added interface headers with latest discussed changes

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@52381 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/dcmemory.h

@@ -0,0 +1,72 @@
+/////////////////////////////////////////////////////////////////////////////
+// Name:        dcmemory.h
+// Purpose:     documentation for wxMemoryDC class
+// Author:      wxWidgets team
+// RCS-ID:      $Id$
+// Licence:     wxWindows license
+/////////////////////////////////////////////////////////////////////////////
+
+/**
+    @class wxMemoryDC
+    @wxheader{dcmemory.h}
+    
+    A memory device context provides a means to draw graphics onto a bitmap. When
+    drawing in to a mono-bitmap, using @c wxWHITE, @c wxWHITE_PEN and
+    @c wxWHITE_BRUSH
+    will draw the background colour (i.e. 0) whereas all other colours will draw the
+    foreground colour (i.e. 1).
+    
+    @library{wxcore}
+    @category{dc}
+    
+    @seealso
+    wxBitmap, wxDC
+*/
+class wxMemoryDC : public wxDC
+{
+public:
+    //@{
+    /**
+        Constructs a new memory device context and calls SelectObject()
+        with the given bitmap.
+        Use the wxDC::IsOk member to test whether the constructor was successful
+        in creating a usable device context.
+    */
+    wxMemoryDC();
+        wxMemoryDC(wxBitmap& bitmap);
+    //@}
+
+    /**
+        Works exactly like SelectObjectAsSource() but
+        this is the function you should use when you select a bitmap because you want
+        to modify
+        it, e.g. drawing on this DC.
+        
+        Using SelectObjectAsSource() when modifying
+        the bitmap may incurr some problems related to wxBitmap being a reference
+        counted object
+        (see @ref overview_trefcount "reference counting overview").
+        
+        Also, before using the updated bitmap data, make sure to select it out of
+        context first
+        (for example by selecting wxNullBitmap into the device context).
+        
+        @sa wxDC::DrawBitmap
+    */
+    void SelectObject(wxBitmap& bitmap);
+
+    /**
+        Selects the given bitmap into the device context, to use as the memory
+        bitmap. Selecting the bitmap into a memory DC allows you to draw into
+        the DC (and therefore the bitmap) and also to use wxDC::Blit to copy
+        the bitmap to a window. For this purpose, you may find wxDC::DrawIcon
+        easier to use instead.
+        
+        If the argument is wxNullBitmap (or some other uninitialised wxBitmap) the
+        current bitmap is
+        selected out of the device context, and the original bitmap restored, allowing
+        the current bitmap to
+        be destroyed safely.
+    */
+    void SelectObjectAsSource(const wxBitmap& bitmap);
+};