/// <summary>
/// This is used to select an item in the drop-down as the current item
/// </summary>
/// <param name="selIdx">The index of the selected item</param>
internal void SelectItem(int selIdx)
{
dgDropDown.ClearSelection();
if (selIdx != -1)
{
DataGridHelper.ConcedeFocus(dgDropDown);
dgDropDown.CurrentRowIndex = selIdx;
dgDropDown.Select(selIdx);
}
}
/// <summary>
/// This is used to set the default selected item, size and position the drop-down, and show it
/// </summary>
public void ShowDropDown()
{
int idx;
if (!hasInitialized)
{
this.CreateHandle();
}
idx = startIndex = owner.SelectedIndex;
dgDropDown.ClearSelection();
dragOffset = Point.Empty;
// Sometimes it shows the edit control so clear it
DataGridHelper.ConcedeFocus(dgDropDown);
if (idx != -1 && DataGridHelper.RowCount(dgDropDown) > idx)
{
dgDropDown.Select(idx);
dgDropDown.CurrentRowIndex = idx;
}
// The owner positions us when using the simple style. There's also an odd sequence of events
// related to updates to bound controls that can cause this control to get disposed after setting
// the data grid's row index above so we'll stop in that case too.
if (this.IsDisposed || owner.DropDownStyle == ComboBoxStyle.Simple)
{
return;
}
if (this.Width < owner.Width)
{
this.Width = owner.Width;
}
// Make sure we are within the screen bounds. Take into account the working area of all screens.
// Note that in certain setups, the leftmost/uppermost screen(s) may have negative coordinates.
Rectangle workingArea, screen = new Rectangle();
foreach (Screen s in Screen.AllScreens)
{
workingArea = s.WorkingArea;
if (workingArea.X < screen.X)
{
screen.X = workingArea.X;
}
if (workingArea.Y < screen.Y)
{
screen.Y = workingArea.Y;
}
if (Math.Abs(workingArea.X) + workingArea.Width > screen.Width)
{
screen.Width = Math.Abs(workingArea.X) + workingArea.Width;
}
if (Math.Abs(workingArea.Y) + workingArea.Height > screen.Height)
{
screen.Height = Math.Abs(workingArea.Y) + workingArea.Height;
}
}
Point pOwner = owner.Parent.PointToScreen(owner.Location);
pOwner.Y += owner.Height;
Point p = pOwner;
if (this.Width > screen.Width)
{
this.Width = screen.Width;
}
if (this.Height > screen.Height)
{
this.Height = screen.Height;
}
if (p.X < screen.X)
{
p.X = screen.X;
}
if (p.Y < screen.Y)
{
p.Y = screen.Y;
}
if (p.X + this.Width > screen.X + screen.Width)
{
p.X = screen.X + screen.Width - this.Width - 1;
}
if (p.Y + this.Height > screen.Y + screen.Height)
{
p.Y = screen.Y + screen.Height - this.Height - 1;
}
// If we are covering the combo box, move the location above the combo box
if (p.Y < pOwner.Y)
{
idx = pOwner.Y - this.Height - owner.Height;
// If we would go off the top of the screen, figure out whether we would have more rows visible
// if we moved the form above the combo box or left it where it is at below the combo box and
// shrink it to fit.
if (idx < screen.Y)
{
if (this.Height + idx > this.Height - (pOwner.Y - p.Y))
{
this.Height += idx;
idx = screen.Y;
}
else
{
this.Height -= (pOwner.Y - p.Y);
idx = pOwner.Y;
}
}
p.Y = idx;
}
this.Location = p;
UnsafeNativeMethods.SetParent(this.Handle, IntPtr.Zero);
this.Show();
// NOTE: We lose capture pretty quickly as the mouse isn't inside the drop-down. MouseLeave grabs it
// for us again.
this.Capture = true;
}
/// <summary>
/// Hide any edit control when the grid is scrolled
/// </summary>
/// <param name="sender">The sender of the event</param>
/// <param name="e">The event arguments</param>
private void DropDownDataGrid_Scroll(object sender, EventArgs e)
{
DataGridHelper.ConcedeFocus(this);
}