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POI am not being notified when CaretIndex is Changed in MVVM
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2013-11-30T16:03:27.070
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I know that CaretIndex is not a Dependency Property. So I registered it as follows: <pre><code> public class TextBoxHelper : TextBox { public static readonly DependencyProperty CaretIndexProperty = DependencyProperty.Register ( "CaretIndex", typeof(int), typeof(TextBoxHelper), new FrameworkPropertyMetadata ( 0, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, CaretIndexChanged ) ); public static int GetCaretIndex(DependencyObject obj) { return (int)obj.GetValue(CaretIndexProperty); } public static void SetCaretIndex(DependencyObject obj, int value) { obj.SetValue(CaretIndexProperty, value); } //public new int CaretIndex //{ // get { return (int)GetValue(CaretIndexProperty); } // set { SetValue(CaretIndexProperty, value); } //} protected override void OnTextChanged(TextChangedEventArgs e) { base.OnTextChanged(e); CaretIndex = base.CaretIndex; } protected override void OnKeyDown(KeyEventArgs e) { base.OnKeyDown(e); CaretIndex = base.CaretIndex; } protected override void OnKeyUp(KeyEventArgs e) { base.OnKeyUp(e); CaretIndex = base.CaretIndex; } protected override void OnMouseDown(MouseButtonEventArgs e) { base.OnMouseDown(e); CaretIndex = base.CaretIndex; } protected override void OnMouseUp(MouseButtonEventArgs e) { base.OnMouseUp(e); CaretIndex = base.CaretIndex; } private static void CaretIndexChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e) { if (obj is TextBox) { ((TextBox)obj).CaretIndex = (int)e.NewValue; } } } </code></pre> Then I created a property named CaretIndex in my ViewModel. It implements the INotifyPropertyChanged interface. <pre><code>private int _caretIndex; public int CaretIndex { get { return _caretIndex; } set { _caretIndex = value; OnPropertyChanged("CaretIndex"); } } </code></pre> Then I created bindings in my ComboBox as follows: <pre><code><ComboBox x:Name="cbUnder" ItemsSource="{Binding GroupsAndCorrespondingEffects}" IsEditable="True" SelectedItem="{Binding SelectedGroup, Mode=TwoWay}" Text="{Binding InputValue, UpdateSourceTrigger=PropertyChanged}" TextSearch.TextPath="GroupName" Grid.Column="1" Grid.ColumnSpan="4" Grid.Row="3" vm:TextBoxHelper.CaretIndex="{Binding CaretIndex, UpdateSourceTrigger=PropertyChanged}"> <ComboBox.Resources> <DataTemplate DataType="{x:Type vm:GroupAndCorrespondingEffect}"> <StackPanel Orientation="Horizontal"> <TextBlock Text="{Binding GroupName}" Width="250"> <TextBlock.Style> <Style TargetType="TextBlock"> <Style.Triggers> <DataTrigger Binding="{Binding IsHighlighted}" Value="True"> <Setter Property="Foreground" Value="Blue" /> <Setter Property="FontWeight" Value="Bold"/> </DataTrigger> </Style.Triggers> </Style> </TextBlock.Style> </TextBlock> <TextBlock Text="{Binding CorrespondingEffect}" /> </StackPanel> </DataTemplate> </ComboBox.Resources> </ComboBox> </code></pre> Still I am not being notified when CaretIndex is Changed. From the code above I have got <code>IsEditable = True</code> and <code>IsTextSearchEnabled = True</code>. But when I type any character in combobox it appends the name of the whole item in the textbox of combobox. I actually want to have a combobox to highlight all the items that matches what I typed but due to the text appending I can get only one item highlighted. So, I need the text that I have typed. i.e. The text that is not selected. (Because the text that is appended is also selected). So, If I get the caretIndex then I can use the substring method on the text to get what I typed. According to that it will highlight the text. Update <pre><code><Style TargetType="ComboBox" BasedOn="{StaticResource {x:Type ComboBox}}"> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="ComboBox"> <TextBox x:Name="PART_EditableTextBox" CaretIndex="vm:TextBoxHelper.CaretIndex" /> </ControlTemplate> </Setter.Value> </Setter> </Style> </code></pre> I have tried the above code but it says me input string was not in a correct format. So, I have replaced the above code with : <pre><code><Style TargetType="ComboBox" BasedOn="{StaticResource {x:Type ComboBox}}"> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="ComboBox"> <TextBox x:Name="PART_EditableTextBox" vm:TextBoxHelper.CaretIndex="{Binding CaretIndex, UpdateSourceTrigger=PropertyChanged}" /> </ControlTemplate> </Setter.Value> </Setter> </Style> </code></pre> Now I do not get any error but my combobox looks like a textbox. I mean it has lost its dropdown part. And I have checked by using breakpoints in my viewmodel. But still I am not getting notified when caretIndex changes. Update2 <pre><code><TextBox x:Name="PART_EditableTextBox" HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}" IsReadOnly="{Binding IsReadOnly, RelativeSource={RelativeSource TemplatedParent}}" Margin="{TemplateBinding Padding}" VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"> <TextBox.Style> <Style TargetType="{x:Type TextBox}"> <Setter Property="vm:TextBoxHelper.CaretIndex" Value="{Binding CaretIndex, UpdateSourceTrigger=PropertyChanged}" /> . . . </code></pre> The above code does not work, So I updated it like below : <pre><code><vm:TextBoxHelper x:Name="PART_EditableTextBox" HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}" IsReadOnly="{Binding IsReadOnly, RelativeSource={RelativeSource TemplatedParent}}" Margin="{TemplateBinding Padding}" VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"> <vm:TextBoxHelper.Style> <Style TargetType="{x:Type vm:TextBoxHelper}"> <Setter Property="vm:TextBoxHelper.CaretIndex" Value="{Binding CaretIndex, UpdateSourceTrigger=PropertyChanged}" /> . . . </code></pre> Still it does not work. Update 3 Here is my <code>App.xaml</code> file <pre><code><Application xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:comboFDD="clr-namespace:ERP_Lite_Trial.Views.DesignRelatedCode" x:Class="ERP_Lite_Trial.App" StartupUri="Views/MainWindow.xaml"> <Application.Resources> <ResourceDictionary> <ResourceDictionary.MergedDictionaries> <ResourceDictionary Source="Views/Pages/ResourceDictionary1.xaml"/> </ResourceDictionary.MergedDictionaries> <Style TargetType="{x:Type ComboBox}"> <Setter Property="comboFDD:ComboBox_ForceDropDown.OpenDropDownAutomatically" Value="True"/> </Style> </ResourceDictionary> </Application.Resources> </Application> </code></pre> Update 4 I have also got a property InputValue in my ViewModel <pre><code>private string _inputValue; public string InputValue { get { return _inputValue; } set { _inputValue = value; OnPropertyChanged("GroupsAndCorrespondingEffects"); for (int i = 0; i < GroupsAndCorrespondingEffects.Count; i++) { string WordToSearch = _inputValue; if (_caretIndex != 0 || _caretIndex != null) { WordToSearch = _inputValue.Substring(0, _caretIndex); } GroupsAndCorrespondingEffects[i].IsHighlighted = GroupsAndCorrespondingEffects[i].GroupName.StartsWith(WordToSearch); } } } </code></pre> Another property I have got is IsHilighted. This property is defined in GroupsAndCorrespondingEffects Class. Using this class I get my data from database. Code for GroupsAndCorrespondingEffects.cs <pre><code>public class GroupAndCorrespondingEffect : INotifyPropertyChanged { private string _groupName; public string GroupName { get { return _groupName; } set { _groupName = value; OnPropertyChanged("GroupName"); } } private string _correspondingEffect; public string CorrespondingEffect { get { return _correspondingEffect; } set { _correspondingEffect = value; OnPropertyChanged("CorrespondingEffect"); } } private bool _isHighlighted; public bool IsHighlighted { get { return _isHighlighted; } set { _isHighlighted = value; OnPropertyChanged("IsHighlighted"); } } public void OnPropertyChanged([CallerMemberName] string propertyName = null) { if (PropertyChanged != null) { PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); } } public event PropertyChangedEventHandler PropertyChanged; } </code></pre> Propcess of invoking properties in ViewModel is as follows: Now when I type 1st Character in combobox : <pre><code>CaretIndex = 0 CaretIndex = 0 InputValue = Text of combobox CaretIndex = 1 CaretIndex = 1 </code></pre> When I type 2nd Character in combobox : <pre><code>CaretIndex = 1 InputValue = Text of combobox CaretIndex = 2 </code></pre> When I type 3rd Character in combobox : <pre><code>CaretIndex = 2 InputValue = Text of combobox CaretIndex = 3 </code></pre> And so on.... My logic for Highlighting Items in combobox is based on change in CaretIndex. This logic is written in the set part of <code>InputValue</code> property. But due to the fact mentioned above that InputValue is invoked before the CaretIndex takes new value I get incorrect HighLights. Update 5 - For Retain Selection Lost I have added SelectionStart and SelectionLength properties in our TextBoxHelper Class as they are not dependency properties. Here is the code: <pre><code> public static readonly DependencyProperty BindableSelectionStartProperty = DependencyProperty.RegisterAttached ( "BindableSelectionStart", typeof(int), typeof(TextBoxHelper), new PropertyMetadata ( BindableSelectionStartChanged ) ); public static readonly DependencyProperty BindableSelectionLengthProperty = DependencyProperty.RegisterAttached ( "BindableSelectionLength", typeof(int), typeof(TextBoxHelper), new PropertyMetadata ( BindableSelectionLengthChanged ) ); public static int GetBindableSelectionStart(DependencyObject obj) { return (int)obj.GetValue(BindableSelectionStartProperty); } public static void SetBindableSelectionStart(DependencyObject obj, int value) { obj.SetValue(BindableSelectionStartProperty, value); } public int BindableSelectionStart { get { return (int)this.GetValue(BindableSelectionStartProperty); } set { this.SetValue(BindableSelectionStartProperty, value); } } public static int GetBindableSelectionLength(DependencyObject obj) { return (int)obj.GetValue(BindableSelectionLengthProperty); } public static void SetBindableSelectionLength(DependencyObject obj, int value) { obj.SetValue(BindableSelectionLengthProperty, value); } public int BindableSelectionLength { get { return (int)this.GetValue(BindableSelectionLengthProperty); } set { this.SetValue(BindableSelectionLengthProperty, value); } } private static void BindableSelectionStartChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { if (d is TextBox) { ((TextBox)d).SelectionStart = (int)e.NewValue; } } private static void BindableSelectionLengthChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { if (d is TextBox) { ((TextBox)d).SelectionLength = (int)e.NewValue; } } protected override void OnSelectionChanged(RoutedEventArgs e) { base.OnSelectionChanged(e); BindableSelectionStart = base.SelectionStart; BindableSelectionLength = base.SelectionLength; } </code></pre> Then I have created the corresponding properties in my ViewModel. <pre><code> private int _selectionStart; public int SelectionStart { get { return _selectionStart; } set { _selectionStart = value; OnPropertyChanged("SelectionStart"); } } private int _selectionLength; public int SelectionLength { get { return _selectionLength; } set { _selectionLength = value; OnPropertyChanged("SelectionLength"); } } </code></pre> After that I have changed <code>CaretIndex</code> and <code>InputValue</code> properties of ViewModel as follows: <pre><code> private int _caretIndex; public int CaretIndex { get { return _caretIndex; } set { _caretIndex = value; OnPropertyChanged("CaretIndex"); if (InputValue != null && CaretIndex >= 0) { SelectionStart = CaretIndex; Debug.WriteLine(string.Format("Selection Start : {0}", SelectionStart)); SelectionLength = InputValue.Length - CaretIndex; Debug.WriteLine(string.Format("Selection Length : {0}", SelectionLength)); } for (int i = 0; i < GroupsAndCorrespondingEffects.Count; i++) { string WordToSearch = InputValue; if (_caretIndex != 0 && _caretIndex > 0) { WordToSearch = InputValue.Substring(0, _caretIndex); } if (WordToSearch != null) { GroupsAndCorrespondingEffects[i].IsHighlighted = GroupsAndCorrespondingEffects[i].GroupName.StartsWith(WordToSearch); } } } } private string _inputValue; public string InputValue { get { return _inputValue; } set { _inputValue = value; OnPropertyChanged("GroupsAndCorrespondingEffects"); if (InputValue != null && CaretIndex >= 0) { SelectionStart = CaretIndex; Debug.WriteLine(string.Format("Selection Start : {0}", SelectionStart)); SelectionLength = InputValue.Length - CaretIndex; Debug.WriteLine(string.Format("Selection Length : {0}", SelectionLength)); } for (int i = 0; i < GroupsAndCorrespondingEffects.Count; i++) { string WordToSearch = _inputValue; if (_caretIndex != 0 && _caretIndex > 0 && _caretIndex < _inputValue.Length) { WordToSearch = _inputValue.Substring(0, _caretIndex); } GroupsAndCorrespondingEffects[i].IsHighlighted = GroupsAndCorrespondingEffects[i].GroupName.StartsWith(WordToSearch); } } } </code></pre> The last change I made was in ResourceDictionary as Follows: <pre><code><vm:TextBoxHelper x:Name="PART_EditableTextBox" MyCaretIndex="{Binding CaretIndex}" BindableSelectionStart="{Binding SelectionStart}" BindableSelectionLength="{Binding SelectionLength}" ........... </code></pre> In output window I can see the SelectionStart as well as SelectionLength changed but can't see any visual change in the combobox.
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I am not being notified when CaretIndex is Changed in MVVM
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