在C＃中使用奇怪行为自动完成文本框

Question

在C＃中的Windows.Forms表单中，我有一个组合框和一个文本框。该文本框通过AutoCompleteCustomSource打开了自动完成功能。 AutoCompleteCustomSource中的元素取决于组合框的选定值。这意味着每次更改组合框的值时都必须更改自动完成值。但这样做我也经历过一些奇怪的行为，我不喜欢：

• 文本是自动完成的离开并重新输入文本框
• 离开并重新输入文本框时后一直选择，光标总是会放置在文本的末尾，即使我点击使用退格键的字符
• 之间的某处使suggestbox出现

我有以下简短的示例代码示出了所描述的行为。 尝试在文本框中输入“必须”。按下键盘上的TAB后，应该建议并附加“Mustang”。现在从组合框中选择“福特”，然后重新输入文本框来查看我的意思。

Form2.Designer.cs

partial class Form2 
{ 
    /// <summary> 
    /// Required designer variable. 
    /// </summary> 
    private System.ComponentModel.IContainer components = null; 

    /// <summary> 
    /// Clean up any resources being used. 
    /// </summary> 
    /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param> 
    protected override void Dispose(bool disposing) 
    { 
     if (disposing && (components != null)) 
     { 
      components.Dispose(); 
     } 
     base.Dispose(disposing); 
    } 

    #region Windows Form Designer generated code 

    /// <summary> 
    /// Required method for Designer support - do not modify 
    /// the contents of this method with the code editor. 
    /// </summary> 
    private void InitializeComponent() 
    { 
     this.comboBox1 = new System.Windows.Forms.ComboBox(); 
     this.label1 = new System.Windows.Forms.Label(); 
     this.label2 = new System.Windows.Forms.Label(); 
     this.textBox1 = new System.Windows.Forms.TextBox(); 
     this.textBox2 = new System.Windows.Forms.TextBox(); 
     this.SuspendLayout(); 
     // 
     // comboBox1 
     // 
     this.comboBox1.FormattingEnabled = true; 
     this.comboBox1.Items.AddRange(new object[] { 
     "Audi", 
     "Fiat", 
     "Ford", 
     "VW"}); 
     this.comboBox1.Location = new System.Drawing.Point(87, 12); 
     this.comboBox1.Name = "comboBox1"; 
     this.comboBox1.Size = new System.Drawing.Size(193, 21); 
     this.comboBox1.TabIndex = 0; 
     // 
     // label1 
     // 
     this.label1.AutoSize = true; 
     this.label1.Location = new System.Drawing.Point(1, 15); 
     this.label1.Name = "label1"; 
     this.label1.Size = new System.Drawing.Size(38, 13); 
     this.label1.TabIndex = 1; 
     this.label1.Text = "Brand:"; 
     // 
     // label2 
     // 
     this.label2.AutoSize = true; 
     this.label2.Location = new System.Drawing.Point(1, 64); 
     this.label2.Name = "label2"; 
     this.label2.Size = new System.Drawing.Size(34, 13); 
     this.label2.TabIndex = 2; 
     this.label2.Text = "Type:"; 
     // 
     // textBox1 
     // 
     this.textBox1.Location = new System.Drawing.Point(87, 61); 
     this.textBox1.Name = "textBox1"; 
     this.textBox1.Size = new System.Drawing.Size(193, 20); 
     this.textBox1.TabIndex = 3; 
     // 
     // textBox2 
     // 
     this.textBox2.Location = new System.Drawing.Point(12, 110); 
     this.textBox2.Multiline = true; 
     this.textBox2.Name = "textBox2"; 
     this.textBox2.ReadOnly = true; 
     this.textBox2.Size = new System.Drawing.Size(268, 144); 
     this.textBox2.TabIndex = 4; 
     // 
     // Form2 
     // 
     this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F); 
     this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font; 
     this.ClientSize = new System.Drawing.Size(292, 266); 
     this.Controls.Add(this.textBox2); 
     this.Controls.Add(this.textBox1); 
     this.Controls.Add(this.label2); 
     this.Controls.Add(this.label1); 
     this.Controls.Add(this.comboBox1); 
     this.Name = "Form2"; 
     this.Text = "Form2"; 
     this.ResumeLayout(false); 
     this.PerformLayout(); 

    } 

    #endregion 

    private System.Windows.Forms.ComboBox comboBox1; 
    private System.Windows.Forms.Label label1; 
    private System.Windows.Forms.Label label2; 
    private System.Windows.Forms.TextBox textBox1; 
    private System.Windows.Forms.TextBox textBox2; 
} 

Form2.cs

public partial class Form2 : Form 
{ 
    private string[] types_audi = new string[] { "A4" }; 
    private string[] types_ford = new string[] { "Mustang", "Focus" }; 
    private string[] types_fiat = new string[] { "Punto", "500" }; 
    private string[] types_vw = new string[] { "Golf" }; 
    private List<string[]> types = new List<string[]>(); 

    public Form2() 
    { 
     InitializeComponent(); 

     this.types.Add(this.types_audi); 
     this.types.Add(this.types_ford); 
     this.types.Add(this.types_fiat); 
     this.types.Add(this.types_vw); 

     this.textBox1.AutoCompleteMode = AutoCompleteMode.SuggestAppend; 
     this.textBox1.AutoCompleteSource = AutoCompleteSource.CustomSource; 
     this.textBox1.AutoCompleteCustomSource = new AutoCompleteStringCollection(); 
     this.textBox1.AutoCompleteCustomSource.AddRange(this.types_audi); 
     this.textBox1.AutoCompleteCustomSource.AddRange(this.types_fiat); 
     this.textBox1.AutoCompleteCustomSource.AddRange(this.types_ford); 
     this.textBox1.AutoCompleteCustomSource.AddRange(this.types_vw); 

     this.textBox1.Enter += new EventHandler(this.textBox1_Enter); 
     this.textBox1.Leave += new EventHandler(this.textBox1_Leave); 
     this.comboBox1.Select(); 
    } 

    private void textBox1_Leave(object sender, EventArgs e) 
    { 
     this.textBox2.Clear(); 
    } 

    private void textBox1_Enter(object sender, EventArgs e) 
    { 
     // reset AutoCompleteCustomSource 
     this.textBox1.AutoCompleteCustomSource.Clear(); 

     switch (this.comboBox1.SelectedItem as string) 
     { 
      case "Audi": 
       this.textBox1.AutoCompleteCustomSource.AddRange(this.types_audi); 
       break; 
      case "Ford": 
       this.textBox1.AutoCompleteCustomSource.AddRange(this.types_ford); 
       break; 
      case "Fiat": 
       this.textBox1.AutoCompleteCustomSource.AddRange(this.types_fiat); 
       break; 
      case "VW": 
       this.textBox1.AutoCompleteCustomSource.AddRange(this.types_vw); 
       break; 
      default: 
       this.textBox1.AutoCompleteCustomSource.AddRange(this.types_audi); 
       this.textBox1.AutoCompleteCustomSource.AddRange(this.types_fiat); 
       this.textBox1.AutoCompleteCustomSource.AddRange(this.types_ford); 
       this.textBox1.AutoCompleteCustomSource.AddRange(this.types_vw); 
       break; 
     } 

     this.textBox2.Text = "Possible values: " + Environment.NewLine; 

     foreach (var val in this.textBox1.AutoCompleteCustomSource) 
     { 
      this.textBox2.Text += Environment.NewLine + val; 
     } 
    } 
} 

Answer 1

您可以创建一个新的字符串对象来存储从ComboBox以前选定的项目，并清除textBox1的在textBox1_Enter方法中，如果组合中选定的项目与先前选择的项目不同，然后将先前选择的项目设置为当前选择编辑项目。

应该是这样的：

private void textBox1_Enter(object sender, EventArgs e) 
{ 
    // reset AutoCompleteCustomSource 
    var selectedItem = comboBox1.SelectedItem as string; 

    if (string.Compare(this.previouslySelectedItem, selectedItem) != 0) 
    { 
     this.textBox1.Clear(); 
     this.previouslySelectedItem = selectedItem; 
    } 

    this.textBox1.AutoCompleteCustomSource.Clear(); 

    switch (this.comboBox1.SelectedItem as string) 
    { 
     case "Audi": 
      this.textBox1.AutoCompleteCustomSource.AddRange(this.types_audi); 
      break; 
     case "Ford": 
      this.textBox1.AutoCompleteCustomSource.AddRange(this.types_ford); 
      break; 
     case "Fiat": 
      this.textBox1.AutoCompleteCustomSource.AddRange(this.types_fiat); 
      break; 
     case "VW": 
      this.textBox1.AutoCompleteCustomSource.AddRange(this.types_vw); 
      break; 
     default: 
      this.textBox1.AutoCompleteCustomSource.AddRange(this.types_audi); 
      this.textBox1.AutoCompleteCustomSource.AddRange(this.types_fiat); 
      this.textBox1.AutoCompleteCustomSource.AddRange(this.types_ford); 
      this.textBox1.AutoCompleteCustomSource.AddRange(this.types_vw); 
      break; 
    } 

    this.textBox2.Text = "Possible values: " + Environment.NewLine; 

    foreach (var val in this.textBox1.AutoCompleteCustomSource) 
    { 
     this.textBox2.Text += Environment.NewLine + val; 
    } 
}