/// <summary>
/// Handler to handel the visiblity change of columns
/// </summary>
/// <param name="sender">ColumnHeaderEx</param>
/// <param name="e"></param>
private void ColumnVisibleChanged(object sender, EventArgs e)
{
ColumnHeaderEx column = (ColumnHeaderEx)sender;
if (column.Visible == true)
{
// Show the hidden column
// Get the position where the hidden column has to be shown
ColumnHeaderEx prevHeader = FindPreviousVisibleColumn(column);
if (prevHeader == null)
{
// This is the first column, so add it at 0 location
base.Insert(0, column);
}
else
{
// Got the location, place it their.
base.Insert(prevHeader.Index + 1, column);
}
}
else
{
// Hide the column.
// Remove it from the base, dont worry we have the
// refrence in columnList to get it back
base.Remove(column);
}
}
/// <summary>
/// Method adds a single column header to the collection.
/// </summary>
/// <param name="str">Text to display</param>
/// <param name="width">Width of column</param>
/// <param name="textAlign">Alignment</param>
/// <returns>new ColumnHeaderEx added</returns>
public override ColumnHeader Add(string str, int width, HorizontalAlignment textAlign)
{
ColumnHeaderEx column = new ColumnHeaderEx(str, width, textAlign);
this.Add(column);
return(column);
}
/// <summary>
/// Adds an existing ColumnHeader to the collection.
/// </summary>
/// <param name="column">The ColumnHeader to
/// add to the collection. </param>
/// <returns>The zero-based index into the collection
/// where the item was added.</returns>
public int Add(ColumnHeaderEx column)
{
// Add the column to the base
int retValue = base.Add(column);
// Keep a refrence in columnList
columnList.Add(column.ColumnID, column);
// Add the its menu to main menu
// ContextMenu.MenuItems.Add(column.ColumnMenuItem);
// Subscribe to the visiblity change event of the column
column.VisibleChanged += new EventHandler(ColumnVisibleChanged);
return(retValue);
}
/// <summary>
/// This method is used to find the first visible column
/// which is present in front of the column specified
/// </summary>
/// <param name="column">refrence columns for search</param>
/// <returns>null if no visible colums are in front of
/// the column specified, else previous columns returned</returns>
private ColumnHeaderEx FindPreviousVisibleColumn(ColumnHeaderEx column)
{
// Get the position of the search column
int index = columnList.IndexOfKey(column.ColumnID);
if (index > 0)
{
// Start a recursive search for a visible column
ColumnHeaderEx prevColumn = (ColumnHeaderEx)columnList.GetByIndex(index - 1);
if ((prevColumn != null) && (prevColumn.Visible == false))
{
prevColumn = FindPreviousVisibleColumn(prevColumn);
}
return(prevColumn);
}
// No visible columns found in font of specified column
return(null);
}
