X-Git-Url: https://git.creatis.insa-lyon.fr/pubgit/?a=blobdiff_plain;f=utilities%2FCxImage%2Fximapng.cpp;h=96b92573c701a0a9dc0ae32fec69ae6326cb80f4;hb=a1ec529a24b721fcfb2c5725f95bcc2c9125b28d;hp=f91bf27c7e34891992f1faa578e401c66f279a70;hpb=3fd15028ab81e6746d3af96695526d7d973a26c8;p=clitk.git

diff --git a/utilities/CxImage/ximapng.cpp b/utilities/CxImage/ximapng.cpp
index f91bf27..96b9257 100644
--- a/utilities/CxImage/ximapng.cpp
+++ b/utilities/CxImage/ximapng.cpp
@@ -1,536 +1,536 @@
-/*
- * File:	ximapng.cpp
- * Purpose:	Platform Independent PNG Image Class Loader and Writer
- * 07/Aug/2001 Davide Pizzolato - www.xdp.it
- * CxImage version 6.0.0 02/Feb/2008
- */
-
-#include "ximapng.h"
-
-#if CXIMAGE_SUPPORT_PNG
-
-#include "ximaiter.h"
-
-////////////////////////////////////////////////////////////////////////////////
-void CxImagePNG::ima_png_error(png_struct *png_ptr, char *message)
-{
-	strcpy(info.szLastError,message);
-	longjmp(png_ptr->jmpbuf, 1);
-}
-////////////////////////////////////////////////////////////////////////////////
-#if CXIMAGE_SUPPORT_DECODE
-////////////////////////////////////////////////////////////////////////////////
-void CxImagePNG::expand2to4bpp(BYTE* prow)
-{
-	BYTE *psrc,*pdst;
-	BYTE pos,idx;
-	for(long x=head.biWidth-1;x>=0;x--){
-		psrc = prow + ((2*x)>>3);
-		pdst = prow + ((4*x)>>3);
-		pos = (BYTE)(2*(3-x%4));
-		idx = (BYTE)((*psrc & (0x03<<pos))>>pos);
-		pos = (BYTE)(4*(1-x%2));
-		*pdst &= ~(0x0F<<pos);
-		*pdst |= (idx & 0x0F)<<pos;
-	}
-}
-////////////////////////////////////////////////////////////////////////////////
-bool CxImagePNG::Decode(CxFile *hFile)
-{
-	png_struct *png_ptr;
-	png_info *info_ptr;
-	BYTE *row_pointers=NULL;
-	CImageIterator iter(this);
-
-  cx_try
-  {
-    /* 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 *)NULL,NULL,NULL);
-	if (png_ptr == NULL)  cx_throw("Failed to create PNG structure");
-
-	/* Allocate/initialize the memory for image information.  REQUIRED. */
-	info_ptr = png_create_info_struct(png_ptr);
-	if (info_ptr == NULL) {
-		png_destroy_read_struct(&png_ptr, (png_infopp)NULL, (png_infopp)NULL);
-		cx_throw("Failed to initialize PNG info structure");
-	}
-
-    /* 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_ptr->jmpbuf)) {
-		/* Free all of the memory associated with the png_ptr and info_ptr */
-		delete [] row_pointers;
-		png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
-		cx_throw("");
-	}
-
-	// use custom I/O functions
-    png_set_read_fn(png_ptr, hFile, /*(png_rw_ptr)*/user_read_data);
-	png_set_error_fn(png_ptr,info.szLastError,/*(png_error_ptr)*/user_error_fn,NULL);
-
-	/* read the file information */
-	png_read_info(png_ptr, info_ptr);
-
-	if (info.nEscape == -1){
-		head.biWidth = info_ptr->width;
-		head.biHeight= info_ptr->height;
-		info.dwType = CXIMAGE_FORMAT_PNG;
-		longjmp(png_ptr->jmpbuf, 1);
-	}
-
-	/* calculate new number of channels */
-	int channels=0;
-	switch(info_ptr->color_type){
-	case PNG_COLOR_TYPE_GRAY:
-	case PNG_COLOR_TYPE_PALETTE:
-		channels = 1;
-		break;
-	case PNG_COLOR_TYPE_GRAY_ALPHA:
-		channels = 2;
-		break;
-	case PNG_COLOR_TYPE_RGB:
-		channels = 3;
-		break;
-	case PNG_COLOR_TYPE_RGB_ALPHA:
-		channels = 4;
-		break;
-	default:
-		strcpy(info.szLastError,"unknown PNG color type");
-		longjmp(png_ptr->jmpbuf, 1);
-	}
-
-	//find the right pixel depth used for cximage
-	int pixel_depth = info_ptr->pixel_depth;
-	if (channels == 1 && pixel_depth>8) pixel_depth=8;
-	if (channels == 2) pixel_depth=8;
-	if (channels >= 3) pixel_depth=24;
-
-	if (!Create(info_ptr->width, info_ptr->height, pixel_depth, CXIMAGE_FORMAT_PNG)){
-		longjmp(png_ptr->jmpbuf, 1);
-	}
-
-	/* get metrics */
-	switch (info_ptr->phys_unit_type)
-	{
-	case PNG_RESOLUTION_UNKNOWN:
-		SetXDPI(info_ptr->x_pixels_per_unit);
-		SetYDPI(info_ptr->y_pixels_per_unit);
-		break;
-	case PNG_RESOLUTION_METER:
-		SetXDPI((long)floor(info_ptr->x_pixels_per_unit * 254.0 / 10000.0 + 0.5));
-		SetYDPI((long)floor(info_ptr->y_pixels_per_unit * 254.0 / 10000.0 + 0.5));
-		break;
-	}
-
-	if (info_ptr->num_palette>0){
-		SetPalette((rgb_color*)info_ptr->palette,info_ptr->num_palette);
-		SetClrImportant(info_ptr->num_palette);
-	} else if (info_ptr->bit_depth ==2) { //<DP> needed for 2 bpp grayscale PNGs
-		SetPaletteColor(0,0,0,0);
-		SetPaletteColor(1,85,85,85);
-		SetPaletteColor(2,170,170,170);
-		SetPaletteColor(3,255,255,255);
-	} else SetGrayPalette(); //<DP> needed for grayscale PNGs
-	
-	int nshift = max(0,(info_ptr->bit_depth>>3)-1)<<3;
-
-	if (info_ptr->num_trans!=0){ //palette transparency
-		if (info_ptr->num_trans==1){
-			if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE){
-				info.nBkgndIndex = info_ptr->trans_values.index;
-			} else{
-				info.nBkgndIndex = info_ptr->trans_values.gray>>nshift;
-			}
-		}
-		if (info_ptr->num_trans>1){
-			RGBQUAD* pal=GetPalette();
-			if (pal){
-				DWORD ip;
-				for (ip=0;ip<min(head.biClrUsed,(unsigned long)info_ptr->num_trans);ip++)
-					pal[ip].rgbReserved=info_ptr->trans[ip];
-				for (ip=info_ptr->num_trans;ip<head.biClrUsed;ip++){
-					pal[ip].rgbReserved=255;
-				}
-				info.bAlphaPaletteEnabled=true;
-			}
-		}
-	}
-
-	if (channels == 3){ //check RGB binary transparency
-		png_bytep trans;
-		int num_trans;
-		png_color_16 *image_background;
-		if (png_get_tRNS(png_ptr, info_ptr, &trans, &num_trans, &image_background)){
-			info.nBkgndColor.rgbRed   = (BYTE)(info_ptr->trans_values.red>>nshift);
-			info.nBkgndColor.rgbGreen = (BYTE)(info_ptr->trans_values.green>>nshift);
-			info.nBkgndColor.rgbBlue  = (BYTE)(info_ptr->trans_values.blue>>nshift);
-			info.nBkgndColor.rgbReserved = 0;
-			info.nBkgndIndex = 0;
-		}
-	}
-
-	int alpha_present = (channels - 1) % 2;
-	if (alpha_present){
-#if CXIMAGE_SUPPORT_ALPHA	// <vho>
-		AlphaCreate();
-#else
-		png_set_strip_alpha(png_ptr);
-#endif //CXIMAGE_SUPPORT_ALPHA
-	}
-
-	// <vho> - flip the RGB pixels to BGR (or RGBA to BGRA)
-	if (info_ptr->color_type & PNG_COLOR_MASK_COLOR){
-		png_set_bgr(png_ptr);
-	}
-
-	// <vho> - handle cancel
-	if (info.nEscape) longjmp(png_ptr->jmpbuf, 1);
-
-	// row_bytes is the width x number of channels x (bit-depth / 8)
-	row_pointers = new BYTE[info_ptr->rowbytes + 8];
-
-	// turn on interlace handling
-	int number_passes = png_set_interlace_handling(png_ptr);
-
-	if (number_passes>1){
-		SetCodecOption(1);
-	} else {
-		SetCodecOption(0);
-	}
-
-	int chan_offset = info_ptr->bit_depth >> 3;
-	int pixel_offset = info_ptr->pixel_depth >> 3;
-
-	for (int pass=0; pass < number_passes; pass++) {
-		iter.Upset();
-		int y=0;
-		do	{
-
-			// <vho> - handle cancel
-			if (info.nEscape) longjmp(png_ptr->jmpbuf, 1);
-
-#if CXIMAGE_SUPPORT_ALPHA	// <vho>
-			if (AlphaIsValid()) {
-
-				//compute the correct position of the line
-				long ax,ay;
-				ay = head.biHeight-1-y;
-				BYTE* prow= iter.GetRow(ay);
-
-				//recover data from previous scan
-				if (info_ptr->interlace_type && pass>0 && pass!=7){
-					for(ax=0;ax<head.biWidth;ax++){
-						long px = ax * pixel_offset;
-						if (channels == 2){
-							row_pointers[px] = prow[ax];
-							row_pointers[px+chan_offset]=AlphaGet(ax,ay);
-						} else {
-							long qx = ax * 3;
-							row_pointers[px]              =prow[qx];
-							row_pointers[px+chan_offset]  =prow[qx+1];
-							row_pointers[px+chan_offset*2]=prow[qx+2];
-							row_pointers[px+chan_offset*3]=AlphaGet(ax,ay);
-						}
-					}
-				}
-
-				//read next row
-				png_read_row(png_ptr, row_pointers, NULL);
-
-				//RGBA -> RGB + A
-				for(ax=0;ax<head.biWidth;ax++){
-					long px = ax * pixel_offset;
-					if (channels == 2){
-						prow[ax] = row_pointers[px];
-						AlphaSet(ax,ay,row_pointers[px+chan_offset]);
-					} else {
-						long qx = ax * 3;
-						prow[qx]  =row_pointers[px];
-						prow[qx+1]=row_pointers[px+chan_offset];
-						prow[qx+2]=row_pointers[px+chan_offset*2];
-						AlphaSet(ax,ay,row_pointers[px+chan_offset*3]);
-					}
-				}
-			} else
-#endif // CXIMAGE_SUPPORT_ALPHA		// vho
-			{
-				//recover data from previous scan
-				if (info_ptr->interlace_type && pass>0){
-					iter.GetRow(row_pointers, info_ptr->rowbytes);
-					//re-expand buffer for images with bit depth > 8
-					if (info_ptr->bit_depth > 8){
-						for(long ax=(head.biWidth*channels-1);ax>=0;ax--)
-							row_pointers[ax*chan_offset] = row_pointers[ax];
-					}
-				}
-
-				//read next row
-				png_read_row(png_ptr, row_pointers, NULL);
-
-				//shrink 16 bit depth images down to 8 bits
-				if (info_ptr->bit_depth > 8){
-					for(long ax=0;ax<(head.biWidth*channels);ax++)
-						row_pointers[ax] = row_pointers[ax*chan_offset];
-				}
-
-				//copy the pixels
-				iter.SetRow(row_pointers, info_ptr->rowbytes);
-				//<DP> expand 2 bpp images only in the last pass
-				if (info_ptr->bit_depth==2 && pass==(number_passes-1))
-					expand2to4bpp(iter.GetRow());
-
-				//go on
-				iter.PrevRow();
-			}
-
-			y++;
-		} while(y<head.biHeight);
-	}
-
-	delete [] row_pointers;
-
-	/* read the rest of the file, getting any additional chunks in info_ptr */
-	png_read_end(png_ptr, info_ptr);
-
-	/* clean up after the read, and free any memory allocated - REQUIRED */
-	png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
-
-  } cx_catch {
-	if (strcmp(message,"")) strncpy(info.szLastError,message,255);
-	if (info.nEscape == -1 && info.dwType == CXIMAGE_FORMAT_PNG) return true;
-	return false;
-  }
-	/* that's it */
-	return true;
-}
-////////////////////////////////////////////////////////////////////////////////
-#endif //CXIMAGE_SUPPORT_DECODE
-////////////////////////////////////////////////////////////////////////////////
-#if CXIMAGE_SUPPORT_ENCODE
-////////////////////////////////////////////////////////////////////////////////
-bool CxImagePNG::Encode(CxFile *hFile)
-{
-	if (EncodeSafeCheck(hFile)) return false;
-
-	CImageIterator iter(this);
-	BYTE trans[256];	//for transparency (don't move)
-	png_struct *png_ptr;
-	png_info *info_ptr;
-
-  cx_try
-  {
-   /* 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 check that
-    * the library version is compatible with the one used at compile time,
-    * in case we are using dynamically linked libraries.  REQUIRED.
-    */
-	png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING,(void *)NULL,NULL,NULL);
-	if (png_ptr == NULL) cx_throw("Failed to create PNG structure");
-
-	/* Allocate/initialize the image information data.  REQUIRED */
-	info_ptr = png_create_info_struct(png_ptr);
-	if (info_ptr == NULL){
-		png_destroy_write_struct(&png_ptr,  (png_infopp)NULL);
-		cx_throw("Failed to initialize PNG info structure");
-	}
-
-   /* Set error handling.  REQUIRED if you aren't supplying your own
-    * error hadnling functions in the png_create_write_struct() call.
-    */
-	if (setjmp(png_ptr->jmpbuf)){
-		/* If we get here, we had a problem reading the file */
-		if (info_ptr->palette) free(info_ptr->palette);
-		png_destroy_write_struct(&png_ptr,  (png_infopp)&info_ptr);
-		cx_throw("Error saving PNG file");
-	}
-            
-	/* set up the output control */
-	//png_init_io(png_ptr, hFile);
-
-	// use custom I/O functions
-    png_set_write_fn(png_ptr,hFile,/*(png_rw_ptr)*/user_write_data,/*(png_flush_ptr)*/user_flush_data);
-
-	/* set the file information here */
-	info_ptr->width = GetWidth();
-	info_ptr->height = GetHeight();
-	info_ptr->pixel_depth = (BYTE)GetBpp();
-	info_ptr->channels = (GetBpp()>8) ? (BYTE)3: (BYTE)1;
-	info_ptr->bit_depth = (BYTE)(GetBpp()/info_ptr->channels);
-	info_ptr->compression_type = info_ptr->filter_type = 0;
-	info_ptr->valid = 0;
-
-	switch(GetCodecOption(CXIMAGE_FORMAT_PNG)){
-	case 1:
-		info_ptr->interlace_type = PNG_INTERLACE_ADAM7;
-		break;
-	default:
-		info_ptr->interlace_type = PNG_INTERLACE_NONE;
-	}
-
-	/* set compression level */
-	//png_set_compression_level(png_ptr, Z_BEST_COMPRESSION);
-
-	bool bGrayScale = IsGrayScale();
-
-	if (GetNumColors()){
-		if (bGrayScale){
-			info_ptr->color_type = PNG_COLOR_TYPE_GRAY;
-		} else {
-			info_ptr->color_type = PNG_COLOR_TYPE_PALETTE;
-		}
-	} else {
-		info_ptr->color_type = PNG_COLOR_TYPE_RGB;
-	}
-#if CXIMAGE_SUPPORT_ALPHA
-	if (AlphaIsValid()){
-		info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
-		info_ptr->channels++;
-		info_ptr->bit_depth = 8;
-		info_ptr->pixel_depth += 8;
-	}
-#endif
-
-	/* set background */
-	png_color_16 image_background={ 0, 255, 255, 255, 0 };
-	RGBQUAD tc = GetTransColor();
-	if (info.nBkgndIndex>=0) {
-		image_background.blue  = tc.rgbBlue;
-		image_background.green = tc.rgbGreen;
-		image_background.red   = tc.rgbRed;
-	}
-	png_set_bKGD(png_ptr, info_ptr, &image_background);
-
-	/* set metrics */
-	png_set_pHYs(png_ptr, info_ptr, head.biXPelsPerMeter, head.biYPelsPerMeter, PNG_RESOLUTION_METER);
-
-	png_set_IHDR(png_ptr, info_ptr, info_ptr->width, info_ptr->height, info_ptr->bit_depth,
-				info_ptr->color_type, info_ptr->interlace_type,
-				PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
-
-	//<DP> simple transparency
-	if (info.nBkgndIndex >= 0){
-		info_ptr->num_trans = 1;
-		info_ptr->valid |= PNG_INFO_tRNS;
-		info_ptr->trans = trans;
-		info_ptr->trans_values.index = (BYTE)info.nBkgndIndex;
-		info_ptr->trans_values.red   = tc.rgbRed;
-		info_ptr->trans_values.green = tc.rgbGreen;
-		info_ptr->trans_values.blue  = tc.rgbBlue;
-		info_ptr->trans_values.gray  = info_ptr->trans_values.index;
-
-		// the transparency indexes start from 0 for non grayscale palette
-		if (!bGrayScale && head.biClrUsed && info.nBkgndIndex)
-			SwapIndex(0,(BYTE)info.nBkgndIndex);
-	}
-
-	/* set the palette if there is one */
-	if (GetPalette()){
-		if (!bGrayScale){
-			info_ptr->valid |= PNG_INFO_PLTE;
-		}
-
-		int nc = GetClrImportant();
-		if (nc==0) nc = GetNumColors();
-
-		if (info.bAlphaPaletteEnabled){
-			for(WORD ip=0; ip<nc;ip++)
-				trans[ip]=GetPaletteColor((BYTE)ip).rgbReserved;
-			info_ptr->num_trans = (WORD)nc;
-			info_ptr->valid |= PNG_INFO_tRNS;
-			info_ptr->trans = trans;
-		}
-
-		// copy the palette colors
-		info_ptr->palette = new png_color[nc];
-		info_ptr->num_palette = (png_uint_16) nc;
-		for (int i=0; i<nc; i++)
-			GetPaletteColor(i, &info_ptr->palette[i].red, &info_ptr->palette[i].green, &info_ptr->palette[i].blue);
-	}  
-
-#if CXIMAGE_SUPPORT_ALPHA	// <vho>
-	//Merge the transparent color with the alpha channel
-	if (AlphaIsValid() && head.biBitCount==24 && info.nBkgndIndex>=0){
-		for(long y=0; y < head.biHeight; y++){
-			for(long x=0; x < head.biWidth ; x++){
-				RGBQUAD c=GetPixelColor(x,y,false);
-				if (*(long*)&c==*(long*)&tc)
-					AlphaSet(x,y,0);
-	}	}	}
-#endif // CXIMAGE_SUPPORT_ALPHA	// <vho>
-
-	int row_size = max(info.dwEffWidth, info_ptr->width*info_ptr->channels*(info_ptr->bit_depth/8));
-	info_ptr->rowbytes = row_size;
-	BYTE *row_pointers = new BYTE[row_size];
-
-	/* write the file information */
-	png_write_info(png_ptr, info_ptr);
-
-	//interlace handling
-	int num_pass = png_set_interlace_handling(png_ptr);
-	for (int pass = 0; pass < num_pass; pass++){
-		//write image
-		iter.Upset();
-		long ay=head.biHeight-1;
-		RGBQUAD c;
-		do	{
-#if CXIMAGE_SUPPORT_ALPHA	// <vho>
-			if (AlphaIsValid()){
-				for (long ax=head.biWidth-1; ax>=0;ax--){
-					c = BlindGetPixelColor(ax,ay);
-					int px = ax * info_ptr->channels;
-					if (!bGrayScale){
-						row_pointers[px++]=c.rgbRed;
-						row_pointers[px++]=c.rgbGreen;
-					}
-					row_pointers[px++]=c.rgbBlue;
-					row_pointers[px] = AlphaGet(ax,ay);
-				}
-				png_write_row(png_ptr, row_pointers);
-				ay--;
-			}
-			else
-#endif //CXIMAGE_SUPPORT_ALPHA	// <vho>
-			{
-				iter.GetRow(row_pointers, row_size);
-				if (info_ptr->color_type == PNG_COLOR_TYPE_RGB) //HACK BY OP
-					RGBtoBGR(row_pointers, row_size);
-				png_write_row(png_ptr, row_pointers);
-			}
-		} while(iter.PrevRow());
-	}
-
-	delete [] row_pointers;
-
-	//if necessary, restore the original palette
-	if (!bGrayScale && head.biClrUsed && info.nBkgndIndex>0)
-		SwapIndex((BYTE)info.nBkgndIndex,0);
-
-	/* It is REQUIRED to call this to finish writing the rest of the file */
-	png_write_end(png_ptr, info_ptr);
-
-	/* if you malloced the palette, free it here */
-	if (info_ptr->palette){
-		delete [] (info_ptr->palette);
-		info_ptr->palette = NULL;
-	}
-
-	/* clean up after the write, and free any memory allocated */
-	png_destroy_write_struct(&png_ptr, (png_infopp)&info_ptr);
-
-  } cx_catch {
-	if (strcmp(message,"")) strncpy(info.szLastError,message,255);
-	return FALSE;
-  }
-	/* that's it */
-	return TRUE;
-}
-////////////////////////////////////////////////////////////////////////////////
-#endif // CXIMAGE_SUPPORT_ENCODE
-////////////////////////////////////////////////////////////////////////////////
-#endif // CXIMAGE_SUPPORT_PNG
+/*
+ * File:	ximapng.cpp
+ * Purpose:	Platform Independent PNG Image Class Loader and Writer
+ * 07/Aug/2001 Davide Pizzolato - www.xdp.it
+ * CxImage version 6.0.0 02/Feb/2008
+ */
+
+#include "ximapng.h"
+
+#if CXIMAGE_SUPPORT_PNG
+
+#include "ximaiter.h"
+
+////////////////////////////////////////////////////////////////////////////////
+void CxImagePNG::ima_png_error(png_struct *png_ptr, char *message)
+{
+	strcpy(info.szLastError,message);
+	longjmp(png_ptr->jmpbuf, 1);
+}
+////////////////////////////////////////////////////////////////////////////////
+#if CXIMAGE_SUPPORT_DECODE
+////////////////////////////////////////////////////////////////////////////////
+void CxImagePNG::expand2to4bpp(BYTE* prow)
+{
+	BYTE *psrc,*pdst;
+	BYTE pos,idx;
+	for(long x=head.biWidth-1;x>=0;x--){
+		psrc = prow + ((2*x)>>3);
+		pdst = prow + ((4*x)>>3);
+		pos = (BYTE)(2*(3-x%4));
+		idx = (BYTE)((*psrc & (0x03<<pos))>>pos);
+		pos = (BYTE)(4*(1-x%2));
+		*pdst &= ~(0x0F<<pos);
+		*pdst |= (idx & 0x0F)<<pos;
+	}
+}
+////////////////////////////////////////////////////////////////////////////////
+bool CxImagePNG::Decode(CxFile *hFile)
+{
+	png_struct *png_ptr;
+	png_info *info_ptr;
+	BYTE *row_pointers=NULL;
+	CImageIterator iter(this);
+
+  cx_try
+  {
+    /* 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 *)NULL,NULL,NULL);
+	if (png_ptr == NULL)  cx_throw("Failed to create PNG structure");
+
+	/* Allocate/initialize the memory for image information.  REQUIRED. */
+	info_ptr = png_create_info_struct(png_ptr);
+	if (info_ptr == NULL) {
+		png_destroy_read_struct(&png_ptr, (png_infopp)NULL, (png_infopp)NULL);
+		cx_throw("Failed to initialize PNG info structure");
+	}
+
+    /* 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_ptr->jmpbuf)) {
+		/* Free all of the memory associated with the png_ptr and info_ptr */
+		delete [] row_pointers;
+		png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
+		cx_throw("");
+	}
+
+	// use custom I/O functions
+    png_set_read_fn(png_ptr, hFile, /*(png_rw_ptr)*/user_read_data);
+	png_set_error_fn(png_ptr,info.szLastError,/*(png_error_ptr)*/user_error_fn,NULL);
+
+	/* read the file information */
+	png_read_info(png_ptr, info_ptr);
+
+	if (info.nEscape == -1){
+		head.biWidth = info_ptr->width;
+		head.biHeight= info_ptr->height;
+		info.dwType = CXIMAGE_FORMAT_PNG;
+		longjmp(png_ptr->jmpbuf, 1);
+	}
+
+	/* calculate new number of channels */
+	int channels=0;
+	switch(info_ptr->color_type){
+	case PNG_COLOR_TYPE_GRAY:
+	case PNG_COLOR_TYPE_PALETTE:
+		channels = 1;
+		break;
+	case PNG_COLOR_TYPE_GRAY_ALPHA:
+		channels = 2;
+		break;
+	case PNG_COLOR_TYPE_RGB:
+		channels = 3;
+		break;
+	case PNG_COLOR_TYPE_RGB_ALPHA:
+		channels = 4;
+		break;
+	default:
+		strcpy(info.szLastError,"unknown PNG color type");
+		longjmp(png_ptr->jmpbuf, 1);
+	}
+
+	//find the right pixel depth used for cximage
+	int pixel_depth = info_ptr->pixel_depth;
+	if (channels == 1 && pixel_depth>8) pixel_depth=8;
+	if (channels == 2) pixel_depth=8;
+	if (channels >= 3) pixel_depth=24;
+
+	if (!Create(info_ptr->width, info_ptr->height, pixel_depth, CXIMAGE_FORMAT_PNG)){
+		longjmp(png_ptr->jmpbuf, 1);
+	}
+
+	/* get metrics */
+	switch (info_ptr->phys_unit_type)
+	{
+	case PNG_RESOLUTION_UNKNOWN:
+		SetXDPI(info_ptr->x_pixels_per_unit);
+		SetYDPI(info_ptr->y_pixels_per_unit);
+		break;
+	case PNG_RESOLUTION_METER:
+		SetXDPI((long)floor(info_ptr->x_pixels_per_unit * 254.0 / 10000.0 + 0.5));
+		SetYDPI((long)floor(info_ptr->y_pixels_per_unit * 254.0 / 10000.0 + 0.5));
+		break;
+	}
+
+	if (info_ptr->num_palette>0){
+		SetPalette((rgb_color*)info_ptr->palette,info_ptr->num_palette);
+		SetClrImportant(info_ptr->num_palette);
+	} else if (info_ptr->bit_depth ==2) { //<DP> needed for 2 bpp grayscale PNGs
+		SetPaletteColor(0,0,0,0);
+		SetPaletteColor(1,85,85,85);
+		SetPaletteColor(2,170,170,170);
+		SetPaletteColor(3,255,255,255);
+	} else SetGrayPalette(); //<DP> needed for grayscale PNGs
+	
+	int nshift = max(0,(info_ptr->bit_depth>>3)-1)<<3;
+
+	if (info_ptr->num_trans!=0){ //palette transparency
+		if (info_ptr->num_trans==1){
+			if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE){
+				info.nBkgndIndex = info_ptr->trans_values.index;
+			} else{
+				info.nBkgndIndex = info_ptr->trans_values.gray>>nshift;
+			}
+		}
+		if (info_ptr->num_trans>1){
+			RGBQUAD* pal=GetPalette();
+			if (pal){
+				DWORD ip;
+				for (ip=0;ip<min(head.biClrUsed,(unsigned long)info_ptr->num_trans);ip++)
+					pal[ip].rgbReserved=info_ptr->trans[ip];
+				for (ip=info_ptr->num_trans;ip<head.biClrUsed;ip++){
+					pal[ip].rgbReserved=255;
+				}
+				info.bAlphaPaletteEnabled=true;
+			}
+		}
+	}
+
+	if (channels == 3){ //check RGB binary transparency
+		png_bytep trans;
+		int num_trans;
+		png_color_16 *image_background;
+		if (png_get_tRNS(png_ptr, info_ptr, &trans, &num_trans, &image_background)){
+			info.nBkgndColor.rgbRed   = (BYTE)(info_ptr->trans_values.red>>nshift);
+			info.nBkgndColor.rgbGreen = (BYTE)(info_ptr->trans_values.green>>nshift);
+			info.nBkgndColor.rgbBlue  = (BYTE)(info_ptr->trans_values.blue>>nshift);
+			info.nBkgndColor.rgbReserved = 0;
+			info.nBkgndIndex = 0;
+		}
+	}
+
+	int alpha_present = (channels - 1) % 2;
+	if (alpha_present){
+#if CXIMAGE_SUPPORT_ALPHA	// <vho>
+		AlphaCreate();
+#else
+		png_set_strip_alpha(png_ptr);
+#endif //CXIMAGE_SUPPORT_ALPHA
+	}
+
+	// <vho> - flip the RGB pixels to BGR (or RGBA to BGRA)
+	if (info_ptr->color_type & PNG_COLOR_MASK_COLOR){
+		png_set_bgr(png_ptr);
+	}
+
+	// <vho> - handle cancel
+	if (info.nEscape) longjmp(png_ptr->jmpbuf, 1);
+
+	// row_bytes is the width x number of channels x (bit-depth / 8)
+	row_pointers = new BYTE[info_ptr->rowbytes + 8];
+
+	// turn on interlace handling
+	int number_passes = png_set_interlace_handling(png_ptr);
+
+	if (number_passes>1){
+		SetCodecOption(1);
+	} else {
+		SetCodecOption(0);
+	}
+
+	int chan_offset = info_ptr->bit_depth >> 3;
+	int pixel_offset = info_ptr->pixel_depth >> 3;
+
+	for (int pass=0; pass < number_passes; pass++) {
+		iter.Upset();
+		int y=0;
+		do	{
+
+			// <vho> - handle cancel
+			if (info.nEscape) longjmp(png_ptr->jmpbuf, 1);
+
+#if CXIMAGE_SUPPORT_ALPHA	// <vho>
+			if (AlphaIsValid()) {
+
+				//compute the correct position of the line
+				long ax,ay;
+				ay = head.biHeight-1-y;
+				BYTE* prow= iter.GetRow(ay);
+
+				//recover data from previous scan
+				if (info_ptr->interlace_type && pass>0 && pass!=7){
+					for(ax=0;ax<head.biWidth;ax++){
+						long px = ax * pixel_offset;
+						if (channels == 2){
+							row_pointers[px] = prow[ax];
+							row_pointers[px+chan_offset]=AlphaGet(ax,ay);
+						} else {
+							long qx = ax * 3;
+							row_pointers[px]              =prow[qx];
+							row_pointers[px+chan_offset]  =prow[qx+1];
+							row_pointers[px+chan_offset*2]=prow[qx+2];
+							row_pointers[px+chan_offset*3]=AlphaGet(ax,ay);
+						}
+					}
+				}
+
+				//read next row
+				png_read_row(png_ptr, row_pointers, NULL);
+
+				//RGBA -> RGB + A
+				for(ax=0;ax<head.biWidth;ax++){
+					long px = ax * pixel_offset;
+					if (channels == 2){
+						prow[ax] = row_pointers[px];
+						AlphaSet(ax,ay,row_pointers[px+chan_offset]);
+					} else {
+						long qx = ax * 3;
+						prow[qx]  =row_pointers[px];
+						prow[qx+1]=row_pointers[px+chan_offset];
+						prow[qx+2]=row_pointers[px+chan_offset*2];
+						AlphaSet(ax,ay,row_pointers[px+chan_offset*3]);
+					}
+				}
+			} else
+#endif // CXIMAGE_SUPPORT_ALPHA		// vho
+			{
+				//recover data from previous scan
+				if (info_ptr->interlace_type && pass>0){
+					iter.GetRow(row_pointers, info_ptr->rowbytes);
+					//re-expand buffer for images with bit depth > 8
+					if (info_ptr->bit_depth > 8){
+						for(long ax=(head.biWidth*channels-1);ax>=0;ax--)
+							row_pointers[ax*chan_offset] = row_pointers[ax];
+					}
+				}
+
+				//read next row
+				png_read_row(png_ptr, row_pointers, NULL);
+
+				//shrink 16 bit depth images down to 8 bits
+				if (info_ptr->bit_depth > 8){
+					for(long ax=0;ax<(head.biWidth*channels);ax++)
+						row_pointers[ax] = row_pointers[ax*chan_offset];
+				}
+
+				//copy the pixels
+				iter.SetRow(row_pointers, info_ptr->rowbytes);
+				//<DP> expand 2 bpp images only in the last pass
+				if (info_ptr->bit_depth==2 && pass==(number_passes-1))
+					expand2to4bpp(iter.GetRow());
+
+				//go on
+				iter.PrevRow();
+			}
+
+			y++;
+		} while(y<head.biHeight);
+	}
+
+	delete [] row_pointers;
+
+	/* read the rest of the file, getting any additional chunks in info_ptr */
+	png_read_end(png_ptr, info_ptr);
+
+	/* clean up after the read, and free any memory allocated - REQUIRED */
+	png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
+
+  } cx_catch {
+	if (strcmp(message,"")) strncpy(info.szLastError,message,255);
+	if (info.nEscape == -1 && info.dwType == CXIMAGE_FORMAT_PNG) return true;
+	return false;
+  }
+	/* that's it */
+	return true;
+}
+////////////////////////////////////////////////////////////////////////////////
+#endif //CXIMAGE_SUPPORT_DECODE
+////////////////////////////////////////////////////////////////////////////////
+#if CXIMAGE_SUPPORT_ENCODE
+////////////////////////////////////////////////////////////////////////////////
+bool CxImagePNG::Encode(CxFile *hFile)
+{
+	if (EncodeSafeCheck(hFile)) return false;
+
+	CImageIterator iter(this);
+	BYTE trans[256];	//for transparency (don't move)
+	png_struct *png_ptr;
+	png_info *info_ptr;
+
+  cx_try
+  {
+   /* 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 check that
+    * the library version is compatible with the one used at compile time,
+    * in case we are using dynamically linked libraries.  REQUIRED.
+    */
+	png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING,(void *)NULL,NULL,NULL);
+	if (png_ptr == NULL) cx_throw("Failed to create PNG structure");
+
+	/* Allocate/initialize the image information data.  REQUIRED */
+	info_ptr = png_create_info_struct(png_ptr);
+	if (info_ptr == NULL){
+		png_destroy_write_struct(&png_ptr,  (png_infopp)NULL);
+		cx_throw("Failed to initialize PNG info structure");
+	}
+
+   /* Set error handling.  REQUIRED if you aren't supplying your own
+    * error hadnling functions in the png_create_write_struct() call.
+    */
+	if (setjmp(png_ptr->jmpbuf)){
+		/* If we get here, we had a problem reading the file */
+		if (info_ptr->palette) free(info_ptr->palette);
+		png_destroy_write_struct(&png_ptr,  (png_infopp)&info_ptr);
+		cx_throw("Error saving PNG file");
+	}
+            
+	/* set up the output control */
+	//png_init_io(png_ptr, hFile);
+
+	// use custom I/O functions
+    png_set_write_fn(png_ptr,hFile,/*(png_rw_ptr)*/user_write_data,/*(png_flush_ptr)*/user_flush_data);
+
+	/* set the file information here */
+	info_ptr->width = GetWidth();
+	info_ptr->height = GetHeight();
+	info_ptr->pixel_depth = (BYTE)GetBpp();
+	info_ptr->channels = (GetBpp()>8) ? (BYTE)3: (BYTE)1;
+	info_ptr->bit_depth = (BYTE)(GetBpp()/info_ptr->channels);
+	info_ptr->compression_type = info_ptr->filter_type = 0;
+	info_ptr->valid = 0;
+
+	switch(GetCodecOption(CXIMAGE_FORMAT_PNG)){
+	case 1:
+		info_ptr->interlace_type = PNG_INTERLACE_ADAM7;
+		break;
+	default:
+		info_ptr->interlace_type = PNG_INTERLACE_NONE;
+	}
+
+	/* set compression level */
+	//png_set_compression_level(png_ptr, Z_BEST_COMPRESSION);
+
+	bool bGrayScale = IsGrayScale();
+
+	if (GetNumColors()){
+		if (bGrayScale){
+			info_ptr->color_type = PNG_COLOR_TYPE_GRAY;
+		} else {
+			info_ptr->color_type = PNG_COLOR_TYPE_PALETTE;
+		}
+	} else {
+		info_ptr->color_type = PNG_COLOR_TYPE_RGB;
+	}
+#if CXIMAGE_SUPPORT_ALPHA
+	if (AlphaIsValid()){
+		info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
+		info_ptr->channels++;
+		info_ptr->bit_depth = 8;
+		info_ptr->pixel_depth += 8;
+	}
+#endif
+
+	/* set background */
+	png_color_16 image_background={ 0, 255, 255, 255, 0 };
+	RGBQUAD tc = GetTransColor();
+	if (info.nBkgndIndex>=0) {
+		image_background.blue  = tc.rgbBlue;
+		image_background.green = tc.rgbGreen;
+		image_background.red   = tc.rgbRed;
+	}
+	png_set_bKGD(png_ptr, info_ptr, &image_background);
+
+	/* set metrics */
+	png_set_pHYs(png_ptr, info_ptr, head.biXPelsPerMeter, head.biYPelsPerMeter, PNG_RESOLUTION_METER);
+
+	png_set_IHDR(png_ptr, info_ptr, info_ptr->width, info_ptr->height, info_ptr->bit_depth,
+				info_ptr->color_type, info_ptr->interlace_type,
+				PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
+
+	//<DP> simple transparency
+	if (info.nBkgndIndex >= 0){
+		info_ptr->num_trans = 1;
+		info_ptr->valid |= PNG_INFO_tRNS;
+		info_ptr->trans = trans;
+		info_ptr->trans_values.index = (BYTE)info.nBkgndIndex;
+		info_ptr->trans_values.red   = tc.rgbRed;
+		info_ptr->trans_values.green = tc.rgbGreen;
+		info_ptr->trans_values.blue  = tc.rgbBlue;
+		info_ptr->trans_values.gray  = info_ptr->trans_values.index;
+
+		// the transparency indexes start from 0 for non grayscale palette
+		if (!bGrayScale && head.biClrUsed && info.nBkgndIndex)
+			SwapIndex(0,(BYTE)info.nBkgndIndex);
+	}
+
+	/* set the palette if there is one */
+	if (GetPalette()){
+		if (!bGrayScale){
+			info_ptr->valid |= PNG_INFO_PLTE;
+		}
+
+		int nc = GetClrImportant();
+		if (nc==0) nc = GetNumColors();
+
+		if (info.bAlphaPaletteEnabled){
+			for(WORD ip=0; ip<nc;ip++)
+				trans[ip]=GetPaletteColor((BYTE)ip).rgbReserved;
+			info_ptr->num_trans = (WORD)nc;
+			info_ptr->valid |= PNG_INFO_tRNS;
+			info_ptr->trans = trans;
+		}
+
+		// copy the palette colors
+		info_ptr->palette = new png_color[nc];
+		info_ptr->num_palette = (png_uint_16) nc;
+		for (int i=0; i<nc; i++)
+			GetPaletteColor(i, &info_ptr->palette[i].red, &info_ptr->palette[i].green, &info_ptr->palette[i].blue);
+	}  
+
+#if CXIMAGE_SUPPORT_ALPHA	// <vho>
+	//Merge the transparent color with the alpha channel
+	if (AlphaIsValid() && head.biBitCount==24 && info.nBkgndIndex>=0){
+		for(long y=0; y < head.biHeight; y++){
+			for(long x=0; x < head.biWidth ; x++){
+				RGBQUAD c=GetPixelColor(x,y,false);
+				if (*(long*)&c==*(long*)&tc)
+					AlphaSet(x,y,0);
+	}	}	}
+#endif // CXIMAGE_SUPPORT_ALPHA	// <vho>
+
+	int row_size = max(info.dwEffWidth, info_ptr->width*info_ptr->channels*(info_ptr->bit_depth/8));
+	info_ptr->rowbytes = row_size;
+	BYTE *row_pointers = new BYTE[row_size];
+
+	/* write the file information */
+	png_write_info(png_ptr, info_ptr);
+
+	//interlace handling
+	int num_pass = png_set_interlace_handling(png_ptr);
+	for (int pass = 0; pass < num_pass; pass++){
+		//write image
+		iter.Upset();
+		long ay=head.biHeight-1;
+		RGBQUAD c;
+		do	{
+#if CXIMAGE_SUPPORT_ALPHA	// <vho>
+			if (AlphaIsValid()){
+				for (long ax=head.biWidth-1; ax>=0;ax--){
+					c = BlindGetPixelColor(ax,ay);
+					int px = ax * info_ptr->channels;
+					if (!bGrayScale){
+						row_pointers[px++]=c.rgbRed;
+						row_pointers[px++]=c.rgbGreen;
+					}
+					row_pointers[px++]=c.rgbBlue;
+					row_pointers[px] = AlphaGet(ax,ay);
+				}
+				png_write_row(png_ptr, row_pointers);
+				ay--;
+			}
+			else
+#endif //CXIMAGE_SUPPORT_ALPHA	// <vho>
+			{
+				iter.GetRow(row_pointers, row_size);
+				if (info_ptr->color_type == PNG_COLOR_TYPE_RGB) //HACK BY OP
+					RGBtoBGR(row_pointers, row_size);
+				png_write_row(png_ptr, row_pointers);
+			}
+		} while(iter.PrevRow());
+	}
+
+	delete [] row_pointers;
+
+	//if necessary, restore the original palette
+	if (!bGrayScale && head.biClrUsed && info.nBkgndIndex>0)
+		SwapIndex((BYTE)info.nBkgndIndex,0);
+
+	/* It is REQUIRED to call this to finish writing the rest of the file */
+	png_write_end(png_ptr, info_ptr);
+
+	/* if you malloced the palette, free it here */
+	if (info_ptr->palette){
+		delete [] (info_ptr->palette);
+		info_ptr->palette = NULL;
+	}
+
+	/* clean up after the write, and free any memory allocated */
+	png_destroy_write_struct(&png_ptr, (png_infopp)&info_ptr);
+
+  } cx_catch {
+	if (strcmp(message,"")) strncpy(info.szLastError,message,255);
+	return FALSE;
+  }
+	/* that's it */
+	return TRUE;
+}
+////////////////////////////////////////////////////////////////////////////////
+#endif // CXIMAGE_SUPPORT_ENCODE
+////////////////////////////////////////////////////////////////////////////////
+#endif // CXIMAGE_SUPPORT_PNG