|
//---------------------------------------------------------------------------
//
// <copyright file="DataTrigger.cs" company="Microsoft">
// Copyright (C) Microsoft Corporation. All rights reserved.
// </copyright>
//
// Description: Defines DataTrigger object, akin to Trigger except it
// gets values from data.
//
//---------------------------------------------------------------------------
using System;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Diagnostics;
using System.Windows.Data;
using System.Windows.Markup;
namespace System.Windows
{
/// <summary>
/// A single Style data conditional dependency driver
/// </summary>
[ContentProperty("Setters")]
[XamlSetMarkupExtensionAttribute("ReceiveMarkupExtension")]
public class DataTrigger : TriggerBase, IAddChild
{
/// <summary>
/// Binding declaration of the conditional
/// </summary>
[Localizability(LocalizationCategory.None, Readability = Readability.Unreadable)] // Not localizable by-default
public BindingBase Binding
{
get
{
// Verify Context Access
VerifyAccess();
return _binding;
}
set
{
// Verify Context Access
VerifyAccess();
if (IsSealed)
{
throw new InvalidOperationException(SR.Get(SRID.CannotChangeAfterSealed, "DataTrigger"));
}
_binding = value;
}
}
/// <summary>
/// Value of the condition (equality check)
/// </summary>
[DependsOn("Binding")]
[Localizability(LocalizationCategory.None, Readability = Readability.Unreadable)] // Not localizable by-default
public object Value
{
get
{
// Verify Context Access
VerifyAccess();
return _value;
}
set
{
// Verify Context Access
VerifyAccess();
if (IsSealed)
{
throw new InvalidOperationException(SR.Get(SRID.CannotChangeAfterSealed, "DataTrigger"));
}
if (value is MarkupExtension)
{
throw new ArgumentException(SR.Get(SRID.ConditionValueOfMarkupExtensionNotSupported,
value.GetType().Name));
}
if( value is Expression )
{
throw new ArgumentException(SR.Get(SRID.ConditionValueOfExpressionNotSupported));
}
_value = value;
}
}
/// <summary>
/// Collection of Setter objects, which describes what to apply
/// when this trigger is active.
/// </summary>
[DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
public SetterBaseCollection Setters
{
get
{
// Verify Context Access
VerifyAccess();
if( _setters == null )
{
_setters = new SetterBaseCollection();
}
return _setters;
}
}
///<summary>
/// This method is called to Add a Setter object as a child of the Style.
///</summary>
///<param name="value">
/// The object to add as a child; it must be a Setter or subclass.
///</param>
void IAddChild.AddChild (Object value)
{
// Verify Context Access
VerifyAccess();
Setters.Add(Trigger.CheckChildIsSetter(value));
}
///<summary>
/// This method is called by the parser when text appears under the tag in markup.
/// As default Styles do not support text, calling this method has no effect.
///</summary>
///<param name="text">
/// Text to add as a child.
///</param>
void IAddChild.AddText (string text)
{
// Verify Context Access
VerifyAccess();
XamlSerializerUtil.ThrowIfNonWhiteSpaceInAddText(text, this);
}
internal sealed override void Seal()
{
if (IsSealed)
{
return;
}
// Process the _setters collection: Copy values into PropertyValueList and seal the Setter objects.
ProcessSettersCollection(_setters);
// Freeze the value for the trigger
StyleHelper.SealIfSealable(_value);
// Build conditions array from collection
TriggerConditions = new TriggerCondition[] {
new TriggerCondition(
_binding,
LogicalOp.Equals,
_value) };
// Set Condition for all data triggers
for (int i = 0; i < PropertyValues.Count; i++)
{
PropertyValue propertyValue = PropertyValues[i];
propertyValue.Conditions = TriggerConditions;
switch (propertyValue.ValueType)
{
case PropertyValueType.Trigger:
propertyValue.ValueType = PropertyValueType.DataTrigger;
break;
case PropertyValueType.PropertyTriggerResource:
propertyValue.ValueType = PropertyValueType.DataTriggerResource;
break;
default:
throw new InvalidOperationException(SR.Get(SRID.UnexpectedValueTypeForDataTrigger, propertyValue.ValueType));
}
// Put back modified struct
PropertyValues[i] = propertyValue;
}
base.Seal();
}
// evaluate the current state of the trigger
internal override bool GetCurrentState(DependencyObject container, UncommonField<HybridDictionary[]> dataField)
{
Debug.Assert( TriggerConditions != null && TriggerConditions.Length == 1,
"This method assumes there is exactly one TriggerCondition." );
return TriggerConditions[0].ConvertAndMatch(StyleHelper.GetDataTriggerValue(dataField, container, TriggerConditions[0].Binding));
}
private BindingBase _binding;
private object _value = DependencyProperty.UnsetValue;
private SetterBaseCollection _setters = null;
public static void ReceiveMarkupExtension(object targetObject, XamlSetMarkupExtensionEventArgs eventArgs)
{
if (targetObject == null)
{
throw new ArgumentNullException("targetObject");
}
if (eventArgs == null)
{
throw new ArgumentNullException("eventArgs");
}
DataTrigger trigger = targetObject as DataTrigger;
if (trigger != null && eventArgs.Member.Name == "Binding" && eventArgs.MarkupExtension is BindingBase)
{
trigger.Binding = eventArgs.MarkupExtension as BindingBase;
eventArgs.Handled = true;
}
else
{
eventArgs.CallBase();
}
}
}
}
|