lcl: properly release control resources on TWinControl.DestroyWnd:

- notify child controls (only TControl, not TWinControl) before parent handle destruction to perform appropriate preparations inside controls
  - release canvas handle of TGraphicControl when before parent handle destruction
(fixes issue #0014152)

git-svn-id: trunk@20874 -

lcl/controls.pp

@@ -979,6 +979,7 @@ type
     function GetCursor: TCursor; virtual;
     procedure SetCursor(Value: TCursor); virtual;
     procedure SetVisible(Value: Boolean); virtual;
+    procedure DoOnParentHandleDestruction; virtual;
   protected
     // sizing/aligning
     procedure DoAutoSize; virtual;
@@ -1905,6 +1906,8 @@ type
     procedure FontChanged(Sender: TObject); override;
     procedure Paint; virtual;
     procedure DoOnChangeBounds; override;
+    procedure DoOnParentHandleDestruction; override;
+
     property OnPaint: TNotifyEvent read FOnPaint write FOnPaint;
   public
     constructor Create(AOwner: TComponent); override;

lcl/include/control.inc

@@ -3499,6 +3499,11 @@ begin
     ControlState := ControlState + [csVisibleSetInLoading];
 end;
 
+procedure TControl.DoOnParentHandleDestruction;
+begin
+  // nothing, implement in descendats
+end;
+
 {------------------------------------------------------------------------------
        TControl.SetZOrder
 

lcl/include/customcontrol.inc

@@ -63,7 +63,7 @@ end;
 
 procedure TCustomControl.DestroyWnd;
 begin
-  if FCanvas<>nil then
+  if FCanvas <> nil then
     TControlCanvas(FCanvas).FreeHandle;
   inherited DestroyWnd;
 end;

lcl/include/graphiccontrol.inc

@@ -104,5 +104,12 @@ begin
     TControlCanvas(Canvas).FreeHandle;
 end;
 
+procedure TGraphicControl.DoOnParentHandleDestruction;
+begin
+  inherited;
+  if Canvas.HandleAllocated then
+    TControlCanvas(Canvas).FreeHandle;
+end;
+
 // included by controls.pp
 

lcl/include/wincontrol.inc

@@ -6839,8 +6839,8 @@ begin
   if not HandleAllocated then
     RaiseGDBException('TWinControl.FinalizeWnd Handle already destroyed');
   // make sure our text is saved
-  if TWSWinControlClass(WidgetSetClass).GetText(Self, S)
-  then FCaption := S;
+  if TWSWinControlClass(WidgetSetClass).GetText(Self, S) then
+    FCaption := S;
   // if color has changed make sure it will be restored
   if FColor<>clWindow then
     Include(FWinControlFlags,wcfColorChanged);
@@ -6999,10 +6999,17 @@ end;
   Destroys the interface object.
  ------------------------------------------------------------------------------}
 procedure TWinControl.DestroyWnd;
+var
+  i: integer;
 begin
   if HandleAllocated then
   begin
     FinalizeWnd;
+
+    if FControls <> nil then
+      for i := 0 to FControls.Count - 1 do
+        TControl(FControls[i]).DoOnParentHandleDestruction;
+
     TWSWinControlClass(WidgetSetClass).DestroyHandle(Self);
     Handle := 0;
     // We don't know why we here. Maybe because handle is not needed at moment