From 8e5e003f09a972f6a125c4f5cb7b9151cd20c780 Mon Sep 17 00:00:00 2001
From: Uwe Bonnes <bon@elektron.ikp.physik.tu-darmstadt.de>
Date: Mon, 20 Aug 2001 19:17:28 +0000
Subject: [PATCH] Added reference counting and delayed destruction of GDI
 objects.

---
 objects/dc.c     |  1 +
 objects/gdiobj.c | 61 +++++++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 59 insertions(+), 3 deletions(-)

diff --git a/objects/dc.c b/objects/dc.c
index 22993616890..675c9dbef3f 100644
--- a/objects/dc.c
+++ b/objects/dc.c
@@ -757,6 +757,7 @@ BOOL WINAPI DeleteDC( HDC hdc )
 	SelectObject( hdc, GetStockObject(BLACK_PEN) );
 	SelectObject( hdc, GetStockObject(WHITE_BRUSH) );
 	SelectObject( hdc, GetStockObject(SYSTEM_FONT) );
+        SelectObject( hdc, GetStockObject(DEFAULT_BITMAP) );
         funcs = dc->funcs;
         if (dc->funcs->pDeleteDC) dc->funcs->pDeleteDC(dc);
     }
diff --git a/objects/gdiobj.c b/objects/gdiobj.c
index ec5b254e2a2..c667902e2d6 100644
--- a/objects/gdiobj.c
+++ b/objects/gdiobj.c
@@ -144,6 +144,48 @@ static HFONT create_stock_font( char const *fontName, const LOGFONTW *font, HKEY
    TRACE("(%04x): " text " %ld\n", (handle), GDI_level.crst.RecursionCount)
 
 
+/***********************************************************************
+ *           inc_ref_count
+ *
+ * Increment the reference count of a GDI object.
+ */
+inline static void inc_ref_count( HGDIOBJ handle )
+{
+    GDIOBJHDR *header;
+
+    if ((header = GDI_GetObjPtr( handle, MAGIC_DONTCARE )))
+    {
+        header->dwCount++;
+        GDI_ReleaseObj( handle );
+    }
+}
+
+
+/***********************************************************************
+ *           dec_ref_count
+ *
+ * Decrement the reference count of a GDI object.
+ */
+inline static void dec_ref_count( HGDIOBJ handle )
+{
+    GDIOBJHDR *header;
+
+    if ((header = GDI_GetObjPtr( handle, MAGIC_DONTCARE )))
+    {
+        if (header->dwCount) header->dwCount--;
+        if (header->dwCount != 0x80000000) GDI_ReleaseObj( handle );
+        else
+        {
+            /* handle delayed DeleteObject*/
+            header->dwCount = 0;
+            GDI_ReleaseObj( handle );
+            TRACE( "executing delayed DeleteObject for %04x\n", handle );
+            DeleteObject( handle );
+        }
+    }
+}
+
+
 /***********************************************************************
  *           GDI_Init
  *
@@ -243,7 +285,6 @@ inline static GDIOBJHDR *alloc_large_heap( WORD size, HGDIOBJ *handle )
  */
 void *GDI_AllocObject( WORD size, WORD magic, HGDIOBJ *handle )
 {
-    static DWORD count = 0;
     GDIOBJHDR *obj;
 
     _EnterSysLevel( &GDI_level );
@@ -269,7 +310,7 @@ void *GDI_AllocObject( WORD size, WORD magic, HGDIOBJ *handle )
 
     obj->hNext   = 0;
     obj->wMagic  = magic|OBJECT_NOSYSTEM;
-    obj->dwCount = ++count;
+    obj->dwCount = 0;
 
     TRACE_SEC( *handle, "enter" );
     return obj;
@@ -427,7 +468,15 @@ BOOL WINAPI DeleteObject( HGDIOBJ obj )
         GDI_ReleaseObj( obj );
 	return TRUE;
     }
-	
+
+    if (header->dwCount)
+    {
+        TRACE("delayed for %04x because object in use, count %ld\n", obj, header->dwCount );
+        header->dwCount |= 0x80000000; /* mark for delete */
+        GDI_ReleaseObj( obj );
+        return TRUE;
+    }
+
     TRACE("%04x\n", obj );
 
       /* Delete object */
@@ -701,6 +750,12 @@ HGDIOBJ WINAPI SelectObject( HDC hdc, HGDIOBJ handle )
     if (dc->funcs->pSelectObject)
         ret = dc->funcs->pSelectObject( dc, handle );
     GDI_ReleaseObj( hdc );
+
+    if (ret && ret != handle)
+    {
+        inc_ref_count( handle );
+        dec_ref_count( ret );
+    }
     return ret;
 }