Implemented Clear in wxSVGFileDC.

Draw a rectangle with the background colour and a transparent pen.
Closes #15788.

include/wx/dcsvg.h

@@ -81,10 +81,7 @@ public:
         return -1;
     }
 
-    virtual void Clear() wxOVERRIDE
-    {
-        wxFAIL_MSG(wxT("wxSVGFILEDC::Clear() Call not implemented \nNot sensible for an output file?"));
-    }
+    virtual void Clear() wxOVERRIDE;
 
     virtual void DestroyClippingRegion() wxOVERRIDE;
 

interface/wx/dcsvg.h

@@ -60,7 +60,7 @@ public:
     void EndPage();
 
     /**
-        This makes no sense in wxSVGFileDC and does nothing.
+        Draws a rectangle the size of the SVG using the wxDC::SetBackground() brush.
     */
     void Clear();
 

src/common/dcsvg.cpp

@@ -305,6 +305,17 @@ wxSize wxSVGFileDCImpl::GetPPI() const
     return wxSize( wxRound(m_dpi), wxRound(m_dpi) );
 }
 
+void wxSVGFileDCImpl::Clear()
+{
+    {
+        wxDCBrushChanger setBackground(*GetOwner(), m_backgroundBrush);
+        wxDCPenChanger setTransp(*GetOwner(), *wxTRANSPARENT_PEN);
+        DoDrawRectangle(0, 0, m_width, m_height);
+    }
+
+    NewGraphicsIfNeeded();
+}
+
 void wxSVGFileDCImpl::DoDrawLine(wxCoord x1, wxCoord y1, wxCoord x2, wxCoord y2)
 {
     NewGraphicsIfNeeded();