ValuePattern.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / UIAutomation / UIAutomationClient / System / Windows / Automation / ValuePattern.cs / 1305600 / ValuePattern.cs
                        
                        
                            //---------------------------------------------------------------------------- 
//
// 
//    Copyright (C) Microsoft Corporation.  All rights reserved.
//  
//
// 
// Description: Client-side wrapper for Value Pattern 
//
// History: 
//  06/23/2003 : BrendanM Ported to WCP
//
//---------------------------------------------------------------------------
 
using System;
using System.Windows.Automation.Provider; 
using MS.Internal.Automation; 

namespace System.Windows.Automation 
{
    /// 
    /// Represents UI elements that are expressing a value
    ///  
#if (INTERNAL_COMPILE)
    internal class ValuePattern: BasePattern 
#else 
    public class ValuePattern: BasePattern
#endif 
    {
        //-----------------------------------------------------
        //
        //  Constructors 
        //
        //----------------------------------------------------- 
 
        #region Constructors
 
        // internal so that RangeValue can derive from this
        internal ValuePattern(AutomationElement el, SafePatternHandle hPattern, bool cached)
            : base(el, hPattern)
        { 
            _hPattern = hPattern;
            _cached = cached; 
        } 

        #endregion Constructors 


        //------------------------------------------------------
        // 
        //  Public Constants / Readonly Fields
        // 
        //----------------------------------------------------- 

        #region Public Constants and Readonly Fields 

        /// Value pattern
        public static readonly AutomationPattern Pattern = ValuePatternIdentifiers.Pattern;
 
        /// Property ID: Value - Value of a value control, as a human-readable string
        public static readonly AutomationProperty ValueProperty = ValuePatternIdentifiers.ValueProperty; 
 
        /// Property ID: IsReadOnly - Indicates that the value can only be read, not modified.
        public static readonly AutomationProperty IsReadOnlyProperty = ValuePatternIdentifiers.IsReadOnlyProperty; 

        #endregion Public Constants and Readonly Fields

 
        //------------------------------------------------------
        // 
        //  Public Methods 
        //
        //------------------------------------------------------ 

        #region Public Methods

        ///  
        /// Request to set the value that this UI element is representing
        ///  
        /// Value to set the UI to, the provider is responsible for converting from a string into the appropriate data type 
        ///
        ///  
        /// This API does not work inside the secure execution environment.
        /// 
        /// 
        public void SetValue( string value ) 
        {
            Misc.ValidateArgumentNonNull(value, "value"); 
 
            // Test the Enabled state prior to the more general Read-Only state.
            object enabled = _el.GetCurrentPropertyValue(AutomationElementIdentifiers.IsEnabledProperty); 
            if (enabled is bool && !(bool)enabled)
            {
                throw new ElementNotEnabledException();
            } 

            // Test the Read-Only state after the more specific Enabled state. 
            object readOnly = _el.GetCurrentPropertyValue(IsReadOnlyProperty); 
            if (readOnly is bool && (bool)readOnly)
            { 
                throw new InvalidOperationException(SR.Get(SRID.ValueReadonly));
            }

            UiaCoreApi.ValuePattern_SetValue(_hPattern,  value); 
        }
 
        #endregion Public Methods 

 
        //-----------------------------------------------------
        //
        //  Public Properties
        // 
        //------------------------------------------------------
 
        #region Public Properties 

        ///  
        /// This member allows access to previously requested
        /// cached properties for this element. The returned object
        /// has accessors for each property defined for this pattern.
        ///  
        /// 
        /// Cached property values must have been previously requested 
        /// using a CacheRequest. If you try to access a cached 
        /// property that was not previously requested, an InvalidOperation
        /// Exception will be thrown. 
        ///
        /// To get the value of a property at the current point in time,
        /// access the property via the Current accessor instead of
        /// Cached. 
        /// 
        public ValuePatternInformation Cached 
        { 
            get
            { 
                Misc.ValidateCached(_cached);
                return new ValuePatternInformation(_el, true);
            }
        } 

        ///  
        /// This member allows access to current property values 
        /// for this element. The returned object has accessors for
        /// each property defined for this pattern. 
        /// 
        /// 
        /// This pattern must be from an AutomationElement with a
        /// Full reference in order to get current values. If the 
        /// AutomationElement was obtained using AutomationElementMode.None,
        /// then it contains only cached data, and attempting to get 
        /// the current value of any property will throw an InvalidOperationException. 
        ///
        /// To get the cached value of a property that was previously 
        /// specified using a CacheRequest, access the property via the
        /// Cached accessor instead of Current.
        /// 
        public ValuePatternInformation Current 
        {
            get 
            { 
                Misc.ValidateCurrent(_hPattern);
                return new ValuePatternInformation(_el, false); 
            }
        }

 
        #endregion Public Properties
 
 
        //-----------------------------------------------------
        // 
        //  Internal Methods
        //
        //-----------------------------------------------------
 
        #region Internal Methods
 
        static internal object Wrap(AutomationElement el, SafePatternHandle hPattern, bool cached) 
        {
            return new ValuePattern(el, hPattern, cached); 
        }

        #endregion Internal Methods
 

        //----------------------------------------------------- 
        // 
        //  Private Fields
        // 
        //------------------------------------------------------

        #region Private Fields
 
        private SafePatternHandle _hPattern;
        private bool _cached; 
 
        #endregion Private Fields
 

        //-----------------------------------------------------
        //
        //  Nested Classes 
        //
        //------------------------------------------------------ 
 
        #region Nested Classes
 
        /// 
        /// This class provides access to either Cached or Current
        /// properties on a pattern via the pattern's .Cached or
        /// .Current accessors. 
        /// 
        public struct ValuePatternInformation 
        { 
            //------------------------------------------------------
            // 
            //  Constructors
            //
            //-----------------------------------------------------
 
            #region Constructors
 
            internal ValuePatternInformation(AutomationElement el, bool useCache) 
            {
                _el = el; 
                _useCache = useCache;
            }

            #endregion Constructors 

 
            //------------------------------------------------------ 
            //
            //  Public Properties 
            //
            //-----------------------------------------------------

            #region Public Properties 

            ///Value of a value control, as a a string. 
            /// 
            /// 
            /// This API does not work inside the secure execution environment. 
            /// 
            /// 
            public string Value
            { 
                get
                { 
                    // 

 

                    object temp = _el.GetPatternPropertyValue(ValueProperty, _useCache);
                    return temp.ToString();
                } 
            }
 
            ///Indicates that the value can only be read, not modified. 
            ///returns True if the control is read-only
            /// 
            /// 
            /// This API does not work inside the secure execution environment.
            /// 
            ///  
            public bool IsReadOnly
            { 
                get 
                {
                    return (bool)_el.GetPatternPropertyValue(IsReadOnlyProperty, _useCache); 
                }
            }

            #endregion Public Properties 

            //----------------------------------------------------- 
            // 
            //  Private Fields
            // 
            //-----------------------------------------------------

            #region Private Fields
 
            private AutomationElement _el; // AutomationElement that contains the cache or live reference
            private bool _useCache; // true to use cache, false to use live reference to get current values 
 
            #endregion Private Fields
        } 
        #endregion Nested Classes
    }
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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