Fix erasing wxHtmlWindow background in wxUniv.

[wxWidgets.git] / src / html / htmlwin.cpp

diff --git a/src/html/htmlwin.cpp b/src/html/htmlwin.cpp
index 7496fa4fd1c3b1a607c44c616b20bd088a99b3e5..22ac09f0098c43bc6bd5bcb4485f97be463462a5 100644 (file)
--- a/src/html/htmlwin.cpp
+++ b/src/html/htmlwin.cpp
@@ -1102,6 +1102,19 @@ void wxHtmlWindow::DoEraseBackground(wxDC& dc)
     }
 }
 
+void wxHtmlWindow::OnEraseBackground(wxEraseEvent& WXUNUSED(event))
+{
+    // We never get real erase background events as we changed our background
+    // style to wxBG_STYLE_PAINT in our ctor so the only time when we get here
+    // is when an artificial wxEraseEvent is generated by our own OnPaint()
+    // below. This handler only exists to stop the event from propagating
+    // downwards to wxWindow which may erase the background itself when it gets
+    // it in some ports (currently this happens in wxUniv), so we simply stop
+    // processing here and set a special flag allowing OnPaint() to see that
+    // the event hadn't been really processed.
+    m_isBgReallyErased = false;
+}
+
 void wxHtmlWindow::OnPaint(wxPaintEvent& WXUNUSED(event))
 {
     wxPaintDC dcPaint(this);
@@ -1134,11 +1147,17 @@ void wxHtmlWindow::OnPaint(wxPaintEvent& WXUNUSED(event))
 
     PrepareDC(*dc);
 
-    // erase the background: for compatibility, we must generate the event to
-    // allow the user-defined handlers to do it
+    // Erase the background: for compatibility, we must generate the event to
+    // allow the user-defined handlers to do it, hence this hack with sending
+    // an artificial wxEraseEvent to trigger the execution of such handlers.
     wxEraseEvent eraseEvent(GetId(), dc);
     eraseEvent.SetEventObject(this);
-    if ( !ProcessWindowEvent(eraseEvent) )
+
+    // Hack inside a hack: the background wasn't really erased if our own
+    // OnEraseBackground() was executed, so we need to check for the flag set
+    // by it whenever it's called.
+    m_isBgReallyErased = true; // Initially assume it wasn't.
+    if ( !ProcessWindowEvent(eraseEvent) || !m_isBgReallyErased )
     {
         // erase background ourselves
         DoEraseBackground(*dc);
@@ -1669,6 +1688,7 @@ BEGIN_EVENT_TABLE(wxHtmlWindow, wxScrolledWindow)
     EVT_RIGHT_UP(wxHtmlWindow::OnMouseUp)
     EVT_MOTION(wxHtmlWindow::OnMouseMove)
     EVT_PAINT(wxHtmlWindow::OnPaint)
+    EVT_ERASE_BACKGROUND(wxHtmlWindow::OnEraseBackground)
 #if wxUSE_CLIPBOARD
     EVT_LEFT_DCLICK(wxHtmlWindow::OnDoubleClick)
     EVT_ENTER_WINDOW(wxHtmlWindow::OnMouseEnter)