commit c43d11cbbabc871a3c71062239b0d9b6db99961e
author Patrick Luby <plubius@neooffice.org> Sat Sep 23 19:26:09 2023 -0400
committer Patrick Luby <plubius@neooffice.org> Sun Sep 24 02:25:12 2023 +0200
tree 65320168c32d5d4400174f2654853e9c7f32b3bd
parent 3399854b66bb1fb175b8504c964008e53167ca7b

tdf#156539 Draw the gradient with polypolygonal clip when using Skia

For some unkown reason, the previous "draw gradient with XOR, draw
polygon with N0, and draw gradient again with XOR" does not work
with Skia/Raster (at least on macOS). Fortunately, Skia supports
polypolygonal clipping so just clip and draw the gradient.

Change-Id: Id069160312a270096f5ec9c670615eb95ec6200b
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/157199
Tested-by: Jenkins
Reviewed-by: Patrick Luby <plubius@neooffice.org>

vcl/source/outdev/gradient.cxx

diff --git a/vcl/source/outdev/gradient.cxx b/vcl/source/outdev/gradient.cxx
index 53dbec3..ef4f883 100644
--- a/vcl/source/outdev/gradient.cxx
+++ b/vcl/source/outdev/gradient.cxx
@@ -24,6 +24,7 @@
#include <vcl/settings.hxx>
#include <vcl/virdev.hxx>
#include <vcl/window.hxx>
#include <vcl/skia/SkiaHelper.hxx>

#include <salgdi.hxx>

@@ -159,15 +160,32 @@ void OutputDevice::ClipAndDrawGradientMetafile ( const Gradient &rGradient, cons
    const bool  bOldOutput = IsOutputEnabled();

    EnableOutput( false );
    Push( vcl::PushFlags::RASTEROP );
    SetRasterOp( RasterOp::Xor );
    DrawGradient( aBoundRect, rGradient );
    SetFillColor( COL_BLACK );
    SetRasterOp( RasterOp::N0 );
    DrawPolyPolygon( rPolyPoly );
    SetRasterOp( RasterOp::Xor );
    DrawGradient( aBoundRect, rGradient );
    Pop();
#if HAVE_FEATURE_SKIA
    // tdf#156539 Draw the gradient with polypolygonal clip when using Skia
    // For some unkown reason, the previous "draw gradient with XOR, draw
    // polygon with N0, and draw gradient again with XOR" does not work
    // with Skia/Raster (at least on macOS). Fortunately, Skia supports
    // polypolygonal clipping so just clip and draw the gradient.
    if ( SkiaHelper::isVCLSkiaEnabled() )
    {
        Push( vcl::PushFlags::CLIPREGION );
        SetClipRegion( vcl::Region( rPolyPoly ) );
        DrawGradient( aBoundRect, rGradient );
        Pop();
    }
    else
#endif
    {
        Push( vcl::PushFlags::RASTEROP );
        SetRasterOp( RasterOp::Xor );
        DrawGradient( aBoundRect, rGradient );
        SetFillColor( COL_BLACK );
        SetRasterOp( RasterOp::N0 );
        DrawPolyPolygon( rPolyPoly );
        SetRasterOp( RasterOp::Xor );
        DrawGradient( aBoundRect, rGradient );
        Pop();
    }
    EnableOutput( bOldOutput );
}