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C# SuggestCombobox
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| public class SuggestComboBox : ComboBox | |
| { | |
| #region fields and properties | |
| private readonly ListBox suggestionListBox = 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 => suggestionListBox.Height; | |
| set { if (value > 0) suggestionListBox.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 => 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 => 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 => suggestListOrderRule; | |
| set | |
| { | |
| if (value == null) return; | |
| suggestListOrderRule = value; | |
| suggestListOrderRuleCompiled = value.Compile(); | |
| } | |
| } | |
| #endregion | |
| /// <summary> | |
| /// ctor | |
| /// </summary> | |
| public SuggestComboBox() | |
| { | |
| filterRuleCompiled = s => s.ToLower().Contains(Text.Trim().ToLower()); | |
| suggestListOrderRuleCompiled = s => s; | |
| propertySelectorCompiled = collection => collection.Cast<string>(); | |
| suggestionListBox.DataSource = suggBindingList; | |
| suggestionListBox.Click += SuggestionListBoxOnClick; | |
| 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(); | |
| if(suggestionListBox.Visible = suggBindingList.Any()) | |
| { | |
| suggestionListBox.BringToFront(); | |
| } | |
| if (suggBindingList.Count == 1 && | |
| suggBindingList.Single().Length == Text.Trim().Length) | |
| { | |
| Text = suggBindingList.Single(); | |
| Select(0, Text.Length); | |
| suggestionListBox.Visible = false; | |
| } | |
| } | |
| #region size and position of suggest box | |
| /// <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(suggestionListBox); | |
| Parent.Controls.SetChildIndex(suggestionListBox, 0); | |
| suggestionListBox.Top = Top + Height; | |
| suggestionListBox.Left = Left; | |
| suggestionListBox.Width = Width; | |
| suggestionListBox.Font = Font; | |
| } | |
| protected override void OnLocationChanged(EventArgs e) | |
| { | |
| base.OnLocationChanged(e); | |
| suggestionListBox.Top = Top + Height; | |
| suggestionListBox.Left = Left; | |
| } | |
| protected override void OnSizeChanged(EventArgs e) | |
| { | |
| base.OnSizeChanged(e); | |
| suggestionListBox.Width = Width; | |
| } | |
| #endregion | |
| #region visibility of suggest box | |
| protected override void OnLostFocus(EventArgs e) | |
| { | |
| if (!suggestionListBox.Focused) | |
| HideSuggBox(); | |
| base.OnLostFocus(e); | |
| } | |
| private void SuggestionListBoxOnClick(object sender, EventArgs eventArgs) | |
| { | |
| Text = suggestionListBox.Text; | |
| Focus(); | |
| } | |
| private void HideSuggBox() | |
| { | |
| suggestionListBox.Visible = false; | |
| } | |
| protected override void OnDropDown(EventArgs e) | |
| { | |
| HideSuggBox(); | |
| base.OnDropDown(e); | |
| } | |
| #endregion | |
| #region keystroke events | |
| private bool ProcessKeyDown(Keys keyData) | |
| { | |
| if (suggestionListBox.Visible) | |
| { | |
| switch (keyData) | |
| { | |
| case Keys.Down: | |
| if (suggestionListBox.SelectedIndex < suggBindingList.Count - 1) | |
| suggestionListBox.SelectedIndex++; | |
| return true; | |
| case Keys.Up: | |
| if (suggestionListBox.SelectedIndex > 0) | |
| suggestionListBox.SelectedIndex--; | |
| return true; | |
| case Keys.Enter: | |
| case Keys.Tab: | |
| case Keys.Right: | |
| Text = suggestionListBox.Text; | |
| Select(0, Text.Length); | |
| suggestionListBox.Visible = false; | |
| return true; | |
| case Keys.Escape: | |
| HideSuggBox(); | |
| return true; | |
| } | |
| } | |
| return false; | |
| } | |
| protected override bool ProcessCmdKey(ref Message msg, Keys keyData) | |
| { | |
| if (ProcessKeyDown(keyData)) | |
| return true; | |
| return base.ProcessCmdKey(ref msg, keyData); | |
| } | |
| #endregion | |
| } |
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Add validation through tab and right arrow keys in addition to the validation with the enter key