/// <summary>
/// Create a visual element based on the properties of the column.
/// </summary>
/// <param name="columnViewColumn">The column that defines the cell.</param>
/// <returns>A visual element that holds the content of the cell.</returns>
public static FrameworkElement CreateCell(ColumnViewColumn columnViewColumn)
{
// Validate the parameters.
if (columnViewColumn == null)
{
throw new ArgumentNullException("columnViewColumn");
}
// This will either create an element based on the templates associated with the ColumnViewColumn, or for simple binding, will create a simple cell and
// bind it using the binding provided in the DisplayMemberBinding property. Both variations return a FrameworkElement that is used as an element in the
// row to display the data associated with the column.
FrameworkElement frameworkElement;
if (columnViewColumn.DisplayMemberBinding == null)
{
// This will create a generic ContentPresenter using the templates associated with the ColumnView and bind the content of the generic control to
// the data context (which contains the row data). It is the responsibility of the cell to select which property of the row data it wants to
// display. It is important to remember that a ContentPresenter is not like other controls. The DataContext is not inheritied from the logical
// parent, it is set to the Content property of the ContentPresenter. The main problem we're solving here is that the child control that's
// generated from the ContentPresenter's template needs a DataContext, but the ContentPresenter doesn't have one since it's pointing to itself. To
// solve this, we'll bind the Content of the ContentPresenter to the ColumnViewRowPresenter that is it's parent. This effectively restores the
// DataContext inheritance that all other controls have. Clear as mud?
ContentPresenter contentPresenter = new ContentPresenter();
contentPresenter.ContentTemplate = columnViewColumn.CellTemplate;
contentPresenter.ContentTemplateSelector = columnViewColumn.CellTemplateSelector;
Binding dataContextBinding = new Binding()
{
Path = new PropertyPath("DataContext")
};
dataContextBinding.RelativeSource = new RelativeSource(RelativeSourceMode.FindAncestor, typeof(ColumnViewRowPresenter), 1);
BindingOperations.SetBinding(contentPresenter, ContentPresenter.ContentProperty, dataContextBinding);
frameworkElement = contentPresenter;
}
else
{
// This will create a cell to display the data provided by the 'DisplayMemberBinding' which selects which property of the row data is to be
// displayed.
ColumnViewColumnCell columnViewColumnCell = new ColumnViewColumnCell();
BindingOperations.SetBinding(columnViewColumnCell, ColumnViewColumnCell.ContentProperty, columnViewColumn.DisplayMemberBinding);
frameworkElement = columnViewColumnCell;
}
// This element is used to present the data.
return(frameworkElement);
}
/// <summary>
/// Handles a change to the column property.
/// </summary>
/// <param name="sender">The Object that originated the event.</param>
/// <param name="propertyChangedEventArgs">The event arguments.</param>
protected override void OnColumnPropertyChanged(Object sender, PropertyChangedEventArgs propertyChangedEventArgs)
{
// Validate the parameters.
if (sender == null)
{
throw new ArgumentNullException("sender");
}
if (propertyChangedEventArgs == null)
{
throw new ArgumentNullException("propertyChangedEventArgs");
}
// This will get the column where the property change occurred from the sender.
ColumnViewColumn columnViewColumn = sender as ColumnViewColumn;
// If the column is visible, then it has a visual element which needs to have its properties reconciled with the ColumnViewColumn properties.
if (columnViewColumn.IsVisible)
{
// This will find the visual element what has properites that must be reconciled with the header.
Int32 columnIndex = this.Columns.IndexOf(columnViewColumn);
ColumnViewColumnCell columnViewColumnCell = this.Children[columnIndex] as ColumnViewColumnCell;
// This will apply the property in the column to the visual element representing that column in the current row.
switch (propertyChangedEventArgs.PropertyName)
{
case "CellTemplate":
case "CellTemplateSelector":
case "DisplayMemberBinding":
// Recreate the cell based on the new properties.
this.Children.RemoveAt(columnIndex);
FrameworkElement frameworkElement = ColumnViewRowPresenter.CreateCell(columnViewColumn);
this.InstallCell(frameworkElement, columnViewColumn);
this.Children.Insert(columnIndex, frameworkElement);
break;
case "Width":
case "MinWidth":
// Forcing a re-measurement of the row will pick up the changes made to the column's width.
this.InvalidateMeasure();
break;
}
}
}