commit 52637f46cc79eb7f65a97524e92a0b2f45d3d598
author Patrick Luby <plubius@neooffice.org> Fri Aug 04 16:36:42 2023 -0400
committer Patrick Luby <plubius@neooffice.org> Sat Aug 05 22:58:28 2023 +0200
tree 0eb090c683ecf5e8cb71df72f27342231b2e9edc
parent 484182b04d35f15437c09008cede361edde71d01

tdf#156540 invert alpha when drawing sprites

Due to the switch from transparency to alpha in commit
81994cb2b8b32453a92bcb011830fcb884f22ff3, a sprite's
alpha mask needs to be inverted when Skia is enabled and
the fAlpha value needs to be inverted when Skia is disabled.

Change-Id: Ie802924b07ddbab536a2eddb57bf82e5146cffe7
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/155358
Tested-by: Jenkins
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>
Reviewed-by: Patrick Luby <plubius@neooffice.org>

canvas/source/vcl/spritehelper.cxx

diff --git a/canvas/source/vcl/spritehelper.cxx b/canvas/source/vcl/spritehelper.cxx
index 3494a5f..54ad522 100644
--- a/canvas/source/vcl/spritehelper.cxx
+++ b/canvas/source/vcl/spritehelper.cxx
@@ -31,6 +31,7 @@
#include <vcl/bitmapex.hxx>
#include <vcl/canvastools.hxx>
#include <vcl/outdev.hxx>
#include <vcl/skia/SkiaHelper.hxx>

#include <canvas/canvastools.hxx>

@@ -136,10 +137,17 @@ namespace vclcanvas
                BitmapEx aMask( mpBackBufferMask->getOutDev().GetBitmapEx( aEmptyPoint,
                                                                       aOutputSize ) );

                AlphaMask aAlpha( aMask.GetBitmap() );
#if HAVE_FEATURE_SKIA
                // tdf#156540 invert alpha mask when using Skia
                if ( SkiaHelper::isVCLSkiaEnabled() )
                    aAlpha.Invert();
#endif

                // Note: since we retrieved aBmp and aMask
                // directly from an OutDev, it's already a
                // 'display bitmap' on windows.
                maContent = BitmapEx( aBmp.GetBitmap(), AlphaMask( aMask.GetBitmap()) );
                maContent = BitmapEx( aBmp.GetBitmap(), aAlpha );
            }
        }

@@ -180,7 +188,13 @@ namespace vclcanvas
        aMoveTransform.translate( aOutPos.X(), aOutPos.Y() );
        aTransform = aMoveTransform * aTransform * aSizeTransform;

        rTargetSurface.DrawTransformedBitmapEx( aTransform, *maContent, fAlpha );
        // tdf#156540 invert alpha when Skia is disabled
        bool bAlpha = false;
#if HAVE_FEATURE_SKIA
        if ( SkiaHelper::isVCLSkiaEnabled() )
            bAlpha = true;
#endif
        rTargetSurface.DrawTransformedBitmapEx( aTransform, *maContent, bAlpha ? fAlpha : 1.0 - fAlpha );

        rTargetSurface.Pop();