public Window1()
{
InitializeComponent();
StackPanel stackPanel = new StackPanel();
MyRichTextBox richTextBox = new MyRichTextBox();
stackPanel.Children.Add(richTextBox);
this.Title = "Custom RichTextBox that auto-detects hyperlink strings while typing";
this.Content = stackPanel;
}
/// <summary>
/// Event handler for KeyDown event to auto-detect hyperlinks on space, enter and backspace keys.
/// </summary>
private static void OnKeyDown(object sender, KeyEventArgs e)
{
MyRichTextBox myRichTextBox = (MyRichTextBox)sender;
if (e.Key != Key.Space && e.Key != Key.Back && e.Key != Key.Return)
{
return;
}
if (!myRichTextBox.Selection.IsEmpty)
{
myRichTextBox.Selection.Text = String.Empty;
}
TextPointer caretPosition = myRichTextBox.Selection.Start;
if (e.Key == Key.Space || e.Key == Key.Return)
{
TextPointer wordStartPosition;
string word = GetPreceedingWordInParagraph(caretPosition, out wordStartPosition);
if (word == "www.microsoft.com") // A real app would need a more sophisticated RegEx match expression for hyperlinks.
{
// Insert hyperlink element at word boundaries.
new Hyperlink(
wordStartPosition.GetPositionAtOffset(0, LogicalDirection.Backward),
caretPosition.GetPositionAtOffset(0, LogicalDirection.Forward));
// No need to update RichTextBox caret position,
// since we only inserted a Hyperlink ElementEnd following current caretPosition.
// Subsequent handling of space input by base RichTextBox will update selection.
}
}
else // Key.Back
{
TextPointer backspacePosition = caretPosition.GetNextInsertionPosition(LogicalDirection.Backward);
Hyperlink hyperlink;
if (backspacePosition != null && IsHyperlinkBoundaryCrossed(caretPosition, backspacePosition, out hyperlink))
{
// Remember caretPosition with forward gravity. This is necessary since we are going to delete
// the hyperlink element preceeding caretPosition and after deletion current caretPosition
// (with backward gravity) will follow content preceeding the hyperlink.
// We want to remember content following the hyperlink to set new caret position at.
TextPointer newCaretPosition = caretPosition.GetPositionAtOffset(0, LogicalDirection.Forward);
// Deleting the hyperlink is done using logic below.
// 1. Copy its children Inline to a temporary array.
InlineCollection hyperlinkChildren = hyperlink.Inlines;
Inline[] inlines = new Inline[hyperlinkChildren.Count];
hyperlinkChildren.CopyTo(inlines, 0);
// 2. Remove each child from parent hyperlink element and insert it after the hyperlink.
for (int i = inlines.Length - 1; i >= 0; i--)
{
hyperlinkChildren.Remove(inlines[i]);
hyperlink.SiblingInlines.InsertAfter(hyperlink, inlines[i]);
}
// 3. Apply hyperlink's local formatting properties to inlines (which are now outside hyperlink scope).
LocalValueEnumerator localProperties = hyperlink.GetLocalValueEnumerator();
TextRange inlineRange = new TextRange(inlines[0].ContentStart, inlines[inlines.Length - 1].ContentEnd);
while (localProperties.MoveNext())
{
LocalValueEntry property = localProperties.Current;
DependencyProperty dp = property.Property;
object value = property.Value;
if (!dp.ReadOnly &&
dp != Inline.TextDecorationsProperty && // Ignore hyperlink defaults.
dp != TextElement.ForegroundProperty &&
!IsHyperlinkProperty(dp))
{
inlineRange.ApplyPropertyValue(dp, value);
}
}
// 4. Delete the (empty) hyperlink element.
hyperlink.SiblingInlines.Remove(hyperlink);
// 5. Update selection, since we deleted Hyperlink element and caretPosition was at that Hyperlink's end boundary.
myRichTextBox.Selection.Select(newCaretPosition, newCaretPosition);
}
}
}
