Make brush hatches in wxGTK consistent with wxMSW.

[wxWidgets.git] / src / common / imagpng.cpp

diff --git a/src/common/imagpng.cpp b/src/common/imagpng.cpp
index 54c3ac8819c0a61afbf4de00cb55aefb6baf18b6..3472c5a1fc8259fd6dbe6214637d99f3bb03c9e0 100644 (file)
--- a/src/common/imagpng.cpp
+++ b/src/common/imagpng.cpp
@@ -1,5 +1,5 @@
 /////////////////////////////////////////////////////////////////////////////
 /////////////////////////////////////////////////////////////////////////////

-// Name:        src/common/imagepng.cpp
+// Name:        src/common/imagpng.cpp

 // Purpose:     wxImage PNG handler
 // Author:      Robert Roebling
 // RCS-ID:      $Id$
 // Purpose:     wxImage PNG handler
 // Author:      Robert Roebling
 // RCS-ID:      $Id$


@@ -11,10 +11,6 @@
 // declarations
 // ============================================================================
 
 // declarations
 // ============================================================================
 

-#if defined(__GNUG__) && !defined(NO_GCC_PRAGMA)
-#pragma implementation "imagpng.h"
-#endif
-

 // ----------------------------------------------------------------------------
 // headers
 // ----------------------------------------------------------------------------
 // ----------------------------------------------------------------------------
 // headers
 // ----------------------------------------------------------------------------


@@ -23,35 +19,26 @@
 #include "wx/wxprec.h"
 
 #ifdef __BORLANDC__
 #include "wx/wxprec.h"
 
 #ifdef __BORLANDC__

-  #pragma hdrstop
-#endif
-
-#ifndef WX_PRECOMP
-  #include "wx/defs.h"
+    #pragma hdrstop

 #endif
 
 #if wxUSE_IMAGE && wxUSE_LIBPNG
 
 #include "wx/imagpng.h"
 #endif
 
 #if wxUSE_IMAGE && wxUSE_LIBPNG
 
 #include "wx/imagpng.h"

-#include "wx/bitmap.h"
-#include "wx/debug.h"
-#include "wx/log.h"
-#include "wx/app.h"
+#include "wx/versioninfo.h"
+
+#ifndef WX_PRECOMP
+    #include "wx/log.h"
+    #include "wx/intl.h"
+    #include "wx/palette.h"
+    #include "wx/stream.h"
+#endif
+

 #include "png.h"
 #include "png.h"

-#include "wx/filefn.h"
-#include "wx/wfstream.h"
-#include "wx/intl.h"
-#include "wx/module.h"

 
 // For memcpy
 #include <string.h>
 
 
 // For memcpy
 #include <string.h>
 

-#ifdef __SALFORDC__
-#ifdef FAR
-#undef FAR
-#endif
-#endif
-

 // ----------------------------------------------------------------------------
 // constants
 // ----------------------------------------------------------------------------
 // ----------------------------------------------------------------------------
 // constants
 // ----------------------------------------------------------------------------


@@ -109,7 +96,9 @@ IMPLEMENT_DYNAMIC_CLASS(wxPNGHandler,wxImageHandler)
 #if wxUSE_STREAMS
 
 #ifndef PNGLINKAGEMODE
 #if wxUSE_STREAMS
 
 #ifndef PNGLINKAGEMODE

-    #ifdef __WATCOMC__
+    #ifdef PNGAPI
+        #define PNGLINKAGEMODE PNGAPI
+    #elif defined(__WATCOMC__)

         // we need an explicit cdecl for Watcom, at least according to
         //
         // http://sf.net/tracker/index.php?func=detail&aid=651492&group_id=9863&atid=109863
         // we need an explicit cdecl for Watcom, at least according to
         //
         // http://sf.net/tracker/index.php?func=detail&aid=651492&group_id=9863&atid=109863


@@ -160,32 +149,39 @@ struct wxPNGInfoStruct
 extern "C"
 {
 
 extern "C"
 {
 

-void PNGLINKAGEMODE wx_PNG_stream_reader( png_structp png_ptr, png_bytep data,
-                                          png_size_t length )
+static void PNGLINKAGEMODE wx_PNG_stream_reader( png_structp png_ptr, png_bytep data,
+                                                 png_size_t length )

 {
     WX_PNG_INFO(png_ptr)->stream.in->Read(data, length);
 }
 
 {
     WX_PNG_INFO(png_ptr)->stream.in->Read(data, length);
 }
 

-void PNGLINKAGEMODE wx_PNG_stream_writer( png_structp png_ptr, png_bytep data,
-                                          png_size_t length )
+static void PNGLINKAGEMODE wx_PNG_stream_writer( png_structp png_ptr, png_bytep data,
+                                                 png_size_t length )

 {
     WX_PNG_INFO(png_ptr)->stream.out->Write(data, length);
 }
 
 {
     WX_PNG_INFO(png_ptr)->stream.out->Write(data, length);
 }
 

-// from pngerror.c
-// so that the libpng doesn't send anything on stderr
-void
-PNGLINKAGEMODE wx_png_error(png_structp WXUNUSED(png_ptr), png_const_charp message)
-{
-    wxLogFatalError( wxString::FromAscii(message) );
-}
-
-void
+static void

 PNGLINKAGEMODE wx_png_warning(png_structp png_ptr, png_const_charp message)
 {
     wxPNGInfoStruct *info = png_ptr ? WX_PNG_INFO(png_ptr) : NULL;
     if ( !info || info->verbose )
 PNGLINKAGEMODE wx_png_warning(png_structp png_ptr, png_const_charp message)
 {
     wxPNGInfoStruct *info = png_ptr ? WX_PNG_INFO(png_ptr) : NULL;
     if ( !info || info->verbose )

+    {

         wxLogWarning( wxString::FromAscii(message) );
         wxLogWarning( wxString::FromAscii(message) );

+    }
+}
+
+// from pngerror.c
+// so that the libpng doesn't send anything on stderr
+static void
+PNGLINKAGEMODE wx_png_error(png_structp png_ptr, png_const_charp message)
+{
+    wx_png_warning(NULL, message);
+
+    // we're not using libpng built-in jump buffer (see comment before
+    // wxPNGInfoStruct above) so we have to return ourselves, otherwise libpng
+    // would just abort
+    longjmp(WX_PNG_INFO(png_ptr)->jmpbuf, 1);

 }
 
 } // extern "C"
 }
 
 } // extern "C"


@@ -278,6 +274,7 @@ FindMaskColour(unsigned char **lines, png_uint_32 width, png_uint_32 height,
             r2 = *p++;
             g2 = *p++;
             b2 = *p++;
             r2 = *p++;
             g2 = *p++;
             b2 = *p++;

+            ++p; // jump over alpha

 
             wxImageHistogramEntry&
                 entry = h[wxImageHistogram:: MakeKey(r2, g2, b2)];
 
             wxImageHistogramEntry&
                 entry = h[wxImageHistogram:: MakeKey(r2, g2, b2)];


@@ -308,7 +305,7 @@ bool wxPNGHandler::DoCanRead( wxInputStream& stream )
 {
     unsigned char hdr[4];
 
 {
     unsigned char hdr[4];
 

-    if ( !stream.Read(hdr, WXSIZEOF(hdr)) )
+    if ( !stream.Read(hdr, WXSIZEOF(hdr)) )     // it's ok to modify the stream position here

         return false;
 
     return memcmp(hdr, "\211PNG", WXSIZEOF(hdr)) == 0;
         return false;
 
     return memcmp(hdr, "\211PNG", WXSIZEOF(hdr)) == 0;


@@ -383,15 +380,15 @@ void CopyDataFromPNG(wxImage *image,
                         if ( IsTransparent(a) )
                         {
                             *ptrDst++ = rMask;
                         if ( IsTransparent(a) )
                         {
                             *ptrDst++ = rMask;

-                            *ptrDst++ = bMask;

                             *ptrDst++ = gMask;
                             *ptrDst++ = gMask;

+                            *ptrDst++ = bMask;

                             break;
                         }
                         // else: !transparent
 
                         // must be opaque then as otherwise we shouldn't be
                         // using the mask at all
                             break;
                         }
                         // else: !transparent
 
                         // must be opaque then as otherwise we shouldn't be
                         // using the mask at all

-                        wxASSERT_MSG( IsOpaque(a), _T("logic error") );
+                        wxASSERT_MSG( IsOpaque(a), wxT("logic error") );

 
                         // fall through
 
 
                         // fall through
 


@@ -451,15 +448,15 @@ void CopyDataFromPNG(wxImage *image,
                         if ( IsTransparent(a) )
                         {
                             *ptrDst++ = rMask;
                         if ( IsTransparent(a) )
                         {
                             *ptrDst++ = rMask;

-                            *ptrDst++ = bMask;

                             *ptrDst++ = gMask;
                             *ptrDst++ = gMask;

+                            *ptrDst++ = bMask;

                             break;
                         }
                         else // !transparent
                         {
                             // must be opaque then as otherwise we shouldn't be
                             // using the mask at all
                             break;
                         }
                         else // !transparent
                         {
                             // must be opaque then as otherwise we shouldn't be
                             // using the mask at all

-                            wxASSERT_MSG( IsOpaque(a), _T("logic error") );
+                            wxASSERT_MSG( IsOpaque(a), wxT("logic error") );

 
                             // if we couldn't find a unique colour for the
                             // mask, we can have real pixels with the same
 
                             // if we couldn't find a unique colour for the
                             // mask, we can have real pixels with the same


@@ -507,13 +504,16 @@ wxPNGHandler::LoadFile(wxImage *image,
                        bool verbose,
                        int WXUNUSED(index))
 {
                        bool verbose,
                        int WXUNUSED(index))
 {

-    // VZ: as this function uses setjmp() the only fool proof error handling
+    // VZ: as this function uses setjmp() the only fool-proof error handling

     //     method is to use goto (setjmp is not really C++ dtors friendly...)
 
     unsigned char **lines = NULL;
     png_infop info_ptr = (png_infop) NULL;
     wxPNGInfoStruct wxinfo;
 
     //     method is to use goto (setjmp is not really C++ dtors friendly...)
 
     unsigned char **lines = NULL;
     png_infop info_ptr = (png_infop) NULL;
     wxPNGInfoStruct wxinfo;
 

+    png_uint_32 i, width, height = 0;
+    int bit_depth, color_type, interlace_type;
+

     wxinfo.verbose = verbose;
     wxinfo.stream.in = &stream;
 
     wxinfo.verbose = verbose;
     wxinfo.stream.in = &stream;
 


@@ -522,7 +522,7 @@ wxPNGHandler::LoadFile(wxImage *image,
     png_structp png_ptr = png_create_read_struct
                           (
                             PNG_LIBPNG_VER_STRING,
     png_structp png_ptr = png_create_read_struct
                           (
                             PNG_LIBPNG_VER_STRING,

-                            (voidp) NULL,
+                            NULL,

                             wx_png_error,
                             wx_png_warning
                           );
                             wx_png_error,
                             wx_png_warning
                           );


@@ -540,11 +540,8 @@ wxPNGHandler::LoadFile(wxImage *image,
     if (setjmp(wxinfo.jmpbuf))
         goto error;
 
     if (setjmp(wxinfo.jmpbuf))
         goto error;
 

-    png_uint_32 i, width, height;
-    int bit_depth, color_type, interlace_type;
-

     png_read_info( png_ptr, info_ptr );
     png_read_info( png_ptr, info_ptr );

-    png_get_IHDR( png_ptr, info_ptr, &width, &height, &bit_depth, &color_type, &interlace_type, (int*) NULL, (int*) NULL );
+    png_get_IHDR( png_ptr, info_ptr, &width, &height, &bit_depth, &color_type, &interlace_type, NULL, NULL );

 
     if (color_type == PNG_COLOR_TYPE_PALETTE)
         png_set_expand( png_ptr );
 
     if (color_type == PNG_COLOR_TYPE_PALETTE)
         png_set_expand( png_ptr );


@@ -564,22 +561,47 @@ wxPNGHandler::LoadFile(wxImage *image,
     if (!image->Ok())
         goto error;
 
     if (!image->Ok())
         goto error;
 

-    lines = (unsigned char **)malloc( (size_t)(height * sizeof(unsigned char *)) );
+    // initialize all line pointers to NULL to ensure that they can be safely
+    // free()d if an error occurs before all of them could be allocated
+    lines = (unsigned char **)calloc(height, sizeof(unsigned char *));

     if ( !lines )
         goto error;
 
     for (i = 0; i < height; i++)
     {
         if ((lines[i] = (unsigned char *)malloc( (size_t)(width * (sizeof(unsigned char) * 4)))) == NULL)
     if ( !lines )
         goto error;
 
     for (i = 0; i < height; i++)
     {
         if ((lines[i] = (unsigned char *)malloc( (size_t)(width * (sizeof(unsigned char) * 4)))) == NULL)

-        {
-            for ( unsigned int n = 0; n < i; n++ )
-                free( lines[n] );

             goto error;
             goto error;

-        }

     }
 
     png_read_image( png_ptr, lines );
     png_read_end( png_ptr, info_ptr );
     }
 
     png_read_image( png_ptr, lines );
     png_read_end( png_ptr, info_ptr );

+
+#if wxUSE_PALETTE
+    if (color_type == PNG_COLOR_TYPE_PALETTE)
+    {
+        png_colorp palette = NULL;
+        int numPalette = 0;
+
+        (void) png_get_PLTE(png_ptr, info_ptr, &palette, &numPalette);
+
+        unsigned char* r = new unsigned char[numPalette];
+        unsigned char* g = new unsigned char[numPalette];
+        unsigned char* b = new unsigned char[numPalette];
+
+        for (int j = 0; j < numPalette; j++)
+        {
+            r[j] = palette[j].red;
+            g[j] = palette[j].green;
+            b[j] = palette[j].blue;
+        }
+
+        image->SetPalette(wxPalette(numPalette, r, g, b));
+        delete[] r;
+        delete[] g;
+        delete[] b;
+    }
+#endif // wxUSE_PALETTE
+

     png_destroy_read_struct( &png_ptr, &info_ptr, (png_infopp) NULL );
 
     // loaded successfully, now init wxImage with this data
     png_destroy_read_struct( &png_ptr, &info_ptr, (png_infopp) NULL );
 
     // loaded successfully, now init wxImage with this data


@@ -593,7 +615,9 @@ wxPNGHandler::LoadFile(wxImage *image,
 
 error:
     if (verbose)
 
 error:
     if (verbose)

+    {

        wxLogError(_("Couldn't load a PNG image - file is corrupted or not enough memory."));
        wxLogError(_("Couldn't load a PNG image - file is corrupted or not enough memory."));

+    }

 
     if ( image->Ok() )
     {
 
     if ( image->Ok() )
     {


@@ -602,6 +626,9 @@ error:
 
     if ( lines )
     {
 
     if ( lines )
     {

+        for ( unsigned int n = 0; n < height; n++ )
+            free( lines[n] );
+

         free( lines );
     }
 
         free( lines );
     }
 


@@ -618,6 +645,44 @@ error:
     return false;
 }
 
     return false;
 }
 

+// ----------------------------------------------------------------------------
+// SaveFile() palette helpers
+// ----------------------------------------------------------------------------
+
+typedef wxLongToLongHashMap PaletteMap;
+
+static unsigned long PaletteMakeKey(const png_color_8& clr)
+{
+    return (wxImageHistogram::MakeKey(clr.red, clr.green, clr.blue) << 8) | clr.alpha;
+}
+
+static long PaletteFind(const PaletteMap& palette, const png_color_8& clr)
+{
+    unsigned long value = PaletteMakeKey(clr);
+    PaletteMap::const_iterator it = palette.find(value);
+
+    return (it != palette.end()) ? it->second : wxNOT_FOUND;
+}
+
+static long PaletteAdd(PaletteMap *palette, const png_color_8& clr)
+{
+    unsigned long value = PaletteMakeKey(clr);
+    PaletteMap::const_iterator it = palette->find(value);
+    size_t index;
+
+    if (it == palette->end())
+    {
+        index = palette->size();
+        (*palette)[value] = index;
+    }
+    else
+    {
+        index = it->second;
+    }
+
+    return index;
+}
+

 // ----------------------------------------------------------------------------
 // writing PNGs
 // ----------------------------------------------------------------------------
 // ----------------------------------------------------------------------------
 // writing PNGs
 // ----------------------------------------------------------------------------


@@ -639,7 +704,9 @@ bool wxPNGHandler::SaveFile( wxImage *image, wxOutputStream& stream, bool verbos
     if (!png_ptr)
     {
         if (verbose)
     if (!png_ptr)
     {
         if (verbose)

+        {

            wxLogError(_("Couldn't save PNG image."));
            wxLogError(_("Couldn't save PNG image."));

+        }

         return false;
     }
 
         return false;
     }
 


@@ -648,7 +715,9 @@ bool wxPNGHandler::SaveFile( wxImage *image, wxOutputStream& stream, bool verbos
     {
         png_destroy_write_struct( &png_ptr, (png_infopp)NULL );
         if (verbose)
     {
         png_destroy_write_struct( &png_ptr, (png_infopp)NULL );
         if (verbose)

+        {

            wxLogError(_("Couldn't save PNG image."));
            wxLogError(_("Couldn't save PNG image."));

+        }

         return false;
     }
 
         return false;
     }
 


@@ -656,7 +725,9 @@ bool wxPNGHandler::SaveFile( wxImage *image, wxOutputStream& stream, bool verbos
     {
         png_destroy_write_struct( &png_ptr, (png_infopp)NULL );
         if (verbose)
     {
         png_destroy_write_struct( &png_ptr, (png_infopp)NULL );
         if (verbose)

+        {

            wxLogError(_("Couldn't save PNG image."));
            wxLogError(_("Couldn't save PNG image."));

+        }

         return false;
     }
 
         return false;
     }
 


@@ -664,51 +735,299 @@ bool wxPNGHandler::SaveFile( wxImage *image, wxOutputStream& stream, bool verbos
     //     explanation why this line is mandatory
     png_set_write_fn( png_ptr, &wxinfo, wx_PNG_stream_writer, NULL);
 
     //     explanation why this line is mandatory
     png_set_write_fn( png_ptr, &wxinfo, wx_PNG_stream_writer, NULL);
 

-    png_set_IHDR( png_ptr, info_ptr, image->GetWidth(), image->GetHeight(), 8,
-        PNG_COLOR_TYPE_RGB_ALPHA, PNG_INTERLACE_NONE,
-        PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
+    const int iHeight = image->GetHeight();
+    const int iWidth = image->GetWidth();
+
+    const bool bHasPngFormatOption
+        = image->HasOption(wxIMAGE_OPTION_PNG_FORMAT);
+
+    int iColorType = bHasPngFormatOption
+                            ? image->GetOptionInt(wxIMAGE_OPTION_PNG_FORMAT)
+                            : wxPNG_TYPE_COLOUR;
+
+    bool bHasAlpha = image->HasAlpha();
+    bool bHasMask = image->HasMask();
+
+    bool bUsePalette = iColorType == wxPNG_TYPE_PALETTE
+#if wxUSE_PALETTE
+        || (!bHasPngFormatOption && image->HasPalette() )
+#endif
+    ;
+
+    png_color_8 mask;

 
 

+    if (bHasMask)
+    {
+        mask.red   = image->GetMaskRed();
+        mask.green = image->GetMaskGreen();
+        mask.blue  = image->GetMaskBlue();
+        mask.alpha = 0;
+        mask.gray  = 0;
+    }
+
+    PaletteMap palette;
+
+    if (bUsePalette)
+    {
+        png_color png_rgb  [PNG_MAX_PALETTE_LENGTH];
+        png_byte  png_trans[PNG_MAX_PALETTE_LENGTH];
+
+        const unsigned char *pColors = image->GetData();
+        const unsigned char* pAlpha  = image->GetAlpha();
+
+        if (bHasMask && !pAlpha)
+        {
+            // Mask must be first
+            PaletteAdd(&palette, mask);
+        }
+
+        for (int y = 0; y < iHeight; y++)
+        {
+            for (int x = 0; x < iWidth; x++)
+            {
+                png_color_8 rgba;
+
+                rgba.red   = *pColors++;
+                rgba.green = *pColors++;
+                rgba.blue  = *pColors++;
+                rgba.gray  = 0;
+                rgba.alpha = (pAlpha && !bHasMask) ? *pAlpha++ : 0;
+
+                // save in our palette
+                long index = PaletteAdd(&palette, rgba);
+
+                if (index < PNG_MAX_PALETTE_LENGTH)
+                {
+                    // save in libpng's palette
+                    png_rgb[index].red   = rgba.red;
+                    png_rgb[index].green = rgba.green;
+                    png_rgb[index].blue  = rgba.blue;
+                    png_trans[index]     = rgba.alpha;
+                }
+                else
+                {
+                    bUsePalette = false;
+                    break;
+                }
+            }
+        }
+
+        if (bUsePalette)
+        {
+            png_set_PLTE(png_ptr, info_ptr, png_rgb, palette.size());
+
+            if (bHasMask && !pAlpha)
+            {
+                wxASSERT(PaletteFind(palette, mask) == 0);
+                png_trans[0] = 0;
+                png_set_tRNS(png_ptr, info_ptr, png_trans, 1, NULL);
+            }
+            else if (pAlpha && !bHasMask)
+            {
+                png_set_tRNS(png_ptr, info_ptr, png_trans, palette.size(), NULL);
+            }
+        }
+    }
+
+    /*
+    If saving palettised was requested but it was decided we can't use a
+    palette then reset the colour type to RGB.
+    */
+    if (!bUsePalette && iColorType == wxPNG_TYPE_PALETTE)
+    {
+        iColorType = wxPNG_TYPE_COLOUR;
+    }
+
+    bool bUseAlpha = !bUsePalette && (bHasAlpha || bHasMask);
+
+    int iPngColorType;
+
+    if (bUsePalette)
+    {
+        iPngColorType = PNG_COLOR_TYPE_PALETTE;
+        iColorType = wxPNG_TYPE_PALETTE;
+    }
+    else if ( iColorType==wxPNG_TYPE_COLOUR )
+    {
+        iPngColorType = bUseAlpha ? PNG_COLOR_TYPE_RGB_ALPHA
+                                  : PNG_COLOR_TYPE_RGB;
+    }
+    else
+    {
+        iPngColorType = bUseAlpha ? PNG_COLOR_TYPE_GRAY_ALPHA
+                                  : PNG_COLOR_TYPE_GRAY;
+    }
+
+    if (image->HasOption(wxIMAGE_OPTION_PNG_FILTER))
+        png_set_filter( png_ptr, PNG_FILTER_TYPE_BASE, image->GetOptionInt(wxIMAGE_OPTION_PNG_FILTER) );
+
+    if (image->HasOption(wxIMAGE_OPTION_PNG_COMPRESSION_LEVEL))
+        png_set_compression_level( png_ptr, image->GetOptionInt(wxIMAGE_OPTION_PNG_COMPRESSION_LEVEL) );
+
+    if (image->HasOption(wxIMAGE_OPTION_PNG_COMPRESSION_MEM_LEVEL))
+        png_set_compression_mem_level( png_ptr, image->GetOptionInt(wxIMAGE_OPTION_PNG_COMPRESSION_MEM_LEVEL) );
+
+    if (image->HasOption(wxIMAGE_OPTION_PNG_COMPRESSION_STRATEGY))
+        png_set_compression_strategy( png_ptr, image->GetOptionInt(wxIMAGE_OPTION_PNG_COMPRESSION_STRATEGY) );
+
+    if (image->HasOption(wxIMAGE_OPTION_PNG_COMPRESSION_BUFFER_SIZE))
+        png_set_compression_buffer_size( png_ptr, image->GetOptionInt(wxIMAGE_OPTION_PNG_COMPRESSION_BUFFER_SIZE) );
+
+    int iBitDepth = !bUsePalette && image->HasOption(wxIMAGE_OPTION_PNG_BITDEPTH)
+                            ? image->GetOptionInt(wxIMAGE_OPTION_PNG_BITDEPTH)
+                            : 8;
+
+    png_set_IHDR( png_ptr, info_ptr, image->GetWidth(), image->GetHeight(),
+                  iBitDepth, iPngColorType,
+                  PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE,
+                  PNG_FILTER_TYPE_BASE);
+
+    int iElements;

     png_color_8 sig_bit;
     png_color_8 sig_bit;

-    sig_bit.red = 8;
-    sig_bit.green = 8;
-    sig_bit.blue = 8;
-    sig_bit.alpha = 8;
+
+    if ( iPngColorType & PNG_COLOR_MASK_COLOR )
+    {
+        sig_bit.red =
+        sig_bit.green =
+        sig_bit.blue = (png_byte)iBitDepth;
+        iElements = 3;
+    }
+    else // grey
+    {
+        sig_bit.gray = (png_byte)iBitDepth;
+        iElements = 1;
+    }
+
+    if ( bUseAlpha )
+    {
+        sig_bit.alpha = (png_byte)iBitDepth;
+        iElements++;
+    }
+
+    if ( iBitDepth == 16 )
+        iElements *= 2;
+
+    // save the image resolution if we have it
+    int resX, resY;
+    switch ( GetResolutionFromOptions(*image, &resX, &resY) )
+    {
+        case wxIMAGE_RESOLUTION_INCHES:
+            {
+                const double INCHES_IN_METER = 10000.0 / 254;
+                resX = int(resX * INCHES_IN_METER);
+                resY = int(resY * INCHES_IN_METER);
+            }
+            break;
+
+        case wxIMAGE_RESOLUTION_CM:
+            resX *= 100;
+            resY *= 100;
+            break;
+
+        case wxIMAGE_RESOLUTION_NONE:
+            break;
+
+        default:
+            wxFAIL_MSG( wxT("unsupported image resolution units") );
+    }
+
+    if ( resX && resY )
+        png_set_pHYs( png_ptr, info_ptr, resX, resY, PNG_RESOLUTION_METER );
+

     png_set_sBIT( png_ptr, info_ptr, &sig_bit );
     png_write_info( png_ptr, info_ptr );
     png_set_shift( png_ptr, &sig_bit );
     png_set_packing( png_ptr );
 
     png_set_sBIT( png_ptr, info_ptr, &sig_bit );
     png_write_info( png_ptr, info_ptr );
     png_set_shift( png_ptr, &sig_bit );
     png_set_packing( png_ptr );
 

-    unsigned char *data = (unsigned char *)malloc( image->GetWidth()*4 );
-    if (!data)
+    unsigned char *
+        data = (unsigned char *)malloc( image->GetWidth() * iElements );
+    if ( !data )

     {
         png_destroy_write_struct( &png_ptr, (png_infopp)NULL );
         return false;
     }
 
     {
         png_destroy_write_struct( &png_ptr, (png_infopp)NULL );
         return false;
     }
 

-    for (int y = 0; y < image->GetHeight(); y++)
+    const unsigned char *
+        pAlpha = (const unsigned char *)(bHasAlpha ? image->GetAlpha() : NULL);
+
+    const unsigned char *pColors = image->GetData();
+
+    for (int y = 0; y != iHeight; ++y)

     {
     {

-        unsigned char *ptr = image->GetData() + (y * image->GetWidth() * 3);
-        for (int x = 0; x < image->GetWidth(); x++)
+        unsigned char *pData = data;
+        for (int x = 0; x != iWidth; x++)

         {
         {

-            data[(x << 2) + 0] = *ptr++;
-            data[(x << 2) + 1] = *ptr++;
-            data[(x << 2) + 2] = *ptr++;
-            if ( image->HasAlpha() )
+            png_color_8 clr;
+            clr.red   = *pColors++;
+            clr.green = *pColors++;
+            clr.blue  = *pColors++;
+            clr.gray  = 0;
+            clr.alpha = (bUsePalette && pAlpha) ? *pAlpha++ : 0; // use with wxPNG_TYPE_PALETTE only
+
+            switch ( iColorType )

             {
             {

-                data[(x << 2) + 3] = image->GetAlpha(x, y);
-            }
-            else if (( !image->HasMask() ) || \
-                (data[(x << 2) + 0] != image->GetMaskRed()) || \
-                (data[(x << 2) + 1] != image->GetMaskGreen()) || \
-                (data[(x << 2) + 2] != image->GetMaskBlue()))
-            {
-                data[(x << 2) + 3] = 255;
+                default:
+                    wxFAIL_MSG( wxT("unknown wxPNG_TYPE_XXX") );
+                    // fall through
+
+                case wxPNG_TYPE_COLOUR:
+                    *pData++ = clr.red;
+                    if ( iBitDepth == 16 )
+                        *pData++ = 0;
+                    *pData++ = clr.green;
+                    if ( iBitDepth == 16 )
+                        *pData++ = 0;
+                    *pData++ = clr.blue;
+                    if ( iBitDepth == 16 )
+                        *pData++ = 0;
+                    break;
+
+                case wxPNG_TYPE_GREY:
+                    {
+                        // where do these coefficients come from? maybe we
+                        // should have image options for them as well?
+                        unsigned uiColor =
+                            (unsigned) (76.544*(unsigned)clr.red +
+                                        150.272*(unsigned)clr.green +
+                                        36.864*(unsigned)clr.blue);
+
+                        *pData++ = (unsigned char)((uiColor >> 8) & 0xFF);
+                        if ( iBitDepth == 16 )
+                            *pData++ = (unsigned char)(uiColor & 0xFF);
+                    }
+                    break;
+
+                case wxPNG_TYPE_GREY_RED:
+                    *pData++ = clr.red;
+                    if ( iBitDepth == 16 )
+                        *pData++ = 0;
+                    break;
+
+                case wxPNG_TYPE_PALETTE:
+                    *pData++ = (unsigned char) PaletteFind(palette, clr);
+                    break;

             }
             }

-            else
+
+            if ( bUseAlpha )

             {
             {

-                data[(x << 2) + 3] = 0;
+                unsigned char uchAlpha = 255;
+                if ( bHasAlpha )
+                    uchAlpha = *pAlpha++;
+
+                if ( bHasMask )
+                {
+                    if ( (clr.red == mask.red)
+                            && (clr.green == mask.green)
+                                && (clr.blue == mask.blue) )
+                        uchAlpha = 0;
+                }
+
+                *pData++ = uchAlpha;
+                if ( iBitDepth == 16 )
+                    *pData++ = 0;

             }
         }
             }
         }

+

         png_bytep row_ptr = data;
         png_write_rows( png_ptr, &row_ptr, 1 );
     }
         png_bytep row_ptr = data;
         png_write_rows( png_ptr, &row_ptr, 1 );
     }


@@ -726,4 +1045,18 @@ bool wxPNGHandler::SaveFile( wxImage *image, wxOutputStream& stream, bool verbos
 
 #endif  // wxUSE_STREAMS
 
 
 #endif  // wxUSE_STREAMS
 

+/*static*/ wxVersionInfo wxPNGHandler::GetLibraryVersionInfo()
+{
+    // The version string seems to always have a leading space and a trailing
+    // new line, get rid of them both.
+    wxString str = png_get_header_version(NULL) + 1;
+    str.Replace("\n", "");
+
+    return wxVersionInfo("libpng",
+                         PNG_LIBPNG_VER_MAJOR,
+                         PNG_LIBPNG_VER_MINOR,
+                         PNG_LIBPNG_VER_RELEASE,
+                         str);
+}
+

 #endif  // wxUSE_LIBPNG
 #endif  // wxUSE_LIBPNG