问题描述
我正在使用 .NET Windows 窗体.我的 MDI 父窗体包含菜单.如果单击菜单,将显示表单.到目前为止没有问题.
I am using .NET Windows Forms. My MDI parent form contains the menu. If click the menu the form will be displayed. Up to now no problem.
UserForm uf = new UserForm(); uf.Show(); uf.MdiParent = this;
如果我再次单击菜单,则会创建表单的另一个副本.如何解决这个问题?
If I click the menu again another duplicate of the form is created. How to solve this issue?
推荐答案
最简洁的方法是简单地跟踪表单实例的生命周期.通过订阅 FormClosed 事件来实现.例如:
The cleanest way is to simply track the lifetime of the form instance. Do so by subscribing the FormClosed event. For example:
private UserForm userFormInstance; private void showUserForm_Click(object sender, EventArgs e) { if (userFormInstance != null) { userFormInstance.WindowState = FormWindowState.Normal; userFormInstance.Focus(); } else { userFormInstance = new UserForm(); userFormInstance.MdiParent = this; userFormInstance.FormClosed += (o, ea) => userFormInstance = null; userFormInstance.Show(); } }