/// <summary>
/// Translates the HorizontalContentAlignment value into a TextAlignment value.
/// </summary>
/// <param name="dependencyObject">The Dependency Property that has changed.</param>
/// <param name="dependencyPropertyChangedEventArgs">The event arguments describing the property change.</param>
public static void OnHorizontalContentAlignmentChanged(DependencyObject dependencyObject,
DependencyPropertyChangedEventArgs dependencyPropertyChangedEventArgs)
{
// The basic idea here is to translate the HorizontalContentAlignment used by the Control class into a TextAlignment
// value that is usable by the TextBlock class. This allows a Control to host a TextBlock with a consistent approach
// to how the alignment of the content is specified.
ValueBlock valueBlock = (ValueBlock)dependencyObject;
HorizontalAlignment horizontalAlignment = (HorizontalAlignment)dependencyPropertyChangedEventArgs.NewValue;
// Translate the HorizontalContentAlignment into a TextAlignment that TextBlocks can use.
switch (horizontalAlignment)
{
case HorizontalAlignment.Center:
valueBlock.SetValue(ValueBlock.TextAlignmentProperty, TextAlignment.Center);
break;
case HorizontalAlignment.Left:
valueBlock.SetValue(ValueBlock.TextAlignmentProperty, TextAlignment.Left);
break;
case HorizontalAlignment.Right:
valueBlock.SetValue(ValueBlock.TextAlignmentProperty, TextAlignment.Right);
break;
}
}
/// <summary>
/// Handles a change to the format of the data.
/// </summary>
/// <param name="dependencyObject">The dependency object that has been changed.</param>
/// <param name="dependencyPropertyChangedEventArgs">The event arguments describing the change to the property.</param>
public static void OnFormatChanged(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs dependencyPropertyChangedEventArgs)
{
// Reformat the text in the control when the format changes.
ValueBlock valueBlock = dependencyObject as ValueBlock;
String format = dependencyPropertyChangedEventArgs.NewValue as String;
Object value = valueBlock.GetValue(ValueBlock.ContentProperty);
valueBlock.SetValue(TextBlock.TextProperty, String.Format(format, value));
}
/// <summary>
/// Handles a change to the value of this control.
/// </summary>
/// <param name="dependencyObject">The dependency object that has been changed.</param>
/// <param name="dependencyPropertyChangedEventArgs">The event arguments describing the change to the property.</param>
public static void OnContentChanged(DependencyObject dependencyObject,
DependencyPropertyChangedEventArgs dependencyPropertyChangedEventArgs)
{
// Display the value using the Format property in the Text property of the base class.
ValueBlock valueBlock = dependencyObject as ValueBlock;
String format = valueBlock.GetValue(ValueBlock.FormatProperty) as String;
Object value = dependencyPropertyChangedEventArgs.NewValue;
valueBlock.SetValue(ValueBlock.TextProperty, String.Format(format, value));
// Recycling this control can lead to false Up/Down indications because the old value is no longer relavent to the new
// value. When the data context of the control has changed, the next property update will not attempt to trigger an
// Up/Down event.
if (valueBlock.ignoreChange)
{
valueBlock.ignoreChange = false;
}
else
{
// This provides feedback indicating whether the control has increased or decreased in value.
if (dependencyPropertyChangedEventArgs.NewValue is IComparable &&
dependencyPropertyChangedEventArgs.OldValue is IComparable)
{
IComparable iComparable = dependencyPropertyChangedEventArgs.NewValue as IComparable;
switch (iComparable.CompareTo(dependencyPropertyChangedEventArgs.OldValue))
{
case 1:
// Indicate that the value has increased.
valueBlock.SetValue(ValueBlock.IsUpProperty, true);
valueBlock.SetValue(ValueBlock.IsDownProperty, false);
// Raise an event that indicates the value has increased.
valueBlock.RaiseEvent(new RoutedEventArgs(ValueBlock.IncreaseEvent));
break;
case -1:
// Indicate that the value has decreased.
valueBlock.SetValue(ValueBlock.IsUpProperty, false);
valueBlock.SetValue(ValueBlock.IsDownProperty, true);
// Raise an event that indicates the value has decreased.
valueBlock.RaiseEvent(new RoutedEventArgs(ValueBlock.DecreaseEvent));
break;
}
}
}
}