Code Snippet
private void richTextBox1_SelectionChanged(object sender, EventArgs e)
{
// Only allows to select from 20th character to 30th character
int allowedStartIndex = 20;
int allowedEndIndex = 30;
int selectionStart = richTextBox1.SelectionStart;
int selectionEnd = richTextBox1.SelectionStart + richTextBox1.SelectionLength;
// starts at 15
if (selectionStart < allowedStartIndex)
{
// ends at 18
if (selectionEnd < allowedStartIndex)
{
richTextBox1.SelectionLength = 0;
}
// ends at 25
else if (selectionEnd <= allowedEndIndex)
{
richTextBox1.SelectionStart = allowedStartIndex;
richTextBox1.SelectionLength = selectionEnd - allowedStartIndex;
}
// ends at 31
else //if (selectionEnd > allowedEndIndex)
{
richTextBox1.SelectionStart = allowedStartIndex;
richTextBox1.SelectionLength = allowedEndIndex - allowedStartIndex;
}
}
// starts at 25
else if (selectionStart <= allowedEndIndex)
{
// ends at 31
if (selectionEnd > allowedEndIndex)
{
richTextBox1.SelectionLength = allowedEndIndex - selectionStart;
}
// ends at 18
else if (selectionEnd < allowedStartIndex)
{
richTextBox1.SelectionLength = selectionStart - allowedStartIndex;
}
}
// starts at 35
else // if(selectionStart > allowedEndIndex)
{
// end at 31
if (selectionEnd > allowedEndIndex)
{
richTextBox1.SelectionLength = 0;
}
// ends at 28
else if (selectionEnd >= allowedStartIndex)
{
richTextBox1.SelectionStart = allowedEndIndex;
richTextBox1.SelectionLength = allowedEndIndex - selectionEnd;
}
// ends at 18
else // if (selectionEnd < allowedStartIndex)
{
richTextBox1.SelectionStart = allowedEndIndex;
richTextBox1.SelectionLength = allowedEndIndex - allowedStartIndex;
}
}
}
index > Windows Forms Designer > Rich text box selection problem
. What i really meant in my earlier question was, how do i disable the user from selecting text from the whitespace that can be found in the rich text box itself? This means, the user is selecting the text when he clicks on the whitespace and not actually clicking on the text itself to select it. Is there a way to detect a user clicking the whitespace region and then disabling the user from doing anything in the whitespace?