make BitmapPalette a COW type

so we can avoid copying it during rendering

Change-Id: Id83d2bb2682f46188ee6ccc90c92d338a1e05b98
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/120759
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

8 files changed, 256 insertions, 144 deletions

diff --git a/include/vcl/BitmapBuffer.hxx b/include/vcl/BitmapBuffer.hxx
index 7468cb987f95..d67e42ac6cad 100644
--- a/include/vcl/BitmapBuffer.hxx
+++ b/include/vcl/BitmapBuffer.hxx
@@ -23,6 +23,7 @@
 #include <sal/config.h>
 
 #include <memory>
+#include <optional>
 
 #include <vcl/dllapi.h>
 #include <vcl/BitmapPalette.hxx>
@@ -46,7 +47,7 @@ struct VCL_DLLPUBLIC BitmapBuffer
 
 VCL_DLLPUBLIC std::unique_ptr<BitmapBuffer> StretchAndConvert(
     const BitmapBuffer& rSrcBuffer, const SalTwoRect& rTwoRect,
-    ScanlineFormat nDstBitmapFormat, const BitmapPalette* pDstPal = nullptr, const ColorMask* pDstMask = nullptr );
+    ScanlineFormat nDstBitmapFormat, std::optional<BitmapPalette> pDstPal = std::nullopt, const ColorMask* pDstMask = nullptr );
 
 #endif // INCLUDED_VCL_BITMAPBUFFER_HXX
 
diff --git a/include/vcl/BitmapPalette.hxx b/include/vcl/BitmapPalette.hxx
index 046bd6c20f0a..53de5276b282 100644
--- a/include/vcl/BitmapPalette.hxx
+++ b/include/vcl/BitmapPalette.hxx
@@ -17,127 +17,63 @@
  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  */
 
-#ifndef INCLUDED_VCL_BITMAPPALETTE_HXX
-#define INCLUDED_VCL_BITMAPPALETTE_HXX
+#pragma once
 
 #include <vcl/dllapi.h>
 #include <vcl/BitmapColor.hxx>
 #include <vcl/checksum.hxx>
 #include <vector>
+#include <o3tl/cow_wrapper.hxx>
+
+class ImplBitmapPalette;
 
 class VCL_DLLPUBLIC BitmapPalette
 {
     friend class SalBitmap;
     friend class BitmapAccess;
 
-private:
-
-    std::vector<BitmapColor> maBitmapColor;
-
 public:
 
-    SAL_DLLPRIVATE const BitmapColor* ImplGetColorBuffer() const
-    {
-        return maBitmapColor.data();
-    }
+    SAL_DLLPRIVATE const BitmapColor* ImplGetColorBuffer() const;
 
-    SAL_DLLPRIVATE BitmapColor* ImplGetColorBuffer()
-    {
-        return maBitmapColor.data();
-    }
+    SAL_DLLPRIVATE BitmapColor* ImplGetColorBuffer();
 
-    BitmapChecksum GetChecksum() const
-    {
-        return vcl_get_checksum(0, maBitmapColor.data(), maBitmapColor.size() * sizeof(BitmapColor));
-    }
+    BitmapChecksum GetChecksum() const;
 
-public:
+    BitmapPalette();
+    BitmapPalette( const BitmapPalette& );
+    BitmapPalette( BitmapPalette&& ) noexcept;
+    BitmapPalette(std::initializer_list<BitmapColor> aBitmapColor);
+    explicit BitmapPalette(sal_uInt16 nCount);
+    ~BitmapPalette();
 
-    BitmapPalette()
-    {
-    }
-
-    BitmapPalette(std::initializer_list<BitmapColor> aBitmapColor) : maBitmapColor(aBitmapColor)
-    {
-    }
-
-    BitmapPalette(sal_uInt16 nCount)
-        : maBitmapColor(nCount)
-    {
-    }
-
-    bool operator==( const BitmapPalette& rBitmapPalette ) const
-    {
-        return maBitmapColor == rBitmapPalette.maBitmapColor;
-    }
+    BitmapPalette& operator=( const BitmapPalette& );
+    BitmapPalette& operator=( BitmapPalette&& ) noexcept;
 
+    bool operator==( const BitmapPalette& rBitmapPalette ) const;
     bool operator!=(const BitmapPalette& rBitmapPalette) const
     {
         return !( *this == rBitmapPalette );
     }
+    bool operator!() const;
 
-    bool operator!() const
-    {
-        return maBitmapColor.empty();
-    }
-
-    sal_uInt16 GetEntryCount() const
-    {
-        return maBitmapColor.size();
-    }
-
-    void SetEntryCount(sal_uInt16 nCount)
-    {
-        maBitmapColor.resize(nCount);
-    }
-
-    const BitmapColor& operator[](sal_uInt16 nIndex) const
-    {
-        assert(nIndex < maBitmapColor.size() && "Palette index is out of range");
-        return maBitmapColor[nIndex];
-    }
+    sal_uInt16 GetEntryCount() const;
+    void SetEntryCount(sal_uInt16 nCount);
 
-    BitmapColor& operator[](sal_uInt16 nIndex)
-    {
-        assert(nIndex < maBitmapColor.size() && "Palette index is out of range");
-        return maBitmapColor[nIndex];
-    }
+    const BitmapColor& operator[](sal_uInt16 nIndex) const;
+    BitmapColor& operator[](sal_uInt16 nIndex);
 
-    sal_uInt16 GetBestIndex(const BitmapColor& rCol) const
-    {
-        sal_uInt16 nRetIndex = 0;
-
-        if (!maBitmapColor.empty())
-        {
-            for (size_t j = 0; j < maBitmapColor.size(); ++j)
-            {
-                if (rCol == maBitmapColor[j])
-                {
-                    return j;
-                }
-            }
-
-            sal_uInt16 nLastErr = SAL_MAX_UINT16;
-            for (size_t i = 0; i < maBitmapColor.size(); ++i)
-            {
-                const sal_uInt16 nActErr = rCol.GetColorError(maBitmapColor[i]);
-                if ( nActErr < nLastErr )
-                {
-                    nLastErr = nActErr;
-                    nRetIndex = i;
-                }
-            }
-        }
-
-        return nRetIndex;
-    }
+    sal_uInt16 GetBestIndex(const BitmapColor& rCol) const;
 
     /// Returns true if the palette is 8-bit grey palette.
     bool IsGreyPalette8Bit() const;
     /// Returns true if the palette is a grey palette (may not be 8-bit).
     bool IsGreyPaletteAny() const;
-};
 
-#endif // INCLUDED_VCL_BITMAPPALETTE_HXX
+    typedef o3tl::cow_wrapper< ImplBitmapPalette > ImplType;
+
+private:
+    ImplType mpImpl;
+};
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/vcl/Library_vcl.mk b/vcl/Library_vcl.mk
index c7a0e5c48986..eb0af8aa8cc4 100644
--- a/vcl/Library_vcl.mk
+++ b/vcl/Library_vcl.mk
@@ -320,6 +320,7 @@ $(eval $(call gb_Library_add_exception_objects,vcl,\
     vcl/source/graphic/VectorGraphicLoader \
     vcl/source/bitmap/impvect \
     vcl/source/bitmap/bitmap \
+    vcl/source/bitmap/bitmappalette \
     vcl/source/bitmap/BitmapEx \
     vcl/source/bitmap/BitmapInfoAccess \
     vcl/source/bitmap/BitmapReadAccess \
diff --git a/vcl/source/bitmap/bitmap.cxx b/vcl/source/bitmap/bitmap.cxx
index e688296aa606..07f2c7bf8219 100644
--- a/vcl/source/bitmap/bitmap.cxx
+++ b/vcl/source/bitmap/bitmap.cxx
@@ -229,46 +229,6 @@ const BitmapPalette& Bitmap::GetGreyPalette( int nEntries )
     return GetGreyPalette(2);
 }
 
-bool BitmapPalette::IsGreyPaletteAny() const
-{
-    const int nEntryCount = GetEntryCount();
-    if( !nEntryCount ) // NOTE: an empty palette means 1:1 mapping
-        return true;
-    // See above: only certain entry values will result in a valid call to GetGreyPalette
-    if( nEntryCount == 2 || nEntryCount == 4 || nEntryCount == 16 || nEntryCount == 256 )
-    {
-        const BitmapPalette& rGreyPalette = Bitmap::GetGreyPalette( nEntryCount );
-        if( rGreyPalette == *this )
-            return true;
-    }
-
-    bool bRet = false;
-    // TODO: is it worth to compare the entries for the general case?
-    if (nEntryCount == 2)
-    {
-       const BitmapColor& rCol0(maBitmapColor[0]);
-       const BitmapColor& rCol1(maBitmapColor[1]);
-       bRet = rCol0.GetRed() == rCol0.GetGreen() && rCol0.GetRed() == rCol0.GetBlue() &&
-              rCol1.GetRed() == rCol1.GetGreen() && rCol1.GetRed() == rCol1.GetBlue();
-    }
-    return bRet;
-}
-
-bool BitmapPalette::IsGreyPalette8Bit() const
-{
-    const int nEntryCount = GetEntryCount();
-    if( !nEntryCount ) // NOTE: an empty palette means 1:1 mapping
-        return true;
-    if( nEntryCount != 256 )
-        return false;
-    for (sal_uInt16 i = 0; i < 256; ++i)
-    {
-        if( maBitmapColor[i] != BitmapColor(i, i, i))
-            return false;
-    }
-    return true;
-}
-
 Bitmap& Bitmap::operator=( const Bitmap& rBitmap )
 {
     if (this == &rBitmap)
diff --git a/vcl/source/bitmap/bitmappalette.cxx b/vcl/source/bitmap/bitmappalette.cxx
new file mode 100644
index 000000000000..e782e34ba1a8
--- /dev/null
+++ b/vcl/source/bitmap/bitmappalette.cxx
@@ -0,0 +1,215 @@
+/* -*- 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 <config_features.h>
+
+#include <sal/log.hxx>
+#include <osl/diagnose.h>
+#include <tools/helpers.hxx>
+
+#include <vcl/BitmapPalette.hxx>
+#include <vcl/bitmapex.hxx>
+#include <vcl/outdev.hxx>
+
+#include <svdata.hxx>
+#include <salinst.hxx>
+
+class ImplBitmapPalette
+{
+public:
+    ImplBitmapPalette(std::initializer_list<BitmapColor> aBitmapColor)
+        : maBitmapColor(aBitmapColor)
+    {
+    }
+    ImplBitmapPalette() {}
+    ImplBitmapPalette(sal_uInt16 nCount)
+        : maBitmapColor(nCount)
+    {
+    }
+    std::vector<BitmapColor>& GetBitmapData() { return maBitmapColor; }
+    const std::vector<BitmapColor>& GetBitmapData() const { return maBitmapColor; }
+    bool operator==(const ImplBitmapPalette& rBitmapPalette) const
+    {
+        return maBitmapColor == rBitmapPalette.maBitmapColor;
+    }
+
+private:
+    std::vector<BitmapColor> maBitmapColor;
+};
+
+namespace
+{
+BitmapPalette::ImplType& GetGlobalDefault()
+{
+    static BitmapPalette::ImplType gDefault;
+    return gDefault;
+}
+}
+
+BitmapPalette::BitmapPalette()
+    : mpImpl(GetGlobalDefault())
+{
+}
+
+BitmapPalette::BitmapPalette(const BitmapPalette& rOther)
+    : mpImpl(rOther.mpImpl)
+{
+}
+
+BitmapPalette::BitmapPalette(BitmapPalette&& rOther) noexcept
+    : mpImpl(std::move(rOther.mpImpl))
+{
+}
+
+BitmapPalette::BitmapPalette(std::initializer_list<BitmapColor> aBitmapColor)
+    : mpImpl(aBitmapColor)
+{
+}
+
+BitmapPalette::BitmapPalette(sal_uInt16 nCount)
+    : mpImpl(nCount)
+{
+}
+
+BitmapPalette::~BitmapPalette() {}
+
+BitmapPalette& BitmapPalette::operator=(const BitmapPalette& rOther)
+{
+    mpImpl = rOther.mpImpl;
+    return *this;
+}
+
+BitmapPalette& BitmapPalette::operator=(BitmapPalette&& rOther) noexcept
+{
+    mpImpl = std::move(rOther.mpImpl);
+    return *this;
+}
+
+SAL_DLLPRIVATE const BitmapColor* BitmapPalette::ImplGetColorBuffer() const
+{
+    return mpImpl->GetBitmapData().data();
+}
+
+SAL_DLLPRIVATE BitmapColor* BitmapPalette::ImplGetColorBuffer()
+{
+    return mpImpl->GetBitmapData().data();
+}
+
+BitmapChecksum BitmapPalette::GetChecksum() const
+{
+    auto const& rBitmapData = mpImpl->GetBitmapData();
+    return vcl_get_checksum(0, rBitmapData.data(), rBitmapData.size() * sizeof(BitmapColor));
+}
+
+bool BitmapPalette::operator==(const BitmapPalette& rOther) const
+{
+    return mpImpl == rOther.mpImpl;
+}
+
+bool BitmapPalette::operator!() const { return mpImpl->GetBitmapData().empty(); }
+
+sal_uInt16 BitmapPalette::GetEntryCount() const { return mpImpl->GetBitmapData().size(); }
+
+void BitmapPalette::SetEntryCount(sal_uInt16 nCount) { mpImpl->GetBitmapData().resize(nCount); }
+
+const BitmapColor& BitmapPalette::operator[](sal_uInt16 nIndex) const
+{
+    assert(nIndex < mpImpl->GetBitmapData().size() && "Palette index is out of range");
+    return mpImpl->GetBitmapData()[nIndex];
+}
+
+BitmapColor& BitmapPalette::operator[](sal_uInt16 nIndex)
+{
+    assert(nIndex < mpImpl->GetBitmapData().size() && "Palette index is out of range");
+    return mpImpl->GetBitmapData()[nIndex];
+}
+
+sal_uInt16 BitmapPalette::GetBestIndex(const BitmapColor& rCol) const
+{
+    auto const& rBitmapColor = mpImpl->GetBitmapData();
+    sal_uInt16 nRetIndex = 0;
+
+    if (!rBitmapColor.empty())
+    {
+        for (size_t j = 0; j < rBitmapColor.size(); ++j)
+        {
+            if (rCol == rBitmapColor[j])
+            {
+                return j;
+            }
+        }
+
+        sal_uInt16 nLastErr = SAL_MAX_UINT16;
+        for (size_t i = 0; i < rBitmapColor.size(); ++i)
+        {
+            const sal_uInt16 nActErr = rCol.GetColorError(rBitmapColor[i]);
+            if (nActErr < nLastErr)
+            {
+                nLastErr = nActErr;
+                nRetIndex = i;
+            }
+        }
+    }
+
+    return nRetIndex;
+}
+
+bool BitmapPalette::IsGreyPaletteAny() const
+{
+    auto const& rBitmapColor = mpImpl->GetBitmapData();
+    const int nEntryCount = GetEntryCount();
+    if (!nEntryCount) // NOTE: an empty palette means 1:1 mapping
+        return true;
+    // See above: only certain entry values will result in a valid call to GetGreyPalette
+    if (nEntryCount == 2 || nEntryCount == 4 || nEntryCount == 16 || nEntryCount == 256)
+    {
+        const BitmapPalette& rGreyPalette = Bitmap::GetGreyPalette(nEntryCount);
+        if (rGreyPalette == *this)
+            return true;
+    }
+
+    bool bRet = false;
+    // TODO: is it worth to compare the entries for the general case?
+    if (nEntryCount == 2)
+    {
+        const BitmapColor& rCol0(rBitmapColor[0]);
+        const BitmapColor& rCol1(rBitmapColor[1]);
+        bRet = rCol0.GetRed() == rCol0.GetGreen() && rCol0.GetRed() == rCol0.GetBlue()
+               && rCol1.GetRed() == rCol1.GetGreen() && rCol1.GetRed() == rCol1.GetBlue();
+    }
+    return bRet;
+}
+
+bool BitmapPalette::IsGreyPalette8Bit() const
+{
+    auto const& rBitmapColor = mpImpl->GetBitmapData();
+    const int nEntryCount = GetEntryCount();
+    if (!nEntryCount) // NOTE: an empty palette means 1:1 mapping
+        return true;
+    if (nEntryCount != 256)
+        return false;
+    for (sal_uInt16 i = 0; i < 256; ++i)
+    {
+        if (rBitmapColor[i] != BitmapColor(i, i, i))
+            return false;
+    }
+    return true;
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/vcl/source/gdi/salmisc.cxx b/vcl/source/gdi/salmisc.cxx
index 037ea8073bae..17161420dc4a 100644
--- a/vcl/source/gdi/salmisc.cxx
+++ b/vcl/source/gdi/salmisc.cxx
@@ -228,7 +228,7 @@ static void ImplTCToPAL( const BitmapBuffer& rSrcBuffer, BitmapBuffer const & rD
 
 std::unique_ptr<BitmapBuffer> StretchAndConvert(
     const BitmapBuffer& rSrcBuffer, const SalTwoRect& rTwoRect,
-    ScanlineFormat nDstBitmapFormat, const BitmapPalette* pDstPal, const ColorMask* pDstMask )
+    ScanlineFormat nDstBitmapFormat, std::optional<BitmapPalette> pDstPal, const ColorMask* pDstMask )
 {
     FncGetPixel     pFncGetPixel;
     FncSetPixel     pFncSetPixel;
diff --git a/vcl/unx/generic/gdi/salbmp.cxx b/vcl/unx/generic/gdi/salbmp.cxx
index c73b40146eee..e3803a518d60 100644
--- a/vcl/unx/generic/gdi/salbmp.cxx
+++ b/vcl/unx/generic/gdi/salbmp.cxx
@@ -230,7 +230,7 @@ std::unique_ptr<BitmapBuffer> X11SalBitmap::ImplCreateDIB(
         {
             const SalTwoRect        aTwoRect = { 0, 0, nWidth, nHeight, 0, 0, nWidth, nHeight };
             BitmapBuffer            aSrcBuf;
-            const BitmapPalette*    pDstPal = nullptr;
+            std::optional<BitmapPalette> pDstPal;
 
             aSrcBuf.mnFormat = ScanlineFormat::TopDown;
             aSrcBuf.mnWidth = nWidth;
@@ -292,15 +292,13 @@ std::unique_ptr<BitmapBuffer> X11SalBitmap::ImplCreateDIB(
             if( aSrcBuf.mnBitCount == 1 )
             {
                 rPal.SetEntryCount( 2 );
-                pDstPal = &rPal;
-
                 rPal[ 0 ] = COL_BLACK;
                 rPal[ 1 ] = COL_WHITE;
+                pDstPal = rPal;
             }
             else if( pImage->depth == 8 && bGrey )
             {
                 rPal.SetEntryCount( 256 );
-                pDstPal = &rPal;
 
                 for( sal_uInt16 i = 0; i < 256; i++ )
                 {
@@ -311,6 +309,7 @@ std::unique_ptr<BitmapBuffer> X11SalBitmap::ImplCreateDIB(
                     rBmpCol.SetBlue( i );
                 }
 
+                pDstPal = rPal;
             }
             else if( aSrcBuf.mnBitCount <= 8 )
             {
@@ -319,7 +318,6 @@ std::unique_ptr<BitmapBuffer> X11SalBitmap::ImplCreateDIB(
                                                   sal_uLong(1) << nDrawableDepth);
 
                 rPal.SetEntryCount( nCols );
-                pDstPal = &rPal;
 
                 for( sal_uInt16 i = 0; i < nCols; i++ )
                 {
@@ -330,6 +328,7 @@ std::unique_ptr<BitmapBuffer> X11SalBitmap::ImplCreateDIB(
                     rBmpCol.SetGreen( nColor.GetGreen() );
                     rBmpCol.SetBlue( nColor.GetBlue() );
                 }
+                pDstPal = rPal;
             }
 
             pDIB = StretchAndConvert( aSrcBuf, aTwoRect, aSrcBuf.mnFormat,
@@ -379,7 +378,7 @@ XImage* X11SalBitmap::ImplCreateXImage(
         {
             std::unique_ptr<BitmapBuffer> pDstBuf;
             ScanlineFormat       nDstFormat = ScanlineFormat::TopDown;
-            std::unique_ptr<BitmapPalette> xPal;
+            std::optional<BitmapPalette> xPal;
             std::unique_ptr<ColorMask> xMask;
 
             switch( pImage->bits_per_pixel )
@@ -424,13 +423,13 @@ XImage* X11SalBitmap::ImplCreateXImage(
 
             if( pImage->depth == 1 )
             {
-                xPal.reset(new BitmapPalette( 2 ));
+                xPal.emplace(2);
                 (*xPal)[ 0 ] = COL_BLACK;
                 (*xPal)[ 1 ] = COL_WHITE;
             }
             else if( pImage->depth == 8 && mbGrey )
             {
-                xPal.reset(new BitmapPalette( 256 ));
+                xPal.emplace(256);
 
                 for( sal_uInt16 i = 0; i < 256; i++ )
                 {
@@ -449,7 +448,7 @@ XImage* X11SalBitmap::ImplCreateXImage(
                                             , static_cast<sal_uLong>(1 << pImage->depth)
                                             );
 
-                xPal.reset(new BitmapPalette( nCols ));
+                xPal.emplace(nCols);
 
                 for( sal_uInt16 i = 0; i < nCols; i++ )
                 {
@@ -462,7 +461,7 @@ XImage* X11SalBitmap::ImplCreateXImage(
                 }
             }
 
-            pDstBuf = StretchAndConvert( *mpDIB, rTwoRect, nDstFormat, xPal.get(), xMask.get() );
+            pDstBuf = StretchAndConvert( *mpDIB, rTwoRect, nDstFormat, xPal, xMask.get() );
             xPal.reset();
             xMask.reset();
 
diff --git a/vcl/win/gdi/salbmp.cxx b/vcl/win/gdi/salbmp.cxx
index 4602565ece51..3538b503f08d 100644
--- a/vcl/win/gdi/salbmp.cxx
+++ b/vcl/win/gdi/salbmp.cxx
@@ -353,7 +353,7 @@ std::shared_ptr<Gdiplus::Bitmap> WinSalBitmap::ImplCreateGdiPlusBitmap(const Win
             *pA,
             aSalTwoRect,
             ScanlineFormat::N8BitPal,
-            &rTargetPalette);
+            rTargetPalette);
 
         pSalA->ReleaseBuffer(pA, BitmapAccessMode::Read);
         pA = pExtraA.get();