我编辑了我的答案，因为它没有像版主指出的那样提供足够的清晰度，因为我提到的源链接可能会被删除。如果您需要进一步说明，链接将在此说明中。好的，解决方法是使用来自 here 的该用户的指南
作者所做的是覆盖 winforms 中的默认组合框设置。我刚刚找到了一种将它绑定到我的代码中并让它运行起来的方法。希望这对将来的某人有所帮助。我将概述它是如何工作的
suggestComboBox.DataSource = new List<person>();
suggestComboBox.DisplayMember = "Name";
// then you have to set the PropertySelector like this:
suggestComboBox.PropertySelector = collection => collection.Cast<person>
().Select(p => p.Name);
// the class Person looks something like this:
class Person
{
public string Name { get; set; }
public DateTime DateOfBirth { get; set; }
public int Height { get; set; }
}</person>
这是自定义组合框的实现：
public class SuggestComboBox : ComboBox
{
#region fields and properties
private readonly ListBox _suggLb = new ListBox { Visible = false, TabStop = false };
private readonly BindingList<string> _suggBindingList = new BindingList<string>();
private Expression<Func<ObjectCollection, IEnumerable<string>>> _propertySelector;
private Func<ObjectCollection, IEnumerable<string>> _propertySelectorCompiled;
private Expression<Func<string, string, bool>> _filterRule;
private Func<string, bool> _filterRuleCompiled;
private Expression<Func<string, string>> _suggestListOrderRule;
private Func<string, string> _suggestListOrderRuleCompiled;
public int SuggestBoxHeight
{
get { return _suggLb.Height; }
set { if (value > 0) _suggLb.Height = value; }
}
/// <summary>
/// If the item-type of the ComboBox is not string,
/// you can set here which property should be used
/// </summary>
public Expression<Func<ObjectCollection, IEnumerable<string>>> PropertySelector
{
get { return _propertySelector; }
set
{
if (value == null) return;
_propertySelector = value;
_propertySelectorCompiled = value.Compile();
}
}
///<summary>
/// Lambda-Expression to determine the suggested items
/// (as Expression here because simple lamda (func) is not serializable)
/// <para>default: case-insensitive contains search</para>
/// <para>1st string: list item</para>
/// <para>2nd string: typed text</para>
///</summary>
public Expression<Func<string, string, bool>> FilterRule
{
get { return _filterRule; }
set
{
if (value == null) return;
_filterRule = value;
_filterRuleCompiled = item => value.Compile()(item, Text);
}
}
///<summary>
/// Lambda-Expression to order the suggested items
/// (as Expression here because simple lamda (func) is not serializable)
/// <para>default: alphabetic ordering</para>
///</summary>
public Expression<Func<string, string>> SuggestListOrderRule
{
get { return _suggestListOrderRule; }
set
{
if (value == null) return;
_suggestListOrderRule = value;
_suggestListOrderRuleCompiled = value.Compile();
}
}
#endregion
/// <summary>
/// ctor
/// </summary>
public SuggestComboBox()
{
// set the standard rules:
_filterRuleCompiled = s => s.ToLower().Contains(Text.Trim().ToLower());
_suggestListOrderRuleCompiled = s => s;
_propertySelectorCompiled = collection => collection.Cast<string>();
_suggLb.DataSource = _suggBindingList;
_suggLb.Click += SuggLbOnClick;
ParentChanged += OnParentChanged;
}
/// <summary>
/// the magic happens here ;-)
/// </summary>
/// <param name="e"></param>
protected override void OnTextChanged(EventArgs e)
{
base.OnTextChanged(e);
if (!Focused) return;
_suggBindingList.Clear();
_suggBindingList.RaiseListChangedEvents = false;
_propertySelectorCompiled(Items)
.Where(_filterRuleCompiled)
.OrderBy(_suggestListOrderRuleCompiled)
.ToList()
.ForEach(_suggBindingList.Add);
_suggBindingList.RaiseListChangedEvents = true;
_suggBindingList.ResetBindings();
_suggLb.Visible = _suggBindingList.Any();
if (_suggBindingList.Count == 1 &&
_suggBindingList.Single().Length == Text.Trim().Length)
{
Text = _suggBindingList.Single();
Select(0, Text.Length);
_suggLb.Visible = false;
}
}
/// <summary>
/// suggest-ListBox is added to parent control
/// (in ctor parent isn't already assigned)
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void OnParentChanged(object sender, EventArgs e)
{
Parent.Controls.Add(_suggLb);
Parent.Controls.SetChildIndex(_suggLb, 0);
_suggLb.Top = Top + Height - 3;
_suggLb.Left = Left + 3;
_suggLb.Width = Width - 20;
_suggLb.Font = new Font("Segoe UI", 9);
}
protected override void OnLostFocus(EventArgs e)
{
// _suggLb can only getting focused by clicking (because TabStop is off)
// --> click-eventhandler 'SuggLbOnClick' is called
if (!_suggLb.Focused)
HideSuggBox();
base.OnLostFocus(e);
}
protected override void OnLocationChanged(EventArgs e)
{
base.OnLocationChanged(e);
_suggLb.Top = Top + Height - 3;
_suggLb.Left = Left + 3;
}
protected override void OnSizeChanged(EventArgs e)
{
base.OnSizeChanged(e);
_suggLb.Width = Width - 20;
}
private void SuggLbOnClick(object sender, EventArgs eventArgs)
{
Text = _suggLb.Text;
Focus();
}
private void HideSuggBox()
{
_suggLb.Visible = false;
}
protected override void OnDropDown(EventArgs e)
{
HideSuggBox();
base.OnDropDown(e);
}
#region keystroke events
/// <summary>
/// if the suggest-ListBox is visible some keystrokes
/// should behave in a custom way
/// </summary>
/// <param name="e"></param>
protected override void OnPreviewKeyDown(PreviewKeyDownEventArgs e)
{
if (!_suggLb.Visible)
{
base.OnPreviewKeyDown(e);
return;
}
switch (e.KeyCode)
{
case Keys.Down:
if (_suggLb.SelectedIndex < _suggBindingList.Count - 1)
_suggLb.SelectedIndex++;
return;
case Keys.Up:
if (_suggLb.SelectedIndex > 0)
_suggLb.SelectedIndex--;
return;
case Keys.Enter:
Text = _suggLb.Text;
Select(0, Text.Length);
_suggLb.Visible = false;
return;
case Keys.Escape:
HideSuggBox();
return;
}
base.OnPreviewKeyDown(e);
}
private static readonly Keys[] KeysToHandle = new[]
{ Keys.Down, Keys.Up, Keys.Enter, Keys.Escape };
protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
{
// the keysstrokes of our interest should not be processed be base class:
if (_suggLb.Visible && KeysToHandle.Contains(keyData))
return true;
return base.ProcessCmdKey(ref msg, keyData);
}
#endregion
}