如何停止将MDI子窗体拖到父窗口边缘之外？

Question

“人物”是MDI父表格 “新”是MDI子表格

如何阻止“新”被拖到“人物”边缘外？

我发现代码工作正常

    protected override void OnMove(EventArgs e)
    {
        //
        // Get the MDI Client window reference
        //
        MdiClient mdiClient = null;
        foreach (Control ctl in MdiParent.Controls)
        {
            mdiClient = ctl as MdiClient;
            if (mdiClient != null)
                break;
        }
        //
        // Don't allow moving form outside of MDI client bounds
        //
        if (Left < mdiClient.ClientRectangle.Left)
            Left = mdiClient.ClientRectangle.Left;
        if (Top < mdiClient.ClientRectangle.Top)
            Top = mdiClient.ClientRectangle.Top;
        if (Top + Height > mdiClient.ClientRectangle.Height)
            Top = mdiClient.ClientRectangle.Height - Height;
        if (Left + Width > mdiClient.ClientRectangle.Width)
            Left = mdiClient.ClientRectangle.Width - Width;
        base.OnMove(e);
    }

Answer 1

MDI父表单重新定位新表单类似于显示多个表单级联。要重新定位窗口，您必须在Form_Loading事件处理程序中设置位置。

Answer 2

将子表单StartPosition设置为CenterParent

Answer 3

隐藏mdi容器的滚动条，示例代码：

internal sealed class NonScrollableWindow : NativeWindow
{
    private readonly MdiClient _mdiClient;

    public NonScrollableWindow(MdiClient parent)
    {
        _mdiClient = parent;
        ReleaseHandle();
        AssignHandle(_mdiClient.Handle);
    }
    internal void OnHandleDestroyed(object sender, EventArgs e)
    {
        ReleaseHandle();
    }
    private const int SB_BOTH = 3;
    [DllImport("user32.dll")]
    private static extern int ShowScrollBar(IntPtr hWnd, int wBar, int bShow);
    protected override void WndProc(ref Message m)
    {
        ShowScrollBar(m.HWnd, SB_BOTH, 0);
        base.WndProc(ref m);
    }
}

用法（在mdi父加载事件中），

 foreach (MdiClient control in Controls.OfType<MdiClient>())
        {
            if (control != null)
            {
                new NonScrollableWindow(control);
                break;
            }
        }

Answer 4

在孩子的移动事件中，您可以使用代码来检测当前位置是否超出您想要的位置。您需要先建立父窗口的顶部，左侧，底部和右侧边缘。

代码如：

BufferWidth = 10; // 10 pixel buffer to edge
// ParentTop is the top Y co-ordinate of the parent window

if (this.location.Y > (ParentTop-BufferWidth))
{
    int LocX = this.Location.X;
    this.location = new Point(LocX, (ParentTop-BufferWidth));
}

您需要为每一方重复此操作。通过预先用缓冲区计算边缘可以更加简化代码，因为它们只会在父窗口移动时改变。