在winforms文本框内的按钮

Question

winforms文本框是否有任何属性可以在框的末尾创建一个嵌入式按钮？

类似Chrome地址框中的收藏夹按钮:

我在一些Excel表单中也看到过如下内容:

---

编辑

我跟随Hans Passant的回答添加了一个click事件处理程序,它似乎工作正常:

protected override void OnLoad(EventArgs e) {
    var btn = new Button();
    btn.Size = new Size(25, textBoxFolder.ClientSize.Height + 2);
    btn.Location = new Point(textBoxFolder.ClientSize.Width - btn.Width, -1);
    btn.Cursor = Cursors.Default;
    btn.Image = Properties.Resources.arrow_diagright;
    btn.Click += btn_Click;     
    textBoxFolder.Controls.Add(btn);
    // Send EM_SETMARGINS to prevent text from disappearing underneath the button
    SendMessage(textBoxFolder.Handle, 0xd3, (IntPtr)2, (IntPtr)(btn.Width << 16));
    base.OnLoad(e);
}

[System.Runtime.InteropServices.DllImport("user32.dll")]
private static extern IntPtr SendMessage(IntPtr hWnd, int msg, IntPtr wp, IntPtr lp);

private void btn_Click(object sender, EventArgs e) {
    MessageBox.Show("hello world");
}

Answer 1

获取TextBox中的按钮只需将其添加到"控件集合"框中.你还需要做一些合理的事情来防止盒子里面的文字消失在按钮下面; 这需要一点点的pinvoke.像这样:

    protected override void OnLoad(EventArgs e) {
        var btn = new Button();
        btn.Size = new Size(25, textBox1.ClientSize.Height + 2);
        btn.Location = new Point(textBox1.ClientSize.Width - btn.Width, -1);
        btn.Cursor = Cursors.Default;
        btn.Image = Properties.Resources.star;
        textBox1.Controls.Add(btn);
        // Send EM_SETMARGINS to prevent text from disappearing underneath the button
        SendMessage(textBox1.Handle, 0xd3, (IntPtr)2, (IntPtr)(btn.Width << 16));
        base.OnLoad(e);  
    }

    [System.Runtime.InteropServices.DllImport("user32.dll")]
    private static extern IntPtr SendMessage(IntPtr hWnd, int msg, IntPtr wp, IntPtr lp);

当我测试右边距时应该看起来像这样(应该选择一个更漂亮的位图):

Answer 2

这是TextBox子类中包含的答案.

public class ButtonTextBox : TextBox {
    private readonly Button _button;

    public event EventHandler ButtonClick { add { _button.Click += value; } remove { _button.Click -= value; } }

    public ButtonTextBox() {
        _button = new Button {Cursor = Cursors.Default};
        _button.SizeChanged += (o, e) => OnResize(e);
        this.Controls.Add(_button); 
    }

    public Button Button {
        get {
            return _button;
        }
    }

    protected override void OnResize(EventArgs e) {
        base.OnResize(e);
        _button.Size = new Size(_button.Width, this.ClientSize.Height + 2);
        _button.Location = new Point(this.ClientSize.Width - _button.Width, -1);
        // Send EM_SETMARGINS to prevent text from disappearing underneath the button
        SendMessage(this.Handle, 0xd3, (IntPtr)2, (IntPtr)(_button.Width << 16));
    }

    [System.Runtime.InteropServices.DllImport("user32.dll")]
    private static extern IntPtr SendMessage(IntPtr hWnd, int msg, IntPtr wp, IntPtr lp);

}

Answer 3

我在Reflector中看到控件包含“ SendMessage（int，int，int）”方法，我发现了另一种方法。

using System;
using System.Reflection;
using System.Windows.Forms;

static class ControlExtensions
{
    static BindingFlags flags = BindingFlags.Instance | BindingFlags.NonPublic;
    static Type[] SendMessageSig = new Type[] { typeof(int), typeof(int), typeof(int) };

    internal static IntPtr SendMessage(this Control control, int msg, int wparam, int lparam)
    {
        MethodInfo MethodInfo = control.GetType().GetMethod("SendMessage", flags, null, SendMessageSig, null);

        return (IntPtr)MethodInfo.Invoke(control, new object[] { msg, wparam, lparam });
    }
}

现在，通过在ButtonTextBox中重写WndProc，我们可以实现所需的效果。

public class ButtonTextBox : TextBox
{
    Button button;

    public ButtonTextBox()
    {
        this.button = new Button();
        this.button.Dock = DockStyle.Right;
        this.button.BackColor = SystemColors.Control;
        this.button.Width = 21;
        this.Controls.Add(this.button);
    }

    protected override void WndProc(ref Message m)
    {
        base.WndProc(ref m);

        switch (m.Msg)
        {
            case 0x30:
                int num = this.button.Width + 3;
                this.SendMessage(0xd3, 2, num << 16);
                return;
        }
    }
}

我认为这是更安全的方法。