imagpng.cpp

来自「A*算法 A*算法 A*算法 A*算法A*算法A*算法」· C++ 代码 · 共 848 行 · 第 1/2 页

                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++ = bMask;
                            *ptrDst++ = gMask;
                            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_uint_32 height = 0;
    png_infop info_ptr = (png_infop) NULL;
    wxPNGInfoStruct wxinfo;

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

    image->Destroy();

    png_structp png_ptr = png_create_read_struct
                          (
                            PNG_LIBPNG_VER_STRING,
                            (voidp) 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_uint_32 i, width;
    int bit_depth, color_type, interlace_type;

    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;

    lines = (unsigned char **)malloc( (size_t)(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)
        {
            for ( unsigned int n = 0; n < i; n++ )
                free( lines[n] );
            goto error;
        }
    }

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