在其父级边界之外的用户控件内显示控件 [英] Show control inside user control outside the boundaries of its parent

问题描述

我有一个包含文本框和列表框的用户控件，它使用它们为用户提供自动完成功能.

I have a usercontrol that has a textbox and a listbox, and it uses them to provides autocomplete functionality to the users.

但是，我希望将列表框绘制在用户控件的边界之外，这样当必须在用户控件的边缘附近绘制列表框时它不会被截断.关于如何做到这一点的任何提示?本质上，我想要一个列表框浮动在其容器控件的边界之外.

However, I want the listbox to be drawn outside of the boundaries of the user control so that it doesn't get cutoff when the listbox has to be drawn near the edge of the user control. Any tips on how to do that? Essentially I want a listbox floating outside the boundaries of its container control.

我能想到的唯一方法是在实例化时将对外部列表框的引用传递给用户控件，然后操纵该列表框而不是将其放在用户控件中，但我不喜欢这种方法.提前致谢.

The only way I can think off is to pass a reference to an outside listbox to the user control on instantiation and then manipulate that listbox instead of having it inside the user control, but I dont like this approach. Thanks in advance.

推荐答案

问题是，您无法逃脱容器表单边界，但您可以将控件托管在其他地方.

Problem is, you can't escape your container form bounds, but you can host your control somewhere else.

这是我通过滥用 ToolstripDropDown 类得到的工作(我用它来显示大型企业应用程序中的日期选择器):

Here's what I got working by abusing the ToolstripDropDown class (I use it to display datepickers in a large enterprise application):

/// <summary>
/// PopupHelper
/// </summary>
public sealed class PopupHelper : IDisposable
{
    private readonly Control m_control;
    private readonly ToolStripDropDown m_tsdd;
    private readonly Panel m_hostPanel; // workarround - some controls don't display correctly if they are hosted directly in ToolStripControlHost

    public PopupHelper(Control pControl)
    {
        m_hostPanel = new Panel();
        m_hostPanel.Padding = Padding.Empty;
        m_hostPanel.Margin = Padding.Empty;
        m_hostPanel.TabStop = false;
        m_hostPanel.BorderStyle = BorderStyle.None;
        m_hostPanel.BackColor = Color.Transparent;

        m_tsdd = new ToolStripDropDown();
        m_tsdd.CausesValidation = false;

        m_tsdd.Padding = Padding.Empty;
        m_tsdd.Margin = Padding.Empty;
        m_tsdd.Opacity = 0.9;

        m_control = pControl;
        m_control.CausesValidation = false;
        m_control.Resize += MControlResize;

        m_hostPanel.Controls.Add(m_control);

        m_tsdd.Padding = Padding.Empty;
        m_tsdd.Margin = Padding.Empty;

        m_tsdd.MinimumSize = m_tsdd.MaximumSize = m_tsdd.Size = pControl.Size;

        m_tsdd.Items.Add(new ToolStripControlHost(m_hostPanel));
    }

    private void ResizeWindow()
    {
        m_tsdd.MinimumSize = m_tsdd.MaximumSize = m_tsdd.Size = m_control.Size;
        m_hostPanel.MinimumSize = m_hostPanel.MaximumSize = m_hostPanel.Size = m_control.Size;
    }

    private void MControlResize(object sender, EventArgs e)
    {
        ResizeWindow();
    }

    /// <summary>
    /// Display the popup and keep the focus
    /// </summary>
    /// <param name="pParentControl"></param>
    public void Show(Control pParentControl)
    {
        if (pParentControl == null) return;

        // position the popup window
        var loc = pParentControl.PointToScreen(new Point(0, pParentControl.Height));
        m_tsdd.Show(loc);
        m_control.Focus();
    }

    public void Close()
    {
        m_tsdd.Close();
    }

    public void Dispose()
    {
        m_control.Resize -= MControlResize;

        m_tsdd.Dispose();
        m_hostPanel.Dispose();
    }
}

用法:

    private PopupHelper m_popup;
    private void ShowPopup()
    {
        if (m_popup == null)
            m_popup = new PopupHelper(yourListControl);

        m_popup.Show(this);
    }

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