I'm trying to use a RichTextBox and my first feeling : "What's it's complicated to use !"... Amazing ...
So I'm trying to highlight a text contained in my RichTextBox.
I currently have the following code:
TextRange range = new TextRange(MyTextInput.Document.ContentStart, MyTextInput.Document.ContentEnd);
range.Text = @"TOP a multiline text or file END";
Regex reg = new Regex("(top|file|end)", RegexOptions.Compiled | RegexOptions.IgnoreCase);
foreach (Match match in reg.Matches(range.Text))
{
TextPointer start = range.Start.GetPositionAtOffset(match.Index, LogicalDirection.Forward);
TextPointer end = range.Start.GetPositionAtOffset(match.Index + match.Length, LogicalDirection.Backward);
// text contains the exact match I want
string text = range.Text.Substring(match.Index, match.Length);
// here the highlighted text isn't the text I searched...
TextRange textrange = new TextRange(start, end);
textrange.ApplyPropertyValue(TextElement.ForegroundProperty, new SolidColorBrush(Colors.Blue));
textrange.ApplyPropertyValue(TextElement.FontWeightProperty, FontWeights.Bold);
}
TOP
is correctly highlighted but not file
or end
but highlight me or
.
Any suggestions?
you have to imagine what the RichTextBox does under the hood to understand the behavior. I don't know exactly but I imagine the following: Line 1-2 set as Content of RichTextBox
a Paragraph
with a Run
.
Then with the first iteration with ApplyPropertyValue
the Content of the RichTextBox gets changed! It now contains a Paragraph
with a Span
(with a Run
inside) and a Run.
And then you have to consider the discrepancy between the Regex match and GetPositionAtOffset
. The Regex match returns an index for a char position in a string.
GetPositionAtOffset uses "An offset, in symbols, for which to calculate and return the position" where a symbol is:
- An opening or closing tag for the TextElement element.
- A UIElement element contained in an InlineUIContainer or BlockUIContainer. Note that such a UIElement is always counted as exactly one symbol; any additional content or elements contained by the UIElement are not counted as symbols.
- A 16-bit Unicode character inside of a text Run element.
So what you might want to do is something like this:
TextRange range = new TextRange(MyTextInput.Document.ContentStart, MyTextInput.Document.ContentEnd);
range.Text = @"TOP a multiline text or file END";
Regex reg = new Regex("(top|file|end)", RegexOptions.Compiled | RegexOptions.IgnoreCase);
var start = MyTextInput.Document.ContentStart;
while (start != null && start.CompareTo(MyTextInput.Document.ContentEnd) < 0)
{
if (start.GetPointerContext(LogicalDirection.Forward) == TextPointerContext.Text)
{
var match=reg.Match(start.GetTextInRun(LogicalDirection.Forward));
var textrange = new TextRange(start.GetPositionAtOffset(match.Index, LogicalDirection.Forward), start.GetPositionAtOffset(match.Index + match.Length, LogicalDirection.Backward));
textrange.ApplyPropertyValue(TextElement.ForegroundProperty, new SolidColorBrush(Colors.Blue));
textrange.ApplyPropertyValue(TextElement.FontWeightProperty, FontWeights.Bold);
start= textrange.End; // I'm not sure if this is correct or skips ahead too far, try it out!!!
}
start = start.GetNextContextPosition(LogicalDirection.Forward);
}
*Disclaimer: I have not tried this as right now I'm nowhere near a development environment. I don't even know if this compiles, but I hope so.