ContentElement.cs source code in C# .NET

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/ DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Core / System / Windows / ContentElement.cs / 1 / ContentElement.cs

                            using MS.Utility;
using MS.Internal;
using MS.Internal.KnownBoxes;
using MS.Internal.PresentationCore; 
using System;
using System.Collections; 
using System.Collections.Generic; 
using System.ComponentModel;
using System.Diagnostics; 
using System.Security;
using System.Security.Permissions;
using System.Windows.Automation.Peers;
using System.Windows.Input; 
using System.Windows.Media.Animation;
using System.Windows.Threading; 
using System.Windows.Markup; 

using SR=MS.Internal.PresentationCore.SR; 
using SRID=MS.Internal.PresentationCore.SRID;

namespace System.Windows
{ 
    /// 
    ///     ContentElement Class is a DependencyObject with IFE - input, focus, and events 
    ///  
    /// 
    public partial class ContentElement : DependencyObject, IInputElement, IAnimatable 
    {
        #region Construction

        ///  
        ///     Static Constructor for ContentElement
        ///  
        ///  
        ///     Critical: This hooks up a bunch of thunks which are all critical since they
        ///     can be used to spoof input 
        ///     TreatAsSafe: Since it does not expose the thunks
        /// 
        [SecurityCritical,SecurityTreatAsSafe]
        static ContentElement() 
        {
            RegisterEvents(); 
            RegisterProperties(); 

            UIElement.IsFocusedPropertyKey.OverrideMetadata( 
                typeof(ContentElement),
                new PropertyMetadata(
                    BooleanBoxes.FalseBox, // default value
                    new PropertyChangedCallback(IsFocused_Changed))); 
        }
 
        #endregion Construction 

        #region DependencyObject 

        #endregion

        ///  
        /// Helper, gives the UIParent under control of which
        /// the OnMeasure or OnArrange are currently called. 
        /// This may be implemented as a tree walk up until 
        /// LayoutElement is found.
        ///  
        internal DependencyObject GetUIParent()
        {
            return GetUIParent(false);
        } 

        internal DependencyObject GetUIParent(bool continuePastVisualTree) 
        { 
            DependencyObject e = null;
 
            // Try to find a UIElement parent in the visual ancestry.
            e = InputElement.GetContainingInputElement(_parent) as DependencyObject;

            // If there was no InputElement parent in the visual ancestry, 
            // check along the logical branch.
            if(e == null && continuePastVisualTree) 
            { 
                DependencyObject doParent = GetUIParentCore();
                e = InputElement.GetContainingInputElement(doParent) as DependencyObject; 
            }

            return e;
        } 

        ///  
        ///     Called to get the UI parent of this element when there is 
        ///     no visual parent.
        ///  
        /// 
        ///     Returns a non-null value when some framework implementation
        ///     of this method has a non-visual parent connection,
        ///  
        protected virtual internal DependencyObject GetUIParentCore()
        { 
            return null; 
        }
 
        internal DependencyObject Parent
        {
            get
            { 
                return _parent;
            } 
        } 

        ///  
        /// OnContentParentChanged is called when the parent of the content element is changed.
        /// 
        /// Old parent or null if the content element did not have a parent before.
        [FriendAccessAllowed] // Built into Core, also used by Framework. 
        internal virtual void OnContentParentChanged(DependencyObject oldParent)
        { 
            SynchronizeReverseInheritPropertyFlags(oldParent, true); 
        }
 
        #region Automation

        /// 
        /// Called by the Automation infrastructure when AutomationPeer 
        /// is requested for this element. The element can return null or
        /// the instance of AutomationPeer-derived clas, if it supports UI Automation 
        ///  
        protected virtual AutomationPeer OnCreateAutomationPeer() { return null; }
 
        /// 
        /// Called by the Automation infrastructure or Control author
        /// to make sure the AutomationPeer is created. The element may
        /// create AP or return null, depending on OnCreateAutomationPeer override. 
        /// 
        internal AutomationPeer CreateAutomationPeer() 
        { 
            VerifyAccess(); //this will ensure the AP is created in the right context
 
            AutomationPeer ap = null;

            if (HasAutomationPeer)
            { 
                ap = AutomationPeerField.GetValue(this);
            } 
            else 
            {
                ap = OnCreateAutomationPeer(); 

                if (ap != null)
                {
                    AutomationPeerField.SetValue(this, ap); 
                    HasAutomationPeer = true;
                } 
            } 
            return ap;
        } 

        /// 
        /// Returns AutomationPeer if one exists.
        /// The AutomationPeer may not exist if not yet created by Automation infrastructure 
        /// or if this element is not supposed to have one.
        ///  
        internal AutomationPeer GetAutomationPeer() 
        {
            VerifyAccess(); 

            if (HasAutomationPeer)
                return AutomationPeerField.GetValue(this);
 
            return null;
        } 
 
        #endregion Automation
 
        #region Input

        //
        // Left/Right Mouse Button Cracking Routine: 
        //
 
        private void CrackMouseButtonEventAndReRaiseEvent(MouseButtonEventArgs e) 
        {
            RoutedEvent newEvent = UIElement.CrackMouseButtonEvent(e); 

            if(newEvent != null)
            {
                ReRaiseEventAs(e, newEvent); 
            }
        } 
 
        /// 
        ///     A property indicating if the mouse is over this element or not. 
        /// 
        public bool IsMouseDirectlyOver
        {
            get 
            {
                // We do not return the cached value of reverse-inherited seed properties. 
                // 
                // The cached value is only used internally to detect a "change".
                // 
                // More Info:
                // The act of invalidating the seed property of a reverse-inherited property
                // on the first side of the path causes the invalidation of the
                // reverse-inherited properties on both sides.  The input system has not yet 
                // invalidated the seed property on the second side, so its cached value can
                // be incorrect. 
                // 
                return IsMouseDirectlyOver_ComputeValue();
            } 
        }

        private bool IsMouseDirectlyOver_ComputeValue()
        { 
            return (Mouse.DirectlyOver == this);
        } 
 
        /// 
        ///     Asynchronously re-evaluate the reverse-inherited properties. 
        /// 
        [FriendAccessAllowed]
        internal void SynchronizeReverseInheritPropertyFlags(DependencyObject oldParent, bool isCoreParent)
        { 
            if(IsKeyboardFocusWithin)
            { 
                Keyboard.PrimaryDevice.ReevaluateFocusAsync(this, oldParent, isCoreParent); 
            }
 
            // Reevelauate the stylus properties first to guarentee that our property change
            // notifications fire before mouse properties.
            if(IsStylusOver)
            { 
                StylusLogic.CurrentStylusLogicReevaluateStylusOver(this, oldParent, isCoreParent);
            } 
 
            if(IsStylusCaptureWithin)
            { 
                StylusLogic.CurrentStylusLogicReevaluateCapture(this, oldParent, isCoreParent);
            }

            if(IsMouseOver) 
            {
                Mouse.PrimaryDevice.ReevaluateMouseOver(this, oldParent, isCoreParent); 
            } 

            if(IsMouseCaptureWithin) 
            {
                Mouse.PrimaryDevice.ReevaluateCapture(this, oldParent, isCoreParent);
            }
        } 

        ///  
            /// BlockReverseInheritance method when overriden stops reverseInheritProperties from updating their parent level properties. 
        /// 
        internal virtual bool BlockReverseInheritance() 
        {
            return false;
        }
 
        /// 
        ///     A property indicating if the mouse is over this element or not. 
        ///  
        public bool IsMouseOver
        { 
            get
            {
                return ReadFlag(CoreFlags.IsMouseOverCache);
            } 
        }
 
        ///  
        ///     A property indicating if the stylus is over this element or not.
        ///  
        public bool IsStylusOver
        {
            get
            { 
                return ReadFlag(CoreFlags.IsStylusOverCache);
            } 
        } 

        ///  
        ///     Indicates if Keyboard Focus is anywhere
        ///     within in the subtree starting at the
        ///     current instance
        ///  
        public bool IsKeyboardFocusWithin
        { 
            get 
            {
                return ReadFlag(CoreFlags.IsKeyboardFocusWithinCache); 
            }
        }

        ///  
        ///     A property indicating if the mouse is captured to this element or not.
        ///  
        public bool IsMouseCaptured 
        {
            get { return (bool) GetValue(IsMouseCapturedProperty); } 
        }

        /// 
        ///     Captures the mouse to this element. 
        /// 
        public bool CaptureMouse() 
        { 
            return Mouse.Capture(this);
        } 

        /// 
        ///     Releases the mouse capture.
        ///  
        public void ReleaseMouseCapture()
        { 
            Mouse.Capture(null); 
        }
 
        /// 
        ///     Indicates if mouse capture is anywhere within in the subtree
        ///     starting at the current instance
        ///  
        public bool IsMouseCaptureWithin
        { 
            get 
            {
                return ReadFlag(CoreFlags.IsMouseCaptureWithinCache); 
            }
        }

        ///  
        ///     A property indicating if the stylus is over this element or not.
        ///  
        public bool IsStylusDirectlyOver 
        {
            get 
            {
                // We do not return the cached value of reverse-inherited seed properties.
                //
                // The cached value is only used internally to detect a "change". 
                //
                // More Info: 
                // The act of invalidating the seed property of a reverse-inherited property 
                // on the first side of the path causes the invalidation of the
                // reverse-inherited properties on both sides.  The input system has not yet 
                // invalidated the seed property on the second side, so its cached value can
                // be incorrect.
                //
                return IsStylusDirectlyOver_ComputeValue(); 
            }
        } 
 
        private bool IsStylusDirectlyOver_ComputeValue()
        { 
            return (Stylus.DirectlyOver == this);
        }

        ///  
        ///     A property indicating if the stylus is captured to this element or not.
        ///  
        public bool IsStylusCaptured 
        {
            get { return (bool) GetValue(IsStylusCapturedProperty); } 
        }

        /// 
        ///     Captures the stylus to this element. 
        /// 
        public bool CaptureStylus() 
        { 
            return Stylus.Capture(this);
        } 

        /// 
        ///     Releases the stylus capture.
        ///  
        public void ReleaseStylusCapture()
        { 
            Stylus.Capture(null); 
        }
 
        /// 
        ///     Indicates if stylus capture is anywhere within in the subtree
        ///     starting at the current instance
        ///  
        public bool IsStylusCaptureWithin
        { 
            get 
            {
                return ReadFlag(CoreFlags.IsStylusCaptureWithinCache); 
            }
        }

        ///  
        ///     A property indicating if the keyboard is focused on this
        ///     element or not. 
        ///  
        public bool IsKeyboardFocused
        { 
            get
            {
                // We do not return the cached value of reverse-inherited seed properties.
                // 
                // The cached value is only used internally to detect a "change".
                // 
                // More Info: 
                // The act of invalidating the seed property of a reverse-inherited property
                // on the first side of the path causes the invalidation of the 
                // reverse-inherited properties on both sides.  The input system has not yet
                // invalidated the seed property on the second side, so its cached value can
                // be incorrect.
                // 
                return IsKeyboardFocused_ComputeValue();
            } 
        } 

        private bool IsKeyboardFocused_ComputeValue() 
        {
            return (Keyboard.FocusedElement == this);
        }
 
        /// 
        ///     Focuses the keyboard on this element. 
        ///  
        public bool Focus()
        { 
            return Keyboard.Focus(this) == this;
        }

        ///  
        ///     Request to move the focus from this element to another element
        ///  
        /// Determine how to move the focus 
        ///  Returns true if focus is moved successfully. Returns false if there is no next element
        public virtual bool MoveFocus(TraversalRequest request) 
        {
            return false;
        }
 
        /// 
        ///     Request to predict the element that should receive focus relative to this element for a 
        /// given direction, without actually moving focus to it. 
        /// 
        /// The direction for which focus should be predicted 
        /// 
        ///     Returns the next element that focus should move to for a given FocusNavigationDirection.
        /// Returns null if focus cannot be moved relative to this element.
        ///  
        public virtual DependencyObject PredictFocus(FocusNavigationDirection direction)
        { 
            return null; 
        }
 
        /// 
        ///     GotFocus event
        /// 
        public static readonly RoutedEvent GotFocusEvent = FocusManager.GotFocusEvent.AddOwner(typeof(ContentElement)); 

        ///  
        ///     An event announcing that IsFocused changed to true. 
        /// 
        public event RoutedEventHandler GotFocus 
        {
            add { AddHandler(GotFocusEvent, value); }
            remove { RemoveHandler(GotFocusEvent, value); }
        } 

        ///  
        ///     LostFocus event 
        /// 
        public static readonly RoutedEvent LostFocusEvent = FocusManager.LostFocusEvent.AddOwner(typeof(ContentElement)); 

        /// 
        ///     An event announcing that IsFocused changed to false.
        ///  
        public event RoutedEventHandler LostFocus
        { 
            add { AddHandler(LostFocusEvent, value); } 
            remove { RemoveHandler(LostFocusEvent, value); }
        } 

        /// 
        ///     The DependencyProperty for IsFocused.
        ///     Flags:              None 
        ///     Read-Only:          true
        ///  
        public static readonly DependencyProperty IsFocusedProperty = 
                    UIElement.IsFocusedProperty.AddOwner(
                                typeof(ContentElement)); 

        private static void IsFocused_Changed(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            ContentElement ce = ((ContentElement) d); 

            if ((bool) e.NewValue) 
            { 
                ce.OnGotFocus(new RoutedEventArgs(GotFocusEvent, ce));
            } 
            else
            {
                ce.OnLostFocus(new RoutedEventArgs(LostFocusEvent, ce));
            } 
        }
 
        ///  
        ///     This method is invoked when the IsFocused property changes to true
        ///  
        /// RoutedEventArgs
        protected virtual void OnGotFocus(RoutedEventArgs e)
        {
            RaiseEvent(e); 
        }
 
        ///  
        ///     This method is invoked when the IsFocused property changes to false
        ///  
        /// RoutedEventArgs
        protected virtual void OnLostFocus(RoutedEventArgs e)
        {
            RaiseEvent(e); 
        }
 
        ///  
        ///     Gettor for IsFocused Property
        ///  
        public bool IsFocused
        {
            get { return (bool) GetValue(IsFocusedProperty); }
        } 

        ///  
        ///     The DependencyProperty for the IsEnabled property. 
        /// 
        public static readonly DependencyProperty IsEnabledProperty = 
                    UIElement.IsEnabledProperty.AddOwner(
                                typeof(ContentElement),
                                new UIPropertyMetadata(
                                            BooleanBoxes.TrueBox, // default value 
                                            new PropertyChangedCallback(OnIsEnabledChanged),
                                            new CoerceValueCallback(CoerceIsEnabled))); 
 

        ///  
        ///     A property indicating if this element is enabled or not.
        /// 
        public bool IsEnabled
        { 
            get { return (bool) GetValue(IsEnabledProperty); }
            set { SetValue(IsEnabledProperty, BooleanBoxes.Box(value)); } 
        } 

        ///  
        ///     IsEnabledChanged event
        /// 
        public event DependencyPropertyChangedEventHandler IsEnabledChanged
        { 
            add { EventHandlersStoreAdd(UIElement.IsEnabledChangedKey, value); }
            remove { EventHandlersStoreRemove(UIElement.IsEnabledChangedKey, value); } 
        } 

        ///  
        ///     Fetches the value that IsEnabled should be coerced to.
        /// 
        /// 
        ///     This method is virtual is so that controls derived from UIElement 
        ///     can combine additional requirements into the coersion logic.
        ///     

/// It is important for anyone overriding this property to also /// call CoerceValue when any of their dependencies change. /// protected virtual bool IsEnabledCore { get { // As of 1/25/2006, the following controls override this method: // Hyperlink.IsEnabledCore: CanExecute return true; } } private static object CoerceIsEnabled(DependencyObject d, object value) { ContentElement ce = (ContentElement) d; // We must be false if our parent is false, but we can be // either true or false if our parent is true. // // Another way of saying this is that we can only be true // if our parent is true, but we can always be false. if((bool) value) { // Use the "logical" parent. This is different that UIElement, which // uses the visual parent. But the "content parent" is not a complete // tree description (for instance, we don't track "content children"), // so the best we can do is use the logical tree for ContentElements. // // Note: we assume the "logical" parent of a ContentElement is either // a UIElement or ContentElement. We explicitly assume that there // is never a raw Visual as the parent. DependencyObject parent = ce.GetUIParentCore(); if(parent == null || (bool)parent.GetValue(IsEnabledProperty)) { return BooleanBoxes.Box(ce.IsEnabledCore); } else { return BooleanBoxes.FalseBox; } } else { return BooleanBoxes.FalseBox; } } private static void OnIsEnabledChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { ContentElement ce = (ContentElement)d; // Raise the public changed event. ce.RaiseDependencyPropertyChanged(UIElement.IsEnabledChangedKey, e); // Invalidate the children so that they will inherit the new value. ce.InvalidateForceInheritPropertyOnChildren(e.Property); // The input manager needs to re-hittest because something changed // that is involved in the hit-testing we do, so a different result // could be returned. InputManager.SafeCurrentNotifyHitTestInvalidated(); } //********************************************************************** #region Focusable Property //********************************************************************* ///

/// The DependencyProperty for the Focusable property. /// [CommonDependencyProperty] public static readonly DependencyProperty FocusableProperty = UIElement.FocusableProperty.AddOwner( typeof(ContentElement), new UIPropertyMetadata( BooleanBoxes.FalseBox, // default value new PropertyChangedCallback(OnFocusableChanged))); /// /// Gettor and Settor for Focusable Property /// public bool Focusable { get { return (bool) GetValue(FocusableProperty); } set { SetValue(FocusableProperty, BooleanBoxes.Box(value)); } } /// /// FocusableChanged event /// public event DependencyPropertyChangedEventHandler FocusableChanged { add {EventHandlersStoreAdd(UIElement.FocusableChangedKey, value);} remove {EventHandlersStoreRemove(UIElement.FocusableChangedKey, value);} } private static void OnFocusableChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { ContentElement ce = (ContentElement) d; // Raise the public changed event. ce.RaiseDependencyPropertyChanged(UIElement.FocusableChangedKey, e); } //********************************************************************* #endregion Focusable Property //********************************************************************* /// /// A property indicating if the inptu method is enabled. /// public bool IsInputMethodEnabled { get { return (bool) GetValue(InputMethod.IsInputMethodEnabledProperty); } } #endregion Input #region Operations private void RaiseMouseButtonEvent(EventPrivateKey key, MouseButtonEventArgs e) { EventHandlersStore store = EventHandlersStore; if (store != null) { Delegate handler = store.Get(key); if (handler != null) { ((MouseButtonEventHandler)handler)(this, e); } } } // Helper method to retrieve and fire Clr Event handlers for DependencyPropertyChanged event private void RaiseDependencyPropertyChanged(EventPrivateKey key, DependencyPropertyChangedEventArgs args) { EventHandlersStore store = EventHandlersStore; if (store != null) { Delegate handler = store.Get(key); if (handler != null) { ((DependencyPropertyChangedEventHandler)handler)(this, args); } } } #endregion Operations #region AllowDrop /// /// The DependencyProperty for the AllowDrop property. /// public static readonly DependencyProperty AllowDropProperty = UIElement.AllowDropProperty.AddOwner( typeof(ContentElement), new PropertyMetadata(BooleanBoxes.FalseBox)); /// /// A dependency property that allows the drop object as DragDrop target. /// public bool AllowDrop { get { return (bool) GetValue(AllowDropProperty); } set { SetValue(AllowDropProperty, BooleanBoxes.Box(value)); } } #endregion AllowDrop #region ForceInherit property support // This has to be virtual, since there is no concept of "core" content children, // so we have no choice by to rely on FrameworkContentElement to use logical // children instead. internal virtual void InvalidateForceInheritPropertyOnChildren(DependencyProperty property) { } #endregion private bool HasAutomationPeer { get { return ReadFlag(CoreFlags.HasAutomationPeer); } set { WriteFlag(CoreFlags.HasAutomationPeer, value); } } #region Data internal DependencyObject _parent; ///// ATTACHED STORAGE ///// internal static readonly UncommonField EventHandlersStoreField = UIElement.EventHandlersStoreField; internal static readonly UncommonField InputBindingCollectionField = UIElement.InputBindingCollectionField; internal static readonly UncommonField CommandBindingCollectionField = UIElement.CommandBindingCollectionField; private static readonly UncommonField AutomationPeerField = new UncommonField(); // Caches the ContentElement's DependencyObjectType private static DependencyObjectType ContentElementType = DependencyObjectType.FromSystemTypeInternal(typeof(ContentElement)); #endregion Data } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. All rights reserved.

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