按住标签移动表格

Question

我正在尝试创建一个以表格为中心的标签，该表格需要我使用label.dock = dockStyle.Fill。因此我尝试实现代码，这意味着当我按住标签时，我可以移动表单。这是我到目前为止所拥有的：

private void messageIndicator_MouseUp(object sender, MouseEventArgs e)
    {
        window.AllowTransparency = true;
        window.TransparencyKey = window.TransparencyKey = window.BackColor;
        isDragging = false;
    }

    void messageIndicator_MouseHover(object sender, EventArgs e)
    {
        window.AllowTransparency = false;
    }

    private void messageIndicator_MouseDown(object sender, MouseEventArgs e)
    {
        // Set the drag mode
        isDragging = true;

        // Get the initial location
        lastLocation = e.Location;
    }

    private void messageIndicator_MouseMove(object sender, MouseEventArgs e)
    {
        // Only drag if in correct state (mouse down)
        if (isDragging)
        {
            // The parameter sender is the form object
            Form f = (Form)sender;

            // Calculate the new location and update the form
            f.Location = new Point((f.Location.X - lastLocation.X) + e.X, (f.Location.Y - lastLocation.Y) + e.Y);
            f.Update();
        }
    }

messageIndicator 是表单上的标签。执行Form f = (form)sender 时确实会崩溃。非常感谢您的帮助:)

Answer 1

试试这个，

public const int WM_NCLBUTTONDOWN = 0xA1;
public const int HT_CAPTION = 0x2;

[DllImportAttribute("user32.dll")]
public static extern int SendMessage(IntPtr hWnd, int Msg, int wParam, int lParam);
[DllImportAttribute("user32.dll")]
public static extern bool ReleaseCapture();

private void YourLabel_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e)
{     
    if (e.Button == MouseButtons.Left)
    {
        ReleaseCapture();
        SendMessage(Handle, WM_NCLBUTTONDOWN, HT_CAPTION, 0);
    }
}

来源：Article