Ensure Cairo is installed before setting wxUSE_GRAPHICS_CONTEXT for

[wxWidgets.git] / include / wx / dcbuffer.h

diff --git a/include/wx/dcbuffer.h b/include/wx/dcbuffer.h
index e7ccff4f55ba1f1a261ae28b3fd7a4dbe4adbdaa..6916ff7eefdf2b3775b09285cf82248163ca632c 100644 (file)
--- a/include/wx/dcbuffer.h
+++ b/include/wx/dcbuffer.h
@@ -16,6 +16,15 @@
 #include "wx/dcclient.h"
 #include "wx/window.h"
 
+// Split platforms into two groups - those which have well-working
+// double-buffering by default, and those which do not.
+#if defined(__WXMAC__) || defined(__WXGTK20__)
+    #define wxALWAYS_NATIVE_DOUBLE_BUFFER       1
+#else
+    #define wxALWAYS_NATIVE_DOUBLE_BUFFER       0
+#endif
+
+
 // ----------------------------------------------------------------------------
 // Double buffering helper.
 // ----------------------------------------------------------------------------
@@ -37,7 +46,9 @@ public:
     }
 
     // Construct a wxBufferedDC using a user supplied buffer.
-    wxBufferedDC(wxDC *dc, const wxBitmap &buffer, int style = wxBUFFER_CLIENT_AREA)
+    wxBufferedDC(wxDC *dc,
+                 const wxBitmap &buffer = wxNullBitmap,
+                 int style = wxBUFFER_CLIENT_AREA)
         : m_dc( dc ),
           m_buffer( buffer ),
           m_style(style)
@@ -67,7 +78,9 @@ public:
 
     // These reimplement the actions of the ctors for two stage creation, but
     // are not used by the ctors themselves to save a few cpu cycles.
-    void Init(wxDC *dc, const wxBitmap &buffer, int style = wxBUFFER_CLIENT_AREA)
+    void Init(wxDC *dc,
+              const wxBitmap &buffer=wxNullBitmap,
+              int style = wxBUFFER_CLIENT_AREA)
     {
         wxASSERT_MSG( m_dc == 0 && m_buffer == wxNullBitmap,
                       _T("wxBufferedDC already initialised") );
@@ -96,7 +109,7 @@ public:
         wxCoord x=0, y=0;
 
         if (m_style & wxBUFFER_CLIENT_AREA)
-            GetDeviceOrigin(& x, & y);
+            GetDeviceOrigin(&x, &y);
 
         m_dc->Blit( 0, 0,
                     m_buffer.GetWidth(), m_buffer.GetHeight(), this,
@@ -112,7 +125,12 @@ private:
     // check that the bitmap is valid and use it
     void UseBuffer()
     {
-        wxASSERT_MSG( m_buffer.Ok(), _T("invalid bitmap in wxBufferedDC") );
+        if (!m_buffer.Ok())
+        {
+            wxCoord w, h;
+            m_dc->GetSize(&w, &h);
+            m_buffer = wxBitmap(w, h);
+        }
 
         SelectObject(m_buffer);
     }
@@ -183,5 +201,66 @@ private:
     DECLARE_NO_COPY_CLASS(wxBufferedPaintDC)
 };
 
-#endif  // _WX_DCBUFFER_H_
 
+
+//
+// wxAutoBufferedPaintDC is a wxPaintDC in toolkits which have double-
+// buffering by default. Otherwise it is a wxBufferedPaintDC. Thus,
+// you can only expect it work with a simple constructor that
+// accepts single wxWindow* argument.
+//
+#if wxALWAYS_NATIVE_DOUBLE_BUFFER
+    #define wxAutoBufferedPaintDCBase           wxPaintDC
+#else
+    #define wxAutoBufferedPaintDCBase           wxBufferedPaintDC
+#endif
+
+
+#ifdef __WXDEBUG__
+
+class wxAutoBufferedPaintDC : public wxAutoBufferedPaintDCBase
+{
+public:
+
+    wxAutoBufferedPaintDC(wxWindow* win)
+        : wxAutoBufferedPaintDCBase(win)
+    {
+        TestWinStyle(win);
+    }
+
+    virtual ~wxAutoBufferedPaintDC() { }
+
+private:
+
+    void TestWinStyle(wxWindow* win)
+    {
+        // Help the user to get the double-buffering working properly.
+        wxASSERT_MSG( win->GetBackgroundStyle() == wxBG_STYLE_CUSTOM,
+                      wxT("In constructor, you need to call GetBackgroundStyle(wxBG_STYLE_CUSTOM), ")
+                      wxT("and also, if needed, paint the background manually in the paint event handler."));
+    }
+
+    DECLARE_NO_COPY_CLASS(wxAutoBufferedPaintDC)
+};
+
+#else // !__WXDEBUG__
+
+// In release builds, just use typedef
+typedef wxAutoBufferedPaintDCBase wxAutoBufferedPaintDC;
+
+#endif
+
+
+// Check if the window is natively double buffered and will return a wxPaintDC
+// if it is, a wxBufferedPaintDC otherwise.  It is the caller's responsibility
+// to delete the wxDC pointer when finished with it.
+inline wxDC* wxAutoBufferedPaintDCFactory(wxWindow* window)
+{
+    if ( window->IsDoubleBuffered() )
+        return new wxPaintDC(window);
+    else
+        return new wxBufferedPaintDC(window);
+}
+            
+
+#endif  // _WX_DCBUFFER_H_