CODEWITHSUNDEEP
c#.netregexwinformsrichtextbox
Joan Venge
Joan Venge

Reputation: 330952

How to implement basic syntax highlighting in Winforms RichTextBox?

I have a list of words I want to highlight in my RichTextBox control, I have an idea on how to do it but having a problem with parsing everything to separate words.

How can I parse a line or the whole text into separate words and then enumerate over them and color them using RichTextBox.Select() method.

Is this a good way? Is there a better/faster way?

Upvotes: 5

Views: 2618

Answers (5)

Jo VdB
Jo VdB

Reputation: 2106

Probably not the fastest way but it works.
First call ClearHighLighting to clear previous and then call SetHighLighting

private readonly List<HighLight> _highLights = new List<HighLight>();
private class HighLight
{
  public int Start { get; set; }
  public int End { get; set; }
}

public void SetHighLighting(string text)
{

    // Clear Previous HighLighting
    ClearHighLighting();

    if (text.Length > 0)
    {
        int startPosition = 0;
        int foundPosition = 0;            
        while (foundPosition > -1)
        {
            foundPosition = richTextBox1.Find(text, startPosition, RichTextBoxFinds.None);
            if (foundPosition >= 0)
            {
                richTextBox1.SelectionBackColor = Color.Yellow;
                int endindex = text.Length;
                richTextBox1.Select(foundPosition, endindex);                        
                startPosition = foundPosition + endindex;                        
                _highLights.Add(new HighLight() { Start = foundPosition, End = endindex });
            }
        }
    }
}

public void ClearHighLighting()
{
    foreach (var highLight in  _highLights)
    {
        richTextBox1.SelectionBackColor = richTextBox1.BackColor;
        richTextBox1.Select(highLight.Start, highLight.End);                        
    }
    _highLights.Clear();
}

Upvotes: 1

Bueller
Bueller

Reputation: 2344

Use the RichTextBox.Find(String, Int32, Int32, RichTextBoxFinds) method to find your strings in the control. You can then iterate by changing the Start point to the point after the current word.

Not sure on the performance of this scheme but it will work.

http://msdn.microsoft.com/en-us/library/yab8wkhy.aspx

Upvotes: 2

Grook
Grook

Reputation: 405

Try string.Split method. It return you array of strings splitted by delimiter.

Also you may found usefull those links: link1 link2

And even more: there is a fine example of similar app

Upvotes: 1

keyboardP
keyboardP

Reputation: 69372

You can use the RichTextBox.Find method in order to find a string in your RichTextBox. This method returns the position of the text it found. The code sample in that link will highlight the text.

Upvotes: 1

Josh M.
Josh M.

Reputation: 27783

You can use Avalon Edit instead of a RichTextBox, it's free. It is the editor used in #develop. I think you may have to pull the assembly out of the #develop source download but it is worth it.

Upvotes: 2

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