C# 中 mdi 父级中的子窗体 [英] Child form in a mdi parent in C#

问题描述

我使用以下代码在 MDI 父窗体中显示子窗体.如您所知，单击该按钮将导致出现一个新表单.继续单击按钮，您的屏幕将充满空白表格.为了阻止这种情况的发生，我将在按钮之外创建表单的代码移动了.

I use the following codes for showing child form in a MDI parent form. As you know clicking the button will cause a new form to appear. Keep clicking the button and your screen will be filled with blank forms. To stop this from happening, I moved the code that creates the form outside of the button.

像这样:

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    Form2 f2 = new Form2();    

    private void button1_Click(object sender, EventArgs e)
    {
        f2.MdiParent = this;
        f2.Show();
    }

但是当我关闭子表单并想再次打开它时，它不会让我.

But when I close the child form and want to open it again, it won't let me.

请帮我解决这个问题.

推荐答案

您需要跟踪表单状态，以便知道您需要创建一个新表单.像这样:

You need to keep track of the form state so you know you need to create a new one. Like this:

private Form2 f2;    

private void button1_Click(object sender, EventArgs e)
{
    if (f2 == null) {
       f2 = new Form2();
       f2.MdiParent = this;
       f2.FormClosed += delegate { f2 = null; };
       f2.Show();
    }
    else {
       f2.Activate();
    }
}

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