writer shadow: Avoid a whole load of unnecessary scaling.

Instead of always scaling the bitmap to the right dimensions, only enlarge it
when necessary, and crop it while painting by using DrawBitmapEx() that
accepts the source size.

Also use BMP_SCALE_FAST, it is enough here.

Change-Id: I702ea5c9f119257ab83d49cf050ce8840e50b196

sw/source/core/layout/paintfrm.cxx

@@ -5921,12 +5921,12 @@ sal_Bool SwPageFrm::IsLeftShadowNeeded() const
 enum PaintArea {LEFT, RIGHT, TOP, BOTTOM};
 
 /// Wrapper around pOut->DrawBitmapEx.
-static void lcl_paintBitmapExToRect(OutputDevice *pOut, Point aPoint, BitmapEx& rBitmapEx, PaintArea eArea)
+static void lcl_paintBitmapExToRect(OutputDevice *pOut, const Point& aPoint, const Size& aSize, const BitmapEx& rBitmapEx, PaintArea eArea)
 {
     // The problem is that if we get called multiple times and the color is
     // partly transparent, then the result will get darker and darker. To avoid
     // this, always paint the background color before doing the real paint.
-    Rectangle aRect(aPoint, rBitmapEx.GetSizePixel());
+    Rectangle aRect(aPoint, aSize);
 
     switch (eArea)
     {
@@ -5940,7 +5940,9 @@ static void lcl_paintBitmapExToRect(OutputDevice *pOut, Point aPoint, BitmapEx&
     pOut->SetLineColor();
     pOut->DrawRect(pOut->PixelToLogic(aRect));
 
-    pOut->DrawBitmapEx(pOut->PixelToLogic(aPoint), rBitmapEx);
+    pOut->DrawBitmapEx(pOut->PixelToLogic(aPoint), pOut->PixelToLogic(aSize),
+            Point(0, 0), aSize,
+            rBitmapEx);
 }
 
 /** paint page border and shadow
@@ -5957,7 +5959,8 @@ static void lcl_paintBitmapExToRect(OutputDevice *pOut, Point aPoint, BitmapEx&
                                                  bool bRightSidebar )
 {
     // No shadow in prefs
-    if( !SwViewOption::IsShadow() ) return;
+    if (!SwViewOption::IsShadow())
+        return;
 
     // #i16816# tagged pdf support
     SwTaggedPDFHelper aTaggedPDFHelper( 0, 0, 0, *_pViewShell->GetOut() );
@@ -5976,20 +5979,19 @@ static void lcl_paintBitmapExToRect(OutputDevice *pOut, Point aPoint, BitmapEx&
     static BitmapEx& aPageTopRightShadow = *aPageTopRightShadowObj.get();
     static BitmapEx& aPageBottomRightShadow = *aPageBottomRightShadowObj.get();
     static BitmapEx& aPageBottomLeftShadow = *aPageBottomLeftShadowObj.get();
-    static BitmapEx& aPageBottomShadowBase = *aPageBottomShadowBaseObj.get();
-    static BitmapEx& aPageRightShadowBase = *aPageRightShadowBaseObj.get();
-    static BitmapEx& aPageTopShadowBase = *aPageTopShadowBaseObj.get();
+    static BitmapEx& aPageBottomShadow = *aPageBottomShadowBaseObj.get();
+    static BitmapEx& aPageRightShadow = *aPageRightShadowBaseObj.get();
+    static BitmapEx& aPageTopShadow = *aPageTopShadowBaseObj.get();
     static BitmapEx& aPageTopLeftShadow = *aPageTopLeftShadowObj.get();
-    static BitmapEx& aPageLeftShadowBase = *aPageLeftShadowBaseObj.get();
+    static BitmapEx& aPageLeftShadow = *aPageLeftShadowBaseObj.get();
     static Color aShadowColor( COL_AUTO );
 
     SwRect aAlignedPageRect( _rPageRect );
     ::SwAlignRect( aAlignedPageRect, _pViewShell );
-    SwRect aPagePxRect =
-        _pViewShell->GetOut()->LogicToPixel( aAlignedPageRect.SVRect() );
-
+    SwRect aPagePxRect = _pViewShell->GetOut()->LogicToPixel( aAlignedPageRect.SVRect() );
 
-    if(aShadowColor != SwViewOption::GetShadowColor() ) {
+    if (aShadowColor != SwViewOption::GetShadowColor())
+    {
         aShadowColor = SwViewOption::GetShadowColor();
 
         AlphaMask aMask( shadowMask.getBottomRight().GetBitmap() );
@@ -6005,12 +6007,12 @@ static void lcl_paintBitmapExToRect(OutputDevice *pOut, Point aPoint, BitmapEx&
         aMask = AlphaMask( shadowMask.getBottom().GetBitmap() );
         aFilledSquare = Bitmap( aMask.GetSizePixel(), 24 );
         aFilledSquare.Erase( aShadowColor );
-        aPageBottomShadowBase = BitmapEx( aFilledSquare, aMask );
+        aPageBottomShadow = BitmapEx( aFilledSquare, aMask );
 
         aMask = AlphaMask( shadowMask.getTop().GetBitmap() );
         aFilledSquare = Bitmap( aMask.GetSizePixel(), 24 );
         aFilledSquare.Erase( aShadowColor );
-        aPageTopShadowBase = BitmapEx( aFilledSquare, aMask );
+        aPageTopShadow = BitmapEx( aFilledSquare, aMask );
 
         aMask = AlphaMask( shadowMask.getTopRight().GetBitmap() );
         aFilledSquare = Bitmap( aMask.GetSizePixel(), 24 );
@@ -6020,7 +6022,7 @@ static void lcl_paintBitmapExToRect(OutputDevice *pOut, Point aPoint, BitmapEx&
         aMask = AlphaMask( shadowMask.getRight().GetBitmap() );
         aFilledSquare = Bitmap( aMask.GetSizePixel(), 24 );
         aFilledSquare.Erase( aShadowColor );
-        aPageRightShadowBase = BitmapEx( aFilledSquare, aMask );
+        aPageRightShadow = BitmapEx( aFilledSquare, aMask );
 
         aMask = AlphaMask( shadowMask.getTopLeft().GetBitmap() );
         aFilledSquare = Bitmap( aMask.GetSizePixel(), 24 );
@@ -6030,7 +6032,7 @@ static void lcl_paintBitmapExToRect(OutputDevice *pOut, Point aPoint, BitmapEx&
         aMask = AlphaMask( shadowMask.getLeft().GetBitmap() );
         aFilledSquare = Bitmap( aMask.GetSizePixel(), 24 );
         aFilledSquare.Erase( aShadowColor );
-        aPageLeftShadowBase = BitmapEx( aFilledSquare, aMask );
+        aPageLeftShadow = BitmapEx( aFilledSquare, aMask );
     }
 
     SwRect aPaintRect;
@@ -6046,13 +6048,17 @@ static void lcl_paintBitmapExToRect(OutputDevice *pOut, Point aPoint, BitmapEx&
         pOut->DrawBitmapEx( pOut->PixelToLogic( Point( aPaintRect.Right(), aPagePxRect.Top() - mnShadowPxWidth ) ),
             aPageTopRightShadow );
 
-        if ( aPagePxRect.Height() > 2 * mnShadowPxWidth)
+        if (aPagePxRect.Height() > 2 * mnShadowPxWidth)
         {
-            BitmapEx aPageRightShadow = aPageRightShadowBase;
-            aPageRightShadow.Scale( 1, aPagePxRect.Height() - 2 * (mnShadowPxWidth - 1) );
-            lcl_paintBitmapExToRect( pOut, Point( aPaintRect.Right() + mnShadowPxWidth,
-                                                 aPagePxRect.Top() + mnShadowPxWidth - 1),
-                                     aPageRightShadow, RIGHT );
+            const long nWidth = aPageRightShadow.GetSizePixel().Width();
+            const long nHeight = aPagePxRect.Height() - 2 * (mnShadowPxWidth - 1);
+            if (aPageRightShadow.GetSizePixel().Height() < nHeight)
+                aPageRightShadow.Scale(Size(nWidth, nHeight), BMP_SCALE_FAST);
+
+            lcl_paintBitmapExToRect(pOut,
+                    Point(aPaintRect.Right() + mnShadowPxWidth, aPagePxRect.Top() + mnShadowPxWidth - 1),
+                    Size(nWidth, nHeight),
+                    aPageRightShadow, RIGHT);
         }
     }
 
@@ -6063,23 +6069,39 @@ static void lcl_paintBitmapExToRect(OutputDevice *pOut, Point aPoint, BitmapEx&
         pOut->DrawBitmapEx( pOut->PixelToLogic( Point( lLeft,
             aPagePxRect.Bottom() + 1 + mnShadowPxWidth - aPageBottomLeftShadow.GetSizePixel().Height() ) ), aPageBottomLeftShadow );
         pOut->DrawBitmapEx( pOut->PixelToLogic( Point( lLeft, aPagePxRect.Top() - mnShadowPxWidth ) ), aPageTopLeftShadow );
-        if ( aPagePxRect.Height() > 2 * mnShadowPxWidth)
+        if (aPagePxRect.Height() > 2 * mnShadowPxWidth)
         {
-            BitmapEx aPageLeftShadow = aPageLeftShadowBase;
-            aPageLeftShadow.Scale( 1, aPagePxRect.Height() - 2 * (mnShadowPxWidth - 1) );
-            lcl_paintBitmapExToRect( pOut, Point( lLeft, aPagePxRect.Top() + mnShadowPxWidth - 1),
-                                     aPageLeftShadow, LEFT );
+            const long nWidth = aPageLeftShadow.GetSizePixel().Width();
+            const long nHeight = aPagePxRect.Height() - 2 * (mnShadowPxWidth - 1);
+            if (aPageLeftShadow.GetSizePixel().Height() < nHeight)
+                aPageLeftShadow.Scale(Size(nWidth, nHeight), BMP_SCALE_FAST);
+
+            lcl_paintBitmapExToRect(pOut,
+                    Point(lLeft, aPagePxRect.Top() + mnShadowPxWidth - 1),
+                    Size(nWidth, nHeight),
+                    aPageLeftShadow, LEFT);
         }
     }
 
-    BitmapEx aPageBottomShadow = aPageBottomShadowBase;
-    aPageBottomShadow.Scale( aPaintRect.Width(), 1 );
-    lcl_paintBitmapExToRect( pOut, Point( aPaintRect.Left(), aPagePxRect.Bottom() + 2 ),
-                             aPageBottomShadow, BOTTOM );
-    BitmapEx aPageTopShadow = aPageTopShadowBase;
-    aPageTopShadow.Scale( aPaintRect.Width(), 1 );
-    lcl_paintBitmapExToRect( pOut, Point( aPaintRect.Left(), aPagePxRect.Top() - mnShadowPxWidth ),
-                             aPageTopShadow, TOP );
+    // Bottom shadow
+    const long nBottomHeight = aPageBottomShadow.GetSizePixel().Height();
+    if (aPageBottomShadow.GetSizePixel().Width() < aPaintRect.Width())
+        aPageBottomShadow.Scale(Size(aPaintRect.Width(), nBottomHeight), BMP_SCALE_FAST);
+
+    lcl_paintBitmapExToRect(pOut,
+            Point(aPaintRect.Left(), aPagePxRect.Bottom() + 2),
+            Size(aPaintRect.Width(), nBottomHeight),
+            aPageBottomShadow, BOTTOM);
+
+    // Top shadow
+    const long nTopHeight = aPageTopShadow.GetSizePixel().Height();
+    if (aPageTopShadow.GetSizePixel().Width() < aPaintRect.Width())
+        aPageTopShadow.Scale(Size(aPaintRect.Width(), nTopHeight), BMP_SCALE_FAST);
+
+    lcl_paintBitmapExToRect(pOut,
+            Point(aPaintRect.Left(), aPagePxRect.Top() - mnShadowPxWidth),
+            Size(aPaintRect.Width(), nTopHeight),
+            aPageTopShadow, TOP);
 }
 
 //mod #i6193# paint sidebar for notes