COMException unhandled in MS Word

Question

We have a function which is supposed to get the range of the viewed text in a word document. However, we are getting the COMException in the first few lines of the function. The function is called with a fixed timer every 10 seconds.

We're dealing with this for quite some time and would appreciate any help/tips, Thank you.

private void GetViewedText()
    {
        // get the rectangle shown on the screen
        IntPtr h = System.Diagnostics.Process.GetCurrentProcess().MainWindowHandle;

        h = FindWindowExW(h, new IntPtr(0), "_WwF", "");        
        h = FindWindowExW(h, new IntPtr(0), "_WwB", this.Application.ActiveDocument.Name);

        h = FindWindowExW(h, new IntPtr(0), "_WwG", "Microsoft Word Document");       

        RECT tagRect = new RECT();
        GetWindowRect(h, out tagRect);
        //-------------------------------------------------------------------------------------------------------

        //get the range in the doc from the rect
        // problem with "ActiveDocument" or "ActiveWindow"
        Word.Range r1 = (Word.Range)this.Application.ActiveWindow.RangeFromPoint(tagRect.left, tagRect.top); 

        Word.Range r2 = (Word.Range)this.Application.ActiveWindow.RangeFromPoint(tagRect.right, tagRect.bottom);

        Word.Range r = this.Application.ActiveDocument.Range(r1.Start, r2.Start);
        //-------------------------------------------------------------------------------------------------------

        //for each paragraph we increase the number of times read it and change the color
        for (int p = 1; p <= r.Paragraphs.Count; p++)
        {
            Word.Range rPar = document.Range(r.Paragraphs[p].Range);
            Word.Range rParNum = document.Range(rPar.Start, rPar.Start + 1);
            Word.Range rParText = document.Range(rPar.Start + 1, rPar.End);
            try
            {
                int parNum = Int32.Parse(rParNum.Text);
                paragraphs[parNum].ReadParagrafh();
                if (paragraphs[parNum].GetCounter() == 1)
                {
                    rParText.HighlightColorIndex = Word.WdColorIndex.wdYellow;
                }
                else if (paragraphs[parNum].GetCounter() == 2)
                {
                    rParText.HighlightColorIndex = Word.WdColorIndex.wdBrightGreen;
                }
                else
                {
                    rParText.HighlightColorIndex = Word.WdColorIndex.wdGreen;
                }
            }
            catch
            {
                continue;
            }
        }
    }

For starters, which line is throwing the exception? And what is the exception message? — Yuval Itzchakov, Mar 16 '15 at 13:59
When we run it the line that throws the exception is: Word.Range rPar = document.Range(r.Paragraphs[p].Range); The exception is COMException was unhandled by user code (I can't find a way to add a print screen): An exception of type 'System.Runtime.InteropServices.COMException' occurred in WordAddIn1.dll but was not handled in user code Additional information: Type mismatch — lironlahav, Mar 16 '15 at 14:56

DRapp · Answer 1 · 2015-03-16T17:39:53.093

0

Are you crashing because of 0-based index reference?

for (int p = 1; p <= r.Paragraphs.Count; p++)

change to

for (int p = 0; p < r.Paragraphs.Count; p++)

So many things are 0-based. Lets say you have 4 paragraphs. Internally to the document, are they referenced as

paragraph[0], paragraph[1], paragraph[2], paragraph[3]

or

paragraph[1], paragraph[2], paragraph[3], paragraph[4]

The COUNT of paragraphs may be 4, but referenced as 0-3... Things may have worked fine, ex: 10 paragraphs, and it worked from 1-9 all valid (since 10 entries would have been 0-9), but then when you tried the 10th, no such reference exists.

Feedback from comment...

Since 1-based, maybe you should try pre-checking for NULL of the range?

if( r.Paragraphs[p].Range == null )
   continue;

Word.Range rPar = document.Range(r.Paragraphs[p].Range);

edited Mar 16 '15 at 17:39

answered Mar 16 '15 at 15:29

DRapp

47,638
12
72
142

no, the paragraph count starts from 1, it's not the reason. some other answers suggest admin rights for COM objects but I'm the admin in the computer :\ – lironlahav Mar 16 '15 at 17:24
@lironlahav, updated answer... maybe check for null before assigning? – DRapp Mar 16 '15 at 17:40
it still exits with the same COMException – lironlahav Mar 17 '15 at 14:24

score 0 · Accepted Answer · answered Mar 17 '15 at 16:08

0

fixed it, had to remove the document.Range so the new line is:

Word.Range rPar = r.Paragraphs[p].Range;

answered Mar 17 '15 at 16:08

lironlahav

13
3

COMException unhandled in MS Word

2 Answers2