1 files changed, 209 insertions, 0 deletions
diff --git a/vcl/source/bitmap/alpha.cxx b/vcl/source/bitmap/alpha.cxx
new file mode 100644
index 0000000000..634fc3cdd6
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+++ b/vcl/source/bitmap/alpha.cxx
@@ -0,0 +1,209 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * This file incorporates work covered by the following license notice:
+ *
+ *   Licensed to the Apache Software Foundation (ASF) under one or more
+ *   contributor license agreements. See the NOTICE file distributed
+ *   with this work for additional information regarding copyright
+ *   ownership. The ASF licenses this file to you under the Apache
+ *   License, Version 2.0 (the "License"); you may not use this file
+ *   except in compliance with the License. You may obtain a copy of
+ *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
+ */
+
+#include <tools/color.hxx>
+#include <vcl/alpha.hxx>
+
+#include <vcl/BitmapWriteAccess.hxx>
+#include <salinst.hxx>
+#include <svdata.hxx>
+#include <salbmp.hxx>
+#include <sal/log.hxx>
+#if HAVE_FEATURE_SKIA
+#include <vcl/skia/SkiaHelper.hxx>
+#endif
+
+
+AlphaMask::AlphaMask() = default;
+
+AlphaMask::AlphaMask( const Bitmap& rBitmap ) :
+    maBitmap( rBitmap )
+{
+    if ( !rBitmap.IsEmpty() )
+        maBitmap.Convert( BmpConversion::N8BitNoConversion );
+#if HAVE_FEATURE_SKIA
+    // Related tdf#156866 force snapshot of alpha mask when using Skia
+    // In release builds, tdf#156629 and tdf#156630 reappear in many
+    // cases because a BitmapInfoAccess is in a debug block. So, instead
+    // of relying on other code to a create a BitmapInfoAccess instance,
+    // create one here to force the alpha mask to handle any pending
+    // scaling and make the alpha mask immutable.
+    else if ( SkiaHelper::isVCLSkiaEnabled() )
+        BitmapInfoAccess aInfoAccess( maBitmap );
+#endif
+    assert( (IsEmpty() || maBitmap.getPixelFormat() == vcl::PixelFormat::N8_BPP) && "alpha bitmap should be 8bpp" );
+    assert( (IsEmpty() || maBitmap.HasGreyPalette8Bit()) && "alpha bitmap should have greyscale palette" );
+}
+
+AlphaMask::AlphaMask( const AlphaMask& ) = default;
+
+AlphaMask::AlphaMask( AlphaMask&& ) = default;
+
+AlphaMask::AlphaMask( const Size& rSizePixel, const sal_uInt8* pEraseTransparency )
+    : maBitmap(rSizePixel, vcl::PixelFormat::N8_BPP, &Bitmap::GetGreyPalette(256))
+{
+    if( pEraseTransparency )
+    {
+        sal_uInt8 nAlpha = 255 - *pEraseTransparency;
+        maBitmap.Erase( Color( nAlpha, nAlpha, nAlpha ) );
+    }
+    else
+        maBitmap.Erase( COL_ALPHA_OPAQUE );
+}
+
+AlphaMask::~AlphaMask() = default;
+
+AlphaMask& AlphaMask::operator=( const Bitmap& rBitmap )
+{
+    maBitmap = rBitmap;
+
+    if( !rBitmap.IsEmpty() )
+        maBitmap.Convert( BmpConversion::N8BitNoConversion );
+
+    assert( maBitmap.getPixelFormat() == vcl::PixelFormat::N8_BPP && "alpha bitmap should be 8bpp" );
+    assert( maBitmap.HasGreyPalette8Bit() && "alpha bitmap should have greyscale palette" );
+
+    return *this;
+}
+
+void AlphaMask::Erase( sal_uInt8 cTransparency )
+{
+    sal_uInt8 nAlpha = 255 - cTransparency;
+    maBitmap.Erase( Color( nAlpha, nAlpha, nAlpha ) );
+}
+
+void AlphaMask::BlendWith(const AlphaMask& rOther)
+{
+    std::shared_ptr<SalBitmap> xImpBmp(ImplGetSVData()->mpDefInst->CreateSalBitmap());
+    if (xImpBmp->Create(*maBitmap.ImplGetSalBitmap()) && xImpBmp->AlphaBlendWith(*rOther.maBitmap.ImplGetSalBitmap()))
+    {
+        maBitmap.ImplSetSalBitmap(xImpBmp);
+        assert( maBitmap.getPixelFormat() == vcl::PixelFormat::N8_BPP && "alpha bitmap should be 8bpp" );
+        assert( maBitmap.HasGreyPalette8Bit() && "alpha bitmap should have greyscale palette" );
+        return;
+    }
+    BitmapScopedReadAccess pOtherAcc(rOther);
+    BitmapScopedWriteAccess pAcc(*this);
+    assert (pOtherAcc && pAcc && pOtherAcc->GetBitCount() == 8 && pAcc->GetBitCount() == 8 && "cannot BlendWith this combination");
+    if (!(pOtherAcc && pAcc && pOtherAcc->GetBitCount() == 8 && pAcc->GetBitCount() == 8))
+    {
+        SAL_WARN("vcl", "cannot BlendWith this combination");
+        return;
+    }
+
+    const tools::Long nHeight = std::min(pOtherAcc->Height(), pAcc->Height());
+    const tools::Long nWidth = std::min(pOtherAcc->Width(), pAcc->Width());
+    for (tools::Long y = 0; y < nHeight; ++y)
+    {
+        Scanline scanline = pAcc->GetScanline( y );
+        ConstScanline otherScanline = pOtherAcc->GetScanline( y );
+        for (tools::Long x = 0; x < nWidth; ++x)
+        {
+            // Use sal_uInt16 for following multiplication
+            const sal_uInt16 nGrey1 = *scanline;
+            const sal_uInt16 nGrey2 = *otherScanline;
+            // Awkward calculation because the original used transparency, and to replicate
+            // the logic we need to translate into transparency, perform the original logic,
+            // then translate back to alpha.
+            // The original looked like:
+            //   auto tmp = nGrey1 + nGrey2 - (nGrey1 * nGrey2 / 255)
+            // which, when converted to using alpha looks like
+            //   auto tmp = 255 - ((255 - nGrey1) + (255 - nGrey2) - (255 - nGrey1) * (255 - nGrey2) / 255);
+            // which then simplifies to:
+            auto tmp = nGrey1 * nGrey2 / 255;
+            *scanline = static_cast<sal_uInt8>(tmp);
+            ++scanline;
+            ++otherScanline;
+        }
+    }
+    pAcc.reset();
+    assert( maBitmap.getPixelFormat() == vcl::PixelFormat::N8_BPP && "alpha bitmap should be 8bpp" );
+    assert( maBitmap.HasGreyPalette8Bit() && "alpha bitmap should have greyscale palette" );
+}
+
+bool AlphaMask::hasAlpha() const
+{
+    // no content, no alpha
+    if(IsEmpty())
+        return false;
+
+    BitmapScopedReadAccess pAcc(*this);
+    const tools::Long nHeight(pAcc->Height());
+    const tools::Long nWidth(pAcc->Width());
+
+    // no content, no alpha
+    if(0 == nHeight || 0 == nWidth)
+        return false;
+
+    for (tools::Long y = 0; y < nHeight; ++y)
+    {
+        for (tools::Long x = 0; x < nWidth; ++x)
+        {
+            if (255 != pAcc->GetColor(y, x).GetRed())
+            {
+                return true;
+            }
+        }
+    }
+
+    return false;
+}
+
+bool AlphaMask::AlphaCombineOr(const AlphaMask& rMask)
+{
+    BitmapScopedReadAccess pMaskAcc(rMask);
+    BitmapScopedWriteAccess pAcc(*this);
+
+    if (!pMaskAcc || !pAcc)
+        return false;
+
+    assert (pMaskAcc->GetBitCount() == 8 && pAcc->GetBitCount() == 8);
+
+    const tools::Long nWidth = std::min(pMaskAcc->Width(), pAcc->Width());
+    const tools::Long nHeight = std::min(pMaskAcc->Height(), pAcc->Height());
+
+    for (tools::Long nY = 0; nY < nHeight; nY++)
+    {
+        Scanline pScanline = pAcc->GetScanline(nY);
+        ConstScanline pScanlineMask = pMaskAcc->GetScanline(nY);
+        for (tools::Long nX = 0; nX < nWidth; nX++)
+        {
+            if (*pScanlineMask != 255 || *pScanline != 255)
+                *pScanline = 0;
+            else
+                *pScanline = 255;
+            ++pScanline;
+            ++pScanlineMask;
+        }
+    }
+
+    return true;
+}
+
+bool AlphaMask::Invert()
+{
+    if (IsEmpty())
+        return false;
+    bool b = maBitmap.Invert();
+    assert( maBitmap.getPixelFormat() == vcl::PixelFormat::N8_BPP && "alpha bitmap should be 8bpp" );
+    assert( maBitmap.HasGreyPalette8Bit() && "alpha bitmap should have greyscale palette" );
+    return b;
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */