C # checked listbox MouseMove vs MouseHover event handler
I am using the following event handler MouseMove
to show the content of a text file as a tooltip in a CheckedListBox, and there is a text file object marked with each checkedListBoxItem.
private void checkedListBox1_MouseMove(object sender, MouseEventArgs e)
{
int itemIndex = checkedListBox1.IndexFromPoint(new Point(e.X, e.Y));
if (itemIndex >= 0)
{
if (checkedListBox1.Items[itemIndex] != null)
{
TextFile tf = (TextFile)checkedListBox1.Items[itemIndex];
string subString = tf.JavaCode.Substring(0, 350);
toolTip1.ToolTipTitle = tf.FileInfo.FullName;
toolTip1.SetToolTip(checkedListBox1, subString + "\n... ... ...");
}
}
}
The problem is my application is slowing down due to frequent mouse movements on the checkedListBox.
Alternatively, I thought I should use an event MouseHover
and its handler. But I couldn't find out which checkListBoxItem my musePointer is currently on. Like this:
private void checkedListBox1_MouseHover(object sender, EventArgs e)
{
if (sender != null)
{
CheckedListBox chk = (CheckedListBox)sender;
int index = chk.SelectedIndex;
if (chk != null)
{
TextFile tf = (TextFile)chk.SelectedItem;
string subString = tf.FileText.Substring(0, 350);
toolTip1.ToolTipTitle = tf.FileInfo.FullName;
toolTip1.SetToolTip(checkedListBox1, subString + "\n... ... ...");
}
}
}
Here int index
returns -1 and chk.SelectedItem
returns null
.
What could be the solution to this type of problem?
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On the MouseHover event, you can use the Cursor.Position property and convert it to the client position and go to IndexFromPoint () to determine which list item contains.
eg.
Point ptCursor = Cursor.Position;
ptCursor = PointToClient(ptCursor);
int itemIndex=checkedTextBox1.IndexFromPoint(ptCursor);
...
...
This is useful for other events as well where you don't have a mouse position specified in the event parameters.
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The problem is that the SelectedItem <> checkedItem selected has a different background, checked means have a check on the left side.
instead
int index = chk.SelectedIndex;
you should use:
int itemIndex = checkedListBox1.IndexFromPoint(new Point(e.X, e.Y));
bool selected = checkedListBox1.GetItemChecked(itemIndex );
then show what you want if selected ...
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