带上拉菜单的文本框

带下拉菜单的文本框

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:

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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:

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#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;

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类代码为:

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1. public?partial?class?TextBoxWithDataPick?:?UserControl??????{??
2. ????????public?TextBoxWithDataPick()??????????{??
3. ????????????InitializeComponent();??????????}??
4. ????????///?<summary>文本</summary>?? ??????????public?string?text??
5. ????????{?get{?return?textBox1.Text;?}????????????set{?textBox1.Text?=?value;}??
6. ????????}??????????///?<summary>可供用户选择的数据集</summary>??? ??
7. ????????public?DataTable?dataSource?=?null;??????????///?<summary>在dataSource中的列名</summary>??? ??
8. ????????public?string?columnName?=?"";??????????private?void?TextBoxWithDataPick_Load(object?sender,?EventArgs?e)??
9. ????????{??????????????//控件载入时,将高度缩为与TextBox相等 ??
10. ????????????this.Height?=?textBox1.Height;??????????}??
11. ????????private?void?textBox1_TextChanged(object?sender,?EventArgs?e)??????????{??
12. ????????????if?(this.textBox1.Text?==?""?)??????????????{??????????????????
13. ????????????????this.Height?=?textBox1.Height;??????????????????this.listBox1.Visible?=?false;??
14. ????????????????this.SendToBack();??????????????????return;??
15. ????????????}??????????????//这些情况下,不弹出选择框 ??
16. ????????????if?(dataSource?==?null?||?columnName?==?""?||?!dataSource.Columns.Contains(columnName))??????????????????return;??
17. ????????????//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();??
18. ????????????for?(int?i?=?0;?i?<?dataSource.Rows.Count;?i++)??????????????{??
19. ????????????????if?(dataSource.Rows[i][columnName].ToString().IndexOf(textBox1.Text)?==?0)??????????????????{??
20. ????????????????????listBox1.Items.Add(dataSource.Rows[i][columnName].ToString());??????????????????}??
21. ????????????}??????????????//如果记录数不为0,则将列表显示出来 ??
22. ????????????if?(listBox1.Items.Count?==?0)??????????????{??
23. ????????????????this.Height?=?textBox1.Height;??????????????????this.listBox1.Visible?=?false;??
24. ????????????????this.SendToBack();??????????????}??
25. ????????????else??????????????{??
26. ????????????????if?(listBox1.Items.Count?==?1)??????????????????{??
27. ????????????????????this.Height?=?textBox1.Height?+?20?*?listBox1.Items.Count;??????????????????????this.listBox1.Visible?=?true;??
28. ????????????????????this.BringToFront();??????????????????}??
29. ????????????????else?if?(listBox1.Items.Count<8)??????????????????{??
30. ????????????????????this.Height?=?textBox1.Height?+?14?*?listBox1.Items.Count;??????????????????????this.listBox1.Visible?=?true;??
31. ????????????????????this.BringToFront();??????????????????}??
32. ????????????????else??????????????????{??
33. ????????????????????this.Height?=?textBox1.Height?+?108;??????????????????????this.listBox1.Visible?=?true;??
34. ????????????????????this.BringToFront();??????????????????}??
35. ????????????}??????????}??
36. ????????//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)??
37. ????????{??????????????if?(e.KeyValue?==?(int)Keys.Enter)??
38. ????????????{??????????????????this.textBox1.Text?=?listBox1.SelectedItem.ToString();??
39. ????????????????this.Height?=?textBox1.Height;??????????????????this.listBox1.Visible?=?false;??
40. ????????????????this.SendToBack();??????????????}??
41. ????????}??????????//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 ??
42. ????????private?void?listBox1_DoubleClick(object?sender,?EventArgs?e)??????????{??
43. ????????????if?(listBox1.SelectedItem?!=?null)??????????????{??
44. ????????????????this.textBox1.Text?=?listBox1.SelectedItem.ToString();??????????????????this.Height?=?textBox1.Height;??
45. ????????????????this.listBox1.Visible?=?false;??????????????????this.SendToBack();??
46. ????????????}??????????}??
47. ????????//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)??
48. ????????{??????????????if?(e.KeyValue?==?(int)Keys.Down)??
49. ????????????{??????????????????if?(listBox1.Items.Count?!=?0)??
50. ????????????????{??????????????????????listBox1.Focus();??
51. ????????????????????listBox1.SelectedIndex?=?0;??????????????????}??
52. ????????????}??????????}??
53. ????????//TextBox失去焦点时,隐藏ListBox ??????????private?void?textBox1_Leave(object?sender,?EventArgs?e)??
54. ????????{??????????????if?(listBox1.Focused?==?false)??
55. ????????????{??????????????????this.Height?=?textBox1.Height;??
56. ????????????????this.listBox1.Visible?=?false;??????????????????this.SendToBack();??
57. ????????????}??????????}??
58. ????????private?void?listBox1_Leave(object?sender,?EventArgs?e)??????????{??
59. ????????????if?(textBox1.Focused?==?false)??????????????{??
60. ????????????????this.Height?=?textBox1.Height;??????????????????this.listBox1.Visible?=?false;??
61. ????????????????this.SendToBack();??????????????}??
62. ????????}????????????
63. ????}??