C# FORM 自定义控件:带弹出(下拉)菜单的TextBox

2017年05月31日 13:50:58 ~typhoon~ 阅读数 5669

程序需要做一个带下拉菜单的文本框以方便用户输入,大概类似于下图中这种TextBox:

控件有一个数据源,用的DataTable格式,还有一个值columnName来表示用Table中的哪一列数据,控件将根据这一列的数据来进行下拉框提示.

界面只添加了一个文本框和一个ListBox,

组件生成器中的代码为:

 #region 组件设计器生成的代码

/// <summary>

/// 设计器支持所需的方法 - 不要

/// 使用代码编辑器修改此方法的内容。

/// </summary>

private void InitializeComponent(){

this.textBox1 = new System.Windows.Forms.TextBox();
this.listBox1 = new System.Windows.Forms.ListBox();
this.SuspendLayout();

//
// textBox1
//
this.textBox1.Dock = System.Windows.Forms.DockStyle.Top;
this.textBox1.Location = new System.Drawing.Point(0, 0);
this.textBox1.Name = "textBox1";
this.textBox1.Size = new System.Drawing.Size(189, 21);
this.textBox1.TabIndex = 0;
this.textBox1.TextChanged += new System.EventHandler(this.textBox1_TextChanged);
this.textBox1.KeyDown += new System.Windows.Forms.KeyEventHandler(this.textBox1_KeyDown);
this.textBox1.Leave += new System.EventHandler(this.textBox1_Leave);

//

// listBox1

//

this.listBox1.Dock = System.Windows.Forms.DockStyle.Fill;

this.listBox1.FormattingEnabled = true;

this.listBox1.ItemHeight = 12;

this.listBox1.Location = new System.Drawing.Point(0, 21);

this.listBox1.Name = "listBox1";

this.listBox1.Size = new System.Drawing.Size(189, 4);

this.listBox1.TabIndex = 1;

this.listBox1.Leave += new System.EventHandler(this.listBox1_Leave);

this.listBox1.DoubleClick += new System.EventHandler(this.listBox1_DoubleClick);

this.listBox1.KeyDown += new System.Windows.Forms.KeyEventHandler(this.listBox1_KeyDown);

//

// TextBoxWithDataPick

//

this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F);

this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;

this.Controls.Add(this.listBox1);

this.Controls.Add(this.textBox1);

this.Name = "TextBoxWithDataPick";

this.Size = new System.Drawing.Size(189, 25);

this.Load += new System.EventHandler(this.TextBoxWithDataPick_Load);

this.ResumeLayout(false);

this.PerformLayout();

}

#endregion

private System.Windows.Forms.TextBox textBox1;

private System.Windows.Forms.ListBox listBox1;

类代码为:

public partial class TextBoxWithDataPick : UserControl

{

public TextBoxWithDataPick()

{

InitializeComponent();

}

/// <summary>文本</summary>

public string text

{ get{ return textBox1.Text; }

set{ textBox1.Text = value;}

}

/// <summary>可供用户选择的数据集</summary>

public DataTable dataSource = null;

/// <summary>在dataSource中的列名</summary>

public string columnName = "";

private void TextBoxWithDataPick_Load(object sender, EventArgs e)

{

//控件载入时,将高度缩为与TextBox相等

this.Height = textBox1.Height;

}

private void textBox1_TextChanged(object sender, EventArgs e)

{

if (this.textBox1.Text == "" )

{

this.Height = textBox1.Height;

this.listBox1.Visible = false;

this.SendToBack();

return;

}

//这些情况下,不弹出选择框

if (dataSource == null || columnName == "" || !dataSource.Columns.Contains(columnName))

return;

//根据用户当前输入的内容,筛选出与内容相符的记录,显示在列表框中

this.listBox1.Items.Clear();

for (int i = 0; i < dataSource.Rows.Count; i++)

{

if (dataSource.Rows[i][columnName].ToString().IndexOf(textBox1.Text) == 0)

{

listBox1.Items.Add(dataSource.Rows[i][columnName].ToString());

}

}

//如果记录数不为0,则将列表显示出来

if (listBox1.Items.Count == 0)

{

this.Height = textBox1.Height;

this.listBox1.Visible = false;

this.SendToBack();

}

else

{

if (listBox1.Items.Count == 1)

{

this.Height = textBox1.Height + 20 * listBox1.Items.Count;

this.listBox1.Visible = true;

this.BringToFront();

}

else if (listBox1.Items.Count<8)

{

this.Height = textBox1.Height + 14 * listBox1.Items.Count;

this.listBox1.Visible = true;

this.BringToFront();

}

else

{

this.Height = textBox1.Height + 108;

this.listBox1.Visible = true;

this.BringToFront();

}

}

}

//用户在焦点为listBox1时按下回车,将当前选中的内容提交到TextBox中,并隐藏ListBox

private void listBox1_KeyDown(object sender, KeyEventArgs e)

{

if (e.KeyValue == (int)Keys.Enter)

{

this.textBox1.Text = listBox1.SelectedItem.ToString();

this.Height = textBox1.Height;

this.listBox1.Visible = false;

this.SendToBack();

}

}

//用户双击listBox1某项时,将当前选中的内容提交到TextBox中,并隐藏ListBox

private void listBox1_DoubleClick(object sender, EventArgs e)

{

if (listBox1.SelectedItem != null)

{

this.textBox1.Text = listBox1.SelectedItem.ToString();

this.Height = textBox1.Height;

this.listBox1.Visible = false;

this.SendToBack();

}

}

//用户在TextBox中点击向下箭头时,将焦点交给ListBox,使用户能够选择其中的项

private void textBox1_KeyDown(object sender, KeyEventArgs e)

{

if (e.KeyValue == (int)Keys.Down)

{

if (listBox1.Items.Count != 0)

{

listBox1.Focus();

listBox1.SelectedIndex = 0;

}

}

}

//TextBox失去焦点时,隐藏ListBox

private void textBox1_Leave(object sender, EventArgs e)

{

if (listBox1.Focused == false)

{

this.Height = textBox1.Height;

this.listBox1.Visible = false;

this.SendToBack();

}

}

private void listBox1_Leave(object sender, EventArgs e)

{

if (textBox1.Focused == false)

{

this.Height = textBox1.Height;

this.listBox1.Visible = false;

this.SendToBack();

}

}

}