tdf#105461 PDF export: handle text fill color

Text portion level background in Writer text was working already, as
Writer paints its background explicitly, and then uses no text fill
color in the metafile (that is turned into a PDF later).

However, text fill color is used for Writer shape text and also in
Impress. The rectangle is not just the text itself, but also the ascent
/ descent region, this matches the desktop rendering result.

Change-Id: I644007ade43a8b9e663890643b826ae12c427ea5
Reviewed-on: https://gerrit.libreoffice.org/33781Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Jenkins <ci@libreoffice.org>

vcl/source/gdi/pdfwriter_impl.cxx

@@ -8748,6 +8748,29 @@ void PDFWriterImpl::drawLayout( SalLayout& rLayout, const OUString& rText, bool
         }
     }
 
+    if (m_aCurrentPDFState.m_aFont.GetFillColor() != Color(COL_TRANSPARENT))
+    {
+        // PDF doesn't have a text fill color, so draw a rectangle before
+        // drawing the actual text.
+        push(PushFlags::FILLCOLOR | PushFlags::LINECOLOR);
+        setFillColor(m_aCurrentPDFState.m_aFont.GetFillColor());
+        // Avoid border around the rectangle for Writer shape text.
+        setLineColor(Color(COL_TRANSPARENT));
+
+        // The rectangle is the bounding box of the text, but also includes
+        // ascent / descent to match the on-screen rendering.
+        Rectangle aRectangle;
+        // This is the top left of the text without ascent / descent.
+        aRectangle.SetPos(m_pReferenceDevice->PixelToLogic(rLayout.GetDrawPosition()));
+        aRectangle.setY(aRectangle.getY() - aRefDevFontMetric.GetAscent());
+        aRectangle.SetSize(m_pReferenceDevice->PixelToLogic(Size(rLayout.GetTextWidth(), 0)));
+        // This includes ascent / descent.
+        aRectangle.setHeight(aRefDevFontMetric.GetLineHeight());
+        drawRectangle(aRectangle);
+
+        pop();
+    }
+
     Point aAlignOffset;
     if ( eAlign == ALIGN_BOTTOM )
         aAlignOffset.Y() -= aRefDevFontMetric.GetDescent();