remove support for BITMASK in vcl backends

Rather use a proper alpha channel if we need transparency.

This is another small step towards merged alpha in our vcl
layer.

I suspect the intent in a lot of this code was to save memory.
Which have been a thing way back then, but these days our
backends mostly end up doing a copy-and-convert to a real
alpha channel anyway, so the existing code is actually
now a pessimisation.

Change-Id: I4a2bcbb2f76b841f05bc00580f364492829c69de
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/114808
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

3 files changed, 6 insertions, 19 deletions

diff --git a/canvas/source/vcl/backbuffer.cxx b/canvas/source/vcl/backbuffer.cxx
index c2779cdf0489..684a02c8bd55 100644
--- a/canvas/source/vcl/backbuffer.cxx
+++ b/canvas/source/vcl/backbuffer.cxx
@@ -27,14 +27,9 @@
 
 namespace vclcanvas
 {
-    BackBuffer::BackBuffer( const OutputDevice& rRefDevice,
-                            bool                bMonochromeBuffer ) :
-        maVDev( VclPtr<VirtualDevice>::Create( rRefDevice,
-                                   bMonochromeBuffer ? DeviceFormat::BITMASK : DeviceFormat::DEFAULT ) )
+    BackBuffer::BackBuffer( const OutputDevice& rRefDevice ) :
+        maVDev( VclPtr<VirtualDevice>::Create( rRefDevice, DeviceFormat::DEFAULT ) )
     {
-        if( bMonochromeBuffer )
-            return;
-
         tools::SetDefaultDeviceAntiAliasing( maVDev );
     }
 
diff --git a/canvas/source/vcl/backbuffer.hxx b/canvas/source/vcl/backbuffer.hxx
index 6bbeb85ec54b..0e31111b6fcf 100644
--- a/canvas/source/vcl/backbuffer.hxx
+++ b/canvas/source/vcl/backbuffer.hxx
@@ -31,15 +31,8 @@ namespace vclcanvas
     class BackBuffer : public OutDevProvider
     {
     public:
-        /** Create a backbuffer for given reference device
-
-            @param bMonochromeBuffer
-            When false, default depth of reference device is
-            chosen. When true, the buffer will be monochrome, i.e. one
-            bit deep.
-         */
-        BackBuffer( const OutputDevice& rRefDevice,
-                    bool                bMonochromeBuffer=false );
+        /** Create a backbuffer for given reference device */
+        BackBuffer( const OutputDevice& rRefDevice );
         virtual ~BackBuffer() override;
 
         virtual OutputDevice&       getOutDev() override;
diff --git a/canvas/source/vcl/canvascustomsprite.cxx b/canvas/source/vcl/canvascustomsprite.cxx
index 9d1f83a74ef7..4bdebd448b0c 100644
--- a/canvas/source/vcl/canvascustomsprite.cxx
+++ b/canvas/source/vcl/canvascustomsprite.cxx
@@ -58,9 +58,8 @@ namespace vclcanvas
         BackBufferSharedPtr pBackBuffer = std::make_shared<BackBuffer>( rOutDevProvider->getOutDev() );
         pBackBuffer->setSize( aSize );
 
-        // create mask backbuffer, with one bit color depth
-        BackBufferSharedPtr pBackBufferMask = std::make_shared<BackBuffer>( rOutDevProvider->getOutDev(),
-                                                             true );
+        // create mask backbuffer
+        BackBufferSharedPtr pBackBufferMask = std::make_shared<BackBuffer>( rOutDevProvider->getOutDev() );
         pBackBufferMask->setSize( aSize );
 
         // TODO(F1): Implement alpha vdev (could prolly enable