basebmp: accelerated method to create a clipping device.

This was some staggering proportion of tiled rendering documents
with complex clipping; it seems 'clear' is not what memset is for
1bit clip masks.

Change-Id: I9142ffb7d7016603feb7782d6f03b9992b9494e3

basebmp/source/bitmapdevice.cxx

@@ -1944,7 +1944,8 @@ BitmapDeviceSharedPtr createBitmapDeviceImplInner( const basegfx::B2IVector&
                                                    boost::shared_array< sal_uInt8 >           pMem,
                                                    PaletteMemorySharedVector                  pPal,
                                                    const basegfx::B2IBox*                     pSubset,
-                                                   const IBitmapDeviceDamageTrackerSharedPtr& rDamage )
+                                                   const IBitmapDeviceDamageTrackerSharedPtr& rDamage,
+                                                   bool bBlack = true)
 {
     OSL_ASSERT(rSize.getX() > 0 && rSize.getY() > 0);
 
@@ -1990,7 +1991,10 @@ BitmapDeviceSharedPtr createBitmapDeviceImplInner( const basegfx::B2IVector&
             &rtl_freeMemory );
         if (pMem.get() == 0 && nMemSize != 0)
             return BitmapDeviceSharedPtr();
-        memset(pMem.get(), 0, nMemSize);
+        if (bBlack)
+            memset(pMem.get(), 0, nMemSize);
+        else
+            memset(pMem.get(), 0xFF, nMemSize);
     }
 
     sal_uInt8* pFirstScanline = nScanlineStride < 0 ?
@@ -2129,9 +2133,10 @@ BitmapDeviceSharedPtr createBitmapDeviceImpl( const basegfx::B2IVector&
                                               boost::shared_array< sal_uInt8 >           pMem,
                                               PaletteMemorySharedVector                  pPal,
                                               const basegfx::B2IBox*                     pSubset,
-                                              const IBitmapDeviceDamageTrackerSharedPtr& rDamage )
+                                              const IBitmapDeviceDamageTrackerSharedPtr& rDamage,
+                                              bool bBlack = true)
 {
-    BitmapDeviceSharedPtr result( createBitmapDeviceImplInner( rSize, bTopDown, nScanlineFormat, pMem, pPal, pSubset, rDamage ) );
+    BitmapDeviceSharedPtr result( createBitmapDeviceImplInner( rSize, bTopDown, nScanlineFormat, pMem, pPal, pSubset, rDamage, bBlack ) );
 
 #ifdef SAL_LOG_INFO
     std::ostringstream subset;
@@ -2194,6 +2199,20 @@ BitmapDeviceSharedPtr createBitmapDevice( const basegfx::B2IVector&        rSize
                                    IBitmapDeviceDamageTrackerSharedPtr() );
 }
 
+BitmapDeviceSharedPtr createClipDevice( const basegfx::B2IVector&        rSize )
+{
+    BitmapDeviceSharedPtr xClip(
+             createBitmapDeviceImpl( rSize,
+                                     false, /* bTopDown */
+                                     basebmp::FORMAT_ONE_BIT_MSB_GREY,
+                                     boost::shared_array< sal_uInt8 >(),
+                                     PaletteMemorySharedVector(),
+                                     NULL,
+                                     IBitmapDeviceDamageTrackerSharedPtr(),
+                                     false /* white */) );
+    return xClip;
+}
+
 BitmapDeviceSharedPtr subsetBitmapDevice( const BitmapDeviceSharedPtr& rProto,
                                           const basegfx::B2IBox&       rSubset )
 {

include/basebmp/bitmapdevice.hxx

@@ -690,6 +690,10 @@ BitmapDeviceSharedPtr BASEBMP_DLLPUBLIC createBitmapDevice( const basegfx::B2IVe
                                                             const PaletteMemorySharedVector& rPalette );
 
 
+/** Function to create a 1 bit grey clipping mask initialized to white.
+ */
+BitmapDeviceSharedPtr BASEBMP_DLLPUBLIC createClipDevice( const basegfx::B2IVector&        rSize );
+
 /** Function to retrieve a subsetted BitmapDevice to the same
     memory.
 

vcl/headless/svpgdi.cxx

@@ -168,8 +168,7 @@ void SvpSalGraphics::ensureClip()
 
     m_aDevice = m_aOrigDevice;
     basegfx::B2IVector aSize = m_aDevice->getSize();
-    m_aClipMap = basebmp::createBitmapDevice( aSize, false, basebmp::FORMAT_ONE_BIT_MSB_GREY );
-    m_aClipMap->clear( basebmp::Color(0xFFFFFFFF) );
+    m_aClipMap = basebmp::createClipDevice( aSize );
 
     RectangleVector aRectangles;
     m_aClipRegion.GetRegionRectangles(aRectangles);