///////////////////////////////////////////////////////////////////////////// // Name: src/common/imagepng.cpp // Purpose: wxImage PNG handler // Author: Robert Roebling // RCS-ID: $Id: imagpng.cpp 67009 2011-02-24 08:42:57Z JS $ // Copyright: (c) Robert Roebling // Licence: wxWindows licence ///////////////////////////////////////////////////////////////////////////// // ============================================================================ // declarations // ============================================================================ // ---------------------------------------------------------------------------- // headers // ---------------------------------------------------------------------------- // For compilers that support precompilation, includes "wx.h". #include "wx/wxprec.h" #ifdef __BORLANDC__ #pragma hdrstop #endif #if wxUSE_IMAGE && wxUSE_LIBPNG #include "wx/imagpng.h" #ifndef WX_PRECOMP #include "wx/log.h" #include "wx/app.h" #include "wx/bitmap.h" #include "wx/module.h" #endif #include "png.h" #include "wx/filefn.h" #include "wx/wfstream.h" #include "wx/intl.h" #include "wx/palette.h" // For memcpy #include #ifdef __SALFORDC__ #ifdef FAR #undef FAR #endif #endif // ---------------------------------------------------------------------------- // constants // ---------------------------------------------------------------------------- // image can not have any transparent pixels at all, have only 100% opaque // and/or 100% transparent pixels in which case a simple mask is enough to // store this information in wxImage or have a real alpha channel in which case // we need to have it in wxImage as well enum Transparency { Transparency_None, Transparency_Mask, Transparency_Alpha }; // ---------------------------------------------------------------------------- // local functions // ---------------------------------------------------------------------------- // return the kind of transparency needed for this image assuming that it does // have transparent pixels, i.e. either Transparency_Alpha or Transparency_Mask static Transparency CheckTransparency(unsigned char **lines, png_uint_32 x, png_uint_32 y, png_uint_32 w, png_uint_32 h, size_t numColBytes); // init the alpha channel for the image and fill it with 1s up to (x, y) static unsigned char *InitAlpha(wxImage *image, png_uint_32 x, png_uint_32 y); // find a free colour for the mask in the PNG data array static void FindMaskColour(unsigned char **lines, png_uint_32 width, png_uint_32 height, unsigned char& rMask, unsigned char& gMask, unsigned char& bMask); // is the pixel with this value of alpha a fully opaque one? static inline bool IsOpaque(unsigned char a) { return a == 0xff; } // is the pixel with this value of alpha a fully transparent one? static inline bool IsTransparent(unsigned char a) { return !a; } // ============================================================================ // wxPNGHandler implementation // ============================================================================ IMPLEMENT_DYNAMIC_CLASS(wxPNGHandler,wxImageHandler) #if wxUSE_STREAMS #ifndef PNGLINKAGEMODE #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 // // more testing is needed for this however, please remove this comment // if you can confirm that my fix works with Watcom 11 #define PNGLINKAGEMODE cdecl #else #define PNGLINKAGEMODE LINKAGEMODE #endif #endif // VS: wxPNGInfoStruct declared below is a hack that needs some explanation. // First, let me describe what's the problem: libpng uses jmp_buf in // its png_struct structure. Unfortunately, this structure is // compiler-specific and may vary in size, so if you use libpng compiled // as DLL with another compiler than the main executable, it may not work // (this is for example the case with wxMGL port and SciTech MGL library // that provides custom runtime-loadable libpng implementation with jmpbuf // disabled altogether). Luckily, it is still possible to use setjmp() & // longjmp() as long as the structure is not part of png_struct. // // Sadly, there's no clean way to attach user-defined data to png_struct. // There is only one customizable place, png_struct.io_ptr, which is meant // only for I/O routines and is set with png_set_read_fn or // png_set_write_fn. The hacky part is that we use io_ptr to store // a pointer to wxPNGInfoStruct that holds I/O structures _and_ jmp_buf. struct wxPNGInfoStruct { jmp_buf jmpbuf; bool verbose; union { wxInputStream *in; wxOutputStream *out; } stream; }; #define WX_PNG_INFO(png_ptr) ((wxPNGInfoStruct*)png_get_io_ptr(png_ptr)) // ---------------------------------------------------------------------------- // helper functions // ---------------------------------------------------------------------------- extern "C" { 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); } 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); } 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 ) wxLogWarning( wxString::FromAscii(message) ); } // from pngerror.c // so that the libpng doesn't send anything on stderr 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" // ---------------------------------------------------------------------------- // LoadFile() helpers // ---------------------------------------------------------------------------- // determine the kind of transparency we need for this image: if the only alpha // values it has are 0 (transparent) and 0xff (opaque) then we can simply // create a mask for it, we should be ok with a simple mask but otherwise we // need a full blown alpha channel in wxImage // // parameters: // lines raw PNG data // x, y starting position // w, h size of the image // numColBytes number of colour bytes (1 for grey scale, 3 for RGB) // (NB: alpha always follows the colour bytes) Transparency CheckTransparency(unsigned char **lines, png_uint_32 x, png_uint_32 y, png_uint_32 w, png_uint_32 h, size_t numColBytes) { // suppose that a mask will suffice and check all the remaining alpha // values to see if it does for ( ; y < h; y++ ) { // each pixel is numColBytes+1 bytes, offset into the current line by // the current x position unsigned const char *ptr = lines[y] + (x * (numColBytes + 1)); for ( png_uint_32 x2 = x; x2 < w; x2++ ) { // skip the grey or colour byte(s) ptr += numColBytes; unsigned char a2 = *ptr++; if ( !IsTransparent(a2) && !IsOpaque(a2) ) { // not fully opaque nor fully transparent, hence need alpha return Transparency_Alpha; } } // during the next loop iteration check all the pixels in the row x = 0; } // mask will be enough return Transparency_Mask; } unsigned char *InitAlpha(wxImage *image, png_uint_32 x, png_uint_32 y) { // create alpha channel image->SetAlpha(); unsigned char *alpha = image->GetAlpha(); // set alpha for the pixels we had so far png_uint_32 end = y * image->GetWidth() + x; for ( png_uint_32 i = 0; i < end; i++ ) { // all the previous pixels were opaque *alpha++ = 0xff; } return alpha; } void FindMaskColour(unsigned char **lines, png_uint_32 width, png_uint_32 height, unsigned char& rMask, unsigned char& gMask, unsigned char& bMask) { // choosing the colour for the mask is more // difficult: we need to iterate over the entire // image for this in order to choose an unused // colour (this is not very efficient but what else // can we do?) wxImageHistogram h; unsigned nentries = 0; unsigned char r2, g2, b2; for ( png_uint_32 y2 = 0; y2 < height; y2++ ) { const unsigned char *p = lines[y2]; for ( png_uint_32 x2 = 0; x2 < width; x2++ ) { r2 = *p++; g2 = *p++; b2 = *p++; ++p; // jump over alpha wxImageHistogramEntry& entry = h[wxImageHistogram:: MakeKey(r2, g2, b2)]; if ( entry.value++ == 0 ) entry.index = nentries++; } } if ( !h.FindFirstUnusedColour(&rMask, &gMask, &bMask) ) { wxLogWarning(_("Too many colours in PNG, the image may be slightly blurred.")); // use a fixed mask colour and we'll fudge // the real pixels with this colour (see // below) rMask = 0xfe; gMask = 0; bMask = 0xff; } } // ---------------------------------------------------------------------------- // reading PNGs // ---------------------------------------------------------------------------- bool wxPNGHandler::DoCanRead( wxInputStream& stream ) { unsigned char hdr[4]; if ( !stream.Read(hdr, WXSIZEOF(hdr)) ) return false; return memcmp(hdr, "\211PNG", WXSIZEOF(hdr)) == 0; } // convert data from RGB to wxImage format static void CopyDataFromPNG(wxImage *image, unsigned char **lines, png_uint_32 width, png_uint_32 height, int color_type) { Transparency transparency = Transparency_None; // only non NULL if transparency == Transparency_Alpha unsigned char *alpha = NULL; // RGB of the mask colour if transparency == Transparency_Mask // (but init them anyhow to avoid compiler warnings) unsigned char rMask = 0, gMask = 0, bMask = 0; unsigned char *ptrDst = image->GetData(); if ( !(color_type & PNG_COLOR_MASK_COLOR) ) { // grey image: GAGAGA... where G == grey component and A == alpha for ( png_uint_32 y = 0; y < height; y++ ) { const unsigned char *ptrSrc = lines[y]; for ( png_uint_32 x = 0; x < width; x++ ) { unsigned char g = *ptrSrc++; unsigned char a = *ptrSrc++; // the first time we encounter a transparent pixel we must // decide about what to do about them if ( !IsOpaque(a) && transparency == Transparency_None ) { // we'll need at least the mask for this image and // maybe even full alpha channel info: the former is // only enough if we have alpha values of 0 and 0xff // only, otherwisewe need the latter transparency = CheckTransparency ( lines, x, y, width, height, 1 ); if ( transparency == Transparency_Mask ) { // let's choose this colour for the mask: this is // not a problem here as all the other pixels are // grey, i.e. R == G == B which is not the case for // this one so no confusion is possible rMask = 0xff; gMask = 0; bMask = 0xff; } else // transparency == Transparency_Alpha { alpha = InitAlpha(image, x, y); } } switch ( transparency ) { case Transparency_Mask: if ( IsTransparent(a) ) { *ptrDst++ = rMask; *ptrDst++ = gMask; *ptrDst++ = bMask; 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") ); // fall through case Transparency_Alpha: if ( alpha ) *alpha++ = a; // fall through case Transparency_None: *ptrDst++ = g; *ptrDst++ = g; *ptrDst++ = g; break; } } } } else // colour image: RGBRGB... { for ( png_uint_32 y = 0; y < height; y++ ) { const unsigned char *ptrSrc = lines[y]; for ( png_uint_32 x = 0; x < width; x++ ) { unsigned char r = *ptrSrc++; unsigned char g = *ptrSrc++; unsigned char b = *ptrSrc++; unsigned char a = *ptrSrc++; // the logic here is the same as for the grey case except // where noted if ( !IsOpaque(a) && transparency == Transparency_None ) { transparency = CheckTransparency ( lines, x, y, width, height, 3 ); if ( transparency == Transparency_Mask ) { FindMaskColour(lines, width, height, rMask, gMask, bMask); } else // transparency == Transparency_Alpha { alpha = InitAlpha(image, x, y); } } switch ( transparency ) { case Transparency_Mask: if ( IsTransparent(a) ) { *ptrDst++ = rMask; *ptrDst++ = gMask; *ptrDst++ = bMask; 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") ); // if we couldn't find a unique colour for the // mask, we can have real pixels with the same // value as the mask and it's better to slightly // change their colour than to make them // transparent if ( r == rMask && g == gMask && b == bMask ) { r++; } } // fall through case Transparency_Alpha: if ( alpha ) *alpha++ = a; // fall through case Transparency_None: *ptrDst++ = r; *ptrDst++ = g; *ptrDst++ = b; break; } } } } if ( transparency == Transparency_Mask ) { image->SetMaskColour(rMask, gMask, bMask); } } // temporarily disable the warning C4611 (interaction between '_setjmp' and // C++ object destruction is non-portable) - I don't see any dtors here #ifdef __VISUALC__ #pragma warning(disable:4611) #endif /* VC++ */ bool wxPNGHandler::LoadFile(wxImage *image, wxInputStream& stream, bool verbose, int WXUNUSED(index)) { // 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; png_uint_32 i, width, height = 0; int bit_depth, color_type, interlace_type; wxinfo.verbose = verbose; wxinfo.stream.in = &stream; image->Destroy(); png_structp png_ptr = png_create_read_struct ( PNG_LIBPNG_VER_STRING, NULL, wx_png_error, wx_png_warning ); if (!png_ptr) goto error; // NB: please see the comment near wxPNGInfoStruct declaration for // explanation why this line is mandatory png_set_read_fn( png_ptr, &wxinfo, wx_PNG_stream_reader); info_ptr = png_create_info_struct( png_ptr ); if (!info_ptr) goto error; if (setjmp(wxinfo.jmpbuf)) goto error; 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 ); if (color_type == PNG_COLOR_TYPE_PALETTE) png_set_expand( png_ptr ); // Fix for Bug [ 439207 ] Monochrome PNG images come up black if (bit_depth < 8) png_set_expand( png_ptr ); png_set_strip_16( png_ptr ); png_set_packing( png_ptr ); if (png_get_valid( png_ptr, info_ptr, PNG_INFO_tRNS)) png_set_expand( png_ptr ); png_set_filler( png_ptr, 0xff, PNG_FILLER_AFTER ); image->Create((int)width, (int)height, (bool) false /* no need to init pixels */); if (!image->Ok()) goto error; // 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) goto error; } png_read_image( png_ptr, lines ); png_read_end( png_ptr, info_ptr ); #if wxUSE_PALETTE if (color_type == PNG_COLOR_TYPE_PALETTE) { int ncolors = 0; png_colorp palette; png_get_PLTE( png_ptr, info_ptr, &palette, &ncolors); unsigned char* r = new unsigned char[ncolors]; unsigned char* g = new unsigned char[ncolors]; unsigned char* b = new unsigned char[ncolors]; int j; for (j = 0; j < ncolors; j++) { r[j] = palette[j].red; g[j] = palette[j].green; b[j] = palette[j].blue; } image->SetPalette(wxPalette(ncolors, 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 CopyDataFromPNG(image, lines, width, height, color_type); for ( i = 0; i < height; i++ ) free( lines[i] ); free( lines ); return true; error: if (verbose) wxLogError(_("Couldn't load a PNG image - file is corrupted or not enough memory.")); if ( image->Ok() ) { image->Destroy(); } if ( lines ) { for ( unsigned int n = 0; n < height; n++ ) free( lines[n] ); free( lines ); } if ( png_ptr ) { if ( info_ptr ) { png_destroy_read_struct( &png_ptr, &info_ptr, (png_infopp) NULL ); free(info_ptr); } else png_destroy_read_struct( &png_ptr, (png_infopp) NULL, (png_infopp) NULL ); } return false; } // ---------------------------------------------------------------------------- // writing PNGs // ---------------------------------------------------------------------------- bool wxPNGHandler::SaveFile( wxImage *image, wxOutputStream& stream, bool verbose ) { wxPNGInfoStruct wxinfo; wxinfo.verbose = verbose; wxinfo.stream.out = &stream; png_structp png_ptr = png_create_write_struct ( PNG_LIBPNG_VER_STRING, NULL, wx_png_error, wx_png_warning ); if (!png_ptr) { if (verbose) wxLogError(_("Couldn't save PNG image.")); return false; } png_infop info_ptr = png_create_info_struct(png_ptr); if (info_ptr == NULL) { png_destroy_write_struct( &png_ptr, (png_infopp)NULL ); if (verbose) wxLogError(_("Couldn't save PNG image.")); return false; } if (setjmp(wxinfo.jmpbuf)) { png_destroy_write_struct( &png_ptr, (png_infopp)NULL ); if (verbose) wxLogError(_("Couldn't save PNG image.")); return false; } // NB: please see the comment near wxPNGInfoStruct declaration for // explanation why this line is mandatory png_set_write_fn( png_ptr, &wxinfo, wx_PNG_stream_writer, NULL); const int iColorType = image->HasOption(wxIMAGE_OPTION_PNG_FORMAT) ? image->GetOptionInt(wxIMAGE_OPTION_PNG_FORMAT) : wxPNG_TYPE_COLOUR; const int iBitDepth = image->HasOption(wxIMAGE_OPTION_PNG_BITDEPTH) ? image->GetOptionInt(wxIMAGE_OPTION_PNG_BITDEPTH) : 8; wxASSERT_MSG( iBitDepth == 8 || iBitDepth == 16, _T("PNG bit depth must be 8 or 16") ); bool bHasAlpha = image->HasAlpha(); bool bHasMask = image->HasMask(); bool bUseAlpha = bHasAlpha || bHasMask; int iPngColorType; 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; } 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; 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 ( iPngColorType & PNG_COLOR_MASK_ALPHA ) { sig_bit.alpha = (png_byte)iBitDepth; iElements++; } if ( iBitDepth == 16 ) iElements *= 2; 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() * iElements ); if ( !data ) { png_destroy_write_struct( &png_ptr, (png_infopp)NULL ); return false; } unsigned char * pAlpha = (unsigned char *)(bHasAlpha ? image->GetAlpha() : NULL); int iHeight = image->GetHeight(); int iWidth = image->GetWidth(); unsigned char uchMaskRed = 0, uchMaskGreen = 0, uchMaskBlue = 0; if ( bHasMask ) { uchMaskRed = image->GetMaskRed(); uchMaskGreen = image->GetMaskGreen(); uchMaskBlue = image->GetMaskBlue(); } unsigned char *pColors = image->GetData(); for (int y = 0; y != iHeight; ++y) { unsigned char *pData = data; for (int x = 0; x != iWidth; x++) { unsigned char uchRed = *pColors++; unsigned char uchGreen = *pColors++; unsigned char uchBlue = *pColors++; switch ( iColorType ) { default: wxFAIL_MSG( _T("unknown wxPNG_TYPE_XXX") ); // fall through case wxPNG_TYPE_COLOUR: *pData++ = uchRed; if ( iBitDepth == 16 ) *pData++ = 0; *pData++ = uchGreen; if ( iBitDepth == 16 ) *pData++ = 0; *pData++ = uchBlue; 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)uchRed + 150.272*(unsigned)uchGreen + 36.864*(unsigned)uchBlue); *pData++ = (unsigned char)((uiColor >> 8) & 0xFF); if ( iBitDepth == 16 ) *pData++ = (unsigned char)(uiColor & 0xFF); } break; case wxPNG_TYPE_GREY_RED: *pData++ = uchRed; if ( iBitDepth == 16 ) *pData++ = 0; break; } if ( bUseAlpha ) { unsigned char uchAlpha = 255; if ( bHasAlpha ) uchAlpha = *pAlpha++; if ( bHasMask ) { if ( (uchRed == uchMaskRed) && (uchGreen == uchMaskGreen) && (uchBlue == uchMaskBlue) ) uchAlpha = 0; } *pData++ = uchAlpha; if ( iBitDepth == 16 ) *pData++ = 0; } } png_bytep row_ptr = data; png_write_rows( png_ptr, &row_ptr, 1 ); } free(data); png_write_end( png_ptr, info_ptr ); png_destroy_write_struct( &png_ptr, (png_infopp)&info_ptr ); return true; } #ifdef __VISUALC__ #pragma warning(default:4611) #endif /* VC++ */ #endif // wxUSE_STREAMS #endif // wxUSE_LIBPNG