c# - 如何在 Winform 应用程序中限制父控件内的子控件？

Question

我在 Panel 控件中动态创建了一个 Label 控件。我正在使用鼠标事件移动标签控件。那个时候标签控件移到面板控件之外。我该如何限制它？

Answer 1

您可以利用 Cursor.Clip 来满足您的要求(尽管我们可以在 MouseMove 事件处理程序中手动处理):

    Point downPoint;
    //MouseDown event handler for your label1
    private void label1_MouseDown(object sender, MouseEventArgs e){
        downPoint = e.Location;
        //this is the most important code to make it works
        Cursor.Clip = yourPanel.RectangleToScreen(new Rectangle(e.X, e.Y, yourPanel.ClientSize.Width - label1.Width, yourPanel.ClientSize.Height - label1.Height));
    }
    //MouseMove event handler for your label1
    private void label1_MouseMove(object sender, MouseEventArgs e) {
        if (e.Button == MouseButtons.Left) {
            label1.Left += e.X - downPoint.X;
            label1.Top += e.Y - downPoint.Y;
        }
    }
    //MouseUp event handler for your label1
    private void label1_MouseUp(object sender, MouseEventArgs e){
        Cursor.Clip = Rectangle.Empty;
    }