Don't apply transparency twice when drawing to mpAlphaVDev

We pass fTransparency to mpAlphaVDev->DrawTransparent; using adjusted
fill/line color is wrong. The correct COL_BLACK/COL_TRANSPARENT were
already set in mpAlphaVDev when SetFillColor/SetLineColor were called
to the virtual device.

Wrong implementation from commit 9c621ee8ea41a1c53bfeca49827290826785973e.

Change-Id: Ic858ede1ba793ac00f831a3960f748ad20ccb70a
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/101262
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>

1 files changed, 2 insertions, 12 deletions

diff --git a/vcl/source/outdev/transparent.cxx b/vcl/source/outdev/transparent.cxx
index f9da8c9975da..839550c0fe1c 100644
--- a/vcl/source/outdev/transparent.cxx
+++ b/vcl/source/outdev/transparent.cxx
@@ -248,6 +248,8 @@ void OutputDevice::DrawTransparent(
 
         // create ObjectToDevice transformation
         const basegfx::B2DHomMatrix aFullTransform(ImplGetDeviceTransformation() * rObjectTransform);
+        // TODO: this must not drop transparency for mpAlphaVDev case, but instead use premultiplied
+        // aplha... but that requires using premultiplied alpha also for already drawn data
         const double fAdjustedTransparency = mpAlphaVDev ? 0 : fTransparency;
         bool bDrawnOk(true);
 
@@ -294,20 +296,8 @@ void OutputDevice::DrawTransparent(
             }
 
             if (mpAlphaVDev)
-            {
-                const Color aFillCol(mpAlphaVDev->GetFillColor());
-                const Color aLineColor(mpAlphaVDev->GetLineColor());
-                const auto nGreyScale = static_cast<sal_uInt8>(std::round(255 * fTransparency));
-                const Color aNewColor(nGreyScale, nGreyScale, nGreyScale);
-                mpAlphaVDev->SetFillColor(aNewColor);
-                mpAlphaVDev->SetLineColor(aNewColor);
-
                 mpAlphaVDev->DrawTransparent(rObjectTransform, rB2DPolyPoly, fTransparency);
 
-                mpAlphaVDev->SetFillColor(aFillCol);
-                mpAlphaVDev->SetLineColor(aLineColor);
-            }
-
             return;
         }
     }