System.Windows.Controls.AutoCompleteBox.UpdateTextCompletion C# (CSharp) Méthode

        private void UpdateTextCompletion(bool userInitiated)
        {
            // By default this method will clear the selected value
            object newSelectedItem = null;
            string text = Text;

            // Text search is StartsWith explicit and only when enabled, in 
            // line with WPF's ComboBox lookup. When in use it will associate 
            // a Value with the Text if it is found in ItemsSource. This is 
            // only valid when there is data and the user initiated the action.
            if(_view.Count > 0)
            {
                if(IsTextCompletionEnabled && TextBox != null && userInitiated)
                {
                    int currentLength = TextBox.Text.Length;
                    int selectionStart = TextBox.SelectionStart;
                    if(selectionStart == text.Length && selectionStart > _textSelectionStart)
                    {
                        // When the FilterMode dependency property is set to 
                        // either StartsWith or StartsWithCaseSensitive, the 
                        // first item in the view is used. This will improve 
                        // performance on the lookup. It assumes that the 
                        // FilterMode the user has selected is an acceptable 
                        // case sensitive matching function for their scenario.
                        object top = FilterMode == AutoCompleteFilterMode.StartsWith || FilterMode == AutoCompleteFilterMode.StartsWithCaseSensitive
                            ? _view[0]
                            : TryGetMatch(text, _view, AutoCompleteSearch.GetFilter(AutoCompleteFilterMode.StartsWith));

                        // If the search was successful, update SelectedItem
                        if(top != null)
                        {
                            newSelectedItem = top;
                            string topString = FormatValue(top, true);

                            // Only replace partially when the two words being the same
                            int minLength = Math.Min(topString.Length, Text.Length);
                            if(AutoCompleteSearch.Equals(Text.Substring(0, minLength), topString.Substring(0, minLength)))
                            {
                                // Update the text
                                UpdateTextValue(topString);

                                // Select the text past the user's caret
                                TextBox.SelectionStart = currentLength;
                                TextBox.SelectionLength = topString.Length - currentLength;
                            }
                        }
                    }
                }
                else
                {
                    // Perform an exact string lookup for the text. This is a 
                    // design change from the original Toolkit release when the 
                    // IsTextCompletionEnabled property behaved just like the 
                    // WPF ComboBox's IsTextSearchEnabled property.
                    //
                    // This change provides the behavior that most people expect
                    // to find: a lookup for the value is always performed.
                    newSelectedItem = TryGetMatch(text, _view, AutoCompleteSearch.GetFilter(AutoCompleteFilterMode.EqualsCaseSensitive));
                }
            }

            // Update the selected item property

            if(SelectedItem != newSelectedItem)
            {
                _skipSelectedItemTextUpdate = true;
            }
            SelectedItem = newSelectedItem;

            // Restore updates for TextSelection
            if(_ignoreTextSelectionChange)
            {
                _ignoreTextSelectionChange = false;
                if(TextBox != null)
                {
                    _textSelectionStart = TextBox.SelectionStart;
                }
            }
        }