C++ png_set_sig_bytes函数代码示例

void LoadPNG( const char *name, byte **pic, int *width, int *height,
	      int *numLayers, int *numMips, int *bits, byte alphaByte )
{
	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         *data;
	byte         *out;
//	int             size;

	// load png
	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 )
	{
		ri.Printf( PRINT_WARNING, "LoadPNG: png_create_write_struct() failed for (%s)\n", name );
		ri.FS_FreeFile( data );
		return;
	}

	// allocate/initialize the memory for image information.  REQUIRED
	info = png_create_info_struct( png );

	if ( !info )
	{
		ri.Printf( PRINT_WARNING, "LoadPNG: png_create_info_struct() failed for (%s)\n", name );
		ri.FS_FreeFile( 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 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 ) 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 ) )
	{
//.........这里部分代码省略.........

bool ImageLoaderPNG::ReadData() {
  
  const int kNumSigBytesToRead = 8;
  uint8 pngSigBuf[kNumSigBytesToRead];
  memcpy(pngSigBuf, m_RawData, kNumSigBytesToRead);

  const int numSigNoMatch = png_sig_cmp(pngSigBuf, 0, kNumSigBytesToRead);
  if(numSigNoMatch) {
    ReportError("Incorrect PNG signature");
    return false;
  }

  png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
  if(!png_ptr) {
    ReportError("Could not create read struct");
    return false;
  }

  png_infop info_ptr = png_create_info_struct(png_ptr);
  if(!info_ptr) {
    ReportError("Could not create info struct");
    png_destroy_read_struct(&png_ptr, NULL, NULL);
    return false;
  }

  // Read from our buffer, not a file pointer...
  png_set_read_fn(png_ptr, this, PNGStreamReader::ReadDataFromStream);

  // Make sure to tell libpng how many bytes we've read...
  png_set_sig_bytes(png_ptr, kNumSigBytesToRead);

  png_read_info(png_ptr, info_ptr);

  int bitDepth = 0;
  int colorType = -1;

  if( 1 != png_get_IHDR(png_ptr, info_ptr, 
    (png_uint_32 *)(&m_Width), (png_uint_32 *)(&m_Height), 
    &bitDepth, &colorType, 
    NULL, NULL, NULL) 
  ) {
    ReportError("Could not read PNG header");
    png_destroy_read_struct(&png_ptr, NULL, NULL);
    return false;
  }

  if(bitDepth != 8) {
    ReportError("Only 8-bit images currently supported.");
    png_destroy_read_struct(&png_ptr, NULL, NULL);
    return false;
  }

  const int numPixels = m_Width * m_Height;
  png_size_t bpr = png_get_rowbytes(png_ptr, info_ptr);
  png_bytep rowData = new png_byte[bpr];

  switch(colorType) {
    default:
      ReportError("PNG color type unsupported");
      png_destroy_read_struct(&png_ptr, NULL, NULL);
      delete [] rowData;
      return false;

    case PNG_COLOR_TYPE_PALETTE:
    {
      m_RedChannelPrecision = bitDepth;
      m_RedData = new unsigned char[numPixels];
      m_GreenChannelPrecision = bitDepth;
      m_GreenData = new unsigned char[numPixels];
      m_BlueChannelPrecision = bitDepth;
      m_BlueData = new unsigned char[numPixels];

      png_colorp palette;
      int nPaletteEntries;
      png_uint_32 ret = png_get_PLTE(png_ptr, info_ptr, &palette, &nPaletteEntries);
      if(ret != PNG_INFO_PLTE) {
        memset(m_BlueData, 0, numPixels);
        memset(m_RedData, 0, numPixels);
        memset(m_GreenData, 0, numPixels);
        assert(!"Couldn't find PLTE chunk");
        break;
      }

      for(uint32 i = 0; i < m_Height; i++) {
        png_read_row(png_ptr, rowData, NULL);
        unsigned int rowOffset = i * m_Width;
        for(uint32 j = 0; j < m_Width; j++) {
          assert(rowData[j] < nPaletteEntries);
          const png_color &c = palette[::std::min<unsigned char>(rowData[j], nPaletteEntries - 1)];
          m_RedData[rowOffset + j] = c.red;
          m_GreenData[rowOffset + j] = c.green;
          m_BlueData[rowOffset + j] = c.blue;
        }
      }
    }
    break;

    case PNG_COLOR_TYPE_GRAY: {
      m_RedChannelPrecision = bitDepth;
      m_RedData = new unsigned char[numPixels];
//.........这里部分代码省略.........

/* This routine is based in part on the Chapter 13 demo code in "PNG: The
 *  Definitive Guide" (http://www.cdrom.com/pub/png/pngbook.html).
 */
BGD_DECLARE(gdImagePtr) gdImageCreateFromPngCtx (gdIOCtx * infile)
{
  png_byte sig[8];
  png_structp png_ptr;
  png_infop info_ptr;
  png_uint_32 width, height, rowbytes;
  int bit_depth, color_type, interlace_type;
  int num_palette, num_trans;
  png_colorp palette;
  png_color_16p trans_gray_rgb;
  png_color_16p trans_color_rgb;
  png_bytep trans;
  png_bytep image_data = NULL;
  png_bytepp row_pointers = NULL;
  gdImagePtr im = NULL;
  int i, j, *open = NULL;
  volatile int transparent = -1;
  volatile int palette_allocated = FALSE;

  /* Make sure the signature can't match by dumb luck -- TBB */
  /* GRR: isn't sizeof(infile) equal to the size of the pointer? */
  memset (infile, 0, sizeof (infile));

  /* first do a quick check that the file really is a PNG image; could
   * have used slightly more general png_sig_cmp() function instead */
  gdGetBuf (sig, 8, infile);
  if (!png_check_sig (sig, 8))
    return NULL;		/* bad signature */

#ifndef PNG_SETJMP_NOT_SUPPORTED
  png_ptr = png_create_read_struct (PNG_LIBPNG_VER_STRING, &gdPngJmpbufStruct,
				    gdPngErrorHandler, NULL);
#else
  png_ptr = png_create_read_struct (PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
#endif
  if (png_ptr == NULL)
    {
      fprintf (stderr, "gd-png error: cannot allocate libpng main struct\n");
      return NULL;
    }

  info_ptr = png_create_info_struct (png_ptr);
  if (info_ptr == NULL)
    {
      fprintf (stderr, "gd-png error: cannot allocate libpng info struct\n");
      png_destroy_read_struct (&png_ptr, NULL, NULL);
      return NULL;
    }

  /* we could create a second info struct here (end_info), but it's only
   * useful if we want to keep pre- and post-IDAT chunk info separated
   * (mainly for PNG-aware image editors and converters) */

  /* setjmp() must be called in every non-callback function that calls a
   * PNG-reading libpng function */
#ifndef PNG_SETJMP_NOT_SUPPORTED
  if (setjmp (gdPngJmpbufStruct.jmpbuf))
    {
      fprintf (stderr, "gd-png error: setjmp returns error condition\n");
      png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
      return NULL;
    }
#endif

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

  png_set_read_fn (png_ptr, (void *) infile, gdPngReadData);
  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,
		&interlace_type, NULL, NULL);
  if ((color_type == PNG_COLOR_TYPE_RGB) ||
      (color_type == PNG_COLOR_TYPE_RGB_ALPHA))
    {
      im = gdImageCreateTrueColor ((int) width, (int) height);
    }
  else
    {
      im = gdImageCreate ((int) width, (int) height);
    }
  if (im == NULL)
    {
      fprintf (stderr, "gd-png error: cannot allocate gdImage struct\n");
      png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
      gdFree (image_data);
      gdFree (row_pointers);
      return NULL;
    }

  if (bit_depth == 16)
    png_set_strip_16 (png_ptr);
  else if (bit_depth < 8)
    png_set_packing (png_ptr);	/* expand to 1 byte per pixel */
  switch (color_type)
    {
    case PNG_COLOR_TYPE_PALETTE:
      png_get_PLTE (png_ptr, info_ptr, &palette, &num_palette);
//.........这里部分代码省略.........

int res_create_surface_png(const char* name, gr_surface* pSurface) {
    GGLSurface* surface = NULL;
    int result = 0;
    unsigned char header[8];
    png_structp png_ptr = NULL;
    png_infop info_ptr = NULL;

    FILE* fp = fopen(name, "rb");
    if (fp == NULL) {
        char resPath[256];
        if (gr_get_rotation() % 180 == 0)
            snprintf(resPath, sizeof(resPath)-1, "/res/portrait/%s.png", name);
        else
            snprintf(resPath, sizeof(resPath)-1, "/res/landscape/%s.png", name);

        resPath[sizeof(resPath)-1] = '\0';
        fp = fopen(resPath, "rb");
        if (fp == NULL)
        {
            result = -1;
            goto exit;
        }
    }

    size_t bytesRead = fread(header, 1, sizeof(header), fp);
    if (bytesRead != sizeof(header)) {
        result = -2;
        goto exit;
    }

    if (png_sig_cmp(header, 0, sizeof(header))) {
        result = -3;
        goto exit;
    }

    png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
    if (!png_ptr) {
        result = -4;
        goto exit;
    }

    info_ptr = png_create_info_struct(png_ptr);
    if (!info_ptr) {
        result = -5;
        goto exit;
    }

    if (setjmp(png_jmpbuf(png_ptr))) {
        result = -6;
        goto exit;
    }

    png_set_packing(png_ptr);

    png_init_io(png_ptr, fp);
    png_set_sig_bytes(png_ptr, sizeof(header));
    png_read_info(png_ptr, info_ptr);

    size_t width = info_ptr->width;
    size_t height = info_ptr->height;
    size_t stride = 4 * width;
    size_t pixelSize = stride * height;

    int color_type = info_ptr->color_type;
    int bit_depth = info_ptr->bit_depth;
    int channels = info_ptr->channels;
    if (!(bit_depth == 8 &&
          ((channels == 3 && color_type == PNG_COLOR_TYPE_RGB) ||
           (channels == 4 && color_type == PNG_COLOR_TYPE_RGBA) ||
           (channels == 1 && color_type == PNG_COLOR_TYPE_PALETTE)))) {
        result = -7;
        goto exit;
    }

    surface = malloc(sizeof(GGLSurface) + pixelSize);
    if (surface == NULL) {
        result = -8;
        goto exit;
    }
    unsigned char* pData = (unsigned char*) (surface + 1);
    surface->version = sizeof(GGLSurface);
    surface->width = width;
    surface->height = height;
    surface->stride = width; /* Yes, pixels, not bytes */
    surface->data = pData;
    surface->format = (channels == 3) ?
            GGL_PIXEL_FORMAT_RGBX_8888 : GGL_PIXEL_FORMAT_RGBA_8888;

    if (color_type == PNG_COLOR_TYPE_PALETTE) {
        png_set_palette_to_rgb(png_ptr);
    }

    int y;
    if (channels < 4) {
        for (y = 0; y < (int) height; ++y) {
            unsigned char* pRow = pData + y * stride;
            png_read_row(png_ptr, pRow, NULL);

            int x;
            for(x = width - 1; x >= 0; x--) {
//.........这里部分代码省略.........

bool ImageLoader::ReadPNG(ImageLoaderParams &ImgInfo)
{
	// Set up libpng reading.
	png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, nullptr, PNGErrorFn, PNGWarnFn);
	if (!png_ptr)
		return false;
	png_infop info_ptr = png_create_info_struct(png_ptr);
	if (!info_ptr)
	{
		png_destroy_read_struct(&png_ptr, (png_infopp)NULL, (png_infopp)NULL);
		return false;
	}
	png_infop end_info = png_create_info_struct(png_ptr);
	if (!end_info)
	{
		png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
		return false;
	}
	if (setjmp(png_jmpbuf(png_ptr)))
	{
		png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
		return false;
	}
	// We read using a FILE*; this could be changed.
	File::IOFile file;
	if (!file.Open(ImgInfo.Path, "rb"))
	{
		return false;
	}
	png_init_io(png_ptr, file.GetHandle());
	png_set_sig_bytes(png_ptr, 0);
	// Process PNG header, etc.
	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);
	// Force RGB (8 or 16-bit).
	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 (color_type == PNG_COLOR_TYPE_GRAY || color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
		png_set_gray_to_rgb(png_ptr);
	// Force 8-bit RGB.
	if (bit_depth == 16)
		png_set_strip_16(png_ptr);
	// Force alpha channel (combined with the above, 8-bit RGBA).
	if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
		png_set_tRNS_to_alpha(png_ptr);
	else if ((color_type & PNG_COLOR_MASK_ALPHA) == 0)
		png_set_add_alpha(png_ptr, 0xFF, PNG_FILLER_AFTER);
	png_read_update_info(png_ptr, info_ptr);
	ImgInfo.Width = width;
	ImgInfo.Height = height;
	ImgInfo.data_size = width * height * 4;
	ImgInfo.dst = ImgInfo.request_buffer_delegate(ImgInfo.data_size, false);
	std::vector<u8*> row_pointers(height);
	u8* row_pointer = ImgInfo.dst;
	for (unsigned i = 0; i < height; ++i)
	{
		row_pointers[i] = row_pointer;
		row_pointer += width * 4;
	}
	png_read_image(png_ptr, row_pointers.data());
	png_read_end(png_ptr, end_info);
	png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
	return true;
}

RawImage* ImageFactory::loadPNG(const char *filename)
{		
	int outWidth, outHeight;
	bool outHasAlpha;
    png_structp png_ptr;
    png_infop info_ptr;
    unsigned int sig_read = 0;
    int color_type, interlace_type;
    FILE* fp = fopen(filename, "rb");
		
    if (fp == NULL)
        return NULL;

    /* Create and initialize the png_struct
     * with the desired error handler
     * functions.  If you want to use the
     * default stderr and longjump method,
     * you can supply NULL for the last
     * three parameters.  We also supply the
     * the compiler header file version, so
     * that we know if the application
     * was compiled with a compatible version
     * of the library.  REQUIRED
     */
    png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
            NULL, NULL, NULL);

    if (png_ptr == NULL) {
        fclose(fp);
        return NULL;
    }

    /* Allocate/initialize the memory
     * for image information.  REQUIRED. */
    info_ptr = png_create_info_struct(png_ptr);
    if (info_ptr == NULL) {
        fclose(fp);
        png_destroy_read_struct(&png_ptr, NULL, NULL);
        return NULL;
    }

    /* 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_ptr))) {
        /* Free all of the memory associated
         * with the png_ptr and info_ptr */
        png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
        fclose(fp);
        /* If we get here, we had a
         * problem reading the file */
        return NULL;
    }

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

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

    /*
     * 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_TRANSFORM_STRIP_16 |
     * PNG_TRANSFORM_PACKING  forces 8 bit
     * PNG_TRANSFORM_EXPAND forces to
     *  expand a palette into RGB
     */
    png_read_png(png_ptr, info_ptr, PNG_TRANSFORM_STRIP_16 | PNG_TRANSFORM_PACKING | PNG_TRANSFORM_EXPAND, NULL);
	png_uint_32 width, height;
	int bit_depth;
	png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type, &interlace_type, NULL, NULL);

    outWidth = width;
    outHeight = height;
    switch (color_type) {
        case PNG_COLOR_TYPE_RGBA:
            outHasAlpha = true;
            break;
        case PNG_COLOR_TYPE_RGB:
            outHasAlpha = false;
//.........这里部分代码省略.........

BMGError ReadPNGInfo( const char *filename,
        struct BMGImageStruct * volatile img )
{
    jmp_buf             err_jmp;
    int                 error;

    FILE * volatile     file = NULL;
    int                 BitDepth;
    int                 ColorType;
    int                 InterlaceType;
    unsigned char       signature[8];
    png_structp volatile png_ptr = NULL;
    png_infop   volatile info_ptr = NULL;
    png_infop   volatile end_info = NULL;
    png_uint_32         Width, Height;

    /* error handler */
    error = setjmp( err_jmp );
    if (error != 0)
    {
        if (end_info != NULL)
            png_destroy_read_struct((png_structp *) &png_ptr, (png_infop *) &info_ptr, (png_infop *) &end_info);
        else if (info_ptr != NULL)
            png_destroy_read_struct((png_structp *) &png_ptr, (png_infop *) &info_ptr, NULL);
        else if (png_ptr != NULL)
            png_destroy_read_struct((png_structp *) &png_ptr, NULL, NULL);
        if (img)
            FreeBMGImage(img);
        if (file)
            fclose(file);
        SetLastBMGError((BMGError) error);
        return (BMGError) error;
    }

    if ( img == NULL )
        longjmp ( err_jmp, (int)errInvalidBMGImage );

    file = fopen( filename, "rb" );
    if ( !file || fread( signature, 1, 8, file ) != 8)
        longjmp ( err_jmp, (int)errFileOpen );

    /* check the signature */
    if ( png_sig_cmp( signature, 0, 8 ) != 0 )
        longjmp( err_jmp, (int)errUnsupportedFileFormat );

    /* create a pointer to the png read structure */
    png_ptr = png_create_read_struct( PNG_LIBPNG_VER_STRING, NULL, NULL, NULL );
    if ( !png_ptr )
        longjmp( err_jmp, (int)errMemoryAllocation );

    /* create a pointer to the png info structure */
    info_ptr = png_create_info_struct( png_ptr );
    if ( !info_ptr )
        longjmp( err_jmp, (int)errMemoryAllocation );

    /* create a pointer to the png end-info structure */
    end_info = png_create_info_struct(png_ptr);
    if (!end_info)
        longjmp( err_jmp, (int)errMemoryAllocation );

    /* bamboozle the PNG longjmp buffer */
    /*generic PNG error handler*/
    /* error will always == 1 which == errLib */
//    error = png_setjmp(png_ptr);
    error = setjmp( png_jmpbuf( png_ptr ) );
    if ( error > 0 )
        longjmp( err_jmp, error );

    /* set function pointers in the PNG library, for read callbacks */
    png_set_read_fn(png_ptr, (png_voidp) file, user_read_data);

    /*let the read functions know that we have already read the 1st 8 bytes */
    png_set_sig_bytes( png_ptr, 8 );

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

    /* extract the data we need to form the HBITMAP from the PNG header */
    png_get_IHDR( png_ptr, info_ptr, &Width, &Height, &BitDepth, &ColorType,
        &InterlaceType, NULL, NULL);

    img->width = (unsigned int) Width;
    img->height = (unsigned int) Height;

    img->bits_per_pixel = (unsigned char)32;
    img->scan_width = Width * 4;

    img->palette_size = (unsigned short)0;
    img->bytes_per_palette_entry = 4U;
    img->bits = NULL;

    png_destroy_read_struct((png_structp *) &png_ptr, (png_infop *) &info_ptr, (png_infop *) &end_info);
    fclose( file );

    return BMG_OK;
}

int read_png_file(uint8_t *data[ 4 ], int linesize[ 4 ],
                  int *width, int *height, enum AVPixelFormat *pix_fmt,
                  const char *filename, void *log_ctx)
{
	png_structp png_ptr;
	png_infop info_ptr;
	int number_of_passes;
	png_bytep *row_pointers;	
	png_bytep image_data;	
	png_byte color_type;
	png_byte bit_depth;
	char header[ 8 ];
	int rowbytes;
	int res = 0;
	
	FILE *fp = fopen(filename,"rb");
	if (! fp) return -1;
 	
	while (true)
	{
		fread(header,1,8,fp);
		
		if (png_sig_cmp(header,0,8)) 
		{ 
			res = -1; 
			break;
		}
		
		png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,NULL,NULL,NULL);

		if (! png_ptr)
		{
			res = -1; 
			break;
		}

		info_ptr = png_create_info_struct(png_ptr);
		
		if (! info_ptr)
		{
			res = -1; 
			break;
		}

		if (setjmp(png_jmpbuf(png_ptr)))
		{
			res = -1; 
			break;
		}

		png_init_io(png_ptr,fp);
		png_set_sig_bytes(png_ptr,8);

		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);
		*pix_fmt = AV_PIX_FMT_RGBA;
		
		color_type = png_get_color_type(png_ptr,info_ptr);
		bit_depth  = png_get_bit_depth (png_ptr,info_ptr);

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

		if (setjmp(png_jmpbuf(png_ptr)))
		{
			res = -1; 
			break;
		}

		rowbytes = png_get_rowbytes(png_ptr,info_ptr);
		image_data = (png_bytep) malloc(rowbytes * *height);
		row_pointers = (png_bytep *) malloc(sizeof(png_bytep) * *height);
		
		int y;
		
		for (y = 0; y < *height; y++)
		{
			row_pointers[ y ] = image_data + (y * rowbytes);
		}

		png_read_image(png_ptr,row_pointers);
	
		data[ 0 ] = image_data;
		data[ 1 ] = 0;
		data[ 2 ] = 0;
		data[ 3 ] = 0;
		
		linesize[ 0 ] = rowbytes;
		linesize[ 1 ] = 0;
		linesize[ 2 ] = 0;
		linesize[ 3 ] = 0;
		
		break;
	}
	
	fclose(fp);
	
	return res;
//.........这里部分代码省略.........

image_t *load_png(char *png) {
	int width = 0;
	int height = 0;
	FILE *f = NULL;
	png_structp png_ptr = NULL;
	png_infop info_ptr = NULL;
	png_infop end_info = NULL;
	png_uint_32 rowbytes = 0;
	image_t *image = NULL;

	f = open_png(png);
	if (f == NULL)
		goto err;

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

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

	end_info = png_create_info_struct(png_ptr);
	if (!end_info)
		goto err;

	if (setjmp(png_jmpbuf(png_ptr))) {
		printf("[read_png_file] Error during read_image");
		goto err;
	}

	png_init_io(png_ptr, f);
	png_set_sig_bytes(png_ptr, HEADER_SIZE);
	png_read_info(png_ptr, info_ptr);
	rowbytes = png_get_rowbytes(png_ptr, info_ptr);
	width = png_get_image_width(png_ptr, info_ptr);
	height = png_get_image_height(png_ptr, info_ptr);

	if (png_get_color_type(png_ptr, info_ptr) != PNG_COLOR_TYPE_RGBA) {
		printf("Error: PNG format is not RGBA\n");
		goto err;
	}

	if (setjmp(png_jmpbuf(png_ptr))) {
		printf("[read_png_file] Error during read_image");
		goto err;
	}

	image = make_image(width, height, rowbytes);
	if (image == NULL)
		goto err;
	png_read_image(png_ptr, image->rows);
	png_read_end(png_ptr, end_info);

	done: if (f != NULL)
		fclose(f);
	if (png_ptr != NULL)
		png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
	return image;
	err: free_image(image);
	image = NULL;
	goto done;
}

/* create a new finfo record, open FITS file */
static Finfo FinfoNew(char *fname)
{
  int len;
  char *e=NULL;
  char *f=NULL;
  char *s=NULL;
#if FITS2PNG
  int i;
  unsigned char header[8];
  /* use volatile to make gcc [-Wclobbered] happy (because of setjmp below) */
  volatile Finfo finfo;	  
#else
  Finfo finfo;	  
#endif


  /* sanity check */
  if( !fname ) return NULL;
  /* return existing finfo, if possible */
  if( (finfo=FinfoLookup(fname)) ) return finfo;
  /* allocate record */
  if( !(finfo = (Finfo)xcalloc(sizeof(FinfoRec), 1)) ){
    fprintf(stderr, "ERROR: can't allocate rec for image\n");
    return NULL;
  }
  /* save file name */
  finfo->fname = xstrdup(fname);
  /* check for file type */
  if( (s = strrchr(fname, '.')) && !strcasecmp(s, ".png") ){
    /* its a PNG */
    finfo->ftype = FTYPE_PNG;
  } else {
    /* assume FITS type */
    finfo->ftype = FTYPE_FITS;
  }
  /* open file */
  switch(finfo->ftype){
  case FTYPE_PNG:
#if FITS2PNG
    /* code taken from "PNG: The Definitive Guide" by Greg Roelofs,
       Chapter 13 "Reading PNG Images" */
    /* set data path */
    datapath = getenv("JS9_DATAPATH");
    /* look for path of the PNG file */
    s = Find(fname, "r", NULL, datapath);
    if( s && *s ){
      if( !(finfo->fp = fopen(s, "rb")) ){
	fprintf(stderr, "ERROR: can't open PNG file '%s'\n", fname);
	goto error;
      }
      fread(header, 1, 8, finfo->fp);
      if( png_sig_cmp(header, 0, 8) ){
	fprintf(stderr, "ERROR: not recognized as a PNG file '%s'\n", fname);
	goto error;
      }
      /* initialize stuff */
      finfo->png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
					      NULL, NULL, NULL);
      if( !finfo->png_ptr ){
	fprintf(stderr, "ERROR: png_create_read_struct failed '%s'\n", fname);
	goto error;
      }
      finfo->info_ptr = png_create_info_struct(finfo->png_ptr);
      if( !finfo->info_ptr ){
	fprintf(stderr, "ERROR: png_create_info_struct failed '%s'\n", fname);
	goto error;
      }
      if( setjmp(png_jmpbuf(finfo->png_ptr)) ){
	fprintf(stderr, "ERROR: during png init_io '%s'\n", fname);
	goto error;
      }
      png_init_io(finfo->png_ptr, finfo->fp);
      png_set_sig_bytes(finfo->png_ptr, 8);
      png_read_info(finfo->png_ptr, finfo->info_ptr);
      /* get the text chunks that come before the image */
      if( png_get_text(finfo->png_ptr, finfo->info_ptr,
		       &(finfo->text_ptr), &(finfo->num_text)) > 0 ){
	/* process all known PNG keywords */
	for(i=0; i<finfo->num_text; i++){
	  if( !strcmp(finfo->text_ptr[i].key, FITSFILE) ){
	    finfo->fitsfile = xstrdup(finfo->text_ptr[i].text);
	    /* remove the extension that was used to generate png */
	    s = strchr(finfo->fitsfile, '[');
	    if( s ){
	      *s = '\0';
	    }
	  }
	}
      }
    } else {
      fprintf(stderr, "ERROR: can't find PNG file '%s' [data path: %s]\n",
	      fname, datapath?datapath:"none");
      goto error;
    }
#else
    fprintf(stderr,
	    "ERROR: for fits2png support, build JS9 using --with-png\n");
    goto error;
#endif
//.........这里部分代码省略.........

bool CGLCG::loadPngImage(const TCHAR *name, int &outWidth, int &outHeight, bool &outHasAlpha, GLubyte **outData) {
    png_structp png_ptr;
    png_infop info_ptr;
    unsigned int sig_read = 0;
    int color_type, interlace_type;
    FILE *fp;

	if ((fp = _tfopen(name, TEXT("rb"))) == NULL)
        return false;

    /* Create and initialize the png_struct
     * with the desired error handler
     * functions.  If you want to use the
     * default stderr and longjump method,
     * you can supply NULL for the last
     * three parameters.  We also supply the
     * the compiler header file version, so
     * that we know if the application
     * was compiled with a compatible version
     * of the library.  REQUIRED
     */
    png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
            NULL, NULL, NULL);

    if (png_ptr == NULL) {
        fclose(fp);
        return false;
    }

    /* Allocate/initialize the memory
     * for image information.  REQUIRED. */
    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);
        return false;
    }

    /* 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_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);
        fclose(fp);
        /* If we get here, we had a
         * problem reading the file */
        return false;
    }

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

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

    /*
     * 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_TRANSFORM_STRIP_16 |
     * PNG_TRANSFORM_PACKING  forces 8 bit
     * PNG_TRANSFORM_EXPAND forces to
     *  expand a palette into RGB
     */
    png_read_png(png_ptr, info_ptr, PNG_TRANSFORM_STRIP_16 | PNG_TRANSFORM_PACKING | PNG_TRANSFORM_EXPAND, (png_voidp)NULL);

    outWidth = png_get_image_width(png_ptr, info_ptr);
    outHeight = png_get_image_height(png_ptr, info_ptr);
    switch (png_get_color_type(png_ptr, info_ptr)) {
        case PNG_COLOR_TYPE_RGBA:
            outHasAlpha = true;
            break;
        case PNG_COLOR_TYPE_RGB:
            outHasAlpha = false;
            break;
        default:
            png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
            fclose(fp);
            return false;
    }
//.........这里部分代码省略.........

void Texture::InitWithFile(string& filepath) {
    FILE* fd = FileIO::OpenFileDescriptor(filepath);
    png_byte header[8];
    fread(header, 1, 8, fd);
    
    int is_png = !png_sig_cmp(header, 0, 8);
    if (!is_png) {
        printf("ERROR: %s is not a valid png file\n", filepath.c_str());
        fclose(fd);
        return;
    }
    
    png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
    if (!png_ptr) {
        fclose(fd);
        return;
    }
    
    png_infop info_ptr = png_create_info_struct(png_ptr);
    if (!info_ptr) {
        png_destroy_read_struct(&png_ptr, (png_infopp) NULL, (png_infopp) NULL);
        fclose(fd);
        return;
    }
    
    png_infop end_info = png_create_info_struct(png_ptr);
    if (!end_info) {
        png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp) NULL);
        fclose(fd);
        return;
    }
    
    if (setjmp(png_jmpbuf(png_ptr))) {
        png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
        fclose(fd);
        return;
    }
    png_init_io(png_ptr, fd);
    
    png_set_sig_bytes(png_ptr, 8);
    
    png_read_info(png_ptr, info_ptr);
    
    GLint bit_depth, color_type;
    
    png_get_IHDR(png_ptr, info_ptr, &m_width, &m_height, &bit_depth, &color_type, NULL, NULL, NULL);
    
    png_read_update_info(png_ptr, info_ptr);
    
    int rowbytes = png_get_rowbytes(png_ptr, info_ptr);
    
    png_byte *image_data = new png_byte[rowbytes * m_height];
    if (!image_data) {
        png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
        fclose(fd);
        return;
    }
    
    png_bytep *row_pointers = new png_bytep[m_height];
    if (!row_pointers) {
        png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
        delete[] image_data;
        fclose(fd);
        return;
    }
    
    for (GLuint i = 0; i < m_height; ++i) {
        row_pointers[i] = image_data + i * rowbytes;
    }
    
    png_read_image(png_ptr, row_pointers);
    
    glGenTextures(1, &m_glTextureID);
    m_dataType = GL_UNSIGNED_BYTE;
    m_pixelFormat = GL_RGBA;
    m_targetType = GL_TEXTURE_2D;
    
    glBindTexture(m_targetType, m_glTextureID);
    glTexImage2D(m_targetType,0, m_pixelFormat, m_width, m_height, 0, m_pixelFormat, m_dataType, (GLvoid*) image_data);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    
    png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
    delete[] image_data;
    delete[] row_pointers;
    fclose(fd);

}

GLuint TextureManager::addFromPNG(const std::string& id, const std::string& texturePath)
{
	FILE *fp = fopen(texturePath.c_str(), "rb");
	if(!fp)
		return GL_INVALID_VALUE;
	png_byte header[8];
	fread(header, 1, 8, fp);
	if(png_sig_cmp(header, 0, 8))
	{
		fclose(fp);
		return GL_INVALID_VALUE;
	}

	png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
	if(!png_ptr)
		return GL_INVALID_VALUE;

	png_infop info_ptr = png_create_info_struct(png_ptr);
	png_infop end_info = png_create_info_struct(png_ptr);
	if(!info_ptr || !end_info || setjmp(png_jmpbuf(png_ptr))) {
		png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
		fclose(fp);
		return GL_INVALID_VALUE;
	}
	png_init_io(png_ptr, fp);
	png_set_sig_bytes(png_ptr, 8);
	png_read_info(png_ptr, info_ptr);
	int bit_depth, color_type;
	png_uint_32 twidth, theight;

	png_get_IHDR(png_ptr, info_ptr, &twidth, &theight, &bit_depth, &color_type, NULL, NULL, NULL);

	int width = twidth;
	int height = theight;

	png_read_update_info(png_ptr, info_ptr);

	int rowbytes = png_get_rowbytes(png_ptr, info_ptr);
	png_byte *image_data = new png_byte[rowbytes * height];
	png_bytepp row_pointers = new png_bytep[height];

	if(!image_data || !row_pointers) {
		png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
		delete[] image_data;
		fclose(fp);
		return GL_INVALID_VALUE;
	}

	for(int i = 0; i < height; ++i)
		row_pointers[height - 1 - i] = image_data + i * rowbytes;

	png_read_image(png_ptr, row_pointers);

	bool hasAlpha;
/*	switch (info_ptr->color_type) {
		case PNG_COLOR_TYPE_RGBA:
			hasAlpha = true;
			break;
		case PNG_COLOR_TYPE_RGB:
			hasAlpha = false;
			break;
		default:
			png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
			fclose(fp);
			return GL_INVALID_VALUE;
	}*/

	glGenTextures(1, &textures[id]);
	glBindTexture(GL_TEXTURE_2D, textures[id]);
	glTexImage2D(GL_TEXTURE_2D, 0, hasAlpha ? GL_RGBA : GL_RGB, width, height, 0, hasAlpha ? GL_RGBA : GL_RGB, GL_UNSIGNED_BYTE, (GLvoid*) image_data);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	delete[] image_data;
	delete[] row_pointers;
	fclose(fp);

	return true;
}

short load_inp_png_file(ImageData& img, const std::string& fname_inp, ProgramOptions& opts)
{
    FILE* pngfile = fopen(fname_inp.c_str(),"rb");
    if (pngfile == NULL) {
        perror(fname_inp.c_str());
        return ERR_CANT_OPEN;
    }
    png_byte header[8];
    if (fread(header,8,1,pngfile) != 1) {
        perror(fname_inp.c_str());
        fclose(pngfile);
        return ERR_FILE_READ;
    }
    if (png_sig_cmp(header,0,8)) {
        LogErr("%s: Not a PNG file",fname_inp.c_str());
        fclose(pngfile);
        return ERR_BAD_FILE;
    }

    img.png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
    if (!img.png_ptr)
    {
        LogErr("%s: png_create_read_struct error",fname_inp.c_str());
        fclose(pngfile);
        return ERR_BAD_FILE;
    }

    img.info_ptr=png_create_info_struct(img.png_ptr);
    if (!img.info_ptr)
    {
        png_destroy_read_struct(&img.png_ptr, (png_infopp)NULL, (png_infopp)NULL);
        LogErr("%s: png_create_info_struct error",fname_inp.c_str());
        fclose(pngfile);
        return ERR_BAD_FILE;
    }

    img.end_info=png_create_info_struct(img.png_ptr);
    if (!img.end_info)
    {
        png_destroy_read_struct(&img.png_ptr, &img.info_ptr, (png_infopp)NULL);
        LogErr("%s: png_create_info_struct error",fname_inp.c_str());
        fclose(pngfile);
        return ERR_BAD_FILE;
    }

    if (setjmp(png_jmpbuf(img.png_ptr)))
    {
        png_destroy_read_struct(&img.png_ptr, &img.info_ptr, &img.end_info);
        LogErr("%s: PNG error",fname_inp.c_str());
        fclose(pngfile);
        exit(1);
    }

    png_init_io(img.png_ptr, pngfile);
    png_set_sig_bytes(img.png_ptr,8);
    int trafo=PNG_TRANSFORM_PACKING|PNG_TRANSFORM_STRIP_16|PNG_TRANSFORM_EXPAND;
    png_read_png(img.png_ptr, img.info_ptr, trafo , NULL);

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

    if ((img.color_type & PNG_COLOR_MASK_COLOR)==0)
    {
        LogErr("%s: Grayscale image not supported",fname_inp.c_str());
        fclose(pngfile);
        return ERR_BAD_FILE;
    }

    fclose(pngfile);

    if (img.color_type==PNG_COLOR_TYPE_PALETTE)
    {
        LogErr("Invalid format. This shouldn't happen. PNG_TRANSFORM_EXPAND transforms image to RGB.");
        return ERR_BAD_FILE;
    }

    if (img.color_type & PNG_COLOR_MASK_ALPHA) {
        img.col_bits = 32;
    } else {
        img.col_bits = 24;
    }

    return ERR_OK;
}

void *png_read_file(const char *name, png_uint_32 *_w, png_uint_32 *_h,
 check_w_h_constraint_t constraint, rgba_surface_allocator_t allocator)
{
  png_uint_32 i, w, h, stride;
  png_structp png_ptr = NULL;
  png_bytep *row_ptrs = NULL;
  png_infop info_ptr = NULL;
  void *pixels, *s = NULL;
  png_byte header[8];
  int type, bpp;
  FILE *f;

  f = fopen_unsafe(name, "rb");
  if(!f)
    goto exit_out;

  if(fread(header, 1, 8, f) < 8)
    goto exit_close;

  if(png_sig_cmp(header, 0, 8))
    goto exit_close;

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

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

  if(setjmp(png_ptr->jmpbuf))
    goto exit_free_close;

  png_init_io(png_ptr, f);
  png_set_sig_bytes(png_ptr, 8);
  png_read_info(png_ptr, info_ptr);
  png_get_IHDR(png_ptr, info_ptr, &w, &h, &bpp, &type, NULL, NULL, NULL);

  if(!constraint(w, h))
  {
    warn("Requested image '%s' failed dimension checks.\n", name);
    goto exit_free_close;
  }

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

  else if(type == PNG_COLOR_TYPE_GRAY_ALPHA || !(type & PNG_COLOR_MASK_COLOR))
    png_set_gray_to_rgb(png_ptr);

  else if(!(type & PNG_COLOR_MASK_COLOR) && bpp < 8)
    png_set_expand_gray_1_2_4_to_8(png_ptr);

  if(bpp == 16)
    png_set_strip_16(png_ptr);

  else if(bpp < 8)
    png_set_packing(png_ptr);

  if(png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
    png_set_tRNS_to_alpha(png_ptr);

  else if(!(type & PNG_COLOR_MASK_ALPHA))
    png_set_add_alpha(png_ptr, 0xff, PNG_FILLER_AFTER);

  // FIXME: Are these necessary?
  png_read_update_info(png_ptr, info_ptr);
  png_get_IHDR(png_ptr, info_ptr, &w, &h, &bpp, &type, NULL, NULL, NULL);

  row_ptrs = cmalloc(sizeof(png_bytep) * h);
  if(!row_ptrs)
    goto exit_free_close;

  s = allocator(w, h, &stride, &pixels);
  if(!s)
    goto exit_free_close;

  for(i = 0; i < h; i++)
    row_ptrs[i] = (png_bytep)(unsigned char *)pixels + i * stride;

  png_read_image(png_ptr, row_ptrs);

  if(_w)
    *_w = w;
  if(_h)
    *_h = h;

exit_free_close:
  png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
  free(row_ptrs);
exit_close:
  fclose(f);
exit_out:
  return s;
}