C++ png_set_palette_to_rgb函数代码示例

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_expand_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;
}

Error ImageLoaderPNG::_load_image(void *rf_up, png_rw_ptr p_func, Ref<Image> p_image) {

	png_structp png;
	png_infop info;

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

	png = png_create_read_struct_2(PNG_LIBPNG_VER_STRING, (png_voidp)NULL, _png_error_function, _png_warn_function, (png_voidp)NULL,
			_png_malloc_fn, _png_free_fn);

	ERR_FAIL_COND_V(!png, ERR_OUT_OF_MEMORY);

	info = png_create_info_struct(png);
	if (!info) {
		png_destroy_read_struct(&png, NULL, NULL);
		ERR_PRINT("Out of Memory");
		return ERR_OUT_OF_MEMORY;
	}

	if (setjmp(png_jmpbuf(png))) {

		png_destroy_read_struct(&png, NULL, NULL);
		ERR_PRINT("PNG Corrupted");
		return ERR_FILE_CORRUPT;
	}

	png_set_read_fn(png, (void *)rf_up, p_func);

	png_uint_32 width, height;
	int depth, color;

	png_read_info(png, info);
	png_get_IHDR(png, info, &width, &height, &depth, &color, NULL, NULL, NULL);

	//https://svn.gov.pt/projects/ccidadao/repository/middleware-offline/trunk/_src/eidmw/FreeImagePTEiD/Source/FreeImage/PluginPNG.cpp
	//png_get_text(png,info,)
	/*
	printf("Image width:%i\n", width);
	printf("Image Height:%i\n", height);
	printf("Bit depth:%i\n", depth);
	printf("Color type:%i\n", color);
	*/

	bool update_info = false;

	if (depth < 8) { //only bit dept 8 per channel is handled

		png_set_packing(png);
		update_info = true;
	};

	if (png_get_color_type(png, info) == PNG_COLOR_TYPE_PALETTE) {
		png_set_palette_to_rgb(png);
		update_info = true;
	}

	if (depth > 8) {
		png_set_strip_16(png);
		update_info = true;
	}

	if (png_get_valid(png, info, PNG_INFO_tRNS)) {
		//png_set_expand_gray_1_2_4_to_8(png);
		png_set_tRNS_to_alpha(png);
		update_info = true;
	}

	if (update_info) {
		png_read_update_info(png, info);
		png_get_IHDR(png, info, &width, &height, &depth, &color, NULL, NULL, NULL);
	}

	int components = 0;

	Image::Format fmt;
	switch (color) {

		case PNG_COLOR_TYPE_GRAY: {

			fmt = Image::FORMAT_L8;
			components = 1;
		} break;
		case PNG_COLOR_TYPE_GRAY_ALPHA: {

			fmt = Image::FORMAT_LA8;
			components = 2;
		} break;
		case PNG_COLOR_TYPE_RGB: {

			fmt = Image::FORMAT_RGB8;
			components = 3;
		} break;
		case PNG_COLOR_TYPE_RGB_ALPHA: {

			fmt = Image::FORMAT_RGBA8;
			components = 4;
		} break;
		default: {

			ERR_PRINT("INVALID PNG TYPE");
//.........这里部分代码省略.........

/*
=================
image_png_load
=================
*/
GNUC_NONNULL static erbool image_png_load (const char *name, image_t *im)
{
    fs_file_t   f;
    int         size, r, width, height, inc;
    png_byte   *image = NULL, *p = NULL;
    png_structp pngst;
    png_infop   info = NULL;
    png_byte    depth, color_type;

    if (NULL == (f = fs_open(name, FS_RDONLY, &size, false)))
        return false;

    if (NULL == (pngst = png_create_read_struct(PNG_LIBPNG_VER_STRING,
                                                NULL,
                                                &epng_error,
                                                &epng_warn)))
    {
        sys_printf("failed to create png read struct\n");
        fs_close(f);
        return false;
    }

    if (NULL == (info = png_create_info_struct(pngst)))
    {
        sys_printf("failed to create png info struct\n");
        goto error;
    }

    if (setjmp(png_jmpbuf(pngst)))
        goto error;

    png_set_user_limits(pngst, IMAGE_MAX_WIDTH, IMAGE_MAX_HEIGHT);
    png_set_read_fn(pngst, f, &epng_read);
    png_read_info(pngst, info);

    width  = png_get_image_width(pngst, info);
    height = png_get_image_height(pngst, info);
    depth  = png_get_bit_depth(pngst, info);

    if (16 == depth)
    {
        /* 16 -> 8 */
        png_set_strip_16(pngst);
        depth = 8;
    }

    color_type = png_get_color_type(pngst, info);

    /* 1/2/4 gray -> 8 gray */
    if (PNG_COLOR_TYPE_GRAY == color_type && depth < 8)
        png_set_expand_gray_1_2_4_to_8(pngst);

    /* gray/palette -> rgb */
    if (PNG_COLOR_TYPE_GRAY == color_type || PNG_COLOR_TYPE_GRAY_ALPHA == color_type)
        png_set_gray_to_rgb(pngst);
    else if (PNG_COLOR_TYPE_PALETTE)
        png_set_palette_to_rgb(pngst);

    /* transparency -> alpha */
    if (png_get_valid(pngst, info, PNG_INFO_tRNS))
    {
        png_set_tRNS_to_alpha(pngst);
    }
    else
    {
        /* to rgba */
        if (PNG_COLOR_TYPE_RGB_ALPHA != color_type &&
            PNG_COLOR_TYPE_GRAY_ALPHA != color_type)
            png_set_add_alpha(pngst, 0xff, PNG_FILLER_AFTER);
    }

    /* deinterlace */
    png_set_interlace_handling(pngst);

    /* read */
    inc = width * 4;

    p = image = mem_alloc(image_mempool, height * inc);

    for (r = 0; r < height ;r++, p += inc)
        png_read_row(pngst, p, NULL);

    png_read_end(pngst, NULL);
    png_destroy_read_struct(&pngst, &info, NULL);

    fs_close(f);

    im->width  = width;
    im->height = height;
    im->data   = image;

    return true;

error:
    if (NULL != f)
//.........这里部分代码省略.........

//.........这里部分代码省略.........
   /* Set up the input control if you are using standard C streams */
   png_init_io(png_ptr, fp);

#else no_streams /* PNG file I/O method 2 */
   /* If you are using replacement read functions, instead of calling
    * png_init_io() here you would call:
    */
   png_set_read_fn(png_ptr, (void *)user_io_ptr, user_read_fn);
   /* where user_io_ptr is a structure you want available to the callbacks */
#endif no_streams /* Use only one I/O method! */

   /* If we have already read some of the signature */
   png_set_sig_bytes(png_ptr, sig_read);

#ifdef hilevel
   /*
    * If you have enough memory to read in the entire image at once,
    * and you need to specify only transforms that can be controlled
    * with one of the PNG_TRANSFORM_* bits (this presently excludes
    * dithering, filling, setting background, and doing gamma
    * adjustment), then you can read the entire image (including
    * pixels) into the info structure with this call:
    */
   png_read_png(png_ptr, info_ptr, png_transforms, png_voidp_NULL);

#else
   /* OK, you're doing it the hard way, with the lower-level functions */

   /* 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, int_p_NULL, int_p_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 the
    * 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_palette_to_rgb(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_gray_1_2_4_to_8(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_tRNS_to_alpha(png_ptr);

   /* Set the background color to draw transparent and alpha images over.
    * It is possible to set the red, green, and blue components directly
    * for paletted images instead of supplying a palette index.  Note that
    * even if the PNG file supplies a background, you are not required to
    * use it - you should use the (solid) application background if it has one.
    */

   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);

   /* Some suggestions as to how to get a screen gamma value
    *
    * Note that screen gamma is the display_exponent, which includes
    * the CRT_exponent and any correction for viewing conditions
    */
   if (/* We have a user-defined screen gamma value */)
   {
      screen_gamma = user-defined screen_gamma;
   }
   /* This is one way that applications share the same screen gamma value */
   else if ((gamma_str = getenv("SCREEN_GAMMA")) != NULL)

Image *
readPNG(const char *filename)
{
    FILE *fp;
    png_structp png_ptr;
    png_infop info_ptr;
    png_infop end_info;
    Image *image;

    fp = fopen(filename, "rb");
    if (!fp)
        goto no_fp;

    png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
    if (!png_ptr)
        goto no_png;

    info_ptr = png_create_info_struct(png_ptr);
    if (!info_ptr) {
        png_destroy_read_struct(&png_ptr, NULL, NULL);
        goto no_png;
    }

    end_info = png_create_info_struct(png_ptr);
    if (!end_info) {
        png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
        goto no_png;
    }

    if (setjmp(png_jmpbuf(png_ptr))) {
        png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
        goto no_png;
    }

    png_init_io(png_ptr, fp);

    png_read_info(png_ptr, info_ptr);

    png_uint_32 width, height;
    int bit_depth, color_type, interlace_type, compression_type, filter_method;

    png_get_IHDR(png_ptr, info_ptr,
                 &width, &height,
                 &bit_depth, &color_type, &interlace_type,
                 &compression_type, &filter_method);

    image = new Image(width, height);
    if (!image)
        goto no_image;

    /* Convert to RGBA8 */
    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);

    for (unsigned y = 0; y < height; ++y) {
        png_bytep row = (png_bytep)(image->pixels + y*width*4);
        png_read_row(png_ptr, row, NULL);
    }

    png_read_end(png_ptr, info_ptr);
    png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
    fclose(fp);
    return image;

no_image:
    png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
no_png:
    fclose(fp);
no_fp:
    return NULL;
}

/*****************************************************************************
 * LoadPNG: loads the PNG logo into memory
 *****************************************************************************/
static picture_t *LoadPNG( vlc_object_t *p_this )
{
    picture_t *p_pic;
    char *psz_filename;
    vlc_value_t val;
    FILE *file;
    int i, j, i_trans;
    vlc_bool_t b_alpha = VLC_TRUE;

    png_uint_32 i_width, i_height;
    int i_color_type, i_interlace_type, i_compression_type, i_filter_type;
    int i_bit_depth;
    png_bytep *p_row_pointers;
    png_structp p_png;
    png_infop p_info, p_end_info;

    var_Create( p_this, "logo-file", VLC_VAR_STRING | VLC_VAR_DOINHERIT );
    var_Get( p_this, "logo-file", &val );
    psz_filename = val.psz_string;
    if( !psz_filename || !*psz_filename )
    {
        msg_Err( p_this, "logo file not specified" );
        return 0;
    }

    if( !(file = fopen( psz_filename , "rb" )) )
    {
        msg_Err( p_this, "logo file (%s) not found", psz_filename );
        free( psz_filename );
        return 0;
    }
    free( psz_filename );

    p_png = png_create_read_struct( PNG_LIBPNG_VER_STRING, 0, 0, 0 );
    p_info = png_create_info_struct( p_png );
    p_end_info = png_create_info_struct( p_png );
    png_init_io( p_png, file );
    png_read_info( p_png, p_info );
    png_get_IHDR( p_png, p_info, &i_width, &i_height,
                  &i_bit_depth, &i_color_type, &i_interlace_type,
                  &i_compression_type, &i_filter_type);

    if( i_color_type == PNG_COLOR_TYPE_PALETTE )
        png_set_palette_to_rgb( p_png );

    if( i_color_type == PNG_COLOR_TYPE_GRAY ||
        i_color_type == PNG_COLOR_TYPE_GRAY_ALPHA )
          png_set_gray_to_rgb( p_png );

    if( png_get_valid( p_png, p_info, PNG_INFO_tRNS ) )
    {
        png_set_tRNS_to_alpha( p_png );
    }
    else if( !(i_color_type & PNG_COLOR_MASK_ALPHA) )
    {
        b_alpha = VLC_FALSE;
    }

    p_row_pointers = malloc( sizeof(png_bytep) * i_height );
    for( i = 0; i < (int)i_height; i++ )
        p_row_pointers[i] = malloc( 4 * ( i_bit_depth + 7 ) / 8 * i_width );

    png_read_image( p_png, p_row_pointers );
    png_read_end( p_png, p_end_info );

    fclose( file );
    png_destroy_read_struct( &p_png, &p_info, &p_end_info );

    /* Convert to YUVA */
    p_pic = malloc( sizeof(picture_t) );
    if( vout_AllocatePicture( p_this, p_pic, VLC_FOURCC('Y','U','V','A'),
                              i_width, i_height, VOUT_ASPECT_FACTOR ) !=
        VLC_SUCCESS )
    {
        for( i = 0; i < (int)i_height; i++ ) free( p_row_pointers[i] );
        free( p_row_pointers );
        return 0;
    }

    var_Create(p_this, "logo-transparency", VLC_VAR_INTEGER|VLC_VAR_DOINHERIT);
    var_Get( p_this, "logo-transparency", &val );
    i_trans = __MAX( __MIN( val.i_int, 255 ), 0 );

    for( j = 0; j < (int)i_height ; j++ )
    {
        uint8_t *p = (uint8_t *)p_row_pointers[j];

        for( i = 0; i < (int)i_width ; i++ )
        {
            int i_offset = i + j * p_pic->p[Y_PLANE].i_pitch;

            p_pic->p[Y_PLANE].p_pixels[i_offset] =
                (p[0] * 257L + p[1] * 504 + p[2] * 98)/1000 + 16;
            p_pic->p[U_PLANE].p_pixels[i_offset] =
                (p[2] * 439L - p[0] * 148 - p[1] * 291)/1000 + 128;
            p_pic->p[V_PLANE].p_pixels[i_offset] =
                (p[0] * 439L - p[1] * 368 - p[2] * 71)/1000 + 128;
//.........这里部分代码省略.........

ImageReaderPNG::ImageType ImageReaderPNG::readData(const std::string& filePath, PNGInfra& infra, bool wantAlpha)
{
	if (filePath.empty())
		return eInvalid;

	infra.pFile = fopen(filePath.c_str(), "rb");
	if (!infra.pFile)
	{
		fprintf(stderr, "Error opening file: %s\n", filePath.c_str());
		return eInvalid;
	}

	unsigned char sig[8];

	// check the signature
	fread(sig, 1, 8, infra.pFile);
	if (!png_check_sig(sig, 8))
	{
		fprintf(stderr, "Cannot open file: %s - not a valid PNG file.\n", filePath.c_str());
		fclose(infra.pFile);
		return eInvalid;
	}

	infra.pPNG = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
	if (!infra.pPNG)
	{
		fclose(infra.pFile);
		return eInvalid;
	}

	infra.pInfo = png_create_info_struct(infra.pPNG);
	if (!infra.pInfo)
	{
		png_destroy_read_struct(&infra.pPNG, NULL, NULL);
		fclose(infra.pFile);
		return eInvalid;
	}

	if (setjmp(png_jmpbuf(infra.pPNG)))
	{
		png_destroy_read_struct(&infra.pPNG, &infra.pInfo, NULL);
		fclose(infra.pFile);
		return eInvalid;
	}

	png_init_io(infra.pPNG, infra.pFile);
	png_set_sig_bytes(infra.pPNG, 8);
	png_read_info(infra.pPNG, infra.pInfo);

	int colorType;
	int bitDepth, interlaceType, compressionType;

	png_get_IHDR(infra.pPNG, infra.pInfo, &infra.width, &infra.height, &bitDepth, &colorType, &interlaceType, &compressionType, NULL);

	if (colorType == PNG_COLOR_TYPE_PALETTE)
		png_set_palette_to_rgb(infra.pPNG);

	if (png_get_valid(infra.pPNG, infra.pInfo, PNG_INFO_tRNS))
	{
		png_set_tRNS_to_alpha(infra.pPNG);
	}

	if (bitDepth == 16)
		png_set_strip_16(infra.pPNG);

	ImageType type = eInvalid;

	if (!wantAlpha)
	{
		// add black Alpha
		if ((colorType & PNG_COLOR_MASK_ALPHA) == 0)
			png_set_add_alpha(infra.pPNG, 0xFF, PNG_FILLER_AFTER);

		if (colorType == PNG_COLOR_TYPE_GRAY || colorType == PNG_COLOR_TYPE_GRAY_ALPHA)
			png_set_gray_to_rgb(infra.pPNG);
		else if (colorType != PNG_COLOR_TYPE_RGB && colorType != PNG_COLOR_TYPE_RGB_ALPHA)
			return eInvalid;

		type = eRGBA;
	}
	else
	{
		if (colorType == PNG_COLOR_TYPE_RGB_ALPHA)
			type = eRGBA;
		else if (colorType == PNG_COLOR_TYPE_GRAY || colorType == PNG_COLOR_TYPE_GRAY_ALPHA)
			type = eA;
		else
			return eInvalid;
	}

	png_read_update_info(infra.pPNG, infra.pInfo);

	infra.pRows = new png_bytep[infra.height * png_sizeof(png_bytep)];

	png_set_rows(infra.pPNG, infra.pInfo, infra.pRows);

	for (unsigned int i = 0; i < infra.height; i++)
	{
		infra.pRows[i] = new png_byte[png_get_rowbytes(infra.pPNG, infra.pInfo)];
	}
//.........这里部分代码省略.........

plMipmap* plPNG::IRead(hsStream* inStream)
{
    plMipmap* newMipmap = NULL;
    png_structp png_ptr;
    png_infop info_ptr;
    png_infop end_info;

    try {
        //  Check PNG Signature
        png_byte sig[PNGSIGSIZE];
        inStream->Read8Bytes((char*) sig);

        if (!png_sig_cmp(sig, 0, PNGSIGSIZE)) {
            //  Allocate required structs
            png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);

            if (!png_ptr) {
                throw false;
            }

            info_ptr = png_create_info_struct(png_ptr);

            if (!info_ptr) {
                png_destroy_read_struct(&png_ptr, (png_infopp)NULL, (png_infopp)NULL);
                throw false;
            }

            end_info = png_create_info_struct(png_ptr);

            if (!end_info) {
                png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
                throw false;
            }

            //  Assign delegate function for reading from hsStream
            png_set_read_fn(png_ptr, (png_voidp)inStream, pngReadDelegate);
            //  Get PNG Header information
            png_set_sig_bytes(png_ptr, PNGSIGSIZE);
            png_read_info(png_ptr, info_ptr);
            png_uint_32 imgWidth =  png_get_image_width(png_ptr, info_ptr);
            png_uint_32 imgHeight = png_get_image_height(png_ptr, info_ptr);
            png_uint_32 bitdepth   = png_get_bit_depth(png_ptr, info_ptr);
            png_uint_32 channels   = png_get_channels(png_ptr, info_ptr);
            png_uint_32 color_type = png_get_color_type(png_ptr, info_ptr);

            //  Convert images to RGB color space
            switch (color_type) {
                case PNG_COLOR_TYPE_PALETTE:
                    png_set_palette_to_rgb(png_ptr);
                    channels = 3;
                    break;
                case PNG_COLOR_TYPE_GRAY:

                    if (bitdepth < 8) {
                        png_set_expand_gray_1_2_4_to_8(png_ptr);
                    }

                    bitdepth = 8;
                    break;
            }

            //  Convert transparency (if needed) to a full alpha channel
            if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
                png_set_tRNS_to_alpha(png_ptr);
                channels += 1;
            } else if (channels == 3) {
                // Add an opaque alpha channel if still none exists
                png_set_filler(png_ptr, 0xff, PNG_FILLER_AFTER);
                channels = 4;
            }

            // Invert color byte-order as used by plMipmap for DirectX
            png_set_bgr(png_ptr);
            /// Construct a new mipmap to hold everything
            newMipmap = new plMipmap(imgWidth, imgHeight, plMipmap::kARGB32Config, 1, plMipmap::kUncompressed);
            char* destp = (char*)newMipmap->GetImage();
            png_bytep* row_ptrs = new png_bytep[imgHeight];
            const unsigned int stride = imgWidth * bitdepth * channels / 8;

            //  Assign row pointers to the appropriate locations in the newly-created Mipmap
            for (size_t i = 0; i < imgHeight; i++) {
                row_ptrs[i] = (png_bytep)destp + (i * stride);
            }

            png_read_image(png_ptr, row_ptrs);
            png_read_end(png_ptr, end_info);
            //  Clean up allocated structs
            png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
            delete [] row_ptrs;
        }
    } catch (...) {
        delete newMipmap;
        newMipmap = nullptr;
    }

    return newMipmap;
}

ImageData ReadPNG(char* fileName)
{
    ImageData meta;
    meta.valid = false;

    // Step 0: Make sure we can open the input file
    FILE* inFile = fopen(fileName, "rb");
    if (!inFile) {
        abort_("ReadPNG: Can't open %s for reading\n", fileName);
    }

    // Step 1: initialize the reader
    png_structp png = png_create_read_struct(
            PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
    if (!png) {
        abort_("ReadPNG: png_create_read_struct() failed\n");
    }

    png_infop info = png_create_info_struct(png);
    if (!info) {
        abort_("ReadPNG: png_create_info_struct() failed\n");
    }

    if (setjmp(png_jmpbuf(png))) {
        abort_("ReadPNG: Error during initialization.\n");
    }
    
    png_init_io(png, inFile);
    png_read_info(png, info);

    // Step 2: Collect image statistics
    int width           = png_get_image_width(png, info);
    int height          = png_get_image_height(png, info);
    png_byte color_type = png_get_color_type(png, info);
    png_byte bit_depth  = png_get_bit_depth(png, info);

    // Make some adjustments
    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);

    // 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);

    // Step 3: Read the data
    if (setjmp(png_jmpbuf(png))) {
        abort_("ReadPNG: Error during image data reading.\n");
    }

    png_bytep row_pointers[height];

    // This method gives a discontiguous array of rows
    // Each row is later copied to the destination image, RGB only.
    // There should be a more streamlined method, but this method works for lena.png
    for (int y = 0; y < height; y++) {
       row_pointers[y] = (png_byte*)malloc(png_get_rowbytes(png, info));
       if (!row_pointers[y]) {
           abort_("ReadPNG: Couldn't allocate row %d\n", y);
        }
    }
    
    // Now we can read the image
    int row_bytes = png_get_rowbytes(png, info);
    png_read_image(png, row_pointers);

    // Convert the image from discontiguous rows to contiguous rows, discarding alpha
    Pixel* image = (Pixel*)malloc(height * width * 3);
    if (!image) {
        abort_("ReadPNG: Couldn't allocate image (%d, %d)\n", height, row_bytes);
    }

    // Brute force copy, skip over ALPHA channel
    for (int row = 0; row < height; row++) {
        for (int pixel = 0; pixel < width; pixel++)
        {
            image[(row * width + pixel)] = 
                *(Pixel*)(row_pointers[row] + pixel * 4);
        }
        // As we use them, delete the pointers to the image rows.
        free(row_pointers[row]);
//.........这里部分代码省略.........

void FPngImageWrapper::UncompressPNGData( const ERGBFormat::Type InFormat, const int32 InBitDepth )
{
	// thread safety
	FScopeLock PNGLock(&GPNGSection);

	check( CompressedData.Num() );
	check( Width > 0 );
	check( Height > 0 );

	// Note that PNGs on PC tend to be BGR
	check( InFormat == ERGBFormat::BGRA || InFormat == ERGBFormat::RGBA || InFormat == ERGBFormat::Gray )	// Other formats unsupported at present
	check( InBitDepth == 8 || InBitDepth == 16 )	// Other formats unsupported at present

	// Reset to the beginning of file so we can use png_read_png(), which expects to start at the beginning.
	ReadOffset = 0;
		
	png_structp png_ptr	= png_create_read_struct_2( PNG_LIBPNG_VER_STRING, this, FPngImageWrapper::user_error_fn, FPngImageWrapper::user_warning_fn, NULL, FPngImageWrapper::user_malloc, FPngImageWrapper::user_free);
	check( png_ptr );

	png_infop info_ptr	= png_create_info_struct( png_ptr );
	check( info_ptr );
	PNGReadGuard PNGGuard( &png_ptr, &info_ptr );
	{
		if (ColorType == PNG_COLOR_TYPE_PALETTE)
		{
			png_set_palette_to_rgb(png_ptr);
		}

		if ((ColorType & PNG_COLOR_MASK_COLOR) == 0 && BitDepth < 8)
		{
			png_set_expand_gray_1_2_4_to_8(png_ptr);
		}

		// Insert alpha channel with full opacity for RGB images without alpha
		if ((ColorType & PNG_COLOR_MASK_ALPHA) == 0 && (InFormat == ERGBFormat::BGRA || InFormat == ERGBFormat::RGBA))
		{
			// png images don't set PNG_COLOR_MASK_ALPHA if they have alpha from a tRNS chunk, but png_set_add_alpha seems to be safe regardless
			if ((ColorType & PNG_COLOR_MASK_COLOR) == 0)
			{
				png_set_tRNS_to_alpha(png_ptr);
			}
			else if (ColorType == PNG_COLOR_TYPE_PALETTE)
			{
				png_set_tRNS_to_alpha(png_ptr);
			}
			if (InBitDepth == 8)
			{
				png_set_add_alpha(png_ptr, 0xff , PNG_FILLER_AFTER);
			}
			else if (InBitDepth == 16)
			{
				png_set_add_alpha(png_ptr, 0xffff , PNG_FILLER_AFTER);
			}
		}

		// Calculate Pixel Depth
		const uint32 PixelChannels = (InFormat == ERGBFormat::Gray) ? 1 : 4;
		const uint32 BytesPerPixel = (InBitDepth * PixelChannels) / 8;
		const uint32 BytesPerRow = BytesPerPixel * Width;
		RawData.Empty(Height * BytesPerRow);
		RawData.AddUninitialized(Height * BytesPerRow);

		png_set_read_fn( png_ptr, this, FPngImageWrapper::user_read_compressed );

		png_bytep* row_pointers = (png_bytep*) png_malloc( png_ptr, Height*sizeof(png_bytep) );
		PNGGuard.SetRowPointers(&row_pointers);
		for (int32 i = 0; i < Height; i++)
		{
			row_pointers[i]= &RawData[i * BytesPerRow];
		}
		png_set_rows(png_ptr, info_ptr, row_pointers);

		uint32 Transform = (InFormat == ERGBFormat::BGRA) ? PNG_TRANSFORM_BGR : PNG_TRANSFORM_IDENTITY;
			
		// PNG files store 16-bit pixels in network byte order (big-endian, ie. most significant bits first).
#if PLATFORM_LITTLE_ENDIAN
		// We're little endian so we need to swap
		if (BitDepth == 16)
		{
			Transform |= PNG_TRANSFORM_SWAP_ENDIAN;
		}
#endif

		// Convert grayscale png to RGB if requested
		if ((ColorType & PNG_COLOR_MASK_COLOR) == 0 &&
			(InFormat == ERGBFormat::RGBA || InFormat == ERGBFormat::BGRA))
		{
			Transform |= PNG_TRANSFORM_GRAY_TO_RGB;
		}

		// Convert RGB png to grayscale if requested
		if ((ColorType & PNG_COLOR_MASK_COLOR) != 0 && InFormat == ERGBFormat::Gray)
		{
			png_set_rgb_to_gray_fixed(png_ptr, 2 /* warn if image is in color */, -1, -1);
		}

		// Strip alpha channel if requested output is grayscale
		if (InFormat == ERGBFormat::Gray)
		{
			// this is not necessarily the best option, instead perhaps:
//.........这里部分代码省略.........

bool  PngDecoder::readData( Mat& img )
{
    bool result = false;
    AutoBuffer<uchar*> _buffer(m_height);
    uchar** buffer = _buffer;
    int color = img.channels() > 1;
    uchar* data = img.data;
    int step = (int)img.step;

    if( m_png_ptr && m_info_ptr && m_end_info && m_width && m_height )
    {
        png_structp png_ptr = (png_structp)m_png_ptr;
        png_infop info_ptr = (png_infop)m_info_ptr;
        png_infop end_info = (png_infop)m_end_info;

        if( setjmp( png_jmpbuf ( png_ptr ) ) == 0 )
        {
            int y;

            if( img.depth() == CV_8U && m_bit_depth == 16 )
                png_set_strip_16( png_ptr );
            else if( !isBigEndian() )
                png_set_swap( png_ptr );

            if(img.channels() < 4)
            {
                /* observation: png_read_image() writes 400 bytes beyond
                 * end of data when reading a 400x118 color png
                 * "mpplus_sand.png".  OpenCV crashes even with demo
                 * programs.  Looking at the loaded image I'd say we get 4
                 * bytes per pixel instead of 3 bytes per pixel.  Test
                 * indicate that it is a good idea to always ask for
                 * stripping alpha..  18.11.2004 Axel Walthelm
                 */
                 png_set_strip_alpha( png_ptr );
            }

            if( m_color_type == PNG_COLOR_TYPE_PALETTE )
                png_set_palette_to_rgb( png_ptr );

            if( m_color_type == PNG_COLOR_TYPE_GRAY && m_bit_depth < 8 )
#if (PNG_LIBPNG_VER_MAJOR*10000 + PNG_LIBPNG_VER_MINOR*100 + PNG_LIBPNG_VER_RELEASE >= 10209) || \
    (PNG_LIBPNG_VER_MAJOR == 1 && PNG_LIBPNG_VER_MINOR == 0 && PNG_LIBPNG_VER_RELEASE >= 18)
                png_set_expand_gray_1_2_4_to_8( png_ptr );
#else
                png_set_gray_1_2_4_to_8( png_ptr );
#endif

            if( CV_MAT_CN(m_type) > 1 && color )
                png_set_bgr( png_ptr ); // convert RGB to BGR
            else if( color )
                png_set_gray_to_rgb( png_ptr ); // Gray->RGB
            else
                png_set_rgb_to_gray( png_ptr, 1, 0.299, 0.587 ); // RGB->Gray

            png_read_update_info( png_ptr, info_ptr );

            for( y = 0; y < m_height; y++ )
                buffer[y] = data + y*step;

            png_read_image( png_ptr, buffer );
            png_read_end( png_ptr, end_info );

            result = true;
        }
    }

    close();
    return result;
}

int load_png( char *file_name, int stype )
{
	char buf[PNG_BYTES_TO_CHECK], *mess;
	unsigned char *rgb, *rgb2, *rgb3;
	int i, row, do_prog, bit_depth, color_type, interlace_type, width, height;
	unsigned int sig_read = 0;
	FILE *fp;
	png_bytep *row_pointers, trans;
	png_color_16p trans_rgb;

	png_structp png_ptr;
	png_infop info_ptr;
	png_uint_32 pwidth, pheight;
	png_colorp png_palette;

	if ((fp = fopen(file_name, "rb")) == NULL) return -1;
	i = fread(buf, 1, PNG_BYTES_TO_CHECK, fp);
	if ( i != PNG_BYTES_TO_CHECK ) goto fail;
	i = !png_sig_cmp(buf, (png_size_t)0, PNG_BYTES_TO_CHECK);
	if ( i<=0 ) goto fail;
	rewind( fp );

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

	if (png_ptr == NULL) goto fail;

	info_ptr = png_create_info_struct(png_ptr);
	if (info_ptr == NULL)
	{
		png_destroy_read_struct(&png_ptr, NULL, NULL);
		goto fail;
	}

	if (setjmp(png_jmpbuf(png_ptr)))
	{
		png_destroy_read_struct(&png_ptr, NULL, NULL);
		fclose(fp);
		return -1;
	}

	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, &pwidth, &pheight, &bit_depth, &color_type,
		&interlace_type, NULL, NULL);

	width = (int) pwidth;
	height = (int) pheight;

	if ( width > MAX_WIDTH || height > MAX_HEIGHT )
	{
		png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
		fclose(fp);
		return TOO_BIG;
	}

	row_pointers = malloc( sizeof(png_bytep) * height );

	if (setjmp(png_jmpbuf(png_ptr)))	// If libpng generates an error now, clean up
	{
		png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
		fclose(fp);
		free(row_pointers);
		return FILE_LIB_ERROR;
	}

	rgb = NULL;
	mess = NULL;
	if ( width*height > FILE_PROGRESS ) do_prog = 1;
	else do_prog = 0;

	if ( stype == 0 )
	{
		mess = _("Loading PNG image");
		rgb = mem_image;
	}
	if ( stype == 1 )
	{
		mess = _("Loading clipboard image");
		rgb = mem_clipboard;
		if ( rgb != NULL ) free( rgb );		// Lose old clipboard
		mem_clip_mask_clear();			// Lose old clipboard mask
	}

	if ( color_type != PNG_COLOR_TYPE_PALETTE || bit_depth>8 )	// RGB PNG file
	{
		png_set_strip_16(png_ptr);
		png_set_gray_1_2_4_to_8(png_ptr);
		png_set_palette_to_rgb(png_ptr);
		png_set_gray_to_rgb(png_ptr);

		if ( stype == 0 )
		{
			mem_pal_copy( mem_pal, mem_pal_def );
			mem_cols = 256;
			if ( mem_new( width, height, 3 ) != 0 ) goto file_too_huge;
			rgb = mem_image;
			if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
//.........这里部分代码省略.........

GLuint loadPNG(const char * file_name, GLuint tex)
{
    png_byte header[8];

    FILE *fp = fopen(file_name, "rb");
    if (fp == 0)
    {
        perror(file_name);
        return 0;
    }

    // read the header
    fread(header, 1, 8, fp);

    if (png_sig_cmp(header, 0, 8))
    {
        fprintf(stderr, "error: %s is not a PNG.\n", file_name);
        fclose(fp);
        return 0;
    }

    png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
    if (!png_ptr)
    {
        fprintf(stderr, "error: png_create_read_struct returned 0.\n");
        fclose(fp);
        return 0;
    }

    // create png info struct
    png_infop info_ptr = png_create_info_struct(png_ptr);
    if (!info_ptr)
    {
        fprintf(stderr, "error: png_create_info_struct returned 0.\n");
        png_destroy_read_struct(&png_ptr, (png_infopp)NULL, (png_infopp)NULL);
        fclose(fp);
        return 0;
    }

    // create png info struct
    png_infop end_info = png_create_info_struct(png_ptr);
    if (!end_info)
    {
        fprintf(stderr, "error: png_create_info_struct returned 0.\n");
        png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp) NULL);
        fclose(fp);
        return 0;
    }

    // the code in this if statement gets called if libpng encounters an error
    if (setjmp(png_jmpbuf(png_ptr))) {
        fprintf(stderr, "error from libpng\n");
        png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
        fclose(fp);
        return 0;
    }

    // init png reading
    png_init_io(png_ptr, fp);

    // let libpng know you already read the first 8 bytes
    png_set_sig_bytes(png_ptr, 8);

    // 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 temp_width, temp_height;

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

    GLint format;
    switch(color_type)
    {
    case PNG_COLOR_TYPE_RGB:
        format = GL_RGB;
        break;
    case PNG_COLOR_TYPE_RGB_ALPHA:
        format = GL_RGBA;
        break;
    case PNG_COLOR_TYPE_GRAY:
        //cout<<"color Type Grey"<<endl;
        format = GL_RGBA;
        png_set_gray_to_rgb(png_ptr);
        png_set_filler(png_ptr, 0xFF, PNG_FILLER_AFTER);

        break;
    case PNG_COLOR_TYPE_GRAY_ALPHA:
        //cout<<"color Type Grey Alpha"<<endl;
        format = GL_RGBA;
        png_set_gray_to_rgb(png_ptr);

        break;
    case PNG_COLOR_TYPE_PALETTE:
        //cout<<"color Type Palette"<<endl;
        format = GL_RGBA;
        png_set_palette_to_rgb(png_ptr);
//.........这里部分代码省略.........

static const char * VS_CC
check_png(img_hnd_t *ih, int n, FILE *fp, vs_args_t *va)
{
    uint8_t signature[PNG_SIG_LENGTH];
    if (fread(signature, 1, PNG_SIG_LENGTH, fp) != PNG_SIG_LENGTH ||
        png_sig_cmp(signature, 0, PNG_SIG_LENGTH)) {
        return "unsupported format";
    }

    png_structp p_str = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL,
                                               NULL, NULL);
    if (!p_str) {
        return "failed to create png_read_struct";
    }

    png_infop p_info = png_create_info_struct(p_str);
    if (!p_info) {
        png_destroy_read_struct(&p_str, NULL, NULL);
        return "failed to create png_info_struct";
    }

    png_init_io(p_str, fp);
    png_set_sig_bytes(p_str, PNG_SIG_LENGTH);
    png_read_info(p_str, p_info);

    png_uint_32 width, height;
    int color_type, bit_depth;
    png_get_IHDR(p_str, p_info, &width, &height, &bit_depth, &color_type,
                 NULL, NULL, NULL);
    if (color_type & PNG_COLOR_TYPE_PALETTE) {
        png_set_palette_to_rgb(p_str);
    }
    if (bit_depth < 8) {
        png_set_packing(p_str);
    }
    if (ih->enable_alpha == 0) {
        if (color_type & PNG_COLOR_MASK_ALPHA) {
            png_set_strip_alpha(p_str);
        }
    } else if ((color_type & PNG_COLOR_MASK_ALPHA) == 0) {
        png_set_add_alpha(p_str, 0x00, PNG_FILLER_AFTER);
    }

    png_read_update_info(p_str, p_info);
    png_get_IHDR(p_str, p_info, &width, &height, &bit_depth, &color_type,
                 NULL, NULL, NULL);
    uint32_t row_size = png_get_rowbytes(p_str, p_info);

    png_destroy_read_struct(&p_str, &p_info, NULL);

    ih->src[n].width = width;

    ih->src[n].height = height;

    VSPresetFormat pf = get_dst_format(color_type, bit_depth);
    if (pf == pfNone) {
        return "unsupported png color type";
    }
    ih->src[n].format = va->vsapi->getFormatPreset(pf, va->core);

    ih->src[n].read = read_png;

    ih->src[n].flip = 0;

    if (row_size > va->max_row_size) {
        va->max_row_size = row_size;
    }

    return NULL;
}

void *readpng(const unsigned char *base, size_t   size, unsigned *_width, unsigned *_height)
{
    PngReader  reader;
    unsigned char *data = 0;
    unsigned char **rowptrs = 0;
    png_structp p = 0;
    png_infop pi = 0;

    png_uint_32 width, height;
    int bitdepth, colortype, imethod, cmethod, fmethod, i;

    p = png_create_read_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0);
    if(p == 0) {
        LOG("%s: failed to allocate png read struct\n", fn);
        return 0;
    }

    pi = png_create_info_struct(p);
    if(pi == 0) {
        LOG("%s: failed to allocate png info struct\n", fn);
        goto oops;
    }

    reader.base   = base;
    reader.end    = base + size;
    reader.cursor = base;

    if(size < 8 || png_sig_cmp((unsigned char*)base, 0, 8)) {
        LOG("%s: header is not a PNG header\n", fn);
        goto oops;
    }

    reader.cursor += 8;

    if(setjmp(png_jmpbuf(p))) {
        LOG("%s: png library error\n", fn);
    oops:
        png_destroy_read_struct(&p, &pi, 0);
        if(data != 0) free(data);
        if(rowptrs != 0) free(rowptrs);
        return 0;
    }

    png_set_read_fn (p, &reader, png_reader_read_data);
    png_set_sig_bytes(p, 8);

    png_read_info(p, pi);

    png_get_IHDR(p, pi, &width, &height, &bitdepth, &colortype,
                 &imethod, &cmethod, &fmethod);
//    printf("PNG: %d x %d (d=%d, c=%d)\n",
//           width, height, bitdepth, colortype);

    switch(colortype){
    case PNG_COLOR_TYPE_PALETTE:
        png_set_palette_to_rgb(p);
        break;

    case PNG_COLOR_TYPE_RGB:
        if(png_get_valid(p, pi, PNG_INFO_tRNS)) {
            png_set_tRNS_to_alpha(p);
        } else {
            png_set_filler(p, 0xff, PNG_FILLER_AFTER);
        }
        break;

    case PNG_COLOR_TYPE_RGB_ALPHA:
        break;

    case PNG_COLOR_TYPE_GRAY:
        if(bitdepth < 8) {
            png_set_gray_1_2_4_to_8(p);
        }

    default:
        LOG("%s: unsupported (grayscale?) color type\n");
        goto oops;
    }

    if(bitdepth == 16) {
        png_set_strip_16(p);
    }

    data    = (unsigned char*) malloc((width * 4) * height);
    rowptrs = (unsigned char **) malloc(sizeof(unsigned char*) * height);

    if((data == 0) || (rowptrs == 0)){
        LOG("could not allocate data buffer\n");
        goto oops;
    }

    for(i = 0; i < height; i++) {
        rowptrs[i] = data + ((width * 4) * i);
    }

    png_read_image(p, rowptrs);

    png_destroy_read_struct(&p, &pi, 0);
    if(rowptrs != 0) free(rowptrs);

//.........这里部分代码省略.........