Merge branch 'paint-debug'

Detect invalid use of wxPaintDC/wxPaintEvent better.

See https://github.com/wxWidgets/wxWidgets/pull/1732

include/wx/event.h

@@ -2335,39 +2335,17 @@ private:
  wxEVT_NC_PAINT
  */
 
-#if wxDEBUG_LEVEL && defined(__WXMSW__)
-    #define wxHAS_PAINT_DEBUG
-
-    // see comments in src/msw/dcclient.cpp where g_isPainting is defined
-    extern WXDLLIMPEXP_CORE int g_isPainting;
-#endif // debug
-
 class WXDLLIMPEXP_CORE wxPaintEvent : public wxEvent
 {
+    // This ctor is only intended to be used by wxWidgets itself, so it's
+    // intentionally declared as private when not building the library itself.
+#ifdef WXBUILDING
 public:
-    wxPaintEvent(int Id = 0)
-        : wxEvent(Id, wxEVT_PAINT)
-    {
-#ifdef wxHAS_PAINT_DEBUG
-        // set the internal flag for the duration of redrawing
-        g_isPainting++;
-#endif // debug
-    }
+#endif // WXBUILDING
+    explicit wxPaintEvent(wxWindowBase* window = NULL);
 
-    // default copy ctor and dtor are normally fine, we only need them to keep
-    // g_isPainting updated in debug build
-#ifdef wxHAS_PAINT_DEBUG
-    wxPaintEvent(const wxPaintEvent& event)
-            : wxEvent(event)
-    {
-        g_isPainting++;
-    }
-
-    virtual ~wxPaintEvent()
-    {
-        g_isPainting--;
-    }
-#endif // debug
+public:
+    // default copy ctor and dtor are fine
 
     virtual wxEvent *Clone() const wxOVERRIDE { return new wxPaintEvent(*this); }
 
@@ -2377,11 +2355,14 @@ private:
 
 class WXDLLIMPEXP_CORE wxNcPaintEvent : public wxEvent
 {
+    // This ctor is only intended to be used by wxWidgets itself, so it's
+    // intentionally declared as private when not building the library itself.
+#ifdef WXBUILDING
 public:
-    wxNcPaintEvent(int winid = 0)
-        : wxEvent(winid, wxEVT_NC_PAINT)
-        { }
+#endif // WXBUILDING
+    explicit wxNcPaintEvent(wxWindowBase* window = NULL);
 
+public:
     virtual wxEvent *Clone() const wxOVERRIDE { return new wxNcPaintEvent(*this); }
 
 private:

include/wx/msw/private/paint.h

@@ -0,0 +1,39 @@
+///////////////////////////////////////////////////////////////////////////////
+// Name:        wx/msw/private/paint.h
+// Purpose:     Helpers for handling repainting
+// Author:      Vadim Zeitlin
+// Created:     2020-02-10
+// Copyright:   (c) 2020 Vadim Zeitlin <vadim@wxwidgets.org>
+// Licence:     wxWindows licence
+///////////////////////////////////////////////////////////////////////////////
+
+#ifndef _WX_MSW_PRIVATE_PAINT_H_
+#define _WX_MSW_PRIVATE_PAINT_H_
+
+#include "wx/stack.h"
+
+namespace wxMSWImpl
+{
+
+// Data used by WM_PAINT handler
+struct PaintData
+{
+    explicit PaintData(wxWindowMSW* window_)
+        : window(window_),
+          createdPaintDC(false)
+    {
+    }
+
+    // The window being repainted (never null).
+    wxWindowMSW* const window;
+
+    // True if the user-defined paint handler created wxPaintDC.
+    bool createdPaintDC;
+};
+
+// Stack storing data for the possibly nested WM_PAINT handlers.
+extern wxStack<PaintData> paintStack;
+
+} // namespace wxMSWImpl
+
+#endif // _WX_MSW_PRIVATE_PAINT_H_