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Get Character Position in a line?

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RichTextBox
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Robert
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Robert asked on 21 May 2012, 03:55 PM
Hi,

How do I go about getting the character position along a given line wherever the caret is placed?

I can get the CaretPosition easily enough, but the I don't want the X & Y coordinates. I need to count how many characters there are along a line up to where the caret is placed.

Thanks for your time,

Rob

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Robert
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answered on 21 May 2012, 05:13 PM
Ok I think I worked this out myself.

This seems to work well. It will count the number of characters along a line up to where the caret is positioned.
It will ignore any custom annotation tags that you may have and only count the number of characters in all of the found Spans  on a given line.

Method Call:
DocumentPosition position = new DocumentPosition(radRichTextBox.Document.CaretPosition);
 
//Get the caret character count on the current line
int charCount = GetCaretCharacterPositionAlongLine(position);
 
 
MessageBox.Show("Character Count: " + charCount.ToString());



Main method:
public static int GetCaretCharacterPositionAlongLine(DocumentPosition position)
{
    int charCount = 0;
 
    while (IsCaretAtLineStart(position) == false)
    {
        position.MoveToPrevious();
        if (position.GetCurrentInlineBox().AssociatedInline is Span)
        {
            charCount++;
        }
    }
 
    return charCount;
}



Here is the method code for "IsCaretAtLineStart":
public static bool IsCaretAtLineStart(DocumentPosition position)
{
    DocumentPosition startLinePosition = new DocumentPosition(position);
    startLinePosition.MoveToCurrentLineStart();
 
    if (position == startLinePosition)
    {
        return true;
    }
 
    return false;
}

I'm all ears (or eyes) if anyone has a better idea.

Thanks,

Rob


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Martin Ivanov
Telerik team
answered on 24 May 2012, 09:07 AM
Hello Robert,

 We think your solution to the problem is good. Here is a little tip:
 This is the implementation of  MoveToCurrentLineStart():
 

public bool MoveToCurrentLineStart()
        {
            this.CallOnPositionChanging();
 
            InlineLayoutBox startInlineBox = this.GetCurrentInlineBox();
            InlineLayoutBox currInlineBox = startInlineBox;
            bool hasPrevious = true;
            while (hasPrevious && currInlineBox.LineInfo == startInlineBox.LineInfo)
            {
                hasPrevious = this.MoveToPreviousInternal();
                currInlineBox = this.GetCurrentInlineBox();
            }
 
            if (currInlineBox == null || currInlineBox.LineInfo != startInlineBox.LineInfo)
            {
                this.MoveToNextInternal();
            }
 
            this.CallOnPositionChanged(true);
 
            return true;
        }
so calling this method on every move can be improved if you move just once to the beginning, and then go to next element till it is the current position. 
Don't hesitate to contact us if you have other questions.

Kind regards,
Martin
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Robert
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answered on 24 May 2012, 09:38 AM
Hi Martin,

Thanks for responding to this post. Your input is greatly appreciated.
I see from what you are saying is that I am making several MoveToLineStart calls that could actually be reduced, thus improving on the performance. Is that correct?

Rob
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Robert
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answered on 24 May 2012, 11:29 AM
Sorry I posted this in the wrong thread.
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Robert
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answered on 24 May 2012, 11:55 AM
Sorry I posted this in the wrong thread.
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Martin Ivanov
Telerik team
answered on 28 May 2012, 12:13 PM
Hello Robert,

 You have understood correctly, the reduced number of calls to MoveToLineStart will improve the performance. Of course, you should test your application and decide which is better for you. 

All the best,
Martin
the Telerik team

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Robert
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Martin Ivanov
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