Webbrowser Find Previous (text)

I am trying to implement search routines: Find Next and Find Previous in Webbrowser. I know that there is Build-in Find dialog inside, but I do not want to use it. Instead I am trying hard to write my own routines, but I can not get through. Following code implements "Find next" nicely:

using mshtml;

....

private void toolStripButton5_Click(object sender, EventArgs e)
        {
            IHTMLDocument2 htmlDocument = WB.Document.DomDocument as IHTMLDocument2;
            IHTMLSelectionObject sel = (IHTMLSelectionObject)htmlDocument.selection;
            IHTMLTxtRange tr = (IHTMLTxtRange)sel.createRange() as IHTMLTxtRange;
            string s = toolStripTextBox1.Text;
            tr.collapse(false); 
            tr.findText(s, 1, 0); // positive value, should search forward, negative backward
            开发者_开发技巧tr.select();
        }

I am totaly helpless making "Find previous" routine. Can any genius forge it? (it will be probably very similar to that above).

Thanks very much

For "Find previous" routine use the same code with 2 modifications: 1) change argument of tr.collapse from false to true; 2) change the second parameter of tr.findText from 1 to -1.

So these line will be the following:

tr.collapse(true); // use true to move caret at the beginning of the current selection
tr.findText(s, -1, 0); // positive value, should search forward, negative backward

IHTMLTxtRange tmprange; private void Find(int Direction, bool Collapse) {

        IHTMLDocument2 htmlDocument = browser.Document.DomDocument as IHTMLDocument2;
        IHTMLSelectionObject sel = (IHTMLSelectionObject)htmlDocument.selection;
        IHTMLTxtRange tr = (IHTMLTxtRange)sel.createRange() as IHTMLTxtRange;
        string s = textBoxFindData.Text;
        if (tmprange == null)
        {
            tr.collapse(Collapse);
            tmprange = tr;
            tr.findText(s, Direction, 0); // positive value, should search forward, negative backward
            if (tr.text == null)
            {
                MessageBox.Show("Can not find string " + "[" + s + "]", "Information", MessageBoxButtons.OK, MessageBoxIcon.Information);
            }
            tr.select();
        }
        else
        {
            tmprange.collapse(Collapse);
            tmprange.findText(s, Direction, 0); // positive value, should search forward, negative backward
            if (tmprange.text == null)
            {
                MessageBox.Show("Can not find string " + "[" + s + "]", "Information", MessageBoxButtons.OK, MessageBoxIcon.Information);
            }
            tmprange.select();

        }
    }

    private void buttonPrevious_Click(object sender, EventArgs e)
    {
        Find(-1, true);
    }