HomeDownloadsSource Code LibraryMiscellaneous (23)Getting the word at the current mouse position

Getting the word at the current mouse position

Author:	TX Text Control Support Department
Language:	C#
Version:	1.0
Released:	March 26, 2007
Last modified:	January 11, 2008
Requirements:	TX Text Control .NET with Visual Studio 2005
Download code:	tx_chars_sample.zip  [13.5 KB, ZIP]

Sometimes, it is necessary to know the word at the current mouse position, in order to display additional information to the end-user.

This sample displays a tool tip with the word's text when the end-user moves the mouse over a word.

The function GetWordFromIndex must be called with the character index and returns the complete word at this position. To avoid a potential flicker that is caused by changing the input position, this sample does not use the Find method to search for the word delimiters like a comma, period or any other punctuation marks.

Instead of the Find method, the function uses the internal .NET String methods IndexOfAny and LastIndexOfAny. These methods return an index of a specific character. The SubString method is used to build the detected word from the complete document's text.

private string GetWordFromIndex(int Index)
{
    string CompleteText = textControl1.Text.Replace("\r\n","\n");
    Char[] chars = new Char[] { ',', ';', ':', '!', '?', '.', ' ', (char)9, (char)10 };
 
    int lastChar = CompleteText.IndexOfAny(chars, Index);
 
    if(lastChar != -1)
        CompleteText = CompleteText.Substring(0, lastChar);
 
    int firstChar = CompleteText.LastIndexOfAny(chars);
 
    return CompleteText.Substring(firstChar + 1);
}

The above function is called in TX Text Control's MouseMove event. The GetItem method of the TextChars collection of TX Text Control returns the character index of a specific location. This method is called with the return value of the MouseMove event. The return value of the GetWordFromIndex function is used to display a tool tip above the specific word.

This approach has the advantage that the current input position must not be changed.

private void textControl1_MouseMove(object sender, MouseEventArgs e)
{
	int charIndex = textControl1.TextChars.GetItem(e.Location, true).Number;
  string currentWord = GetWordFromIndex(charIndex);
 
  if (currentWord != "")
  {
      toolTip1.ToolTipTitle = currentWord;
      toolTip1.Show("Index: " + charIndex.ToString(), this, e.X + 20, e.Y - 10);
  }
  else
      toolTip1.Hide(this);
}

The sample requires Visual Studio 2005 and at least a trial version of TX Text Control .NET 13.0.

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