C++ png_read_image函数代码示例

//.........这里部分代码省略.........

	// get rid of lower-order byte in 16-bit images
	// TODO: could allow this and read in IntImage in this case...
	if (bits == 16)
		png_set_strip_16(png_ptr);

	// change palette color into RGB
	if (colorType == PNG_COLOR_TYPE_PALETTE)
		png_set_expand(png_ptr);

	// want at least 8 bits
	if (bits < 8)
		png_set_expand(png_ptr);

	// if there is a transparent palette entry, create alpha channel
	if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
		png_set_expand(png_ptr);

	// make gray images with alpha channel into RGBA -- TODO: or just ignore alpha?
	if (colorType == PNG_COLOR_TYPE_GRAY_ALPHA)
		// colorType == PNG_COLOR_TYPE_GRAY       // but leave gray images alone
		png_set_gray_to_rgb(png_ptr);

	// set the background color to draw transparent and alpha images over.
	// only needed for gray images with alpha 
	if (colorType == PNG_COLOR_TYPE_GRAY_ALPHA ||
		colorType == PNG_COLOR_TYPE_GRAY) {
		png_color_16 *pBackground;
		if (png_get_bKGD(png_ptr, info_ptr, &pBackground))
			png_set_background(png_ptr, pBackground, PNG_BACKGROUND_GAMMA_FILE, 1, 1.0);
		}

	// if required set gamma conversion
	// this seems to cause problems, so let's just leave gamma alone.
	//double gamma;
	//if (png_get_gAMA(png_ptr, info_ptr, &gamma)) {
	// //fprintf(stderr, "\n reading gamma %lf\n", gamma);
	//png_set_gamma(png_ptr, 1.0, gamma);
	//}

	// we need colors in BGR order, not RGB
	png_set_bgr(png_ptr);

	// always convert 3-band to 4-band images (add alpha):
	if (colorType == PNG_COLOR_TYPE_RGB)
		png_set_add_alpha(png_ptr, 255, PNG_FILLER_AFTER);

	// after the transformations have been registered update info_ptr data
	png_read_update_info(png_ptr, info_ptr);

	// get again width, height and the new bit-depth and color-type

	png_get_IHDR(png_ptr, info_ptr, 
		     &pwidth, &pheight,
		     //(png_uint_32 *)&width, (png_uint_32 *)&height,
		     &bits, &colorType, NULL, NULL, NULL);
	
	width = pwidth;
	height = pheight;

	nBands = (int)png_get_channels(png_ptr, info_ptr);

	if (DEBUG_ImageIOpng)
	fprintf(stderr, "  -> w=%d, h=%d, %2d bits, %s, nB=%d\n",
		width, height, bits,
		colorType == PNG_COLOR_TYPE_GRAY ? "gray" :
		colorType == PNG_COLOR_TYPE_PALETTE ? "plt " :
		colorType == PNG_COLOR_TYPE_RGB ? "rgb " :
		colorType == PNG_COLOR_TYPE_RGB_ALPHA ? "rgba" :
		colorType == PNG_COLOR_TYPE_GRAY_ALPHA ? "gr-a" : "??? ",
		nBands);
	

	if (! (nBands==1 || nBands==3 || nBands==4)) {
        fclose(stream);
		throw CError("ReadFilePNG: Can't handle nBands=%d", nBands);
	}

	// Set the image shape
	CShape sh(width, height, nBands);

	// Allocate the image if necessary
	img.ReAllocate(sh);

	//  allocate a vector of row pointers
	std::vector<uchar *> rowPtrs;
	rowPtrs.resize(height);
	for (int y = 0; y<height; y++)
		rowPtrs[y] = &img.Pixel(0, y, 0);

	// read the whole image
	png_read_image(png_ptr, &rowPtrs[0]);

 	// read the additional chunks in the PNG file (not really needed)
	png_read_end(png_ptr, NULL);

	png_destroy_read_struct(&png_ptr, &info_ptr, NULL);

	fclose(stream);
}

static void read_png(unsigned char** block, unsigned* width, unsigned* height, FILE* file, const int base_img_size)
{
	png_structp png_ptr;
	png_infop   info_ptr;
	png_bytep* row_pointers;
	unsigned row, x, y;
	int rowbytes;
	char* dst;

	//png_uint_32 is 64 bit on some architectures!
	png_uint_32 widthpu32,heightpu32;

	png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,NULL,NULL,NULL);
	if (png_ptr == NULL) {
		printf("read_png: Could not create read struct.\n");
		exit(1);
	}

	info_ptr = png_create_info_struct(png_ptr);
	if (info_ptr == NULL) {
		printf("read_png: Could not create info struct.\n");
		png_destroy_read_struct(&png_ptr, (png_infopp)NULL, (png_infopp)NULL);
		exit(1);
	}


	if (setjmp(png_ptr->jmpbuf)) {
		printf("read_png: fatal error.\n");
		png_destroy_read_struct(&png_ptr, &info_ptr, (png_info**)0);
		/* free pointers before returning, if necessary */
		free(png_ptr);
		free(info_ptr);
		exit(1);
	}

	/* Set up the input control if you are using standard C streams */
	png_init_io(png_ptr, file);


	/* 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_ptr, info_ptr);

	png_get_IHDR(
		png_ptr, info_ptr,
		&widthpu32, &heightpu32, &bit_depth, &color_type,
		&interlace_type, NULL, NULL
	);
	*width = widthpu32;
	*height = heightpu32;

	if (*height % base_img_size != 0 || *width % base_img_size != 0) {
		printf("read_png: Invalid image size.\n");
		exit(1);
	}
	// printf("read_png: width=%d, height=%d, bit_depth=%d\n", width, height, bit_depth);
	// printf("read_png: color_type=%d, interlace_type=%d\n", color_type, interlace_type);


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


	/* Extract multiple pixels with bit depths of 1, 2, and 4 from a single
	 * byte into separate bytes (useful for paletted and grayscale images).
	 */
	png_set_packing(png_ptr);


	/* Expand paletted colors into true RGB triplets */
	png_set_expand(png_ptr);


	png_start_read_image(png_ptr);

	/* The easiest way to read the image: */

	rowbytes = png_get_rowbytes(png_ptr, info_ptr) * 3;
	row_pointers = malloc(*height * sizeof(*row_pointers));

	row_pointers[0] = malloc(rowbytes * *height * 2);

	for (row = 1; row < *height; row++) {
		row_pointers[row] = row_pointers[row - 1] + rowbytes * 2;
	}
	/* Read the entire image in one go */
	png_read_image(png_ptr, row_pointers);

	// we use fixed height here because block is of limited, fixed size
	// not fixed any more

	*block = realloc(*block, *height * *width * 6);

	// *block = malloc(*height * *width * 6);

	dst = *block;
	for (y = 0; y < *height; y++) {
		for (x = 0; x < *width * 3; x++) {
			*dst++ = row_pointers[y][x];
//.........这里部分代码省略.........

//.........这里部分代码省略.........
	/*
	 * Set error handling if you are using the setjmp/longjmp method (this is
	 * the common 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
		ri.Printf( PRINT_WARNING, "LoadPNG: first exception handler called for (%s)\n", name );
		ri.FS_FreeFile( data );
		png_destroy_read_struct( &png, ( png_infopp ) & info, ( png_infopp ) nullptr );
		return;
	}

	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, nullptr, nullptr, nullptr );

	// 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

	// 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 );
	}

	png_set_interlace_handling( png );

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

	// allocate the memory to hold the image
	*width = w;
	*height = h;
	*pic = out = ( byte * ) ri.Z_Malloc( w * h * 4 );

	row_pointers = ( png_bytep * ) ri.Hunk_AllocateTempMemory( sizeof( png_bytep ) * h );

	// set a new exception handler
	if ( setjmp( png_jmpbuf( png ) ) )
	{
		ri.Printf( PRINT_WARNING, "LoadPNG: second exception handler called for (%s)\n", name );
		ri.Hunk_FreeTempMemory( row_pointers );
		ri.FS_FreeFile( data );
		png_destroy_read_struct( &png, ( png_infopp ) & info, ( png_infopp ) nullptr );
		return;
	}

	for ( row = 0; row < h; row++ )
	{
		row_pointers[ row ] = ( png_bytep )( out + ( row * 4 * w ) );
	}

	// read image data
	png_read_image( png, row_pointers );

	// read rest of file, and get additional chunks in info
	png_read_end( png, info );

	// clean up after the read, and free any memory allocated
	png_destroy_read_struct( &png, &info, ( png_infopp ) nullptr );

	ri.Hunk_FreeTempMemory( row_pointers );
	ri.FS_FreeFile( data );
}

bool
wxPNGHandler::LoadFile(wxImage *image,
                       wxInputStream& stream,
                       bool verbose,
                       int WXUNUSED(index))
{
    // VZ: as this function uses setjmp() the only fool-proof error handling
    //     method is to use goto (setjmp is not really C++ dtors friendly...)

    unsigned char **lines = NULL;
    png_infop info_ptr = (png_infop) NULL;
    wxPNGInfoStruct wxinfo;

    png_uint_32 i, width, height = 0;
    int bit_depth, color_type, interlace_type;

    wxinfo.verbose = verbose;
    wxinfo.stream.in = &stream;

    image->Destroy();

    png_structp png_ptr = png_create_read_struct
                          (
                            PNG_LIBPNG_VER_STRING,
                            NULL,
                            wx_PNG_error,
                            wx_PNG_warning
                          );
    if (!png_ptr)
        goto error;

    // NB: please see the comment near wxPNGInfoStruct declaration for
    //     explanation why this line is mandatory
    png_set_read_fn( png_ptr, &wxinfo, wx_PNG_stream_reader);

    info_ptr = png_create_info_struct( png_ptr );
    if (!info_ptr)
        goto error;

    if (setjmp(wxinfo.jmpbuf))
        goto error;

    png_read_info( png_ptr, info_ptr );
    png_get_IHDR( png_ptr, info_ptr, &width, &height, &bit_depth, &color_type, &interlace_type, NULL, NULL );

    if (color_type == PNG_COLOR_TYPE_PALETTE)
        png_set_expand( png_ptr );

    // Fix for Bug [ 439207 ] Monochrome PNG images come up black
    if (bit_depth < 8)
        png_set_expand( png_ptr );

    png_set_strip_16( png_ptr );
    png_set_packing( png_ptr );
    if (png_get_valid( png_ptr, info_ptr, PNG_INFO_tRNS))
        png_set_expand( png_ptr );
    png_set_filler( png_ptr, 0xff, PNG_FILLER_AFTER );

    image->Create((int)width, (int)height, (bool) false /* no need to init pixels */);

    if (!image->IsOk())
        goto error;

    // initialize all line pointers to NULL to ensure that they can be safely
    // free()d if an error occurs before all of them could be allocated
    lines = (unsigned char **)calloc(height, sizeof(unsigned char *));
    if ( !lines )
        goto error;

    for (i = 0; i < height; i++)
    {
        if ((lines[i] = (unsigned char *)malloc( (size_t)(width * 4))) == NULL)
            goto error;
    }

    png_read_image( png_ptr, lines );
    png_read_end( png_ptr, info_ptr );

#if wxUSE_PALETTE
    if (color_type == PNG_COLOR_TYPE_PALETTE)
    {
        png_colorp palette = NULL;
        int numPalette = 0;

        (void) png_get_PLTE(png_ptr, info_ptr, &palette, &numPalette);

        unsigned char* r = new unsigned char[numPalette];
        unsigned char* g = new unsigned char[numPalette];
        unsigned char* b = new unsigned char[numPalette];

        for (int j = 0; j < numPalette; j++)
        {
            r[j] = palette[j].red;
            g[j] = palette[j].green;
            b[j] = palette[j].blue;
        }

        image->SetPalette(wxPalette(numPalette, r, g, b));
        delete[] r;
        delete[] g;
//.........这里部分代码省略.........

//.........这里部分代码省略.........
   if (transforms & PNG_TRANSFORM_PACKSWAP)
       png_set_packswap(png_ptr);
#endif

#if defined(PNG_READ_EXPAND_SUPPORTED)
   /* Expand paletted colors into true RGB triplets
    * Expand grayscale images to full 8 bits from 1, 2, or 4 bits/pixel
    * Expand paletted or RGB images with transparency to full alpha
    * channels so the data will be available as RGBA quartets.
    */
   if (transforms & PNG_TRANSFORM_EXPAND)
       if ((png_ptr->bit_depth < 8) ||
           (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ||
           (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)))
         png_set_expand(png_ptr);
#endif

   /* We don't handle background color or gamma transformation or dithering.
    */

#if defined(PNG_READ_INVERT_SUPPORTED)
   /* invert monochrome files to have 0 as white and 1 as black
    */
   if (transforms & PNG_TRANSFORM_INVERT_MONO)
       png_set_invert_mono(png_ptr);
#endif

#if defined(PNG_READ_SHIFT_SUPPORTED)
   /* If you want to shift the pixel values from the range [0,255] or
    * [0,65535] to the original [0,7] or [0,31], or whatever range the
    * colors were originally in:
    */
   if ((transforms & PNG_TRANSFORM_SHIFT)
       && png_get_valid(png_ptr, info_ptr, PNG_INFO_sBIT))
   {
      png_color_8p sig_bit;

      png_get_sBIT(png_ptr, info_ptr, &sig_bit);
      png_set_shift(png_ptr, sig_bit);
   }
#endif

#if defined(PNG_READ_BGR_SUPPORTED)
   /* flip the RGB pixels to BGR (or RGBA to BGRA)
    */
   if (transforms & PNG_TRANSFORM_BGR)
       png_set_bgr(png_ptr);
#endif

#if defined(PNG_READ_SWAP_ALPHA_SUPPORTED)
   /* swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR)
    */
   if (transforms & PNG_TRANSFORM_SWAP_ALPHA)
       png_set_swap_alpha(png_ptr);
#endif

#if defined(PNG_READ_SWAP_SUPPORTED)
   /* swap bytes of 16 bit files to least significant byte first
    */
   if (transforms & PNG_TRANSFORM_SWAP_ENDIAN)
       png_set_swap(png_ptr);
#endif

   /* We don't handle adding filler bytes */

   /* Optional call to gamma correct and add the background to the palette
    * and update info structure.  REQUIRED if you are expecting libpng to
    * update the palette for you (i.e., you selected such a transform above).
    */
   png_read_update_info(png_ptr, info_ptr);

   /* -------------- image transformations end here ------------------- */

#ifdef PNG_FREE_ME_SUPPORTED
   png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0);
#endif
   if(info_ptr->row_pointers == NULL)
   {
      info_ptr->row_pointers = (png_bytepp)png_malloc(png_ptr,
         info_ptr->height * png_sizeof(png_bytep));
#ifdef PNG_FREE_ME_SUPPORTED
      info_ptr->free_me |= PNG_FREE_ROWS;
#endif
      for (row = 0; row < (int)info_ptr->height; row++)
      {
         info_ptr->row_pointers[row] = (png_bytep)png_malloc(png_ptr,
            png_get_rowbytes(png_ptr, info_ptr));
      }
   }

   png_read_image(png_ptr, info_ptr->row_pointers);
   info_ptr->valid |= PNG_INFO_IDAT;

   /* read rest of file, and get additional chunks in info_ptr - REQUIRED */
   png_read_end(png_ptr, info_ptr);

   if(transforms == 0 || params == NULL)
      /* quiet compiler warnings */ return;

}

//.........这里部分代码省略.........
      png_row_bytes = png_width * 3;
      png_channels = 3;
    }

    rwidth = png_width;
    rheight = png_height;
    components = png_channels;

    /* possible integer overflow? */
    assert ((int) png_row_bytes > 0);
    assert ((int) png_height > 0);
    assert (((int)png_row_bytes) * ((int)png_height) * sizeof(png_byte) > 0);
    buf = rxvt_malloc(png_row_bytes * png_height * sizeof(png_byte));
    if (buf == NULL){
      rxvt_msg (DBG_ERROR, DBG_IMAGES, "png read error: out of memory..\n");
      png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
      fclose(ifile);
      return -1;
    }
    /* possible integer overflow? */
    assert ((int) png_height > 0);
    assert (sizeof(png_bytep) * ((int)png_height) > 0);
    png_row_ptrs = rxvt_malloc (sizeof(png_bytep)*png_height);
    if (png_row_ptrs == NULL){
      rxvt_msg (DBG_ERROR, DBG_IMAGES, "png read error: out of memory..\n");
      png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
      fclose(ifile);
      return -1;
    }

    for(i = 0; i < (int)png_height; i++){
      png_row_ptrs[i] = (png_byte*)(buf + i * png_row_bytes);
    }
    png_read_image(png_ptr, png_row_ptrs);
    png_read_end(png_ptr,NULL);
    rxvt_free(png_row_ptrs);

    vwidth = *w;
    vheight = *h;
    stretched =0;
    if (*w == 0 || *h == 0){
      *w = rwidth;
      *h = rheight;
    }else{
      if ((long)((double)rwidth * vheight/vwidth) < rheight){
        *w = (long)((double)vheight * rwidth/rheight);
      }else{
        *h = (long)((double)vwidth * rheight/rwidth);
      }
      stretched = 1;
    }
    vwidth = *w;
    vheight = *h;



    image = 0;
    visual = XDefaultVisual(display,XDefaultScreen(display));
    if (display_depth >16){
      image = XCreateImage(display,visual, display_depth,
                           ZPixmap,0,0,vwidth,vheight,32,0);
    }else
    if (display_depth >8){
      image = XCreateImage(display,visual, display_depth,
                           ZPixmap,0,0,vwidth,vheight,16,0);
    }else{

unsigned char *	ReadPNG(FILE * fp, unsigned int & sizeX, unsigned int &sizeY, int &img_depth, int &img_color_type, unsigned char *** row_pointer_ptr)
{
	png_structp png_ptr;
	png_bytepp row_pointers;
	png_infop info_ptr;
	int  interlace_type;

	png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, (png_error_ptr)png_cexcept_error, (png_error_ptr)NULL);
	if (png_ptr == NULL)
	{
		exit(1);
		return NULL;
	}
	info_ptr = png_create_info_struct(png_ptr);
	if (info_ptr == NULL)
	{
		png_destroy_read_struct(&png_ptr, (png_infopp)NULL, (png_infopp)NULL);
		fprintf(stderr,"VSImage ERROR : PNG info_ptr == NULL !!!\n");
		exit(1);
		return NULL;
	}
	if (setjmp(png_jmpbuf(png_ptr)))
	{
		/* Free all of the memory associated with the png_ptr and info_ptr */
		png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
		/* If we get here, we had a problem reading the file */
		exit(1);
		return NULL;
	}

        png_init_io(png_ptr, fp);

	//png_set_sig_bytes(png_ptr, 8);
	png_read_info(png_ptr, info_ptr);  /* read all PNG info up to image data */
	png_get_IHDR(png_ptr, info_ptr, (png_uint_32 *)&sizeX, (png_uint_32 *)&sizeY, &img_depth, &img_color_type, &interlace_type, NULL, NULL);

# if __BYTE_ORDER != __BIG_ENDIAN
	if (img_depth==16)
		png_set_swap (png_ptr);
#endif

	if (img_depth==16)//for now
		png_set_strip_16(png_ptr);
	if (img_color_type == PNG_COLOR_TYPE_PALETTE)
		png_set_palette_to_rgb(png_ptr);
		   
	if (img_color_type == PNG_COLOR_TYPE_GRAY && img_depth < 8)
		png_set_gray_1_2_4_to_8(png_ptr);

	png_set_expand (png_ptr);
	png_read_update_info (png_ptr,info_ptr);
	png_get_IHDR(png_ptr, info_ptr, (png_uint_32 *)&sizeX, (png_uint_32 *)&sizeY, &img_depth, &img_color_type, &interlace_type, NULL, NULL);
	row_pointers = (unsigned char **)malloc (sizeof (unsigned char *) *sizeY);
	int numchan=1;
	if (img_color_type&PNG_COLOR_MASK_COLOR)
		numchan =3;
	if (img_color_type &PNG_COLOR_MASK_PALETTE)
		numchan =1;
	if (img_color_type&PNG_COLOR_MASK_ALPHA)
		numchan++;
	unsigned long stride = numchan*sizeof (unsigned char)*img_depth/8;
	unsigned char * image = (unsigned char *) malloc (stride*sizeX*sizeY);
	for (unsigned int i=0;i<sizeY;i++)
	{
		row_pointers[i] = &image[i*stride*sizeX];
	}
	png_read_image (png_ptr,row_pointers);
	unsigned char * result;
        result = image;
	//free (row_pointers);
        *row_pointer_ptr=row_pointers;
	png_read_end(png_ptr, info_ptr);
	png_destroy_read_struct(&png_ptr, &info_ptr, NULL);

	return result;
}

//.........这里部分代码省略.........
        png_set_swap(png_ptr);
    }

    // Convert palletes to full RGB
    if (png_get_color_type(png_ptr, info_ptr) == PNG_COLOR_TYPE_PALETTE)
    {
        png_set_palette_to_rgb(png_ptr);
    }

    // If there's an alpha channel convert gray to RGB
    if (png_get_color_type(png_ptr, info_ptr) == PNG_COLOR_TYPE_GRAY_ALPHA)
    {
        png_set_gray_to_rgb(png_ptr);
    }

    png_set_interlace_handling(png_ptr);
    png_read_update_info(png_ptr, info_ptr);

    /* read file */
    if (setjmp(png_jmpbuf(png_ptr)))
    {
        throw Py::RuntimeError(
            "_image_module::readpng: error during read_image");
    }

    png_bytep *row_pointers = new png_bytep[height];
    png_uint_32 row;

    for (row = 0; row < height; row++)
    {
        row_pointers[row] = new png_byte[png_get_rowbytes(png_ptr,info_ptr)];
    }

    png_read_image(png_ptr, row_pointers);

    npy_intp dimensions[3];
    dimensions[0] = height;  //numrows
    dimensions[1] = width;   //numcols
    if (png_get_color_type(png_ptr, info_ptr) & PNG_COLOR_MASK_ALPHA)
    {
        dimensions[2] = 4;     //RGBA images
    }
    else if (png_get_color_type(png_ptr, info_ptr) & PNG_COLOR_MASK_COLOR)
    {
        dimensions[2] = 3;     //RGB images
    }
    else
    {
        dimensions[2] = 1;     //Greyscale images
    }
    //For gray, return an x by y array, not an x by y by 1
    int num_dims  = (png_get_color_type(png_ptr, info_ptr)
                                & PNG_COLOR_MASK_COLOR) ? 3 : 2;

    PyArrayObject *A = NULL;
    if (float_result) {
        double max_value = (1 << bit_depth) - 1;
        PyArrayObject *A = (PyArrayObject *) PyArray_SimpleNew(
            num_dims, dimensions, PyArray_FLOAT);

        if (A == NULL)
        {
            throw Py::MemoryError("Could not allocate image array");
        }

        for (png_uint_32 y = 0; y < height; y++)

static gboolean
gst_gl_differencematte_loader (GstGLFilter * filter)
{
  GstGLDifferenceMatte *differencematte = GST_GL_DIFFERENCEMATTE (filter);

  png_structp png_ptr;
  png_infop info_ptr;
  guint sig_read = 0;
  png_uint_32 width = 0;
  png_uint_32 height = 0;
  gint bit_depth = 0;
  gint color_type = 0;
  gint interlace_type = 0;
  png_FILE_p fp = NULL;
  guint y = 0;
  guchar **rows = NULL;
  gint filler;

  if (!GST_GL_BASE_FILTER (filter)->context)
    return TRUE;

  if ((fp = fopen (differencematte->location, "rb")) == NULL)
    LOAD_ERROR ("file not found");

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

  if (png_ptr == NULL) {
    fclose (fp);
    LOAD_ERROR ("failed to initialize the png_struct");
  }

  png_set_error_fn (png_ptr, NULL, NULL, user_warning_fn);

  info_ptr = png_create_info_struct (png_ptr);
  if (info_ptr == NULL) {
    fclose (fp);
    png_destroy_read_struct (&png_ptr, png_infopp_NULL, png_infopp_NULL);
    LOAD_ERROR ("failed to initialize the memory for image information");
  }

  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, int_p_NULL, int_p_NULL);

  if (color_type == PNG_COLOR_TYPE_RGB) {
    filler = 0xff;
    png_set_filler (png_ptr, filler, PNG_FILLER_AFTER);
    color_type = PNG_COLOR_TYPE_RGB_ALPHA;
  }

  if (color_type != PNG_COLOR_TYPE_RGB_ALPHA) {
    fclose (fp);
    png_destroy_read_struct (&png_ptr, png_infopp_NULL, png_infopp_NULL);
    LOAD_ERROR ("color type is not rgb");
  }

  differencematte->pbuf_width = width;
  differencematte->pbuf_height = height;

  differencematte->pixbuf =
      (guchar *) malloc (sizeof (guchar) * width * height * 4);

  rows = (guchar **) malloc (sizeof (guchar *) * height);

  for (y = 0; y < height; ++y)
    rows[y] = (guchar *) (differencematte->pixbuf + y * width * 4);

  png_read_image (png_ptr, rows);

  free (rows);

  png_read_end (png_ptr, info_ptr);
  png_destroy_read_struct (&png_ptr, &info_ptr, png_infopp_NULL);
  fclose (fp);

  return TRUE;
}

//.........这里部分代码省略.........
  /* Initialize the setjmp for returning properly after a libpng
     error occured */
  if (setjmp (png_jmpbuf(png_ptr))) {
    fclose (fp);
    png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
    
    if (texinfo) {
      if (texinfo->texels)
	free (texinfo->texels);      
      free (texinfo);
    }    
    return NULL;
  }

  /* Setup libpng for using standard C fread() function
     with our FILE pointer */
  png_init_io (png_ptr, fp);
  
  /* Tell libpng that we have already read the magic number */
  png_set_sig_bytes (png_ptr, sizeof (magic));
  
  /* Read png info */
  png_read_info (png_ptr, info_ptr);

  int bit_depth, color_type;
  
  /* Get some usefull information from header */
  bit_depth = png_get_bit_depth (png_ptr, info_ptr);
  color_type = png_get_color_type (png_ptr, info_ptr);
  
  /* Convert index color images to RGB images */
  if (color_type == PNG_COLOR_TYPE_PALETTE)
    png_set_palette_to_rgb (png_ptr);

  /* Convert 1-2-4 bits grayscale images to 8 bits
     grayscale. */
  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 (bit_depth == 16)
    png_set_strip_16 (png_ptr);
  else if (bit_depth < 8)
    png_set_packing (png_ptr);

  /* Update info structure to apply transformations */
  png_read_update_info (png_ptr, info_ptr);

  /* Retrieve updated information */
  png_uint_32 w, h;
  
  png_get_IHDR (png_ptr, info_ptr, &w, &h, &bit_depth,&color_type, NULL, NULL, NULL);
  texinfo->width = w;
  texinfo->height = h;
  switch (color_type) {
  case PNG_COLOR_TYPE_GRAY:
    texinfo->format = GL_LUMINANCE;
    texinfo->internalFormat = 1;
    break;
    
  case PNG_COLOR_TYPE_GRAY_ALPHA:
    texinfo->format = GL_LUMINANCE_ALPHA;
    texinfo->internalFormat = 2;
    break;
    
  case PNG_COLOR_TYPE_RGB:
    texinfo->format = GL_RGB;
    texinfo->internalFormat = 3;
    break;

  case PNG_COLOR_TYPE_RGB_ALPHA:
    texinfo->format = GL_RGBA;
    texinfo->internalFormat = 4;
    break;

  default:
    /* Badness */
    break;
  }
  /* We can now allocate memory for storing pixel data */
  texinfo->texels = (GLubyte *)malloc (sizeof (GLubyte)*texinfo->width*texinfo->height*texinfo->internalFormat);
  
  png_bytep *row_pointers;
  
  /* Setup a pointer array.  Each one points at the begening of a row. */
  row_pointers = (png_bytep *)malloc (sizeof (png_bytep) * texinfo->height);
  
  for (int i = 0; i < texinfo->height; ++i) 
    row_pointers[i] = (png_bytep)(texinfo->texels + ((texinfo->height - (i + 1)) * texinfo->width * texinfo->internalFormat));
  
  /* Read pixel data using row pointers */
  png_read_image(png_ptr, row_pointers);
  
  /* We don't need row pointers anymore */
  free (row_pointers);
  
  return(texinfo);
  
}

//.........这里部分代码省略.........
    /* 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_ptr, info_ptr);
    
    png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
                 &interlace_type, NULL, NULL);
    
    /**** Set up the data transformations you want.  Note that these are all
     **** optional.  Only call them if you want/need them.  Many of the
     **** transformations only work on specific types of images, and many
     **** are mutually exclusive.
     ****/
    
    /* tell libpng to strip 16 bit/color files down to 8 bits/color */
    png_set_strip_16(png_ptr);
    
    /* strip alpha bytes from the input data without combining with th
     * background (not recommended) */
    /* png_set_strip_alpha(png_ptr); */
    
    /* extract multiple pixels with bit depths of 1, 2, and 4 from a single
     * byte into separate bytes (useful for paletted and grayscale images).
     */
    /* png_set_packing(png_ptr); */
    
    /* change the order of packed pixels to least significant bit first
     * (not useful if you are using png_set_packing). */
    /* png_set_packswap(png_ptr); */
    
    /* expand paletted colors into true RGB triplets */
    if (color_type == PNG_COLOR_TYPE_PALETTE)
        png_set_expand(png_ptr);
    
    /* 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_expand(png_ptr);
    
    /* 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_ptr, info_ptr, PNG_INFO_tRNS))
        png_set_expand(png_ptr);
    
    /* Add filler (or alpha) byte (before/after each RGB triplet) */
    /* png_set_filler(png_ptr, 0xff, PNG_FILLER_AFTER); */
    
    png_read_update_info(png_ptr, info_ptr);
    
    channels = png_get_channels(png_ptr, info_ptr);
    
    /* allocate the memory to hold the image using the fields of info_ptr. */
    
    bytes_per_row = png_get_rowbytes(png_ptr, info_ptr);
    
    
    buffer = (unsigned char*) malloc(bytes_per_row*height);
    
    format = channels;
    
    row_pointers = (png_bytepp) malloc(height*sizeof(png_bytep));
    for (y = 0; y < height; y++) {
        row_pointers[height-y-1] = buffer + y*bytes_per_row;
    }
    
    png_read_image(png_ptr, row_pointers);
    png_read_end(png_ptr, info_ptr);
    
    free(row_pointers);
    
    /* clean up after the read, and free any memory allocated - REQUIRED */
    png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
    
    /* close the file */
    fclose(fp);
    
    /* that's it */
    if (buffer) {
        *width_ret = width;
        *height_ret = height;
        switch(format) {
        case 1:
            *type_ret = GL_LUMINANCE;
            break;
        case 2:
            *type_ret = GL_LUMINANCE_ALPHA;
            break;
        case 3:
            *type_ret = GL_RGB;
            break;
        case 4:
            *type_ret = GL_RGBA;
            break;
        }
        pngerror = ERR_NO_ERROR;
    }
    else {
        pngerror = ERR_MEM;
    }
    return buffer;
}

//.........这里部分代码省略.........
        printf("png ptr not created\n");
        return 0;
    }

    if (setjmp(png_jmpbuf(png_ptr))) {
        printf("set jmp failed\n");
        return 0;
    }

    info_ptr = png_create_info_struct(png_ptr);

    if (!info_ptr) {
        printf("cant get png info ptr\n");
        return 0;
    }

    png_init_io(png_ptr, pngFile);
    png_read_info(png_ptr, info_ptr);
    bitDepth = png_get_bit_depth(png_ptr, info_ptr);
    colourType = png_get_color_type(png_ptr, info_ptr);

    if (colourType == PNG_COLOR_TYPE_PALETTE)
        png_set_palette_to_rgb(png_ptr);
    if (colourType == PNG_COLOR_TYPE_GRAY && bitDepth < 8)
        //png_set_gray_1_2_4_to_8(png_ptr);
        png_set_expand_gray_1_2_4_to_8(png_ptr);  // thanks to Jesse Jaara for bug fix for newer libpng...
    if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
        png_set_tRNS_to_alpha(png_ptr);

    if (bitDepth == 16)
        png_set_strip_16(png_ptr);
    else if (bitDepth < 8)
        png_set_packing(png_ptr);

    png_read_update_info(png_ptr, info_ptr);

    png_uint_32 width, height;
    png_get_IHDR(png_ptr, info_ptr, &width, &height,
                 &bitDepth, &colourType, NULL, NULL, NULL);

    int components;		// = GetTextureInfo(colourType);
    switch (colourType) {
    case PNG_COLOR_TYPE_GRAY:
        components = 1;
        break;
    case PNG_COLOR_TYPE_GRAY_ALPHA:
        components = 2;
        break;
    case PNG_COLOR_TYPE_RGB:
        components = 3;
        break;
    case PNG_COLOR_TYPE_RGB_ALPHA:
        components = 4;
        break;
    default:
        components = -1;
    }

    if (components == -1) {
        if (png_ptr)
            png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
        printf("%s broken?\n", filename);
        return 0;
    }

    GLubyte *pixels =
        (GLubyte *) malloc(sizeof(GLubyte) * (width * height * components));
    row_pointers = (png_bytep *) malloc(sizeof(png_bytep) * height);

    for (int i = 0; i < height; ++i)
        row_pointers[i] =
            (png_bytep) (pixels + (i * width * components));

    png_read_image(png_ptr, row_pointers);
    png_read_end(png_ptr, NULL);

    glGenTextures(1, &texture);
    glBindTexture(GL_TEXTURE_2D, texture);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    GLuint glcolours;
    (components == 4) ? (glcolours = GL_RGBA) : (0);
    (components == 3) ? (glcolours = GL_RGB) : (0);
    (components == 2) ? (glcolours = GL_LUMINANCE_ALPHA) : (0);
    (components == 1) ? (glcolours = GL_LUMINANCE) : (0);

    //printf("%s has %i colour components\n",filename,components);
    //glTexImage2D(GL_TEXTURE_2D, 0, components, width, height, 0, glcolours, GL_UNSIGNED_BYTE, pixels);
    glTexImage2D(GL_TEXTURE_2D, 0, glcolours, width, height, 0, glcolours,
                 GL_UNSIGNED_BYTE, pixels);

    png_destroy_read_struct(&png_ptr, &info_ptr, NULL);

    fclose(pngFile);
    free(row_pointers);
    free(pixels);

    return texture;

}

int
SplashDecodePng(Splash * splash, png_rw_ptr read_func, void *io_ptr)
{
    int stride;
    ImageFormat srcFormat;
    png_uint_32 i, rowbytes;
    png_bytepp row_pointers = NULL;
    png_bytep image_data = NULL;
    int success = 0;
    double gamma;

    png_structp png_ptr = NULL;
    png_infop info_ptr = NULL;

    png_uint_32 width, height;
    int bit_depth, color_type;

    ImageRect srcRect, dstRect;

    png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
    if (!png_ptr) {
        goto done;
    }

    info_ptr = png_create_info_struct(png_ptr);
    if (!info_ptr) {
        goto done;
    }

#ifdef __APPLE__
    /* use setjmp/longjmp versions that do not save/restore the signal mask */
    if (_setjmp(png_set_longjmp_fn(png_ptr, _longjmp, sizeof(jmp_buf)))) {
#else
    if (setjmp(png_jmpbuf(png_ptr))) {
#endif
        goto done;
    }

    png_set_read_fn(png_ptr, io_ptr, read_func);

    png_set_sig_bytes(png_ptr, SIG_BYTES);      /* we already read the 8 signature bytes */

    png_read_info(png_ptr, info_ptr);   /* read all PNG info up to image data */

    png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
        NULL, NULL, NULL);

    /* expand palette images to RGB, low-bit-depth grayscale images to 8 bits,
     * transparency chunks to full alpha channel; strip 16-bit-per-sample
     * images to 8 bits per sample; and convert grayscale to RGB[A]
     * this may be sub-optimal but this simplifies implementation */

    png_set_expand(png_ptr);
    png_set_tRNS_to_alpha(png_ptr);
    png_set_filler(png_ptr, 0xff, PNG_FILLER_AFTER);
    png_set_strip_16(png_ptr);
    png_set_gray_to_rgb(png_ptr);

    if (png_get_gAMA(png_ptr, info_ptr, &gamma))
        png_set_gamma(png_ptr, 2.2, gamma);

    png_set_interlace_handling(png_ptr);
    png_read_update_info(png_ptr, info_ptr);

    rowbytes = png_get_rowbytes(png_ptr, info_ptr);

    if (!SAFE_TO_ALLOC(rowbytes, height)) {
        goto done;
    }

    if ((image_data = (unsigned char *) malloc(rowbytes * height)) == NULL) {
        goto done;
    }

    if (!SAFE_TO_ALLOC(height, sizeof(png_bytep))) {
        goto done;
    }
    if ((row_pointers = (png_bytepp) malloc(height * sizeof(png_bytep)))
            == NULL) {
        goto done;
    }

    for (i = 0; i < height; ++i)
        row_pointers[i] = image_data + i * rowbytes;

    png_read_image(png_ptr, row_pointers);

    SplashCleanup(splash);

    splash->width = width;
    splash->height = height;

    if (!SAFE_TO_ALLOC(splash->width, splash->imageFormat.depthBytes)) {
        goto done;
    }
    stride = splash->width * splash->imageFormat.depthBytes;

    if (!SAFE_TO_ALLOC(splash->height, stride)) {
        goto done;
    }
//.........这里部分代码省略.........

//.........这里部分代码省略.........

	// read all the info up to the image data
	png_read_info(png_ptr, info_ptr);

	//variables to pass to get info
	int bit_depth, color_type;
	png_uint_32 twidth, theight;

	// get info about png
	png_get_IHDR(png_ptr, info_ptr, &twidth, &theight, &bit_depth, &color_type,
	  NULL, NULL, NULL);

	//update width and height based on png info
	width = twidth;
	height = theight;

	// Update the png info struct.
	png_read_update_info(png_ptr, info_ptr);

	// Row size in bytes.
	int rowbytes = png_get_rowbytes(png_ptr, info_ptr);

	// Allocate the image_data as a big block, to be given to opengl
	png_byte *image_data = new png_byte[rowbytes * height];
	if (!image_data) {
	//clean up memory and close stuff
	png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
	fclose(fp);
	return;
	}

	//row_pointers is for pointing to image_data for reading the png with libpng
	png_bytep *row_pointers = new png_bytep[height];
	if (!row_pointers) {
	//clean up memory and close stuff
	png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
	delete[] image_data;
	fclose(fp);
	return ;
	}
	// set the individual row_pointers to point at the correct offsets of image_data
	if(!flipY){
		for (int i = 0; i < height; ++i)
			row_pointers[i] = image_data + i * rowbytes;
	}
	else
	{
		for (int i = 0; i < height; ++i)
			row_pointers[height - 1 - i] = image_data + i * rowbytes;
	}
	
	//read the png into image_data through row_pointers
	png_read_image(png_ptr, row_pointers);

	/*

	  // set the individual row_pointers to point at the correct offsets of image_data
	  for (int i = 0; i < height; ++i)
		row_pointers[height - 1 - i] = (png_bytep)(image_data + i * rowbytes);

	///////////////////////////////////////////////////////////////
	*/
	//png_read_image(png_ptr, row_pointers);
	//png_set_rows(png_ptr,info_ptr,row_pointers);
	//png_read_png(png_ptr,info_ptr,/*PNG_TRANSFORM_BGR |*/ PNG_TRANSFORM_INVERT_ALPHA,NULL);
	//png_destroy_read_struct(&png_ptr, &info_ptr,NULL);

	unsigned int* pixels = (unsigned int*)malloc(rowbytes * height);
	memcpy(pixels,image_data,rowbytes * height);
	tex.mPixelData = pixels;
	tex.mWidth = width;
	tex.mHeight = height;
	if(color_type == PNG_COLOR_TYPE_RGB_ALPHA)
	{
		tex.mNumberOfColors = 4;
	}
	else if(color_type == PNG_COLOR_TYPE_RGB)
	{
		tex.mNumberOfColors = 3;
	}
	else
	{
		tex.mNumberOfColors = 3;
	}
	tex.mHasAlpha = tex.mNumberOfColors==4?true:false;
	tex.mBitsPerPixel = tex.mNumberOfColors * bit_depth;
	if(tex.mNumberOfColors == 4)
	{
		tex.mPixelFormat  = GL_RGBA;
	}
	else
	{
		tex.mPixelFormat  = GL_RGB;
	}
	//clean up memory and close stuff
	png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
	delete[] image_data;
	delete[] row_pointers;
	fclose(fp);
}

static NATIVECALL(png_new){
    Link * args = array_getArray(Arg);

    unsigned char pngheader[HEADERSIZE];
    png_structp png;
    png_infop info;
    png_bytep * row_pointers;
    png_byte* row ;

    FILE *fp;
    int  y, width, height;

    /* open the file args[0] is the filename */
    string_t filename_string = object_getString(args[0]);
    fp = fopen(filename_string->data , "rb");
    if (! fp){
        return exception("CouldNotOpenFile", NULL, NULL);
    }

    /* read the png header and ensure it is a png */
	fread(pngheader, 1, HEADERSIZE, fp);
	if (png_sig_cmp(pngheader, 0, HEADERSIZE)){
        return exception("NotPNG", NULL, NULL);
    }

	png = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
    png_set_sig_bytes(png, HEADERSIZE);
	info = png_create_info_struct(png);

	png_init_io(png, fp);

	png_read_info(png, info);

    Link obj = object_create(image_type);

    Image self = obj->value.vptr;

    self->width = info->width;

    self->height = info->height;

	width = info->width;

	height = info->height;

    //info->bit_depth;
    //info->channels;
	//info->color_type;
    //printf(" bit depth:%i    channels:%i    color type:%i   rowbytes:%i\n", info->bit_depth, info->channels, info->color_type , info->rowbytes);


    /* read png information */
	png_read_update_info(png, info);

    /* allocate memory for rows */
	row_pointers = malloc(sizeof(png_bytep) * height);
	for (y=0; y<height; y++) row_pointers[y] = malloc(info->rowbytes);

    /* read image into allocated memory */
	png_read_image(png, row_pointers);

    fclose(fp);

    png_byte * pdata;

    self->format = info->channels;
    self->data = pdata = malloc(self->width * self->height * self->format);
    for (y=0; y<height; y++) {
        row = row_pointers[height-y-1];
        memcpy(pdata,row, self->width * self->format);
        pdata+=self->width * self->format;
        free(row);
    }

    free(row_pointers);
    png_destroy_read_struct(&png, &info, NULL);

    return obj;
}