TriggerAction.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Framework / System / Windows / TriggerAction.cs / 1305600 / TriggerAction.cs
                        
                        
                            /****************************************************************************\ 
*
* File: TriggerAction.cs
*
* A TriggerAction is stored within a Trigger object as one of the actions to 
*  be performed by that trigger.  A Trigger object is similar to an if/then
*  statement, and by that analogy a TriggerActionCollection is the entire 
*  "then" block of the Trigger, and a TriggerAction is a single line within 
*  the "then" block.
* 
* Copyright (C) by Microsoft Corporation.  All rights reserved.
*
\***************************************************************************/
 
using System;
using MS.Internal; 
 
namespace System.Windows
{ 
    /// 
    ///   A class that describes an action to perform for a trigger
    /// 
    public abstract class TriggerAction : DependencyObject 
    {
        ///  
        ///     Internal constructor - nobody is supposed to ever create an instance 
        /// of this class.  Use a derived class instead.
        ///  
        internal TriggerAction()
        {
        }
 
        /// 
        ///     Called when all conditions have been satisfied for this action to be 
        /// invoked.  (Conditions are not described on this TriggerAction object, 
        /// but on the Trigger object holding it.)
        ///  
        /// 
        ///     This variant is called when the Trigger lives in a Style, and
        /// hence given a reference to its corresponding Style object.
        ///  
        internal abstract void Invoke( FrameworkElement fe,
                                      FrameworkContentElement fce, 
                                      Style targetStyle, 
                                      FrameworkTemplate targetTemplate,
                                      Int64 layer); 

        /// 
        ///     Called when all conditions have been satisfied for this action to be
        /// invoked.  (Conditions are not described on this TriggerAction object, 
        /// but on the Trigger object holding it.)
        ///  
        ///  
        ///     This variant is called when the Trigger lives on an element, as
        /// opposed to Style, so it is given only the reference to the element. 
        /// 
        internal abstract void Invoke( FrameworkElement fe );

        ///  
        ///     The EventTrigger object that contains this action.
        ///  
        ///  
        ///     A TriggerAction may need to get back to the Trigger that
        /// holds it, this is the back-link to allow that.  Also, this allows 
        /// us to verify that each TriggerAction is associated with one and
        /// only one Trigger.
        /// 
        internal TriggerBase ContainingTrigger 
        {
            get 
            { 
                return _containingTrigger;
            } 
        }

        /// 
        ///     Seal this TriggerAction to prevent further updates 
        /// 
        ///  
        ///     TriggerActionCollection will call this method to seal individual 
        /// TriggerAction objects.  We do some check here then call the
        /// parameter-less Seal() so subclasses can also do what they need to do. 
        /// 
        internal void Seal( TriggerBase containingTrigger )
        {
            if( IsSealed && containingTrigger != _containingTrigger ) 
            {
                throw new InvalidOperationException(SR.Get(SRID.TriggerActionMustBelongToASingleTrigger)); 
            } 
            _containingTrigger = containingTrigger;
            Seal(); 
        }

        /// 
        ///     A derived class overrideing Seal() should set object state such 
        /// that further changes are not allowed.  This is also a time to make
        /// validation checks to see if all parameters make sense. 
        ///  
        internal override void Seal()
        { 
            if( IsSealed )
            {
                throw new InvalidOperationException(SR.Get(SRID.TriggerActionAlreadySealed));
            } 
            base.Seal();
        } 
 
        /// 
        ///     Checks sealed status and throws exception if object is sealed 
        /// 
        internal void CheckSealed()
        {
            if( IsSealed ) 
            {
                throw new InvalidOperationException(SR.Get(SRID.CannotChangeAfterSealed, "TriggerAction")); 
            } 
        }
 
        // Define the DO's inheritance context

        internal override DependencyObject InheritanceContext
        { 
            get { return _inheritanceContext; }
        } 
 
        // Receive a new inheritance context (this will be a FE/FCE)
        internal override void AddInheritanceContext(DependencyObject context, DependencyProperty property) 
        {
            InheritanceContextHelper.AddInheritanceContext(context,
                                                              this,
                                                              ref _hasMultipleInheritanceContexts, 
                                                              ref _inheritanceContext);
        } 
 
        // Remove an inheritance context (this will be a FE/FCE)
        internal override void RemoveInheritanceContext(DependencyObject context, DependencyProperty property) 
        {
            InheritanceContextHelper.RemoveInheritanceContext(context,
                                                                  this,
                                                                  ref _hasMultipleInheritanceContexts, 
                                                                  ref _inheritanceContext);
        } 
 
        /// 
        ///     Says if the current instance has multiple InheritanceContexts 
        /// 
        internal override bool HasMultipleInheritanceContexts
        {
            get { return _hasMultipleInheritanceContexts; } 
        }
 
 
        private TriggerBase _containingTrigger = null;
 
        // Fields to implement DO's inheritance context
        private DependencyObject _inheritanceContext = null;
        private bool _hasMultipleInheritanceContexts = false;
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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TriggerAction.cs source code in C# .NET

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