From 7561aacd5e3bcd5f98f4cdadcec5e94d1550b369 Mon Sep 17 00:00:00 2001
From: Vadim Zeitlin <vadim@wxwidgets.org>
Date: Mon, 21 May 2001 23:10:31 +0000
Subject: [PATCH] fix for releasing the HDC in WM_DRAWITEM handler

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@10261 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
---
 include/wx/msw/dc.h | 16 ++++++++++++++--
 src/msw/listbox.cpp |  7 +++----
 src/msw/window.cpp  | 23 ++++++++++++-----------
 3 files changed, 29 insertions(+), 17 deletions(-)

diff --git a/include/wx/msw/dc.h b/include/wx/msw/dc.h
index 257f86cd50..4d53cb7205 100644
--- a/include/wx/msw/dc.h
+++ b/include/wx/msw/dc.h
@@ -73,8 +73,6 @@
 
 class WXDLLEXPORT wxDC : public wxDCBase
 {
-    DECLARE_DYNAMIC_CLASS(wxDC)
-
 public:
     wxDC();
     ~wxDC();
@@ -224,6 +222,20 @@ protected:
     WXHBRUSH          m_oldBrush;
     WXHFONT           m_oldFont;
     WXHPALETTE        m_oldPalette;
+
+    DECLARE_DYNAMIC_CLASS(wxDC)
+};
+
+// ----------------------------------------------------------------------------
+// wxDCTemp: a wxDC which doesn't free the given HDC (used by wxWindows
+// only/mainly)
+// ----------------------------------------------------------------------------
+
+class WXDLLEXPORT wxDCTemp : public wxDC
+{
+public:
+    wxDCTemp(WXHDC hdc) { SetHDC(hdc); }
+    virtual ~wxDCTemp() { SetHDC((WXHDC)NULL); }
 };
 
 #endif
diff --git a/src/msw/listbox.cpp b/src/msw/listbox.cpp
index 462c26bb82..147e73c917 100644
--- a/src/msw/listbox.cpp
+++ b/src/msw/listbox.cpp
@@ -773,14 +773,13 @@ bool wxListBox::MSWOnDraw(WXDRAWITEMSTRUCT *item)
 
     wxListBoxItem *pItem = (wxListBoxItem *)data;
 
-    wxDC dc;
-    dc.SetHDC((WXHDC)pStruct->hDC, FALSE);
+    wxDCTemp dc((WXHDC)pStruct->hDC);
     wxRect rect(wxPoint(pStruct->rcItem.left, pStruct->rcItem.top),
                 wxPoint(pStruct->rcItem.right, pStruct->rcItem.bottom));
 
     return pItem->OnDrawItem(dc, rect,
-            (wxOwnerDrawn::wxODAction)pStruct->itemAction,
-            (wxOwnerDrawn::wxODStatus)pStruct->itemState);
+                             (wxOwnerDrawn::wxODAction)pStruct->itemAction,
+                             (wxOwnerDrawn::wxODStatus)pStruct->itemState);
 }
 
 #endif
diff --git a/src/msw/window.cpp b/src/msw/window.cpp
index 11a6da140e..184d7da24b 100644
--- a/src/msw/window.cpp
+++ b/src/msw/window.cpp
@@ -2923,19 +2923,20 @@ bool wxWindow::MSWOnDrawItem(int id, WXDRAWITEMSTRUCT *itemStruct)
 
         wxCHECK( pMenuItem->IsKindOf(CLASSINFO(wxMenuItem)), FALSE );
 
-        // prepare to call OnDrawItem()
-        wxDC dc;
-        dc.SetHDC((WXHDC)pDrawStruct->hDC, FALSE);
+        // prepare to call OnDrawItem(): notice using of wxDCTemp to prevent
+        // the DC from being released
+        wxDCTemp dc((WXHDC)pDrawStruct->hDC);
         wxRect rect(pDrawStruct->rcItem.left, pDrawStruct->rcItem.top,
                     pDrawStruct->rcItem.right - pDrawStruct->rcItem.left,
                     pDrawStruct->rcItem.bottom - pDrawStruct->rcItem.top);
 
         return pMenuItem->OnDrawItem
-                          (
-                            dc, rect,
-                            (wxOwnerDrawn::wxODAction)pDrawStruct->itemAction,
-                            (wxOwnerDrawn::wxODStatus)pDrawStruct->itemState
-                          );
+               (
+                dc,
+                rect,
+                (wxOwnerDrawn::wxODAction)pDrawStruct->itemAction,
+                (wxOwnerDrawn::wxODStatus)pDrawStruct->itemState
+               );
     }
 
     wxWindow *item = FindItem(id);
@@ -3103,9 +3104,8 @@ bool wxWindow::HandleEraseBkgnd(WXHDC hdc)
     if ( ::IsIconic(GetHwnd()) )
         return TRUE;
 
-    wxDC dc;
+    wxDCTemp dc(hdc);
 
-    dc.SetHDC(hdc);
     dc.SetWindow(this);
     dc.BeginDrawing();
 
@@ -3114,8 +3114,9 @@ bool wxWindow::HandleEraseBkgnd(WXHDC hdc)
     bool rc = GetEventHandler()->ProcessEvent(event);
 
     dc.EndDrawing();
+
+    // must be called manually as ~wxDC doesn't do anything for wxDCTemp
     dc.SelectOldObjects(hdc);
-    dc.SetHDC((WXHDC) NULL);
 
     return rc;
 }
-- 
2.45.2