C++ png_read_info函数代码示例

void TextureLoader::loadPNGTexture(std::ifstream& textureFile, unsigned int& width, unsigned int& height, unsigned char*& data) {
	// Read and validate header
	png_byte header[8];
	textureFile.read((char*) header, 8);
	if (png_sig_cmp(header, 0, 8)) {
		return;
	}

	// Create PNG structs
	png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
	if (!png_ptr) {
		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);
		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);
		return;
	}

	// PNG error handling
	if (setjmp(png_jmpbuf(png_ptr))) {
		png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
		return;
	}

	// Setup stream read function
	png_set_read_fn(png_ptr, (png_voidp)& textureFile, readPNGData);
	
	// Read PNG info
	png_set_sig_bytes(png_ptr, 8);
	png_read_info(png_ptr, info_ptr);

	png_set_strip_16(png_ptr);
	png_set_expand_gray_1_2_4_to_8(png_ptr);
	png_set_palette_to_rgb(png_ptr);
	if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
		png_set_tRNS_to_alpha(png_ptr);
	}
	png_read_update_info(png_ptr, info_ptr);
	
	int channels = png_get_channels(png_ptr, info_ptr);
	if(channels != 4) {
		png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
		return;
	}
	width =  png_get_image_width(png_ptr, info_ptr);
	height = png_get_image_height(png_ptr, info_ptr);

	// Allocate memory for data
	int rowbytes = png_get_rowbytes(png_ptr, info_ptr);
	data = new unsigned char[rowbytes * height];
	png_bytep *row_pointers = new png_bytep[height];
	if (!data || !row_pointers) {
		png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
		return;
	}

	// Set up row_pointers to point at the correct offsets of data[]
	for(unsigned int i = 0; i < height; ++i) {
		//row_pointers[height - 1 - i] = data + i * rowbytes; // same thing
		row_pointers[i] = data + (height - 1 - i) * rowbytes;
	}

	// Read the data
	png_read_image(png_ptr, row_pointers);
}

BOOL png2pnm (FILE *png_file, FILE *pnm_file, FILE *alpha_file,
    volatile BOOL raw, BOOL alpha)
{
  png_struct    *png_ptr = NULL;
  png_info        *info_ptr = NULL;
  png_byte      buf[8];
  png_byte      *png_pixels = NULL;
  png_byte      **row_pointers = NULL;
  png_byte      *pix_ptr = NULL;
  png_uint_32   row_bytes;

  png_uint_32   width;
  png_uint_32   height;
  int           bit_depth;
  int           channels;
  int           color_type;
  int           alpha_present;
  int           row, col;
  int           ret;
  int           i;
  long          dep_16;

  /* read and check signature in PNG file */
  ret = fread (buf, 1, 8, png_file);
  if (ret != 8)
    return FALSE;

  ret = png_sig_cmp (buf, 0, 8);
  if (ret)
    return FALSE;

  /* create png and info structures */

  png_ptr = png_create_read_struct (png_get_libpng_ver(NULL),
    NULL, NULL, NULL);
  if (!png_ptr)
    return FALSE;   /* out of memory */

  info_ptr = png_create_info_struct (png_ptr);
  if (!info_ptr)
  {
    png_destroy_read_struct (&png_ptr, NULL, NULL);
    return FALSE;   /* out of memory */
  }

  if (setjmp (png_jmpbuf(png_ptr)))
  {
    png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
    return FALSE;
  }

  /* set up the input control for C streams */
  png_init_io (png_ptr, png_file);
  png_set_sig_bytes (png_ptr, 8);  /* we already read the 8 signature bytes */

  /* read the file information */
  png_read_info (png_ptr, info_ptr);

  /* get size and bit-depth of the PNG-image */
  png_get_IHDR (png_ptr, info_ptr,
    &width, &height, &bit_depth, &color_type,
    NULL, NULL, NULL);

  /* set-up the transformations */

  /* transform paletted images into full-color rgb */
  if (color_type == PNG_COLOR_TYPE_PALETTE)
    png_set_expand (png_ptr);
  /* expand images to bit-depth 8 (only applicable for grayscale images) */
  if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
    png_set_expand (png_ptr);
  /* transform transparency maps into full alpha-channel */
  if (png_get_valid (png_ptr, info_ptr, PNG_INFO_tRNS))
    png_set_expand (png_ptr);

#ifdef NJET
  /* downgrade 16-bit images to 8-bit */
  if (bit_depth == 16)
    png_set_strip_16 (png_ptr);
  /* transform grayscale images into full-color */
  if (color_type == PNG_COLOR_TYPE_GRAY ||
    color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
    png_set_gray_to_rgb (png_ptr);
  /* only if file has a file gamma, we do a correction */
  if (png_get_gAMA (png_ptr, info_ptr, &file_gamma))
    png_set_gamma (png_ptr, (double) 2.2, file_gamma);
#endif

  /* all transformations have been registered; now update info_ptr data,
   * get rowbytes and channels, and allocate image memory */

  png_read_update_info (png_ptr, info_ptr);

  /* get the new color-type and bit-depth (after expansion/stripping) */
  png_get_IHDR (png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
    NULL, NULL, NULL);

  /* check for 16-bit files */
  if (bit_depth == 16)
  {
//.........这里部分代码省略.........

// load in the image data
IImage* CImageLoaderPng::loadImage(io::IReadFile* file) const
{
#ifdef _IRR_COMPILE_WITH_LIBPNG_
	if (!file)
		return 0;

	video::IImage* image = 0;
	//Used to point to image rows
	u8** RowPointers = 0;

	png_byte buffer[8];
	// Read the first few bytes of the PNG file
	if( file->read(buffer, 8) != 8 )
	{
		os::Printer::log("LOAD PNG: can't read file\n", file->getFileName(), ELL_ERROR);
		return 0;
	}

	// Check if it really is a PNG file
	if( png_sig_cmp(buffer, 0, 8) )
	{
		os::Printer::log("LOAD PNG: not really a png\n", file->getFileName(), ELL_ERROR);
		return 0;
	}

	// Allocate the png read struct
	png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
		NULL, (png_error_ptr)png_cpexcept_error, NULL);
	if (!png_ptr)
	{
		os::Printer::log("LOAD PNG: Internal PNG create read struct failure\n", file->getFileName(), ELL_ERROR);
		return 0;
	}

	// Allocate the png info struct
	png_infop info_ptr = png_create_info_struct(png_ptr);
	if (!info_ptr)
	{
		os::Printer::log("LOAD PNG: Internal PNG create info struct failure\n", file->getFileName(), ELL_ERROR);
		png_destroy_read_struct(&png_ptr, NULL, NULL);
		return 0;
	}

	// for proper error handling
	if (setjmp(png_jmpbuf(png_ptr)))
	{
		png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
		if (RowPointers)
			delete [] RowPointers;
		return 0;
	}

	// changed by zola so we don't need to have public FILE pointers
	png_set_read_fn(png_ptr, file, user_read_data_fcn);

	png_set_sig_bytes(png_ptr, 8); // Tell png that we read the signature

	png_read_info(png_ptr, info_ptr); // Read the info section of the png file

	u32 Width;
	u32 Height;
	s32 BitDepth;
	s32 ColorType;
	{
		// Use temporary variables to avoid passing casted pointers
		png_uint_32 w,h;
		// Extract info
		png_get_IHDR(png_ptr, info_ptr,
			&w, &h,
			&BitDepth, &ColorType, NULL, NULL, NULL);
		Width=w;
		Height=h;
	}

	// Convert palette color to true color
	if (ColorType==PNG_COLOR_TYPE_PALETTE)
		png_set_palette_to_rgb(png_ptr);

	// Convert low bit colors to 8 bit colors
	if (BitDepth < 8)
	{
		if (ColorType==PNG_COLOR_TYPE_GRAY || ColorType==PNG_COLOR_TYPE_GRAY_ALPHA)
			png_set_gray_1_2_4_to_8(png_ptr);
		else
			png_set_packing(png_ptr);
	}

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

	// Convert high bit colors to 8 bit colors
	if (BitDepth == 16)
		png_set_strip_16(png_ptr);

	// Convert gray color to true color
	if (ColorType==PNG_COLOR_TYPE_GRAY || ColorType==PNG_COLOR_TYPE_GRAY_ALPHA)
		png_set_gray_to_rgb(png_ptr);

	// Update the changes
//.........这里部分代码省略.........

GLuint png_texture_load(const char * file_name, int * width, int * height)
{
    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);

    if (width){ *width = temp_width; }
    if (height){ *height = temp_height; }

    //printf("%s: %lux%lu %d\n", file_name, temp_width, temp_height, color_type);

    if (bit_depth != 8)
    {
        fprintf(stderr, "%s: Unsupported bit depth %d.  Must be 8.\n", file_name, bit_depth);
        return 0;
    }

    GLint format;
    switch(color_type)
    {
    case PNG_COLOR_TYPE_RGB:
        format = GL_RGB;
        break;
    case PNG_COLOR_TYPE_RGB_ALPHA:
        format = GL_RGBA;
        break;
    default:
        fprintf(stderr, "%s: Unknown libpng color type %d.\n", file_name, color_type);
        return 0;
    }

    // Update the png info struct.
//.........这里部分代码省略.........

int APIENTRY pngLoadRawF(FILE *fp, pngRawInfo *pinfo) {
	unsigned char header[8];
	png_structp png;
	png_infop   info;
	png_infop   endinfo;
	png_bytep   data;
   png_bytep  *row_p;
   double	fileGamma;

	png_uint_32 width, height;
	int depth, color;

	png_uint_32 i;

	if (pinfo == NULL) return 0;

	fread(header, 1, 8, fp);
	if (!png_check_sig(header, 8)) return 0;

	png = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
	info = png_create_info_struct(png);
	endinfo = png_create_info_struct(png);

	// DH: added following lines
	if (setjmp(png->jmpbuf))
	{
		png_destroy_read_struct(&png, &info, &endinfo);
		return 0;
	}
	// ~DH

	png_init_io(png, fp);
	png_set_sig_bytes(png, 8);
	png_read_info(png, info);
	png_get_IHDR(png, info, &width, &height, &depth, &color, NULL, NULL, NULL);

	pinfo->Width  = width;
	pinfo->Height = height;
	pinfo->Depth  = depth;

	/*--GAMMA--*/
	checkForGammaEnv();
	if (png_get_gAMA(png, info, &fileGamma))
		png_set_gamma(png, screenGamma, fileGamma);
	else
		png_set_gamma(png, screenGamma, 1.0/2.2);

	png_read_update_info(png, info);

	data = (png_bytep) malloc(png_get_rowbytes(png, info)*height);
	row_p = (png_bytep *) malloc(sizeof(png_bytep)*height);

	for (i = 0; i < height; i++) {
		if (StandardOrientation)
			row_p[height - 1 - i] = &data[png_get_rowbytes(png, info)*i];
		else
			row_p[i] = &data[png_get_rowbytes(png, info)*i];
	}

	png_read_image(png, row_p);
	free(row_p);

	if (color == PNG_COLOR_TYPE_PALETTE) {
		int cols;
		png_get_PLTE(png, info, (png_colorp *) &pinfo->Palette, &cols);
	}
	else {
		pinfo->Palette = NULL;
	}

	if (color&PNG_COLOR_MASK_ALPHA) {
		if (color&PNG_COLOR_MASK_PALETTE || color == PNG_COLOR_TYPE_GRAY_ALPHA)
			pinfo->Components = 2;
		else
			pinfo->Components = 4;
		pinfo->Alpha = 8;
	}
	else {
		if (color&PNG_COLOR_MASK_PALETTE || color == PNG_COLOR_TYPE_GRAY)
			pinfo->Components = 1;
		else
			pinfo->Components = 3;
		pinfo->Alpha = 0;
	}

	pinfo->Data = data;

   png_read_end(png, endinfo);
	png_destroy_read_struct(&png, &info, &endinfo);

	return 1;
}

/**
 * loadTexture takes a filename and returns a Texture pointer to the texture place in memory
 */
Texture *Graphics::loadTexture(const char *filename)
{
	// log it out
	Log::info("Loading texture \"%s\"...", filename);

	// header for testing if it is a png
	png_byte header[8];

	// open file as binary
	FILE *fp = fopen(filename, "rb");
	if (!fp)
	{	
		Log::error("File failed to load!");
		return NULL;
	}

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

	// test if png
	int is_png = !png_sig_cmp(header, 0, 8);
	if (!is_png) 
	{
		Log::error("Image is not a PNG!");
		fclose(fp);
		return NULL;
	}

	// create png struct
	png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
	if (!png_ptr) 
	{
		Log::error("png_ptr failed to create read struct!");
		fclose(fp);
		return NULL;
	}

	// create png info struct
	png_infop info_ptr = png_create_info_struct(png_ptr);
	if (!info_ptr) 
	{
		Log::error("info_ptr failed to create struct!");
		png_destroy_read_struct(&png_ptr, (png_infopp) NULL, (png_infopp) NULL);
		fclose(fp);
		return NULL;
	}

	// create png info struct
	png_infop end_info = png_create_info_struct(png_ptr);
	if (!end_info) 
	{
		Log::error("end_info failed to create struct!");
		png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp) NULL);
		fclose(fp);
		return NULL;
	}

	// png error stuff, not sure libpng man suggests this.
	if (setjmp(png_jmpbuf(png_ptr))) 
	{
		Log::error("png_jumpbuf overflow!");
		png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
		fclose(fp);
		return NULL;
	}

	// 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 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
	int width = twidth;
	int 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) 
	{
		Log::error("image_data failed to create a new png_byte!");
//.........这里部分代码省略.........

GLubyte* 
glmReadPNG(const char* filename, GLboolean alpha, int* width_ret, int* height_ret, int* type_ret)
{
  png_structp png_ptr;
  png_infop info_ptr;
  png_uint_32 width, height;
  
  int bit_depth, color_type, interlace_type;
  FILE *fp;
  unsigned char *buffer;
  int y, bytes_per_row;
  int channels;
  int format;
  png_bytepp row_pointers;

  if ((fp = fopen(filename, "rb")) == NULL) {
    pngerror = ERR_OPEN;
    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,
      (void *)user_error_ptr, user_error_fn, user_warning_fn);*/

  png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
				   NULL, err_callback, warn_callback);
  
  if (png_ptr == NULL) {
    pngerror = ERR_MEM;
    fclose(fp);
    return 0;
  }

  /* Allocate/initialize the memory for image information.  REQUIRED. */
  info_ptr = png_create_info_struct(png_ptr);
  if (info_ptr == NULL) {
    pngerror = ERR_MEM;
    fclose(fp);
    png_destroy_read_struct(&png_ptr, (png_infopp)NULL, (png_infopp)NULL);
    return 0;
  }
  
  /* 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.
   */

  buffer = NULL;

  if (setjmp(setjmp_buffer)) {
    pngerror = ERR_PNGLIB;
    /* 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 */

    if (buffer) free(buffer);
    return NULL;
  }
  
  /* Set up the input control if you are using standard C streams */
  png_init_io(png_ptr, fp);

  /* 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)
//.........这里部分代码省略.........

int load_png(char * file_name, int * w, int * h, int * depth, char ** data)
{
#if COMPILE_PNG_CODE
    FILE *fp;
    png_structp png_ptr;
    png_infop info_ptr;
    png_uint_32 width, height;
    int bit_depth, color_type, interlace_type,
        compression_type, filter_type;
    int rowbytes, channels;
    unsigned int i;
    char * buff;
    char ** row_pointers;

    fp = fopen(file_name, "rb");
    if (!fp){
        error_print("Cannot load required png-file (%s). Terminating!",file_name);
        sys_exit(1);
    }

    png_ptr = png_create_read_struct
       (PNG_LIBPNG_VER_STRING, (png_voidp)NULL/*user_error_ptr*/,
        NULL/*user_error_fn*/, NULL/*user_warning_fn*/);
    if (!png_ptr) {
        error_print("Error png-ptr png-file (%s). Terminating!",file_name);
        sys_exit(1);
     }

    info_ptr = png_create_info_struct(png_ptr);
    if (!info_ptr)
    {
        png_destroy_read_struct(&png_ptr, (png_infopp)NULL, (png_infopp)NULL);
        error_print("Error create info struct png-file (%s). Terminating!",file_name);
        sys_exit(1);
    }

    png_init_io(png_ptr, fp);

    png_read_info(png_ptr, info_ptr);

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

    channels = png_get_channels(png_ptr, info_ptr);

    rowbytes = png_get_rowbytes(png_ptr, info_ptr);

    buff         = (char *)  malloc(height*rowbytes);
    row_pointers = (char **) malloc(height*sizeof(char *));
    for(i=0;i<height;i++){
        row_pointers[i]=&buff[rowbytes*i];
    }

    png_read_image(png_ptr, (png_bytepp)row_pointers);

    //fprintf(stderr,"load_png: rgstereo=%d\n",options_rgstereo_on);

    if( options_rgstereo_on ){
        //fprintf(stderr,"load_png: graying out texture\n");
        for(i=0;i<height;i++){
            int j,k,d;
            for(j=0;j<rowbytes;j+=channels){
                d=0;
                for(k=0;k<channels;k++) d+=(unsigned char)row_pointers[i][j+k];
                d/=channels;
                for(k=0;k<channels;k++) row_pointers[i][j+k]=d;
            }
        }
    }

    free(row_pointers);
    free(info_ptr);
    free(png_ptr);
    fclose(fp);

    *data  = buff;
    *w     = width;
    *h     = height;
    *depth = channels*bit_depth;

    return 1;
#else
    *data  = 0;
    *w     = 0;
    *h     = 0;
    *depth = 0;
    return 1;
#endif
}

void PNGCodec::decode(std::vector<uint8_t> &in,
	std::vector<uint8_t> *out, unsigned int *width, 
	unsigned int *height, ColorFormat *format, uint8_t level)
{
	if (level != 0)
	{
		// TODO: Error handling.
		return;
	}

	if (png_check_sig(in.data(), SIGNATURE_LENGTH) == false)
	{
		// TODO: Error handling.
		return;
	}

	png_structp pngPtr = png_create_read_struct(
		PNG_LIBPNG_VER_STRING, nullptr, nullptr, nullptr);

	if (pngPtr == nullptr)
	{
		// TODO: Error handling.
		return;
	}

	png_infop pngInfoPtr = png_create_info_struct(pngPtr);

	if (pngInfoPtr == nullptr)
	{
		// TODO: Error handling.
		png_destroy_read_struct(&pngPtr, nullptr, nullptr);
		return;
	}

	PNGVectorStream stream;
	stream.vec = &in;
	stream.offset = 0;

	png_set_read_fn(pngPtr, &stream, PNGReadCallback);
	png_read_info(pngPtr, pngInfoPtr);

	int bitDepth = 0;
	int colorType = -1;
	png_uint_32 retval = png_get_IHDR(pngPtr, pngInfoPtr,
		width,
		height,
		&bitDepth,
		&colorType,
		nullptr, nullptr, nullptr);

	if (retval != 1)
	{
		// TODO: Error handling.
		png_destroy_read_struct(&pngPtr, &pngInfoPtr, nullptr);
		return;
	}

	switch (colorType)
	{
	case PNG_COLOR_TYPE_RGB:
		*format = ColorFormat::RGB;
		break;

	case PNG_COLOR_TYPE_RGBA:
		*format = ColorFormat::RGBA;
		break;

	default:
		// TODO: Error handling.
		png_destroy_read_struct(&pngPtr, &pngInfoPtr, nullptr);
		return;
	}

	out->resize((*width) * (*height) * static_cast<unsigned int>(*format));

	for (unsigned int i = 0; i < *height; ++i)
		png_read_row(pngPtr, 
			&(*out)[i * (*width) * static_cast<unsigned int>(*format)], nullptr);

	png_destroy_read_struct(&pngPtr, &pngInfoPtr, nullptr);
}

int loadPNG(const char *filename) {
    GLuint texture;
    png_structp png_ptr = NULL;
    png_infop info_ptr = NULL;
    png_bytep *row_pointers = NULL;
    int bitDepth, colourType;
    FILE *pngFile = fopen(filename, "rb");
    if (!pngFile)
        return 0;
    png_byte sig[8];
    fread(&sig, 8, sizeof(png_byte), pngFile);
    rewind(pngFile);
    if (!png_check_sig(sig, 8)) {
        //SDL_Log("png sig failure\n");
        return 0;
    }
    png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
    if (!png_ptr) {
        //SDL_Log("png ptr not created\n");
        return 0;
    }
    if (setjmp(png_jmpbuf(png_ptr))) {
        //SDL_Log("set jmp failed\n");
        return 0;
    }
    info_ptr = png_create_info_struct(png_ptr);
    if (!info_ptr) {
        //SDL_Log("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);
        //SDL_Log("%s broken?\n", filename);
        return 0;
    }

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

    int i = 0;
    for (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);

    //SDL_Log("%s has %i colour components\n",filename,components);
    //glTexImage2D(GL_TEXTURE_2D, 0, components, width, height, 0, glcolours, GL_UNSIGNED_BYTE, pixels);
//.........这里部分代码省略.........

void RawImage::loadPNG(FILE* file) throw(ImageException)
{
  png_structp pngData = NULL;
  png_infop pngInfo = NULL;
  unsigned char** rowPtrs = NULL;

  try {
    pngData = png_create_read_struct(PNG_LIBPNG_VER_STRING,
      NULL,   // error_ptr
      NULL,   // error_fn
      NULL    // warn_fn
    );
    pngInfo = png_create_info_struct(pngData);

    unsigned char header[8];
    if (fread(header, 1, 8, file) < 8)
      throw ImageException("Missing PNG header data.");
    if (png_sig_cmp(header, 0, 8) != 0)
      throw ImageException("Not a PNG file!");
    if (setjmp(png_jmpbuf(pngData)))
      throw ImageException("PNG library error.");

    png_init_io(pngData, file);
    png_set_sig_bytes(pngData, 8);
    png_read_info(pngData, pngInfo);

    png_uint_32 width, height;
    int bitDepth, colorType, iMethod, cMethod, fMethod;
    png_get_IHDR(pngData, pngInfo, &width, &height, &bitDepth, &colorType,
        &iMethod, &cMethod, &fMethod);

    int bytesPerChannel = (bitDepth / 8);
    if (bitDepth % 8 != 0)
      ++bytesPerChannel;

    _width = width;
    _height = height;
    switch (colorType) {
      case PNG_COLOR_TYPE_PALETTE:
        png_set_palette_to_rgb(pngData);
        _type = GL_RGB;
        _bytesPerPixel = bytesPerChannel * 3;
        break;
      case PNG_COLOR_TYPE_RGBA:
        _type = GL_RGBA;
        _bytesPerPixel = bytesPerChannel * 4;
        break;
      case PNG_COLOR_TYPE_RGB:
        _type = GL_RGB;
        _bytesPerPixel = bytesPerChannel * 3;
        break;
      case PNG_COLOR_TYPE_GRAY:
        if (bitDepth < 8)
          png_set_gray_1_2_4_to_8(pngData);
        _type = GL_ALPHA;
        _bytesPerPixel = bytesPerChannel;
        break;
      default:
        throw ImageException("Unknown PNG type.");
    }

    _pixels = new unsigned char[_bytesPerPixel * _width * _height];
    rowPtrs = new unsigned char*[_height];
    for (size_t i = 0; i < _height; ++i)
      rowPtrs[i] = &_pixels[_bytesPerPixel * _width * (_height - i - 1)];
    png_read_image(pngData, rowPtrs);

    png_destroy_read_struct(&pngData, &pngInfo, NULL);
    delete[] rowPtrs;
  } catch (ImageException& e) {
    png_destroy_read_struct(&pngData, &pngInfo, NULL);
    if (rowPtrs != NULL)
      delete[] rowPtrs;
    throw e;
  }
}

bool PNGLoader::doDecodeImage(const byte *fileDataPtr, uint fileSize, byte *&uncompressedDataPtr, int &width, int &height, int &pitch) {
#ifndef USE_INTERNAL_PNG_DECODER
	png_structp png_ptr = NULL;
	png_infop   info_ptr = NULL;

	int         bitDepth;
	int         colorType;
	int         interlaceType;
	int         i;

	// Check for valid PNG signature
	if (!doIsCorrectImageFormat(fileDataPtr, fileSize)) {
		error("png_check_sig failed");
	}

	// Die beiden PNG Strukturen erstellen
	png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
	if (!png_ptr) {
		error("Could not create libpng read struct.");
	}

	info_ptr = png_create_info_struct(png_ptr);
	if (!info_ptr) {
		error("Could not create libpng info struct.");
	}

	// Alternative Lesefunktion benutzen
	const byte **ref = &fileDataPtr;
	png_set_read_fn(png_ptr, (void *)ref, png_user_read_data);

	// PNG Header einlesen
	png_read_info(png_ptr, info_ptr);

	// PNG Informationen auslesen

	png_uint_32 w, h;
	png_get_IHDR(png_ptr, info_ptr, &w, &h, &bitDepth, &colorType, &interlaceType, NULL, NULL);
	width = w;
	height = h;

	// Pitch des Ausgabebildes berechnen
	pitch = GraphicEngine::calcPitch(GraphicEngine::CF_ARGB32, width);

	// Speicher für die endgültigen Bilddaten reservieren
	// Dieses geschieht vor dem reservieren von Speicher für temporäre Bilddaten um die Fragmentierung des Speichers gering zu halten
	uncompressedDataPtr = new byte[pitch * height];
	if (!uncompressedDataPtr) {
		error("Could not allocate memory for output image.");
	}

	// Bilder jeglicher Farbformate werden zunächst in ARGB Bilder umgewandelt
	if (bitDepth == 16)
		png_set_strip_16(png_ptr);
	if (colorType == PNG_COLOR_TYPE_PALETTE)
		png_set_expand(png_ptr);
	if (bitDepth < 8)
		png_set_expand(png_ptr);
	if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
		png_set_expand(png_ptr);
	if (colorType == PNG_COLOR_TYPE_GRAY ||
	        colorType == PNG_COLOR_TYPE_GRAY_ALPHA)
		png_set_gray_to_rgb(png_ptr);

	png_set_bgr(png_ptr);

	if (colorType != PNG_COLOR_TYPE_RGB_ALPHA)
		png_set_filler(png_ptr, 0xff, PNG_FILLER_AFTER);

	// Nachdem die Transformationen registriert wurden, werden die Bilddaten erneut eingelesen
	png_read_update_info(png_ptr, info_ptr);
	png_get_IHDR(png_ptr, info_ptr, &w, &h, &bitDepth, &colorType, NULL, NULL, NULL);
	width = w;
	height = h;

	if (interlaceType == PNG_INTERLACE_NONE) {
		// PNGs without interlacing can simply be read row by row.
		for (i = 0; i < height; i++) {
			png_read_row(png_ptr, uncompressedDataPtr + i * pitch, NULL);
		}
	} else {
		// PNGs with interlacing require us to allocate an auxillary
		// buffer with pointers to all row starts.

		// Allocate row pointer buffer
		png_bytep *pRowPtr = new png_bytep[height];
		if (!pRowPtr) {
			error("Could not allocate memory for row pointers.");
		}

		// Initialize row pointers
		for (i = 0; i < height; i++)
			pRowPtr[i] = uncompressedDataPtr + i * pitch;

		// Read image data
		png_read_image(png_ptr, pRowPtr);

		// Free row pointer buffer
		delete[] pRowPtr;
	}

//.........这里部分代码省略.........

/* pngReadImage: Reads an image from a memory buffer.
   Returns: non-zero if successful.
*/
int pngReadImage(int w, int h, int d, char* bits, char *data, int nBytes) {
  png_bytep *row_pointers = NULL;
  pngReadState rs;
  png_structp png_ptr;
  png_infop info_ptr;
  png_uint_32 width, height;
  int bit_depth, color_type, interlace_type;

  DBG("pngReadImage: png_sig_cmp");
  /* Compare the first PNG_BYTES_TO_CHECK bytes of the signature. */
  if(png_sig_cmp(data, (png_size_t)0, PNG_BYTES_TO_CHECK)) return 0;

  DBG("pngReadImage: png_create_read_struct");
  /* Create the png_struct */
  png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
  if (png_ptr == NULL) return 0;

  DBG("pngReadImage: png_create_info_struct");
  /* Allocate/initialize the image information data.  REQUIRED */
  info_ptr = png_create_info_struct(png_ptr);
  if (info_ptr == NULL) {
    png_destroy_read_struct(&png_ptr, &info_ptr, png_infopp_NULL);
    return 0;
  }

  /* Set error handling.  REQUIRED if you aren't supplying your own
   * error handling functions in the png_create_read_struct() call.
   */
  if (setjmp(png_jmpbuf(png_ptr))) {
    DBG("pngReadImage: triggered png_error");
    /* If we get here, we had a problem reading the file */
    png_destroy_read_struct(&png_ptr, &info_ptr, png_infopp_NULL);
    if(row_pointers) free(row_pointers);
    return 0;
  }
  rs.data = data;
  rs.position = 0;
  rs.length = nBytes;
  png_set_read_fn(png_ptr, (void *)&rs, readBytes);


  DBG("pngReadImage: png_read_info");
  /* 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);

   /* flip the RGB pixels to BGR (or RGBA to BGRA) */
  if (color_type & PNG_COLOR_MASK_COLOR) {
    DBG("pngReadImage: png_set_bgr");
    png_set_bgr(png_ptr);
  }

  if(d == 32 && color_type == PNG_COLOR_TYPE_RGB) {
    /* Add filler (or alpha) byte (before/after each RGB triplet) */
    DBG("pngReadImage: png_set_filler");
    png_set_filler(png_ptr, 0xff, PNG_FILLER_AFTER);
  }

  if(0) {
    /* 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_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);


  if(0) {
//.........这里部分代码省略.........

//.........这里部分代码省略.........
		PNG_LIBPNG_VER_STRING,
		(png_voidp)NULL, (png_error_ptr)NULL, (png_error_ptr)NULL
	);
	if (png_ptr == NULL) {
		fputs(MSG[E_GENERIC], stderr);
		fputc('\n', stderr);
		fclose(f);
		return EXIT_FAILURE;
	}
	
	info_ptr = png_create_info_struct(png_ptr);
	end_info = png_create_info_struct(png_ptr);

	try_png_read(
		(info_ptr == NULL) || (end_info == NULL),
		&png_ptr, &info_ptr, &end_info, f, (char*)NULL
	);

	try_png_read(
		setjmp(png_jmpbuf(png_ptr)),
		&png_ptr, &info_ptr, &end_info, f, MSG[E_READ]
	);

   	png_init_io(png_ptr, f);
	png_set_sig_bytes(png_ptr, SIG_BYTES);

	/* Bildinfo lesen: Bilddimensionen und ggf. Farbpalette.
	 * Palette ggf. konvertieren. *********************************************/

	long int width, height, pwidth, pheight;
//	png_uint_32 width, height, pwidth, pheight;
	comp_t *image, **row, *rwp;

	png_read_info(png_ptr, info_ptr);

	width = info_ptr->width;
	height = info_ptr->height;
	
	const long int original_width = info_ptr->width;

	const int bit_depth = info_ptr->bit_depth,
			 color_type = info_ptr->color_type;
	const bool image_is_pal = (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE);
	const bool image_is_gray = (
		(color_type == PNG_COLOR_TYPE_GRAY) ||
		(color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
	);
	const bool alpha = (
		(color_type == PNG_COLOR_TYPE_GRAY_ALPHA) ||
		(color_type == PNG_COLOR_TYPE_RGB_ALPHA)
	);

	int num_palette = 0;
	png_color *png_pal_got = NULL;

	if (image_is_pal)

		try_png_read(
			!png_get_PLTE(png_ptr, info_ptr, &png_pal_got, &num_palette),
			&png_ptr, &info_ptr, &end_info, f, MSG[E_READPAL]
		);

	png_color   png_pal[num_palette];	
	comp_t     comp_pal[num_palette];	

	if (image_is_pal)

void PNGAPI
png_read_png(png_structp png_ptr, png_infop info_ptr,
                           int transforms,
                           voidp params)
{
   int row;

#if defined(PNG_READ_INVERT_ALPHA_SUPPORTED)
   /* invert the alpha channel from opacity to transparency */
   if (transforms & PNG_TRANSFORM_INVERT_ALPHA)
       png_set_invert_alpha(png_ptr);
#endif

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

   /* -------------- image transformations start here ------------------- */

#if defined(PNG_READ_16_TO_8_SUPPORTED)
   /* tell libpng to strip 16 bit/color files down to 8 bits/color */
   if (transforms & PNG_TRANSFORM_STRIP_16)
       png_set_strip_16(png_ptr);
#endif

#if defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
   /* Strip alpha bytes from the input data without combining with the
    * background (not recommended).
    */
   if (transforms & PNG_TRANSFORM_STRIP_ALPHA)
       png_set_strip_alpha(png_ptr);
#endif

#if defined(PNG_READ_PACK_SUPPORTED) && !defined(PNG_READ_EXPAND_SUPPORTED)
   /* Extract multiple pixels with bit depths of 1, 2, and 4 from a single
    * byte into separate bytes (useful for paletted and grayscale images).
    */
   if (transforms & PNG_TRANSFORM_PACKING)
       png_set_packing(png_ptr);
#endif

#if defined(PNG_READ_PACKSWAP_SUPPORTED)
   /* Change the order of packed pixels to least significant bit first
    * (not useful if you are using png_set_packing). */
   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)
//.........这里部分代码省略.........