c# - 加载表单时禁用按钮并在关闭表单时启用按钮

Question

我想在加载第二个无模式表单 (Form2) 时禁用主表单上的按钮 (button3)，然后在加载时重新启用该按钮无模式表单已关闭。

这是我尝试过的:

private void button3_Click(object sender, EventArgs e)
{
    Form2 p = new Form2(label1.Text);
    p.Show();

    if (p.Shown)
        this.button3.Click += new System.EventHandler(this.button3_Click);
    else
        this.button3.Click -= new System.EventHandler(this.button3_Click);
}

Answer 1

实现此目的的最佳方法是在显示 Form2 之前禁用 button3，并在 Form2 上使用 FormClosed 事件 表单关闭后重新启用 button3:

public partial class Form1 : Form
{
    ...

    private void button3_Click(object sender, EventArgs e)
    {
        // Instantiate the form and assign the FormClosed event
        var form = new Form2(label1.Text);
        form.FormClosed += Form2_FormClosed;

        // Disable button3
        button3.Enabled = false;

        // Show the form
        form.Show();
    }

    // Occurs when Form2 is closed
    private void Form2_FormClosed(object sender, FormClosedEventArgs e)
    {
        // Re-enable button3
        button3.Enabled = true;
    }
}

另一种方法，将 lambda 表达式分配给 FormClosed 事件:

private void button3_Click(object sender, EventArgs e)
{
    // Instantiate the form
    var form = new Form2(label1.Text);

    // Assign a lambda method to the FormClosed event to re-enable button3
    form.FormClosed += (s, a) => button3.Enabled = true;

    // Disable button3
    button3.Enabled = false;

    // Show the form
    form.Show();
}