/// <summary>
/// Calculate an acceptable position of the DropDownForm even in a
/// multi screen environment.
/// </summary>
/// <param name="DropDown"></param>
/// <returns></returns>
private Point GetDropDownPosition(DropDownForm DropDown)
{
Point lt = Parent.PointToScreen(new Point(Left, Top));
Point rb = Parent.PointToScreen(new Point(Right, Bottom));
Rectangle screen = Screen.FromControl(this).Bounds;
Point point = new Point();
if (((lt.X + DropDown.Width) > (screen.X + screen.Width)) && ((rb.X - DropDown.Width) >= screen.X))
{
point.X = rb.X - DropDown.Width;
if ((point.X + DropDown.Width) > (screen.X + screen.Width))
{
point.X = ((screen.X + screen.Width) - DropDown.Width);
}
}
else
{
point.X = lt.X;
if (point.X < screen.X)
{
point.X = screen.X;
}
}
if (((rb.Y + DropDown.Height) > (screen.Y + screen.Height)) && ((lt.Y - DropDown.Height) >= screen.Y))
{
point.Y = lt.Y - DropDown.Height;
if (point.Y < screen.Y)
{
point.Y = screen.Y;
}
}
else
{
point.Y = rb.Y;
if ((point.Y + DropDown.Height) > (screen.Y + screen.Height))
{
point.Y = ((screen.Y + screen.Height) - DropDown.Height);
}
}
return(point);
}
/// <summary>
/// We make our DropDownForm host the choosen control and show it instead
/// of the dropdown portion of the ComboBox.
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void Combo_DropDown(object sender, EventArgs e)
{
if (!_dropDownHelper.DropDownShowing)
{
DropDownForm dropDown = new DropDownForm(_dropDownControl);
dropDown.FinishEditing += new DropDownValueChangedEventHandler(DropDown_FinishEditing);
dropDown.ValueChanged += new DropDownValueChangedEventHandler(DropDown_ValueChanged);
combo.DroppedDown = false;
_dropDownHelper.ShowDropDown(_owner, dropDown, GetDropDownPosition(dropDown));
}
else
{
_dropDownHelper.CloseDropDown();
this.Focus();
}
}