG_FILLER_AFTER);
    }

    return true;
}

void _gTexLoadPNG(FILE* fp, gImage* tex)
{
  png_structp png_ptr;
  png_infop info_ptr;
  unsigned int sig_read = 0;
  png_uint_32 width, height;
  int bit_depth, color_type, interlace_type, x, y;
  u32* line;
  png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,NULL,NULL,NULL);
  png_set_error_fn(png_ptr,NULL,NULL,NULL);
  info_ptr = png_create_info_struct(png_ptr);
  png_init_io(png_ptr,fp);
  png_set_sig_bytes(png_ptr,sig_read);
  png_read_info(png_ptr,info_ptr);
  png_get_IHDR(png_ptr,info_ptr,&width,&height,&bit_depth,&color_type,
                                &interlace_type,NULL,NULL);
  png_set_strip_16(png_ptr);
  png_set_packing(png_ptr);
  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);
  png_set_filler(png_ptr, 0xff, PNG_FILLER_AFTER);
  tex->w = width;
  tex->h = height;
  tex->tw = _getNextPower2(width);
  tex->th = _getNextPower2(height);
  tex->ratio = (float)width / height;
  tex->data = memalign(16, tex->tw * tex->th * sizeof(gColor));
  line = malloc(width * 4);
  for (y = 0; y < height; y++) {
    png_read_row(png_ptr, (u8*) line, png_bytep_NULL);
    for (x = 0; x < width; x++) {
      u32 color = line[x];
      tex->data[x + y * tex->tw] =  color;
    }
  }
  free(line);
  png_read_end(png_ptr, info_ptr);
  png_destroy_read_struct(&png_ptr, &info_ptr, png_infopp_NULL);
}

/* This function is called (as set by png_set_progressive_read_fn() above) when enough data has been supplied so all of the header has been read.  */
void info_callback(png_structp png_ptr, png_infop info) {

  file_end=0;
  width = png_get_image_width(png_ptr,info);
  height = png_get_image_height(png_ptr,info);
  pixel_depth = png_get_bit_depth(png_ptr,info);
  
  channels = png_get_channels(png_ptr,info);
  
  color_type = png_get_color_type(png_ptr,info);
  if(color_type == PNG_COLOR_TYPE_GRAY)      {}
  if(color_type == PNG_COLOR_TYPE_GRAY_ALPHA){}
  if(color_type == PNG_COLOR_TYPE_RGB)       {}
  if(color_type == PNG_COLOR_TYPE_RGB_ALPHA) {}
  if(color_type == PNG_COLOR_TYPE_PALETTE )  {

    int r = png_get_PLTE(png_ptr,info,&palette,&num_palette);
    if(r == 0) {
    }
    
    png_uint_16p histogram = NULL;

    png_get_hIST(png_ptr, info, &histogram);
    png_set_expand(png_ptr);
    png_set_filler(png_ptr, 0xFF, PNG_FILLER_AFTER);
    png_read_update_info(png_ptr, info);
    pixel_depth = 8;
  }

  int row_bytes = png_get_rowbytes(png_ptr,info);

  row_pointers = malloc(sizeof(png_bytep *) * height);
  for(size_t n=0;n<height;n++) {
    row_pointers[n] = malloc(row_bytes);
  }

  png_start_read_image(png_ptr);
}

void LoadPNGBuffer(byte * data, byte ** pic, int *width, int *height)
{
	int             bit_depth;
	int             color_type;
	png_uint_32     w;
	png_uint_32     h;
	unsigned int    row;
	size_t          rowbytes;
	png_infop       info;
	png_structp     png;
	png_bytep      *row_pointers;
	byte           *out;
	int             size;
	byte            alphaByte = 255;

	// load png
//  size = ri.FS_ReadFile(name, (void **)&data);

	if(!data)
		return;

	//png = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
	png = png_create_read_struct(PNG_LIBPNG_VER_STRING, (png_voidp) NULL, png_user_error_fn, png_user_warning_fn);

	if(!png)
	{
		Sys_FPrintf(SYS_WRN, "LoadPNGBuffer: png_create_write_struct() failed\n");
		//free(data);
		return;
	}

	// allocate/initialize the memory for image information.  REQUIRED
	info = png_create_info_struct(png);
	if(!info)
	{
		Sys_FPrintf(SYS_WRN, "LoadPNGBuffer: png_create_info_struct() failed\n");
		//free(data);
		png_destroy_read_struct(&png, (png_infopp) NULL, (png_infopp) NULL);
		return;
	}

	//
	// Set error handling if you are using the setjmp/longjmp method (this is
	// the normal method of doing things with libpng).  REQUIRED unless you
	// set up your own error handlers in the png_create_read_struct() earlier.
	//
	if(setjmp(png_jmpbuf(png)))
	{
		// if we get here, we had a problem reading the file
		Sys_FPrintf(SYS_WRN, "LoadPNGBuffer: first exception handler called\n");
		//free(data);
		png_destroy_read_struct(&png, (png_infopp) & info, (png_infopp) NULL);
		return;
	}

	//png_set_write_fn(png, buffer, png_write_data, png_flush_data);
	png_set_read_fn(png, data, png_read_data);

	png_set_sig_bytes(png, 0);

	// The call to png_read_info() gives us all of the information from the
	// PNG file before the first IDAT (image data chunk).  REQUIRED
	png_read_info(png, info);

	// get picture info
	png_get_IHDR(png, info, (png_uint_32 *) & w, (png_uint_32 *) & h, &bit_depth, &color_type, NULL, NULL, NULL);

	// tell libpng to strip 16 bit/color files down to 8 bits/color
	png_set_strip_16(png);

	// expand paletted images to RGB triplets
	if(color_type & PNG_COLOR_MASK_PALETTE)
		png_set_expand(png);

	// expand gray-scaled images to RGB triplets
	if(!(color_type & PNG_COLOR_MASK_COLOR))
		png_set_gray_to_rgb(png);

	// expand grayscale images to the full 8 bits from 1, 2, or 4 bits/pixel
	//if(color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
	//  png_set_gray_1_2_4_to_8(png);

	// expand paletted or RGB images with transparency to full alpha channels
	// so the data will be available as RGBA quartets
	if(png_get_valid(png, info, PNG_INFO_tRNS))
		png_set_tRNS_to_alpha(png);

	// if there is no alpha information, fill with alphaByte
	if(!(color_type & PNG_COLOR_MASK_ALPHA))
		png_set_filler(png, alphaByte, PNG_FILLER_AFTER);

	// expand pictures with less than 8bpp to 8bpp
	if(bit_depth < 8)
		png_set_packing(png);

	// update structure with the above settings
	png_read_update_info(png, info);

	// allocate the memory to hold the image
	*width = w;
//.........这里部分代码省略.........