DataTrigger.cs source code in C# .NET

                        Code:
                         / DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Framework / System / Windows / DataTrigger.cs / 1 / DataTrigger.cs
                        
                        
                            //---------------------------------------------------------------------------- 
//
// 
//    Copyright (C) Microsoft Corporation.  All rights reserved.
//  
//
// 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 
{
    /// 
    ///     A single Style data conditional dependency driver
    ///  
    [ContentProperty("Setters")]
    public class DataTrigger : TriggerBase, IAddChild 
    { 
        /// 
        ///     Binding declaration of the conditional 
        /// 
        [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; 
            }
        } 
 
        /// 
        ///     Value of the condition (equality check) 
        /// 
        [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; 
            }
        } 

        /// 
        ///     Collection of Setter objects, which describes what to apply
        /// when this trigger is active. 
        /// 
        [DesignerSerializationVisibility(DesignerSerializationVisibility.Content)] 
        public SetterBaseCollection Setters 
        {
            get 
            {
                // Verify Context Access
                VerifyAccess();
 
                if( _setters == null )
                { 
                    _setters = new SetterBaseCollection(); 
                }
                return _setters; 
            }
        }

        /// 
        /// This method is called to Add a Setter object as a child of the Style.
        /// 
        /// 
        /// The object to add as a child; it must be a Setter or subclass.
        /// 
        void IAddChild.AddChild (Object value)
        {
            // Verify Context Access
            VerifyAccess(); 

            Setters.Add(Trigger.CheckChildIsSetter(value)); 
        } 

        /// 
        /// 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.
        ///
        /// 
        /// Text to add as a child.
        /// 
        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 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;
    } 
}



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

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