tdf#115843 avoid using transparent virtualdevice when 100% opaque

which for the common case avoids the narrowing of hidpi outputdevices
through non-hidpi bitmaps

Change-Id: Ibdc004a0946e8cb118818e58a01e5791c869353a
Reviewed-on: https://gerrit.libreoffice.org/69930
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

drawinglayer/source/processor2d/vclprocessor2d.cxx

@@ -729,29 +729,32 @@ namespace drawinglayer
                         // back to old OutDev
                         mpOutputDevice = pLastOutputDevice;
 
-                        // draw mask
-                        if(getOptionsDrawinglayer().IsAntiAliasing())
+                        // if the mask fills the whole area we can skip
+                        // creating a transparent vd and filling it.
+                        if (!basegfx::utils::isRectangle(aMask))
                         {
-                            // with AA, use 8bit AlphaMask to get nice borders
-                            VirtualDevice& rTransparence = aBufferDevice.getTransparence();
-                            rTransparence.SetLineColor();
-                            rTransparence.SetFillColor(COL_BLACK);
-                            rTransparence.DrawPolyPolygon(aMask);
-
-                            // dump buffer to outdev
-                            aBufferDevice.paint();
-                        }
-                        else
-                        {
-                            // No AA, use 1bit mask
-                            VirtualDevice& rMask = aBufferDevice.getMask();
-                            rMask.SetLineColor();
-                            rMask.SetFillColor(COL_BLACK);
-                            rMask.DrawPolyPolygon(aMask);
-
-                            // dump buffer to outdev
-                            aBufferDevice.paint();
+                            // draw mask
+                            if(getOptionsDrawinglayer().IsAntiAliasing())
+                            {
+                                // with AA, use 8bit AlphaMask to get nice borders
+                                VirtualDevice& rTransparence = aBufferDevice.getTransparence();
+                                rTransparence.SetLineColor();
+                                rTransparence.SetFillColor(COL_BLACK);
+                                rTransparence.DrawPolyPolygon(aMask);
+                            }
+                            else
+                            {
+                                // No AA, use 1bit mask
+                                VirtualDevice& rMask = aBufferDevice.getMask();
+                                rMask.SetLineColor();
+                                rMask.SetFillColor(COL_BLACK);
+                                rMask.DrawPolyPolygon(aMask);
+                            }
                         }
+
+                        // dump buffer to outdev
+                        aBufferDevice.paint();
+
                     }
                 }
             }