private void ApplyFilter()
{
string text = listFilterText.ToString();
mainControlText.Text = text;
// Remove existing highlight
highlightedItem?.ModifyStatesView(showHighlight: false);
// Find menu items starting with the given filter text
var firstMatchedItem = MenuItems.Where(m => m.Text.IndexOf(text, StringComparison.OrdinalIgnoreCase) == 0).FirstOrDefault();
if (firstMatchedItem != null)
{
// Highlight our new match
highlightedItem = firstMatchedItem;
highLightedIndex = MenuItems.IndexOf(highlightedItem);
highlightedItem.ModifyStatesView(showHighlight: true);
// and scroll into view
DropDownContainer.ScrollIntoView(highlightedItem);
}
}
protected override void ShowMenu()
{
if (this.Parent == null)
{
return;
}
base.ShowMenu();
if (selectedIndex >= MenuItems.Count - 1)
{
selectedIndex = MenuItems.Count - 1;
}
// Show and highlight the previously selected or the first item
if (selectedIndex >= 0)
{
var selectedMenuItem = MenuItems[selectedIndex];
// Scroll the selected item into view
DropDownContainer.ScrollIntoView(selectedMenuItem);
// Highlight the selected item
highlightedItem = selectedMenuItem;
highlightedItem.ModifyStatesView(showHighlight: true);
}
else if (MenuItems.Count > 0)
{
highlightedItem = MenuItems[0];
highlightedItem?.ModifyStatesView(showHighlight: true);
}
listFilterText = new StringBuilder();
DropDownContainer.KeyPressed += (s, e) =>
{
listFilterText.Append(e.KeyChar);
ApplyFilter();
};
DropDownContainer.KeyUp += (s, e) =>
{
switch (e.KeyCode)
{
case Keys.Up:
if (highLightedIndex > 0)
{
highLightedIndex--;
}
break;
case Keys.Down:
if (highLightedIndex < this.MenuItems.Count - 1)
{
highLightedIndex++;
}
break;
}
// Remove existing
highlightedItem?.ModifyStatesView(showHighlight: false);
highlightedItem = this.MenuItems[highLightedIndex];
highlightedItem?.ModifyStatesView(showHighlight: true);
// if (!highlightedItem.Visible) // only scroll if clipped
{
DropDownContainer.ScrollIntoView(highlightedItem);
}
this.Invalidate();
};
DropDownContainer.KeyDown += (s, keyEvent) =>
{
switch (keyEvent.KeyCode)
{
case Keys.Escape:
listFilterText = new StringBuilder();
DropDownContainer.CloseMenu();
break;
case Keys.Enter:
if (highlightedItem != null)
{
SelectedIndex = MenuItems.IndexOf(highlightedItem);
DropDownContainer.CloseMenu();
listFilterText = null;
}
break;
case Keys.Back:
if (listFilterText != null && listFilterText.Length > 0)
{
listFilterText.Length -= 1;
}
keyEvent.Handled = true;
keyEvent.SuppressKeyPress = true;
ApplyFilter();
break;
}
};
DropDownContainer.Closed += (s, e) =>
{
mainControlText.Text = selectedIndex == -1 ? this.noSelectionString : MenuItems[SelectedIndex].Text;
this.Focus();
};
}