vcl/source/bitmap/alpha.cxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
   3  * This file is part of the LibreOffice project.
   4  *
   5  * This Source Code Form is subject to the terms of the Mozilla Public
   6  * License, v. 2.0. If a copy of the MPL was not distributed with this
   7  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   8  *
   9  * This file incorporates work covered by the following license notice:
  10  *
  11  *   Licensed to the Apache Software Foundation (ASF) under one or more
  12  *   contributor license agreements. See the NOTICE file distributed
  13  *   with this work for additional information regarding copyright
  14  *   ownership. The ASF licenses this file to you under the Apache
  15  *   License, Version 2.0 (the "License"); you may not use this file
  16  *   except in compliance with the License. You may obtain a copy of
  17  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  18  */
  19
  20 #include <config_features.h>
  21
  22 #include <tools/color.hxx>
  23 #include <vcl/alpha.hxx>
  24
  25 #include <vcl/BitmapWriteAccess.hxx>
  26 #include <salinst.hxx>
  27 #include <svdata.hxx>
  28 #include <salbmp.hxx>
  29 #include <sal/log.hxx>
  30 #if HAVE_FEATURE_SKIA
  31 #include <vcl/skia/SkiaHelper.hxx>
  32 #endif
  33
  34
  35 AlphaMask::AlphaMask() = default;
  36
  37 AlphaMask::AlphaMask( const Bitmap& rBitmap ) :
  38     maBitmap( rBitmap )
  39 {
  40     if ( !rBitmap.IsEmpty() )
  41         maBitmap.Convert( BmpConversion::N8BitNoConversion );
  42 #if HAVE_FEATURE_SKIA
  43     // Related tdf#156866 force snapshot of alpha mask when using Skia
  44     // In release builds, tdf#156629 and tdf#156630 reappear in many
  45     // cases because a BitmapInfoAccess is in a debug block. So, instead
  46     // of relying on other code to a create a BitmapInfoAccess instance,
  47     // create one here to force the alpha mask to handle any pending
  48     // scaling and make the alpha mask immutable.
  49     else if ( SkiaHelper::isVCLSkiaEnabled() )
  50         BitmapInfoAccess aInfoAccess( maBitmap );
  51 #endif
  52     assert( (IsEmpty() || maBitmap.getPixelFormat() == vcl::PixelFormat::N8_BPP) && "alpha bitmap should be 8bpp" );
  53     assert( (IsEmpty() || maBitmap.HasGreyPalette8Bit()) && "alpha bitmap should have greyscale palette" );
  54 }
  55
  56 AlphaMask::AlphaMask( const AlphaMask& ) = default;
  57
  58 AlphaMask::AlphaMask( AlphaMask&& ) = default;
  59
  60 AlphaMask::AlphaMask( const Size& rSizePixel, const sal_uInt8* pEraseTransparency )
  61     : maBitmap(rSizePixel, vcl::PixelFormat::N8_BPP, &Bitmap::GetGreyPalette(256))
  62 {
  63     if( pEraseTransparency )
  64     {
  65         sal_uInt8 nAlpha = 255 - *pEraseTransparency;
  66         maBitmap.Erase( Color( nAlpha, nAlpha, nAlpha ) );
  67     }
  68     else
  69         maBitmap.Erase( COL_ALPHA_OPAQUE );
  70 }
  71
  72 AlphaMask::~AlphaMask() = default;
  73
  74 AlphaMask& AlphaMask::operator=( const Bitmap& rBitmap )
  75 {
  76     maBitmap = rBitmap;
  77
  78     if( !rBitmap.IsEmpty() )
  79         maBitmap.Convert( BmpConversion::N8BitNoConversion );
  80
  81     assert( maBitmap.getPixelFormat() == vcl::PixelFormat::N8_BPP && "alpha bitmap should be 8bpp" );
  82     assert( maBitmap.HasGreyPalette8Bit() && "alpha bitmap should have greyscale palette" );
  83
  84     return *this;
  85 }
  86
  87 void AlphaMask::Erase( sal_uInt8 cTransparency )
  88 {
  89     sal_uInt8 nAlpha = 255 - cTransparency;
  90     maBitmap.Erase( Color( nAlpha, nAlpha, nAlpha ) );
  91 }
  92
  93 void AlphaMask::BlendWith(const AlphaMask& rOther)
  94 {
  95     std::shared_ptr<SalBitmap> xImpBmp(ImplGetSVData()->mpDefInst->CreateSalBitmap());
  96     if (xImpBmp->Create(*maBitmap.ImplGetSalBitmap()) && xImpBmp->AlphaBlendWith(*rOther.maBitmap.ImplGetSalBitmap()))
  97     {
  98         maBitmap.ImplSetSalBitmap(xImpBmp);
  99         assert( maBitmap.getPixelFormat() == vcl::PixelFormat::N8_BPP && "alpha bitmap should be 8bpp" );
 100         assert( maBitmap.HasGreyPalette8Bit() && "alpha bitmap should have greyscale palette" );
 101         return;
 102     }
 103     BitmapScopedReadAccess pOtherAcc(rOther);
 104     BitmapScopedWriteAccess pAcc(*this);
 105     assert (pOtherAcc && pAcc && pOtherAcc->GetBitCount() == 8 && pAcc->GetBitCount() == 8 && "cannot BlendWith this combination");
 106     if (!(pOtherAcc && pAcc && pOtherAcc->GetBitCount() == 8 && pAcc->GetBitCount() == 8))
 107     {
 108         SAL_WARN("vcl", "cannot BlendWith this combination");
 109         return;
 110     }
 111
 112     const tools::Long nHeight = std::min(pOtherAcc->Height(), pAcc->Height());
 113     const tools::Long nWidth = std::min(pOtherAcc->Width(), pAcc->Width());
 114     for (tools::Long y = 0; y < nHeight; ++y)
 115     {
 116         Scanline scanline = pAcc->GetScanline( y );
 117         ConstScanline otherScanline = pOtherAcc->GetScanline( y );
 118         for (tools::Long x = 0; x < nWidth; ++x)
 119         {
 120             // Use sal_uInt16 for following multiplication
 121             const sal_uInt16 nGrey1 = *scanline;
 122             const sal_uInt16 nGrey2 = *otherScanline;
 123             // Awkward calculation because the original used transparency, and to replicate
 124             // the logic we need to translate into transparency, perform the original logic,
 125             // then translate back to alpha.
 126             // The original looked like:
 127             //   auto tmp = nGrey1 + nGrey2 - (nGrey1 * nGrey2 / 255)
 128             // which, when converted to using alpha looks like
 129             //   auto tmp = 255 - ((255 - nGrey1) + (255 - nGrey2) - (255 - nGrey1) * (255 - nGrey2) / 255);
 130             // which then simplifies to:
 131             auto tmp = nGrey1 * nGrey2 / 255;
 132             *scanline = static_cast<sal_uInt8>(tmp);
 133             ++scanline;
 134             ++otherScanline;
 135         }
 136     }
 137     pAcc.reset();
 138     assert( maBitmap.getPixelFormat() == vcl::PixelFormat::N8_BPP && "alpha bitmap should be 8bpp" );
 139     assert( maBitmap.HasGreyPalette8Bit() && "alpha bitmap should have greyscale palette" );
 140 }
 141
 142 bool AlphaMask::hasAlpha() const
 143 {
 144     // no content, no alpha
 145     if(IsEmpty())
 146         return false;
 147
 148     BitmapScopedReadAccess pAcc(*this);
 149     const tools::Long nHeight(pAcc->Height());
 150     const tools::Long nWidth(pAcc->Width());
 151
 152     // no content, no alpha
 153     if(0 == nHeight || 0 == nWidth)
 154         return false;
 155
 156     for (tools::Long y = 0; y < nHeight; ++y)
 157     {
 158         for (tools::Long x = 0; x < nWidth; ++x)
 159         {
 160             if (255 != pAcc->GetColor(y, x).GetRed())
 161             {
 162                 return true;
 163             }
 164         }
 165     }
 166
 167     return false;
 168 }
 169
 170 bool AlphaMask::AlphaCombineOr(const AlphaMask& rMask)
 171 {
 172     BitmapScopedReadAccess pMaskAcc(rMask);
 173     BitmapScopedWriteAccess pAcc(*this);
 174
 175     if (!pMaskAcc || !pAcc)
 176         return false;
 177
 178     assert (pMaskAcc->GetBitCount() == 8 && pAcc->GetBitCount() == 8);
 179
 180     const tools::Long nWidth = std::min(pMaskAcc->Width(), pAcc->Width());
 181     const tools::Long nHeight = std::min(pMaskAcc->Height(), pAcc->Height());
 182
 183     for (tools::Long nY = 0; nY < nHeight; nY++)
 184     {
 185         Scanline pScanline = pAcc->GetScanline(nY);
 186         ConstScanline pScanlineMask = pMaskAcc->GetScanline(nY);
 187         for (tools::Long nX = 0; nX < nWidth; nX++)
 188         {
 189             if (*pScanlineMask != 255 || *pScanline != 255)
 190                 *pScanline = 0;
 191             else
 192                 *pScanline = 255;
 193             ++pScanline;
 194             ++pScanlineMask;
 195         }
 196     }
 197
 198     return true;
 199 }
 200
 201 bool AlphaMask::Invert()
 202 {
 203     if (IsEmpty())
 204         return false;
 205     bool b = maBitmap.Invert();
 206     assert( maBitmap.getPixelFormat() == vcl::PixelFormat::N8_BPP && "alpha bitmap should be 8bpp" );
 207     assert( maBitmap.HasGreyPalette8Bit() && "alpha bitmap should have greyscale palette" );
 208     return b;
 209 }
 210
 211 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */