tdf#134969 Add solid transparence in color gradient

Converts a 'FillTransparence' percent value to a Gray color and
stores it in a TransparenceGradient, so that it can be used by
WriteGradientFill(). Use of third parameter rXPropSet is not possible,
because it would overwrite a true transparency gradient.
Causion, the property 'FillTransparenceGradient' might exist in an
XPropSet of a shape with some default values. To detect, whether a
gradient is actually used, you have to examine the property
'FillTransparenceGradientName'.

Change-Id: Icbef599f02ebae2fcb5825fe64f546295eb78510
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/99145
Tested-by: Jenkins
Reviewed-by: Regina Henschel <rb.henschel@t-online.de>

1 files changed, 20 insertions, 3 deletions

diff --git a/oox/source/export/drawingml.cxx b/oox/source/export/drawingml.cxx
index 517d9801bba6..155c33796f70 100644
--- a/oox/source/export/drawingml.cxx
+++ b/oox/source/export/drawingml.cxx
@@ -540,10 +540,27 @@ void DrawingML::WriteGradientFill( const Reference< XPropertySet >& rXPropSet )
     else
     {
         mpFS->startElementNS(XML_a, XML_gradFill, XML_rotWithShape, "0");
-        if( GetProperty(rXPropSet, "FillTransparenceGradient") )
-            aTransparenceGradient = *o3tl::doAccess<awt::Gradient>(mAny);
+        OUString sFillTransparenceGradientName;
+        if (GetProperty(rXPropSet, "FillTransparenceGradientName")
+            && (mAny >>= sFillTransparenceGradientName)
+            && !sFillTransparenceGradientName.isEmpty())
+        {
+            if (GetProperty(rXPropSet, "FillTransparenceGradient"))
+                aTransparenceGradient = *o3tl::doAccess<awt::Gradient>(mAny);
+        }
+        else if (GetProperty(rXPropSet, "FillTransparence"))
+        {
+            // currently only StartColor and EndColor are evaluated in WriteGradientFill()
+            sal_Int32 nTransparency = 0;
+            mAny >>= nTransparency;
+            // convert percent to gray color
+            nTransparency = nTransparency * 255/100;
+            const sal_Int32 aGrayColor = static_cast<sal_Int32>( nTransparency | nTransparency << 8 | nTransparency << 16 );
+            aTransparenceGradient.StartColor = aGrayColor;
+            aTransparenceGradient.EndColor = aGrayColor;
+        }
         WriteGradientFill(aGradient, aTransparenceGradient);
-        mpFS->endElementNS( XML_a, XML_gradFill );
+        mpFS->endElementNS(XML_a, XML_gradFill);
     }
 }