大家好,我想知道是否有任何事件或方法可以拦截当所有 MDI 窗体关闭时的情况。
示例:
我想在我的主窗体中实现一个事件,在关闭所有 MDI 窗体时触发此事件。
如果有人能帮忙,将不胜感激。
MDI子窗体(实际上是任何窗体)在销毁时会通知主窗体。您可以使用此通知机制。示例:
type
TForm1 = class(TForm)
..
protected
procedure Notification(AComponent: TComponent; Operation: TOperation);
override;
..
procedure TForm1.Notification(AComponent: TComponent; Operation: TOperation);
begin
inherited;
if (Operation = opRemove) and (AComponent is TForm) and
(TForm(AComponent).FormStyle = fsMDIChild) and
(MDIChildCount = 0) then begin
// do work
end;
end;
捕获发送到MDI客户端窗口的WM_MDIDESTROY
消息:
type
TForm1 = class(TForm)
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
private
FOldClientWndProc: TFarProc;
procedure NewClientWndProc(var Message: TMessage);
end;
...
procedure TForm1.FormCreate(Sender: TObject);
begin
if FormStyle = fsMDIForm then
begin
HandleNeeded;
FOldClientWndProc := Pointer(GetWindowLong(ClientHandle, GWL_WNDPROC));
SetWindowLong(ClientHandle, GWL_WNDPROC,
Integer(MakeObjectInstance(NewClientWndProc)));
end;
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
SetWindowLong(ClientHandle, GWL_WNDPROC, Integer(FOldClientWndProc));
end;
procedure TForm1.NewClientWndProc(var Message: TMessage);
begin
if Message.Msg = WM_MDIDESTROY then
if MDIChildCount = 1 then
// do work
with Message do
Result := CallWindowProc(FOldClientWndProc, ClientHandle, Msg, WParam,
LParam);
end;
您可以让主窗体为创建的每个MDI子窗体分配一个OnClose
或OnDestroy
事件处理程序。每次关闭/销毁MDI客户端时,处理程序可以检查是否还有更多MDI子窗体仍然处于打开状态,如果没有,则执行其需要执行的操作。
procedure TMainForm.ChildClosed(Sender: TObject; var Action: TCloseAction);
begin
Action := caFree;
// the child being closed is still in the MDIChild list as it has not been freed yet...
if MDIChildCount = 1 then
begin
// do work
end;
end;
或者:
const
APPWM_CHECK_MDI_CHILDREN = WM_APP + 1;
procedure TMainForm.ChildDestroyed(Sender: TObject);
begin
PostMessage(Handle, APPWM_CHECK_MDI_CHILDREN, 0, 0);
end;
procedure TMainForm.WndProc(var Message: TMessage);
begin
if Message.Msg = APPWM_CHECK_MDI_CHILDREN then
begin
if MDIChildCount = 0 then
begin
// do work
end;
Exit;
end;
inherited;
end;