/// ------------------------------------------------------------------------------------
/// <summary>
/// Determine if the drop down should go above the ScrPassageControl or
/// below it.
/// </summary>
/// <param name="screenPoint">point on the screen of the</param>
/// <param name="dropDown">drop down control</param>
/// <returns>true to go above, false to go below</returns>
/// ------------------------------------------------------------------------------------
private bool DropDownShouldGoUp(Point screenPoint, ScrPassageDropDown dropDown)
{
// determine the usable space on the screen that contains the top left
// corner of the ScrPassageControl.
Rectangle rcAllowable = ScreenHelper.AdjustedWorkingArea(Screen.FromPoint(screenPoint));
// If there is not enough space to go down, then go up
return (rcAllowable.Height - screenPoint.Y - Height - dropDown.Height < 0);
}
/// ------------------------------------------------------------------------------------
/// <summary>
/// Position the drop down control.
/// </summary>
/// ------------------------------------------------------------------------------------
private void PositionDropDown(ScrPassageDropDown dropDown)
{
Point screenPoint = PointToScreen(new Point(0, 0));
// If there is no room below the ScrPassageControl for the drop down then
// position above, otherwise position below.
if (DropDownShouldGoUp(screenPoint, dropDown))
screenPoint.Y -= dropDown.Height;
else
screenPoint.Y += Height;
dropDown.DesktopLocation = screenPoint;
// Make sure that the drop down fits on the screen.
Rectangle rect = new Rectangle(dropDown.DesktopLocation,
new Size(dropDown.Width, dropDown.Height));
ScreenHelper.EnsureVisibleRect(ref rect);
dropDown.DesktopLocation = new Point(rect.Left, rect.Top);
}