Move code for creating a disabled bitmap to wxBitmap

To allow using it from multiple places

include/wx/gtk/bitmap.h

@@ -136,6 +136,7 @@ public:
     cairo_t* CairoCreate() const;
     void Draw(cairo_t* cr, int x, int y, bool useMask = true, const wxColour* fg = NULL, const wxColour* bg = NULL) const;
     void SetSourceSurface(cairo_t* cr, int x, int y, const wxColour* fg = NULL, const wxColour* bg = NULL) const;
+    wxBitmap CreateDisabled() const;
 #else
     GdkPixmap *GetPixmap() const;
     bool HasPixmap() const;

src/gtk/bitmap.cpp

@@ -1372,6 +1372,32 @@ void wxBitmap::Draw(cairo_t* cr, int x, int y, bool useMask, const wxColour* fg,
     else
         cairo_paint(cr);
 }
+
+wxBitmap wxBitmap::CreateDisabled() const
+{
+    wxBitmap disabled;
+    if (m_refData == NULL)
+        return disabled;
+
+    const wxBitmapRefData* bmpData = M_BMPDATA;
+    wxBitmapRefData* newRef = new wxBitmapRefData(bmpData->m_width, bmpData->m_height, 32);
+    newRef->m_scaleFactor = bmpData->m_scaleFactor;
+    disabled.m_refData = newRef;
+
+    cairo_t* cr = disabled.CairoCreate();
+    cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
+    cairo_set_source_rgba(cr, 0, 0, 0, 0);
+    // clear to transparent
+    cairo_paint(cr);
+    // draw in this bitmap
+    Draw(cr, 0, 0);
+    cairo_set_source_rgba(cr, 0, 0, 0, 0);
+    // create disabled appearance
+    cairo_paint_with_alpha(cr, 0.5);
+    cairo_destroy(cr);
+
+    return disabled;
+}
 #else
 GdkPixbuf* wxBitmap::GetPixbufNoMask() const
 {

src/gtk/toolbar.cpp

@@ -189,20 +189,7 @@ image_expose_event(GtkWidget* widget, GdkEventExpose*, wxToolBarTool* tool)
         if (!disabled.IsOk() && bitmap.IsOk() && bitmap.GetScaleFactor() > 1)
         {
             // make scaled disabled bitmap from normal one
-
+            disabled = bitmap.CreateDisabled();
-            disabled.CreateScaled(bitmap.GetScaledHeight(), bitmap.GetScaledWidth(),
-                32, bitmap.GetScaleFactor());
-            cairo_t* cr2 = disabled.CairoCreate();
-            // clear to transparent
-            cairo_set_operator(cr2, CAIRO_OPERATOR_SOURCE);
-            cairo_set_source_rgba(cr2, 0, 0, 0, 0);
-            cairo_paint(cr2);
-            // draw in normal bitmap
-            bitmap.Draw(cr2, 0, 0);
-            // create disabled appearance, this seems to be how GTK does it
-            cairo_set_source_rgba(cr2, 0, 0, 0, 0);
-            cairo_paint_with_alpha(cr2, 0.5);
-            cairo_destroy(cr2);
         }
         bitmap = disabled;
     }