C++ png_jmpbuf函数代码示例

bool YImage::save( const char* fname, bool fast )
const
{
	FILE* fp = NULL ;
	bool rval = true ;
	png_structp png_ptr = NULL ;
	png_infop info_ptr = NULL ;
	
	// Open the file for reading in binary mode.
	fp = fopen( fname, "wb" ) ;
	if( !fp )
	{
		fprintf( stderr, ERROR_STRING_OPEN, fname ) ;
		rval = false ;
		goto YImage_save_cleanup ;
	}
	
	// Allocate the png structs.
	png_ptr = png_create_write_struct( PNG_LIBPNG_VER_STRING, NULL, NULL, NULL ) ;
	if( !png_ptr )
	{
		fprintf( stderr, ERROR_STRING_WRITING, fname ) ;
		rval = false ;
		goto YImage_save_cleanup ;
	}
	info_ptr = png_create_info_struct( png_ptr ) ;
	if( !info_ptr )
	{
		fprintf( stderr, ERROR_STRING_WRITING, fname ) ;
		rval = false ;
		goto YImage_save_cleanup ;
    }
	
	// Set up the png error routine.
	if( setjmp(png_jmpbuf(png_ptr)) )
	{
		fprintf( stderr, ERROR_STRING_WRITING, fname ) ;
		rval = false ;
		goto YImage_save_cleanup ;
    }
	
	// Give libpng the FILE*.
	// png_init_io( png_ptr, fp ) ;
	// or
	// use our own write callback
	png_set_write_fn( png_ptr, fp, (png_rw_ptr) user_write_data, user_flush_data ) ;
	
	// We'll use the low-level interface since the high-level interface won't handle
	// png_set_filler() which we need to tell libpng to strip out the A from our
	// 4-byte pixels.
	
	// First we set and write the info struct.
	png_set_IHDR(
		png_ptr, info_ptr,
		m_width, m_height,
		8, PNG_COLOR_TYPE_RGB_ALPHA,
		PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT
		) ;
	png_write_info( png_ptr, info_ptr ) ;
	
	// If we've been asked to write quickly, speed up the compression.
	if( fast ) png_set_compression_level( png_ptr, Z_BEST_SPEED );
	
	// Then we set up transforms.
	/*
	// 1. tell libpng to strip out the filler byte in our 4-byte pixels
	// if YPixel::a comes after any other member (b,g,r), we strip AFTER
	if( offsetof( YPixel, a ) > offsetof( YPixel, b ) ) {
		png_set_filler( png_ptr, 0, PNG_FILLER_AFTER ) ;
		// printf("alpha after\n");
	} else {
		png_set_filler( png_ptr, 0, PNG_FILLER_BEFORE ) ;
		// printf("alpha before\n");
	}
	*/
	if( offsetof( YPixel, a ) < offsetof( YPixel, b ) )
		png_set_swap_alpha( png_ptr ) ;
	// 2. tell libpng how our color triples are stored (b < r or vice versa)
	if( offsetof( YPixel, b ) < offsetof( YPixel, r ) )
	{
		png_set_bgr( png_ptr ) ;
		// printf("bgr\n") ;
	}
	// else { printf("rgb\n"); }
	// printf( "offsetof r, b: %d %d\n", offsetof( YPixel, r ), offsetof( YPixel, b ) );
	
	// Finally we create a row_pointers[] pointing into our data* and write the png out to the FILE*.
	{
		// 1. allocate row pointers array
		png_bytep* row_pointers = (png_bytep*) png_malloc( png_ptr, m_height * sizeof(png_bytep) ) ;
		// 2. point row pointers into m_data
		for( int i = 0 ; i < m_height ; ++i ) {
			row_pointers[i] = (png_bytep) (m_data + i*m_width) ;
		}
		// 3. write the image data
		png_write_image( png_ptr, row_pointers ) ;
		// 4. free row pointers array
		png_free( png_ptr, row_pointers ) ;
	}
	
//.........这里部分代码省略.........

//.........这里部分代码省略.........
        sample_size = sizeof(int32_t) * 2;
        reader = read_samples_int32;
        break;
    case FORMAT_UINT32:
        sample_size = sizeof(uint32_t) * 2;
        reader = read_samples_uint32;
        break;
    case FORMAT_FLOAT32:
        sample_size = sizeof(float) * 2;
        reader = read_samples_float32;
        break;
    case FORMAT_FLOAT64:
        sample_size = sizeof(double) * 2;
        reader = read_samples_float64;
        break;
    }
    params.reader = reader;

    uint64_t nsamples = size / sample_size;
    if ((params.clip > 0) && (nsamples > params.clip)) {
        nsamples = params.clip;
    }

    if (params.overlap > params.fftsize) {
        fprintf(stderr, "Overlap of %d is greater than FFT frame size of %d.\n",
                params.overlap, params.fftsize);
        return EXIT_FAILURE;
    }

    params.frames = nsamples / (params.fftsize - params.overlap);

    if (!strcmp(outfile, "")) {
        strcpy(outfile, infile);
        strcat(outfile, ".png");
    }

    if (verbose) {
        printf("Reading %s samples from %s...\n", fmt_s, infile);
        printf("Writing %d x %d output to %s...\n", params.fftsize,
               params.frames, outfile);
    }

    FILE *writefp = fopen(outfile, "wb");
    if (!writefp) {
        fprintf(stderr, "Error: failed to write to %s.\n", outfile);
        return EXIT_FAILURE;
    }

    png_structp png_ptr =
        png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
    if (!png_ptr) {
        fprintf(stderr, "Error: could not initialize write struct.\n");
        return EXIT_FAILURE;
    }

    png_infop info_ptr = png_create_info_struct(png_ptr);
    if (!info_ptr) {
        fprintf(stderr, "Error: could not initialize info struct.\n");
        png_destroy_write_struct(&png_ptr, NULL);
        return EXIT_FAILURE;
    }

    if (setjmp(png_jmpbuf(png_ptr))) {
        fprintf(stderr, "Error: libpng error.\n");
        png_destroy_write_struct(&png_ptr, &info_ptr);
        fclose(writefp);
        return EXIT_FAILURE;
    }

    if (verbose)
        printf("Writing PNG header..\n");
    png_init_io(png_ptr, writefp);
    png_set_IHDR(png_ptr, info_ptr, params.fftsize, params.frames, 8,
                 PNG_COLOR_TYPE_RGB, PNG_INTERLACE_NONE,
                 PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
    png_write_info(png_ptr, info_ptr);

    if (verbose)
        printf("Rendering (this may take a while)...\n");
    waterfall(png_ptr, readfp, params);

    if (verbose)
        printf("Writing PNG footer...\n");
    png_write_end(png_ptr, NULL);

    png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
    png_destroy_write_struct(&png_ptr, NULL);

    if (verbose)
        printf("Cleaning up...\n");
    fclose(writefp);
    fclose(readfp);

    destroy_window(win);

    if (verbose)
        print_scale_stats();

    return EXIT_SUCCESS;
}

char *sng_load_png_texture(const char *filename, int flipVertical, int flipHorizontal, int pre_multiply_alpha,
	int *w, int *h, int *hasAlpha, char *whynot, int whynotlen)
{
#ifndef WITHOUTOPENGL
	int i, j, bit_depth, color_type, row_bytes, image_data_row_bytes;
	png_byte header[8];
	png_uint_32 tw, th;
	png_structp png_ptr = NULL;
	png_infop info_ptr = NULL;
	png_infop end_info = NULL;
	png_byte *image_data = NULL;

	FILE *fp = fopen(filename, "rb");
	if (!fp) {
		snprintf(whynot, whynotlen, "Failed to open '%s': %s",
			filename, strerror(errno));
		return 0;
	}

	if (fread(header, 1, 8, fp) != 8) {
		snprintf(whynot, whynotlen, "Failed to read 8 byte header from '%s'\n",
				filename);
		goto cleanup;
	}
	if (png_sig_cmp(header, 0, 8)) {
		snprintf(whynot, whynotlen, "'%s' isn't a png file.",
			filename);
		goto cleanup;
	}

	png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
							NULL, NULL, NULL);
	if (!png_ptr) {
		snprintf(whynot, whynotlen,
			"png_create_read_struct() returned NULL");
		goto cleanup;
	}

	info_ptr = png_create_info_struct(png_ptr);
	if (!info_ptr) {
		snprintf(whynot, whynotlen,
			"png_create_info_struct() returned NULL");
		goto cleanup;
	}

	end_info = png_create_info_struct(png_ptr);
	if (!end_info) {
		snprintf(whynot, whynotlen,
			"2nd png_create_info_struct() returned NULL");
		goto cleanup;
	}

	if (setjmp(png_jmpbuf(png_ptr))) {
		snprintf(whynot, whynotlen, "libpng encounted an error");
		goto cleanup;
	}

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

	/*
	 * 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_get_IHDR(png_ptr, info_ptr, &tw, &th, &bit_depth, &color_type, NULL, NULL, NULL);

	if (bit_depth != 8) {
		snprintf(whynot, whynotlen, "load_png_texture only supports 8-bit image channel depth");
		goto cleanup;
	}

	if (color_type != PNG_COLOR_TYPE_RGB && color_type != PNG_COLOR_TYPE_RGB_ALPHA) {
		snprintf(whynot, whynotlen, "load_png_texture only supports RGB and RGBA");
		goto cleanup;
	}

	if (w)
		*w = tw;
	if (h)
		*h = th;
	int has_alpha = (color_type == PNG_COLOR_TYPE_RGB_ALPHA);
	if (hasAlpha)
		*hasAlpha = has_alpha;

	row_bytes = png_get_rowbytes(png_ptr, info_ptr);
	image_data_row_bytes = row_bytes;

	/* align to 4 byte boundary */
	if (image_data_row_bytes & 0x03)
		image_data_row_bytes += 4 - (image_data_row_bytes & 0x03);

	png_bytepp row_pointers = png_get_rows(png_ptr, info_ptr);

	image_data = malloc(image_data_row_bytes * th * sizeof(png_byte) + 15);
	if (!image_data) {
		snprintf(whynot, whynotlen, "malloc failed in load_png_texture");
		goto cleanup;
//.........这里部分代码省略.........

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;
}

static GstFlowReturn
gst_pngdec_chain (GstPad * pad, GstBuffer * buffer)
{
  GstPngDec *pngdec;
  GstFlowReturn ret = GST_FLOW_OK;

  pngdec = GST_PNGDEC (gst_pad_get_parent (pad));

  GST_LOG_OBJECT (pngdec, "Got buffer, size=%u", GST_BUFFER_SIZE (buffer));

  if (G_UNLIKELY (!pngdec->setup))
    goto not_configured;

  /* Something is going wrong in our callbacks */
  ret = pngdec->ret;
  if (G_UNLIKELY (ret != GST_FLOW_OK)) {
    GST_WARNING_OBJECT (pngdec, "we have a pending return code of %d", ret);
    goto beach;
  }

  /* Let libpng come back here on error */
  if (setjmp (png_jmpbuf (pngdec->png))) {
    GST_WARNING_OBJECT (pngdec, "error during decoding");
    ret = GST_FLOW_ERROR;
    goto beach;
  }

  pngdec->in_timestamp = GST_BUFFER_TIMESTAMP (buffer);
  pngdec->in_duration = GST_BUFFER_DURATION (buffer);

  /* Progressive loading of the PNG image */
  png_process_data (pngdec->png, pngdec->info, GST_BUFFER_DATA (buffer),
      GST_BUFFER_SIZE (buffer));

  if (pngdec->image_ready) {
    if (pngdec->framed) {
      /* Reset ourselves for the next frame */
      gst_pngdec_libpng_clear (pngdec);
      gst_pngdec_libpng_init (pngdec);
      GST_LOG_OBJECT (pngdec, "setting up callbacks for next frame");
      png_set_progressive_read_fn (pngdec->png, pngdec,
          user_info_callback, user_endrow_callback, user_end_callback);
    } else {
      GST_LOG_OBJECT (pngdec, "sending EOS");
      pngdec->ret = gst_pad_push_event (pngdec->srcpad, gst_event_new_eos ());
    }
    pngdec->image_ready = FALSE;
  }

  /* grab new return code */
  ret = pngdec->ret;

  /* And release the buffer */
  gst_buffer_unref (buffer);

beach:
  gst_object_unref (pngdec);

  return ret;

  /* ERRORS */
not_configured:
  {
    GST_LOG_OBJECT (pngdec, "we are not configured yet");
    ret = GST_FLOW_WRONG_STATE;
    goto beach;
  }
}

void CachedTexture::reload() {
    //..... load file ......
    GLenum internal_format = GL_RGB;
    GLenum data_format = GL_RGB;
    unsigned char *data = NULL;
    if (filename.size() >= 4 && filename.substr(filename.size()-4,4) == ".png") {
        //Load a png file, as per the libpng docs:
        FILE *fp = fopen(filename.c_str(), "rb");
        if (!fp) {
            cerr << "  cannot open file." << endl;
            return;
        }
        png_structp png = png_create_read_struct(PNG_LIBPNG_VER_STRING, (png_voidp)NULL, (png_error_ptr)NULL, (png_error_ptr)NULL);
        if (!png) {
            cerr << "  cannot alloc read struct." << endl;
            fclose(fp);
            return;
        }
        png_infop info = png_create_info_struct(png);
        if (!info) {
            cerr << "  cannot alloc info struct." << endl;
            png_destroy_read_struct(&png, (png_infopp)NULL, (png_infopp)NULL);
            fclose(fp);
            return;
        }
        png_bytep *row_pointers = NULL;
        if (setjmp(png_jmpbuf(png))) {
            cerr << "  png interal error." << endl;
            png_destroy_read_struct(&png, &info, (png_infopp)NULL);
            if (data != NULL) delete[] data;
            if (row_pointers != NULL) delete[] row_pointers;
            fclose(fp);
            return;
        }
        png_init_io(png, fp);
        png_read_info(png, info);
        w = png_get_image_width(png, info);
        h = png_get_image_height(png, info);
        {   //find power-of-two dimensions...
            tw = 1;
            while (tw < w) tw *= 2;
            th = 1;
            while (th < h) th *= 2;
        }
        if (!pad && (tw != w || th != h)) {
            if (!have_ARB_texture_non_power_of_two()) {
                cerr << "WARNING: trying to load texture of size " << w << " x " << h << ", but non-power-of-two textures not supported." << endl;
            }
            tw = w;
            th = h;
        }
        if (png_get_color_type(png, info) == PNG_COLOR_TYPE_PALETTE)
            png_set_palette_to_rgb(png);
        if (png_get_bit_depth(png, info) < 8)
            png_set_packing(png);
        if (png_get_bit_depth(png,info) == 16)
            png_set_strip_16(png);
        png_read_update_info(png, info);
        unsigned int rowbytes = png_get_rowbytes(png, info);
        //Make sure it's the format we think it is...
        bool problem = false;
        if (png_get_color_type(png, info) == PNG_COLOR_TYPE_GRAY) {
            data_format = internal_format = GL_LUMINANCE;
            if (rowbytes != w*1) problem = true;
        } else if (png_get_color_type(png, info) == PNG_COLOR_TYPE_GRAY_ALPHA) {
            data_format = internal_format = GL_LUMINANCE_ALPHA;
            if (rowbytes != w*2) problem = true;
        } else if (png_get_color_type(png, info) == PNG_COLOR_TYPE_PALETTE || png_get_color_type(png, info) == PNG_COLOR_TYPE_RGB) {
            data_format = internal_format = GL_RGB;
            if (rowbytes != w*3) problem = true;
        } else if (png_get_color_type(png, info) == PNG_COLOR_TYPE_RGB_ALPHA) {
            data_format = internal_format = GL_RGBA;
            if (rowbytes != w*4) problem = true;
        } else {
            cerr << "  unknown color format." << endl;
            problem = true;
        }
        if (problem) {
            cerr << "  color format problem. (rowbytes: " << rowbytes << " w:" << w << ")" << endl;
            png_destroy_read_struct(&png, &info, NULL);
            fclose(fp);
            return;
        }

        unsigned int pixelbytes = rowbytes / w;
        assert(rowbytes == pixelbytes * w); //sanity check, should have bailed earlier if this was the case.
        data = new uint8_t[th*tw*pixelbytes];
        row_pointers = new png_bytep[th];
        if (flip) {
            //texture origin goes top-left, as in most images:
            for (unsigned int r = 0; r < th; ++r) {
                row_pointers[r] = (png_bytep)(data + r*pixelbytes*tw);
            }
        } else {
            //texture origin goes bottom-left, as GL says:
            for (unsigned int r = 0; r < th; ++r) {
                row_pointers[th-1-r] = (png_bytep)(data + r*tw*pixelbytes);
            }
        }
        png_read_image(png, row_pointers);
//.........这里部分代码省略.........

int read_png_file(const char *file, int32 *pwidth, int32 *pheight, uint8 **image_data_ptr)
{
	FILE         *infile;         /* PNG file pointer */
	png_structp   png_ptr;        /* internally used by libpng */
	png_infop     info_ptr;       /* user requested transforms */
	
	uint8 *image_data;      /* raw png image data */
	char         sig[8];           /* PNG signature array */
	/*char         **row_pointers;   */
	
	int           bit_depth;
	int           color_type;
	
	png_uint_32 width;            /* PNG image width in pixels */
	png_uint_32 height;           /* PNG image height in pixels */
	unsigned int rowbytes;         /* raw bytes at row n in image */
	
	image_data = NULL;
	int i;
	png_bytepp row_pointers = NULL;
	
	/* Open the file. */
	infile = fopen(file, "rb");
	if (!infile) {
		
		return 0;
	}
	
	
	/*
	 * 		13.3 readpng_init()
	 */
	
	/* Check for the 8-byte signature */
	fread(sig, 1, 8, infile);
	
	if (png_sig_cmp((unsigned char *) sig, 0, 8) != 0) {
		fclose(infile);
		return 0;
	}
	
	/* 
	 * Set up the PNG structs 
	 */
	png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
	if (!png_ptr) {
		fclose(infile);
		return 4;    /* out of memory */
	}
	
	info_ptr = png_create_info_struct(png_ptr);
	if (!info_ptr) {
		png_destroy_read_struct(&png_ptr, (png_infopp) NULL, (png_infopp) NULL);
		fclose(infile);
		return 4;    /* out of memory */
	}
	
	
	/*
	 * block to handle libpng errors, 
	 * then check whether the PNG file had a bKGD chunk
	 */
	if (setjmp(png_jmpbuf(png_ptr))) {
		png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
		fclose(infile);
		return 0;
	}
	
	/* 
	 * takes our file stream pointer (infile) and 
	 * stores it in the png_ptr struct for later use.
	 */
	/* png_ptr->io_ptr = (png_voidp)infile;*/
	png_init_io(png_ptr, infile);
	
	/*
	 * lets libpng know that we already checked the 8 
	 * signature bytes, so it should not expect to find 
	 * them at the current file pointer location
	 */
	png_set_sig_bytes(png_ptr, 8);
	
	/* Read the image info.*/
	
	/*
	 * reads and processes not only the PNG file's IHDR chunk 
	 * but also any other chunks up to the first IDAT 
	 * (i.e., everything before the image data).
	 */
	
	/* read all the info up to the image data  */
	png_read_info(png_ptr, info_ptr);
	
	png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, 
				 &color_type, NULL, NULL, NULL);
	
	*pwidth = width;
	*pheight = height;

	if (bit_depth > 8) {
//.........这里部分代码省略.........

static int save_png_to_file (bitmap_t *bitmap, const char *path)
{
    FILE * fp;
    png_structp png_ptr = NULL;
    png_infop info_ptr = NULL;
    size_t x, y;
    png_byte ** row_pointers = NULL;
    /* "status" contains the return value of this function. At first
       it is set to a value which means 'failure'. When the routine
       has finished its work, it is set to a value which means
       'success'. */
    int status = -1;
    /* The following number is set by trial and error only. I cannot
       see where it it is documented in the libpng manual.
    */
    int pixel_size = 3;
    int depth = 8;

    fp = fopen (path, "wb");
    if (! fp) {
        goto fopen_failed;
    }

    png_ptr = png_create_write_struct (PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
    if (png_ptr == NULL) {
        goto png_create_write_struct_failed;
    }

    info_ptr = png_create_info_struct (png_ptr);
    if (info_ptr == NULL) {
        goto png_create_info_struct_failed;
    }

    /* Set up error handling. */

    if (setjmp (png_jmpbuf (png_ptr))) {
        goto png_failure;
    }

    /* Set image attributes. */

    png_set_IHDR (png_ptr,
                  info_ptr,
                  bitmap->width,
                  bitmap->height,
                  depth,
                  PNG_COLOR_TYPE_RGB,
                  PNG_INTERLACE_NONE,
                  PNG_COMPRESSION_TYPE_DEFAULT,
                  PNG_FILTER_TYPE_DEFAULT);

    /* Initialize rows of PNG. */

    row_pointers = png_malloc (png_ptr, bitmap->height * sizeof (png_byte *));
    for (y = 0; y < bitmap->height; ++y) {
        png_byte *row =
            png_malloc (png_ptr, sizeof (uint8_t) * bitmap->width * pixel_size);
        row_pointers[y] = row;
        for (x = 0; x < bitmap->width; ++x) {
            pixel_t * pixel = pixel_at (bitmap, x, y);
            *row++ = pixel->red;
            *row++ = pixel->green;
            *row++ = pixel->blue;
        }
    }

    /* Write the image data to "fp". */

    png_init_io (png_ptr, fp);
    png_set_rows (png_ptr, info_ptr, row_pointers);
    png_write_png (png_ptr, info_ptr, PNG_TRANSFORM_IDENTITY, NULL);

    /* The routine has successfully written the file, so we set
       "status" to a value which indicates success. */

    status = 0;

    for (y = 0; y < bitmap->height; y++) {
        png_free (png_ptr, row_pointers[y]);
    }
    png_free (png_ptr, row_pointers);

png_failure:
png_create_info_struct_failed:
    png_destroy_write_struct (&png_ptr, &info_ptr);
png_create_write_struct_failed:
    fclose (fp);
fopen_failed:
    return status;
}

static GstFlowReturn
gst_pngenc_handle_frame (GstVideoEncoder * encoder, GstVideoCodecFrame * frame)
{
  GstPngEnc *pngenc;
  gint row_index;
  png_byte **row_pointers;
  GstFlowReturn ret = GST_FLOW_OK;
  GstVideoInfo *info;
  GstVideoFrame vframe;

  pngenc = GST_PNGENC (encoder);
  info = &pngenc->input_state->info;

  GST_DEBUG_OBJECT (pngenc, "BEGINNING");

  /* initialize png struct stuff */
  pngenc->png_struct_ptr = png_create_write_struct (PNG_LIBPNG_VER_STRING,
      (png_voidp) NULL, user_error_fn, user_warning_fn);
  if (pngenc->png_struct_ptr == NULL)
    goto struct_init_fail;

  pngenc->png_info_ptr = png_create_info_struct (pngenc->png_struct_ptr);
  if (!pngenc->png_info_ptr)
    goto png_info_fail;

  /* non-0 return is from a longjmp inside of libpng */
  if (setjmp (png_jmpbuf (pngenc->png_struct_ptr)) != 0)
    goto longjmp_fail;

  png_set_filter (pngenc->png_struct_ptr, 0,
      PNG_FILTER_NONE | PNG_FILTER_VALUE_NONE);
  png_set_compression_level (pngenc->png_struct_ptr, pngenc->compression_level);

  png_set_IHDR (pngenc->png_struct_ptr,
      pngenc->png_info_ptr,
      GST_VIDEO_INFO_WIDTH (info),
      GST_VIDEO_INFO_HEIGHT (info),
      pngenc->depth,
      pngenc->png_color_type,
      PNG_INTERLACE_NONE,
      PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);

  png_set_write_fn (pngenc->png_struct_ptr, pngenc,
      (png_rw_ptr) user_write_data, user_flush_data);

  row_pointers = g_new (png_byte *, GST_VIDEO_INFO_HEIGHT (info));
  if (!gst_video_frame_map (&vframe, &pngenc->input_state->info,
          frame->input_buffer, GST_MAP_READ)) {
    GST_ELEMENT_ERROR (pngenc, STREAM, FORMAT, (NULL),
        ("Failed to map video frame, caps problem?"));
    ret = GST_FLOW_ERROR;
    goto done;
  }

  for (row_index = 0; row_index < GST_VIDEO_INFO_HEIGHT (info); row_index++) {
    row_pointers[row_index] = GST_VIDEO_FRAME_COMP_DATA (&vframe, 0) +
        (row_index * GST_VIDEO_FRAME_COMP_STRIDE (&vframe, 0));
  }

  /* allocate the output buffer */
  pngenc->buffer_out = gst_buffer_new ();

  png_write_info (pngenc->png_struct_ptr, pngenc->png_info_ptr);
  png_write_image (pngenc->png_struct_ptr, row_pointers);
  png_write_end (pngenc->png_struct_ptr, NULL);

  g_free (row_pointers);
  gst_video_frame_unmap (&vframe);

  png_destroy_info_struct (pngenc->png_struct_ptr, &pngenc->png_info_ptr);
  png_destroy_write_struct (&pngenc->png_struct_ptr, (png_infopp) NULL);

  /* Set final size and store */
  frame->output_buffer = pngenc->buffer_out;

  pngenc->buffer_out = NULL;

  if ((ret = gst_video_encoder_finish_frame (encoder, frame)) != GST_FLOW_OK)
    goto done;

  if (pngenc->snapshot)
    ret = GST_FLOW_EOS;

done:
  GST_DEBUG_OBJECT (pngenc, "END, ret:%d", ret);

  return ret;

  /* ERRORS */
struct_init_fail:
  {
    GST_ELEMENT_ERROR (pngenc, LIBRARY, INIT, (NULL),
        ("Failed to initialize png structure"));
    return GST_FLOW_ERROR;
  }

png_info_fail:
  {
    png_destroy_write_struct (&(pngenc->png_struct_ptr), (png_infopp) NULL);
    GST_ELEMENT_ERROR (pngenc, LIBRARY, INIT, (NULL),
//.........这里部分代码省略.........

void _mapcache_imageio_png_decode_to_image(mapcache_context *ctx, mapcache_buffer *buffer,
      mapcache_image *img) {
   int bit_depth,color_type,i;
   unsigned char **row_pointers;
   png_structp png_ptr = NULL;
   png_infop info_ptr = NULL;
   _mapcache_buffer_closure b;
   b.buffer = buffer;
   b.ptr = buffer->buf;
   png_uint_32 width, height;


   /* could pass pointers to user-defined error handlers instead of NULLs: */
   png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
   if (!png_ptr) {
      ctx->set_error(ctx, 500, "failed to allocate png_struct structure");
      return;
   }

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

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

   png_read_info(png_ptr,info_ptr);
   if(!png_get_IHDR(png_ptr, info_ptr, &width, &height,&bit_depth, &color_type,NULL,NULL,NULL)) {
      ctx->set_error(ctx, 500, "failed to read png header");
      return;
   }

   img->w = width;
   img->h = height;
   if(!img->data) {
      img->data = calloc(1,img->w*img->h*4*sizeof(unsigned char));
      apr_pool_cleanup_register(ctx->pool, img->data, (void*)free, apr_pool_cleanup_null) ;
      img->stride = img->w * 4;
   }
   row_pointers = apr_pcalloc(ctx->pool,img->h * sizeof(unsigned char*));

   unsigned char *rowptr = img->data;
   for(i=0;i<img->h;i++) {
      row_pointers[i] = rowptr;
      rowptr += img->stride;
   }


   png_set_expand(png_ptr);
   png_set_strip_16(png_ptr);
   png_set_gray_to_rgb(png_ptr);
   png_set_add_alpha(png_ptr, 0xff, PNG_FILLER_AFTER);
   
   png_read_update_info(png_ptr, info_ptr);

   png_read_image(png_ptr, row_pointers);
   
   png_read_end(png_ptr,NULL);
   png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
}

pointer PNG_READ_IMAGE(register context *ctx, int n, register pointer *argv)
{
  char *file_name;
  pointer ret, image_ptr;
  ckarg(1);
  if (isstring(argv[0])) file_name = argv[0]->c.str.chars;
  else error(E_NOSTRING);

  FILE *fp = fopen(file_name, "rb");
  if (!fp) {
    error(E_OPENFILE);
    return(NIL);
  }

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

  if (setjmp(png_jmpbuf(png_ptr))) {
    png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
    fclose(fp);
    error(E_EOF);
    return(NIL);
  }

  png_init_io(png_ptr, fp);
  png_read_info(png_ptr, info_ptr);
  int width = png_get_image_width(png_ptr, info_ptr);
  int height = png_get_image_height(png_ptr, info_ptr);
  int bit_depth = png_get_bit_depth(png_ptr, info_ptr);
  int channels = png_get_channels(png_ptr, info_ptr);
  int color_type = png_get_color_type(png_ptr, info_ptr);
  //fprintf(stderr, "bit_depth = %d, channels %d, color_type =%d (pal:%d,gray:%d,rgb:%d,rgba:%d)\n", bit_depth, channels, color_type, PNG_COLOR_TYPE_PALETTE,PNG_COLOR_TYPE_GRAY,PNG_COLOR_TYPE_RGB,PNG_COLOR_TYPE_RGB_ALPHA);
  switch (color_type) {
  case PNG_COLOR_TYPE_PALETTE:
    png_set_palette_to_rgb(png_ptr);
    break;
  case PNG_COLOR_TYPE_GRAY:
    #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
    if ( bit_depth < 8) png_set_gray_to_rgb(png_ptr);
    #else
    if ( bit_depth < 8) png_set_gray_1_2_4_to_8(png_ptr);
    #endif
    break;
  case PNG_COLOR_TYPE_RGB:
    //png_set_bgr(png_ptr);
    if (bit_depth == 16) png_set_strip_16(png_ptr); // 16bit -> 8bit
    break;
  case PNG_COLOR_TYPE_RGB_ALPHA:
    if (bit_depth == 16) png_set_strip_16(png_ptr); // 16bit -> 8bit
    png_set_invert_alpha(png_ptr);
    //png_set_bgr(png_ptr);
    //png_set_strip_alpha(png_ptr);
    // RGBA -> rgb , GA -> g
    png_color_16 my_background = {0xff, 0xff, 0xff, 0xff, 0xff};
    png_set_background(png_ptr, &my_background,
                       PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0);

    break;
  }
  png_read_update_info(png_ptr, info_ptr);
  width = png_get_image_width(png_ptr, info_ptr); height = png_get_image_height(png_ptr, info_ptr);;
  bit_depth = png_get_bit_depth(png_ptr, info_ptr); channels = png_get_channels(png_ptr, info_ptr);
  color_type = png_get_color_type(png_ptr, info_ptr);

  png_bytep * row_pointers = (png_bytep *)malloc(height*sizeof(png_bytep));
  int y, byte_per_scanline = png_get_rowbytes(png_ptr, info_ptr);
  image_ptr = makebuffer(height*byte_per_scanline);
  for(y=0;y<height;y++){
    row_pointers[y] = image_ptr->c.str.chars+y*byte_per_scanline;
  }
  png_read_image(png_ptr, row_pointers);
  free(row_pointers);
  png_read_end(png_ptr,info_ptr);
  png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
  fclose(fp);

  ret=cons(ctx,image_ptr,NIL);
  ret=cons(ctx,makeint(channels),ret);
  ret=cons(ctx,makeint(height),ret);
  ret=cons(ctx,makeint(width),ret);
  return (ret);
}

static int qrwrap_writePNG(const char *outfile, QRcode *qrcode)
{
	static FILE *fp;
	png_structp png_ptr;
	png_infop info_ptr;
	unsigned char *row, *p, *q;
	int x, y, xx, yy, bit;
	int realwidth;
	const int margin = 0;
	const int size = 8;
	const int width = qrcode->width;

	realwidth = (width + margin * 2) * size;
	row = (unsigned char *)vj_malloc((realwidth + 7) / 8);
	if(row == NULL) {
		return 0;
	}

	fp = fopen(outfile, "wb");
	if(fp == NULL) {
		veejay_msg(VEEJAY_MSG_ERROR, "Unable to write QR code to file:%s", outfile);
		return 0;
	}
	

	png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
	if(png_ptr == NULL) {
		fclose(fp);
		return 0;
	}

	info_ptr = png_create_info_struct(png_ptr);
	if(info_ptr == NULL) {
		fclose(fp);
		return 0;
	}

	if(setjmp(png_jmpbuf(png_ptr))) {
		png_destroy_write_struct(&png_ptr, &info_ptr);
		fclose(fp);
		return 0;
	}

	png_init_io(png_ptr, fp);
	png_set_IHDR(png_ptr, info_ptr,
			realwidth, realwidth,
			1,
			PNG_COLOR_TYPE_GRAY,
			PNG_INTERLACE_NONE,
			PNG_COMPRESSION_TYPE_DEFAULT,
			PNG_FILTER_TYPE_DEFAULT);
	png_write_info(png_ptr, info_ptr);

	/* top margin */
	veejay_memset(row, 0xff, (realwidth + 7) / 8);
	for(y=0; y<margin * size; y++) {
		png_write_row(png_ptr, row);
	}

	/* data */
	p = qrcode->data;
	for(y=0; y<width; y++) {
		bit = 7;
		veejay_memset(row, 0xff, (realwidth + 7) / 8);
		q = row;
		q += margin * size / 8;
		bit = 7 - (margin * size % 8);
		for(x=0; x<width; x++) {
			for(xx=0; xx<size; xx++) {
				*q ^= (*p & 1) << bit;
				bit--;
				if(bit < 0) {
					q++;
					bit = 7;
				}
			}
			p++;
		}
		for(yy=0; yy<size; yy++) {
			png_write_row(png_ptr, row);
		}
	}
	/* bottom margin */
	veejay_memset(row, 0xff, (realwidth + 7) / 8);
	for(y=0; y<margin * size; y++) {
		png_write_row(png_ptr, row);
	}

	png_write_end(png_ptr, info_ptr);
	png_destroy_write_struct(&png_ptr, &info_ptr);

	fclose(fp);
	free(row);

	return 0;
}

bool8 S9xDoScreenshot (int width, int height)
{
	Settings.TakeScreenshot = FALSE;

#ifdef HAVE_LIBPNG
	FILE		*fp;
	png_structp	png_ptr;
	png_infop	info_ptr;
	png_color_8	sig_bit;
	int			imgwidth, imgheight;
	const char	*fname;

	fname = S9xGetFilenameInc(".png", SCREENSHOT_DIR);

	fp = fopen(fname, "wb");
	if (!fp)
	{
		S9xMessage(S9X_ERROR, 0, "Failed to take screenshot.");
		return (FALSE);
	}

	png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
	if (!png_ptr)
	{
		fclose(fp);
		remove(fname);
		S9xMessage(S9X_ERROR, 0, "Failed to take screenshot.");
		return (FALSE);
	}

	info_ptr = png_create_info_struct(png_ptr);
	if (!info_ptr)
	{
		png_destroy_write_struct(&png_ptr, (png_infopp) NULL);
		fclose(fp);
		remove(fname);
		S9xMessage(S9X_ERROR, 0, "Failed to take screenshot.");
		return (FALSE);
	}

	if (setjmp(png_jmpbuf(png_ptr)))
	{
		png_destroy_write_struct(&png_ptr, &info_ptr);
		fclose(fp);
		remove(fname);
		S9xMessage(S9X_ERROR, 0, "Failed to take screenshot.");
		return (FALSE);
	}

	imgwidth  = width;
	imgheight = height;

	if (Settings.StretchScreenshots == 1)
	{
		if (width > SNES_WIDTH && height <= SNES_HEIGHT_EXTENDED)
			imgheight = height << 1;
	}
	else
	if (Settings.StretchScreenshots == 2)
	{
		if (width  <= SNES_WIDTH)
			imgwidth  = width  << 1;
		if (height <= SNES_HEIGHT_EXTENDED)
			imgheight = height << 1;
	}

	png_init_io(png_ptr, fp);

	png_set_IHDR(png_ptr, info_ptr, imgwidth, imgheight, 8, PNG_COLOR_TYPE_RGB, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);

	sig_bit.red   = 5;
	sig_bit.green = 5;
	sig_bit.blue  = 5;
	png_set_sBIT(png_ptr, info_ptr, &sig_bit);
	png_set_shift(png_ptr, &sig_bit);

	png_write_info(png_ptr, info_ptr);

	png_set_packing(png_ptr);

	png_byte	*row_pointer = new png_byte[png_get_rowbytes(png_ptr, info_ptr)];
	uint16		*screen = GFX.Screen;

	for (int y = 0; y < height; y++, screen += GFX.RealPPL)
	{
		png_byte	*rowpix = row_pointer;

		for (int x = 0; x < width; x++)
		{
			uint32	r, g, b;

			DECOMPOSE_PIXEL(screen[x], r, g, b);

			*(rowpix++) = r;
			*(rowpix++) = g;
			*(rowpix++) = b;

			if (imgwidth != width)
			{
				*(rowpix++) = r;
//.........这里部分代码省略.........

// Loads a PNG image
//
// filename - name of the targa file to load
// image_data - allocated storage for the bitmap
//
// returns - true if succesful, false otherwise
//
int png_read_bitmap(char *real_filename, ubyte *image_data, ubyte *bpp, int dest_size, int cf_type)
{
	char filename[MAX_FILENAME_LEN];
	png_infop info_ptr;
	png_structp png_ptr;
	png_bytepp row_pointers;
	unsigned int i, len;

	png_file = NULL;

	strcpy_s( filename, real_filename );
	char *p = strchr( filename, '.' );
	if ( p ) *p = 0;
	strcat_s( filename, ".png" );

	png_file = cfopen(filename, "rb", CFILE_NORMAL, cf_type);

	if (png_file == NULL)
		return PNG_ERROR_READING;

	/* 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)
	{
		mprintf(("png_read_bitmap: png_ptr went wrong\n"));
		cfclose(png_file);
		return PNG_ERROR_READING;
	}

	/* Allocate/initialize the memory for image information.  REQUIRED. */
	info_ptr = png_create_info_struct(png_ptr);
	if (info_ptr == NULL)
	{
		mprintf(("png_read_bitmap: info_ptr went wrong\n"));
		cfclose(png_file);
		png_destroy_read_struct(&png_ptr, NULL, NULL);
		return PNG_ERROR_READING;
	}

	if (setjmp(png_jmpbuf(png_ptr)))
	{
		mprintf(("png_read_bitmap: something went wrong\n"));
		/* Free all of the memory associated with the png_ptr and info_ptr */
		png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
		cfclose(png_file);
		/* If we get here, we had a problem reading the file */
		return PNG_ERROR_READING;
	}

	png_set_read_fn(png_ptr, &png_file, png_scp_read_data);

	png_read_png(png_ptr, info_ptr, PNG_TRANSFORM_BGR | PNG_TRANSFORM_EXPAND | PNG_TRANSFORM_STRIP_16, NULL);
	len = png_get_rowbytes(png_ptr, info_ptr);

	row_pointers = png_get_rows(png_ptr, info_ptr);

	if(bpp)
		*bpp = (ubyte)(len / png_get_image_width(png_ptr, info_ptr)) << 3;

	//copy row data to image
	unsigned int height = png_get_image_height(png_ptr, info_ptr);
	for (i = 0; i < height; i++) {
		memcpy(&image_data[i * len], row_pointers[i], len);
	}

	png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
	cfclose(png_file);

	return PNG_ERROR_NONE;
}

bool IGN_Create_PNG_JPR(LPCSTR mapname, long minx, long miny, long maxx, long maxy)
{
char tstring[256];
long bitmap_width = TILE_WIDTH*(maxx-minx)/1000;
long bitmap_size = bitmap_width*TILE_WIDTH;
unsigned char * bitmap_memory = (unsigned char *)malloc(bitmap_size);
CIGNTileDatabase	db;


	if (bitmap_memory == NULL) {
		printf("Couldn't allocate %d bytes of memory\n");
		return false;
	}


	// Create PNG header and write out palette
	sprintf(tstring, "%s.png", mapname);
	FILE * fp_png = fopen(tstring, "wb");
	if (fp_png == NULL) {
		printf("Couldn't open %s\n", tstring);
		return false;
	}
	
	// Create and initialize the png_struct with the desired error handler functions.
	png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
	if (png_ptr == NULL) {
		fclose(fp_png);
		return false;
	}
	
	/* Allocate/initialize the image information data.  REQUIRED */
	png_infop info_ptr = png_create_info_struct(png_ptr);
	if (info_ptr == NULL) {
		png_destroy_write_struct(&png_ptr, (png_infopp)NULL);
		fclose(fp_png);
		return false;
	}
	
	/* Set error handling.  REQUIRED */
	if (setjmp(png_jmpbuf(png_ptr))) {
		/* If we get here, we had a problem reading the file */
		png_destroy_write_struct(&png_ptr, &info_ptr);
		fclose(fp_png);
		return false;
	}

	/* set up the output control if you are using standard C streams */
	png_init_io(png_ptr, fp_png);
	
	/* Set the image information here.  Width and height are up to 2^31,
	 * bit_depth is one of 1, 2, 4, 8, or 16, but valid values also depend on
	 * the color_type selected. color_type is one of PNG_COLOR_TYPE_GRAY,
	 * PNG_COLOR_TYPE_GRAY_ALPHA, PNG_COLOR_TYPE_PALETTE, PNG_COLOR_TYPE_RGB,
	 * or PNG_COLOR_TYPE_RGB_ALPHA.  interlace is either PNG_INTERLACE_NONE or
	 * PNG_INTERLACE_ADAM7, and the compression_type and filter_type MUST
	 * currently be PNG_COMPRESSION_TYPE_BASE and PNG_FILTER_TYPE_BASE. REQUIRED
	 */
	png_set_IHDR(png_ptr, info_ptr, TILE_WIDTH*(maxx-minx)/1000, TILE_WIDTH*((maxy-miny)/1000), 8, PNG_COLOR_TYPE_PALETTE,
				PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);

	/* set the palette if there is one.  REQUIRED for indexed-color images */
	png_colorp png_palette = (png_colorp)png_malloc(png_ptr, PNG_MAX_PALETTE_LENGTH * sizeof (png_color));


	int i;
	BYTE * pal_ptr = (BYTE *)png_palette;
	BYTE * palette = ign_palette;
	for (i=0; i<256; i++) {
		*pal_ptr++ = palette[i*4 + 2];
		*pal_ptr++ = palette[i*4 + 1];
		*pal_ptr++ = palette[i*4 + 0];
	}

	/* ... set palette colors ... */
	png_set_PLTE(png_ptr, info_ptr, png_palette, PNG_MAX_PALETTE_LENGTH);
	/* You must not free palette here, because png_set_PLTE only makes a link to
	 * the palette that you malloced.  Wait until you are about to destroy
	 *the png structure. */
	
	/* Write the file header information.  REQUIRED */
	png_write_info(png_ptr, info_ptr);

CProgressWindow wndProgress;
wndProgress.Initialize();

wndProgress.ResetProgressBar("Tile:", (maxy-miny)/500*(maxx-minx)/500);


	for (int y=maxy-1000; y>=miny; y-=1000) {
		memset(bitmap_memory, 0x00, bitmap_size);
		for (int x=minx; x<maxx; x+=1000) {
			IGN_read_bmp(y, x, &db, bitmap_memory+(x-minx)/1000*TILE_WIDTH, bitmap_width);
		}


		// write row of PNG to file
		for (int x=0; x<TILE_WIDTH; x++) {
			png_write_row(png_ptr, bitmap_memory + x*bitmap_width);

			if (!wndProgress.ProgressBar()) return false;
//.........这里部分代码省略.........