Cache a static wavy line as bitmap and reuse it

DrawWaveLine is cpu costly so render it as big as
possible so we can only crop it
Edit:
1) Moved the Cache class to textline.cxx file
as it is local to that
2) Provided a custom hash method for the unordered_map
to avoid double hashing the key. Used boost:hash_combine
for hashing.
3) changed unordered_map to o3tl::lru_map

Change-Id: I0ab191f7bb72ccd5074c78858de9831c1a462b7b
Signed-off-by: merttumer <mert.tumer@collabora.com>
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/117362
Reviewed-by: Michael Meeks <michael.meeks@collabora.com>
Tested-by: Jenkins CollaboraOffice <jenkinscollaboraoffice@gmail.com>

1 files changed, 98 insertions, 3 deletions

diff --git a/vcl/source/outdev/textline.cxx b/vcl/source/outdev/textline.cxx
index e52b02410ebd..452a9dbfdfe9 100644
--- a/vcl/source/outdev/textline.cxx
+++ b/vcl/source/outdev/textline.cxx
@@ -25,6 +25,7 @@
 #include <vcl/outdev.hxx>
 #include <vcl/settings.hxx>
 #include <vcl/virdev.hxx>
+#include <vcl/lazydelete.hxx>
 
 #include <tools/helpers.hxx>
 
@@ -33,10 +34,70 @@
 
 #include <basegfx/matrix/b2dhommatrixtools.hxx>
 #include <basegfx/polygon/WaveLine.hxx>
+#include <boost/functional/hash.hpp>
+#include <o3tl/lru_map.hxx>
 
 #define UNDERLINE_LAST      LINESTYLE_BOLDWAVE
 #define STRIKEOUT_LAST      STRIKEOUT_X
 
+struct WavyLineCache final
+{
+    WavyLineCache () : m_aItems( 10 ) {}
+
+    bool find( Color aLineColor, size_t nLineWidth, size_t nWaveHeight, size_t nWordWidth, BitmapEx& rOutput )
+    {
+        Key aKey = { nWaveHeight, aLineColor.mValue };
+        auto item = m_aItems.find( aKey );
+        if ( item == m_aItems.end() )
+            return false;
+        // needs update
+        if ( item->second.m_aLineWidth != nLineWidth || item->second.m_aWordWidth < nWordWidth )
+        {
+            return false;
+        }
+        rOutput = item->second.m_Bitmap;
+        return true;
+    }
+
+    void insert( const BitmapEx& aBitmap, const Color& aLineColor, const size_t nLineWidth, const size_t nWaveHeight, const size_t nWordWidth, BitmapEx& rOutput )
+    {
+        Key aKey = { nWaveHeight, aLineColor.mValue };
+        m_aItems.insert( std::pair< Key, WavyLineCacheItem>( aKey, { nLineWidth, nWordWidth, aBitmap } ) );
+        rOutput = aBitmap;
+    }
+
+    private:
+    struct WavyLineCacheItem
+    {
+        size_t m_aLineWidth;
+        size_t m_aWordWidth;
+        BitmapEx m_Bitmap;
+    };
+
+    struct Key
+    {
+        size_t m_aFirst;
+        size_t m_aSecond;
+        bool operator ==( const Key& rOther ) const
+        {
+            return ( m_aFirst == rOther.m_aFirst && m_aSecond == rOther.m_aSecond );
+        }
+    };
+
+    struct Hash
+    {
+        size_t operator() ( const Key& rKey ) const
+        {
+            size_t aSeed = 0;
+            boost::hash_combine(aSeed, rKey.m_aFirst);
+            boost::hash_combine(aSeed, rKey.m_aSecond);
+            return aSeed;
+        }
+    };
+
+    o3tl::lru_map< Key, WavyLineCacheItem, Hash > m_aItems;
+};
+
 void OutputDevice::ImplInitTextLineSize()
 {
     mpFontInstance->mxFontMetric->ImplInitTextLineSize( this );
@@ -1000,6 +1061,43 @@ void OutputDevice::DrawWaveLine(const Point& rStartPos, const Point& rEndPos, lo
         nLineWidth = 1;
     }
 
+    if ( fOrientation == 0.0 )
+    {
+        static vcl::DeleteOnDeinit< WavyLineCache > snLineCache( new WavyLineCache() );
+        if ( !snLineCache.get() )
+            return;
+        WavyLineCache& rLineCache = *snLineCache.get();
+        BitmapEx aWavylinebmp;
+        if ( !rLineCache.find( GetLineColor(), nLineWidth, nWaveHeight, nEndX - nStartX, aWavylinebmp ) )
+        {
+            size_t nWordLength = nEndX - nStartX;
+            // start with something big to avoid updating it frequently
+            nWordLength = nWordLength < 1024 ? 1024 : nWordLength;
+            ScopedVclPtrInstance< VirtualDevice > pVirtDev( *this, DeviceFormat::DEFAULT,
+                                                           DeviceFormat::DEFAULT );
+            pVirtDev->SetAntialiasing( AntialiasingFlags::EnableB2dDraw );
+            pVirtDev->SetOutputSizePixel( Size( nWordLength, nWaveHeight * 2 ), false );
+            pVirtDev->SetLineColor( GetLineColor() );
+            pVirtDev->SetBackground( Wallpaper( COL_TRANSPARENT ) );
+            pVirtDev->ImplDrawWaveLineBezier( 0, 0, nWordLength, 0, nWaveHeight, fOrientation, nLineWidth );
+            rLineCache.insert( pVirtDev->GetBitmapEx( Point( 0, 0 ), pVirtDev->GetOutputSize() ), GetLineColor(), nLineWidth, nWaveHeight, nWordLength, aWavylinebmp );
+        }
+        if ( aWavylinebmp.ImplGetBitmapSalBitmap() != nullptr )
+        {
+            Size _size( nEndX - nStartX, aWavylinebmp.GetSizePixel().Height() );
+            DrawBitmapEx(Point( rStartPos.X(), rStartPos.Y() ), PixelToLogic( _size ), Point(), _size, aWavylinebmp);
+        }
+        return;
+    }
+
+    ImplDrawWaveLineBezier( nStartX, nStartY, nEndX, nEndY, nWaveHeight, fOrientation, nLineWidth );
+
+    if( mpAlphaVDev )
+        mpAlphaVDev->DrawWaveLine( rStartPos, rEndPos, nLineWidth );
+}
+
+void OutputDevice::ImplDrawWaveLineBezier(long nStartX, long nStartY, long nEndX, long nEndY, long nWaveHeight, double fOrientation, long nLineWidth)
+{
     const basegfx::B2DRectangle aWaveLineRectangle(nStartX, nStartY, nEndX, nEndY + nWaveHeight);
     const basegfx::B2DPolygon aWaveLinePolygon = basegfx::createWaveLinePolygon(aWaveLineRectangle);
     const basegfx::B2DHomMatrix aRotationMatrix = basegfx::utils::createRotateAroundPoint(nStartX, nStartY, basegfx::deg2rad(-fOrientation));
@@ -1018,9 +1116,6 @@ void OutputDevice::DrawWaveLine(const Point& rStartPos, const Point& rEndPos, lo
             basegfx::deg2rad(15.0),
             bPixelSnapHairline,
             this);
-
-    if( mpAlphaVDev )
-        mpAlphaVDev->DrawWaveLine( rStartPos, rEndPos, nLineWidth );
 }
 
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