Button.cs source code in C# .NET

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Code:

/ 4.0 / 4.0 / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Framework / System / Windows / Controls / Button.cs / 1458001 / Button.cs

                            using System; 
using System.ComponentModel;
using System.Windows.Threading;

using System.Windows; 
using System.Windows.Automation.Peers;
using System.Windows.Controls.Primitives; 
 
using System.Windows.Input;
using System.Windows.Media; 
using System.Windows.Shapes;

using MS.Utility;
using MS.Internal.KnownBoxes; 

namespace System.Windows.Controls 
{ 
    /// 
    ///     Represents the standard button component that inherently reacts to the Click event. 
    /// The Button control is one of the most basic forms of user interface (UI).
    /// 
    public class Button: ButtonBase
    { 
        #region Constructors
 
        static Button() 
        {
            DefaultStyleKeyProperty.OverrideMetadata(typeof(Button), new FrameworkPropertyMetadata(typeof(Button))); 
            _dType = DependencyObjectType.FromSystemTypeInternal(typeof(Button));

            // WORKAROUND: the following if statement is a workaround to get the ButtonBase cctor to run before we
            // override metadata. 
            if (ButtonBase.CommandProperty != null)
            { 
                IsEnabledProperty.OverrideMetadata(typeof(Button), new FrameworkPropertyMetadata(new PropertyChangedCallback(OnIsEnabledChanged))); 
            }
        } 

        /// 
        ///     Default Button constructor
        ///  
        /// 
        ///     Automatic determination of current Dispatcher. Use alternative constructor 
        ///     that accepts a Dispatcher for best performance. 
        /// 
        public Button() : base() 
        {
        }

        #endregion 

        #region Properties 
 
        #region IsDefault
 
        /// 
        ///     The DependencyProperty for the IsDefault property.
        ///     Flags:              None
        ///     Default Value:      false 
        /// 
        public static readonly DependencyProperty IsDefaultProperty 
            = DependencyProperty.Register("IsDefault", typeof(bool), typeof(Button), 
                                          new FrameworkPropertyMetadata(BooleanBoxes.FalseBox,
                                                                        new PropertyChangedCallback(OnIsDefaultChanged))); 

        /// 
        /// Specifies whether or not this button is the default button.
        ///  
        /// 
        public bool IsDefault 
        { 
            get { return (bool) GetValue(IsDefaultProperty); }
            set { SetValue(IsDefaultProperty, BooleanBoxes.Box(value)); } 
        }

        private static void OnIsDefaultChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        { 
            Button b = d as Button;
            KeyboardFocusChangedEventHandler focusChangedEventHandler = FocusChangedEventHandlerField.GetValue(b); 
            if (focusChangedEventHandler == null) 
            {
                focusChangedEventHandler = new KeyboardFocusChangedEventHandler(b.OnFocusChanged); 
                FocusChangedEventHandlerField.SetValue(b, focusChangedEventHandler);
            }

            if ((bool) e.NewValue) 
            {
                AccessKeyManager.Register("\x000D", b); 
                KeyboardNavigation.Current.FocusChanged += focusChangedEventHandler; 
                b.UpdateIsDefaulted(Keyboard.FocusedElement);
            } 
            else
            {
                AccessKeyManager.Unregister("\x000D", b);
                KeyboardNavigation.Current.FocusChanged -= focusChangedEventHandler; 
                b.UpdateIsDefaulted(null);
            } 
        } 

        private static void OnIsEnabledChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
        {
            // This value is cached in FE, so all we have to do here is look at the new value
            Button b = ((Button)d);
 
            // If it's not a default button we don't need to update the IsDefaulted property
            if (b.IsDefault) 
            { 
                b.UpdateIsDefaulted(Keyboard.FocusedElement);
            } 
        }

        #endregion
 
        #region IsCancel
 
        ///  
        ///     The DependencyProperty for the IsCancel property.
        ///     Flags:              None 
        ///     Default Value:      false
        /// 
        public static readonly DependencyProperty IsCancelProperty =
                DependencyProperty.Register( 
                        "IsCancel",
                        typeof(bool), 
                        typeof(Button), 
                        new FrameworkPropertyMetadata(
                                BooleanBoxes.FalseBox, 
                                new PropertyChangedCallback(OnIsCancelChanged)));

        /// 
        /// Specifies whether or not this button is the cancel button. 
        /// 
        ///  
        public bool IsCancel 
        {
            get { return (bool) GetValue(IsCancelProperty); } 
            set { SetValue(IsCancelProperty, BooleanBoxes.Box(value)); }
        }

        private static void OnIsCancelChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
        {
            Button b = d as Button; 
            if ((bool) e.NewValue) 
            {
                AccessKeyManager.Register("\x001B", b); 
            }
            else
            {
                AccessKeyManager.Unregister("\x001B", b); 
            }
        } 
 
        #endregion
 
        #region IsDefaulted

        /// 
        ///     The key needed set a read-only property. 
        /// 
        private static readonly DependencyPropertyKey IsDefaultedPropertyKey 
            = DependencyProperty.RegisterReadOnly("IsDefaulted", typeof(bool), typeof(Button), 
                                          new FrameworkPropertyMetadata(BooleanBoxes.FalseBox));
 
        /// 
        ///     The DependencyProperty for the IsDefaulted property.
        ///     Flags:              None
        ///     Default Value:      false 
        /// 
        public static readonly DependencyProperty IsDefaultedProperty 
            = IsDefaultedPropertyKey.DependencyProperty; 

        ///  
        /// Specifies whether or not this button is the button that would be invoked when Enter is pressed.
        /// 
        /// 
        public bool IsDefaulted 
        {
            get 
            { 
                return (bool)GetValue(IsDefaultedProperty);
            } 
        }

        #endregion
 
        #endregion
 
        #region Private helpers 

        private void OnFocusChanged(object sender, KeyboardFocusChangedEventArgs e) 
        {
            UpdateIsDefaulted(Keyboard.FocusedElement);
        }
 
        private void UpdateIsDefaulted(IInputElement focus)
        { 
            // If it's not a default button, or nothing is focused, or it's disabled then it's not defaulted. 
            if (!IsDefault || focus == null || !IsEnabled)
            { 
                SetValue(IsDefaultedPropertyKey, BooleanBoxes.FalseBox);
                return;
            }
 
            DependencyObject focusDO = focus as DependencyObject;
            object thisScope, focusScope; 
 
            // If the focused thing is not in this scope then IsDefaulted = false
            AccessKeyPressedEventArgs e; 

            object isDefaulted = BooleanBoxes.FalseBox;
            try
            { 
                // Step 1: Determine the AccessKey scope from currently focused element
                e = new AccessKeyPressedEventArgs(); 
                focus.RaiseEvent(e); 
                focusScope = e.Scope;
 
                // Step 2: Determine the AccessKey scope from this button
                e = new AccessKeyPressedEventArgs();
                this.RaiseEvent(e);
                thisScope = e.Scope; 

                // Step 3: Compare scopes 
                if (thisScope == focusScope && (focusDO == null || (bool)focusDO.GetValue(KeyboardNavigation.AcceptsReturnProperty) == false)) 
                {
                    isDefaulted = BooleanBoxes.TrueBox; 
                }
            }
            finally
            { 
                SetValue(IsDefaultedPropertyKey, isDefaulted);
            } 
 
        }
 
        #endregion Private helpers

        #region Override methods
 
        /// 
        /// Creates AutomationPeer () 
        ///  
        protected override System.Windows.Automation.Peers.AutomationPeer OnCreateAutomationPeer()
        { 
            return new System.Windows.Automation.Peers.ButtonAutomationPeer(this);
        }

        ///  
        /// This method is called when button is clicked.
        ///  
        protected override void OnClick() 
        {
            if (AutomationPeer.ListenerExists(AutomationEvents.InvokePatternOnInvoked)) 
            {
                AutomationPeer peer = UIElementAutomationPeer.CreatePeerForElement(this);
                if (peer != null)
                    peer.RaiseAutomationEvent(AutomationEvents.InvokePatternOnInvoked); 
            }
 
            // base.OnClick should be called first. 
            // Our default command for Cancel Button to close dialog should happen
            // after Button's click event handler has been called. 
            // If there is excption and it's a Cancel button and RoutedCommand is null,
            // We will raise Window.DialogCancelCommand.
            try
            { 
                base.OnClick();
            } 
            finally 
            {
                // When the Button RoutedCommand is null, if it's a Cancel Button, Window.DialogCancelCommand will 
                // be the default command. Do not assign Window.DialogCancelCommand to Button.Command.
                // If in Button click handler user nulls the Command, we still want to provide the default behavior.
                if ((Command == null) && IsCancel)
                { 
                    // Can't invoke Window.DialogCancelCommand directly. Have to raise event.
                    // Filed bug 936090: Commanding perf issue: can't directly invoke a command. 
                    MS.Internal.Commands.CommandHelpers.ExecuteCommand(Window.DialogCancelCommand, null, this); 
                }
            } 
        }

        //
        //  This property 
        //  1. Finds the correct initial size for the _effectiveValues store on the current DependencyObject
        //  2. This is a performance optimization 
        // 
        internal override int EffectiveValuesInitialSize
        { 
            get { return 42; }
        }

        #endregion 

        #region Data 
 
        // This field is used to hang on to the event handler that we
        // hand out to KeyboardNavigation.  On the KeyNav side it's tracked 
        // as a WeakReference so when we hand it out we need to make sure
        // that we hold a strong reference ourselves.  We only need this
        // handler when we are a Default button (very uncommon).
        private static readonly UncommonField FocusChangedEventHandlerField = new UncommonField(); 

        #endregion 
 
        #region DTypeThemeStyleKey
 
        // Returns the DependencyObjectType for the registered ThemeStyleKey's default
        // value. Controls will override this method to return approriate types.
        internal override DependencyObjectType DTypeThemeStyleKey
        { 
            get { return _dType; }
        } 
 
        private static DependencyObjectType _dType;
 
        #endregion DTypeThemeStyleKey

    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
using System; 
using System.ComponentModel;
using System.Windows.Threading;

using System.Windows; 
using System.Windows.Automation.Peers;
using System.Windows.Controls.Primitives; 
 
using System.Windows.Input;
using System.Windows.Media; 
using System.Windows.Shapes;

using MS.Utility;
using MS.Internal.KnownBoxes; 

namespace System.Windows.Controls 
{ 
    /// 
    ///     Represents the standard button component that inherently reacts to the Click event. 
    /// The Button control is one of the most basic forms of user interface (UI).
    /// 
    public class Button: ButtonBase
    { 
        #region Constructors
 
        static Button() 
        {
            DefaultStyleKeyProperty.OverrideMetadata(typeof(Button), new FrameworkPropertyMetadata(typeof(Button))); 
            _dType = DependencyObjectType.FromSystemTypeInternal(typeof(Button));

            // WORKAROUND: the following if statement is a workaround to get the ButtonBase cctor to run before we
            // override metadata. 
            if (ButtonBase.CommandProperty != null)
            { 
                IsEnabledProperty.OverrideMetadata(typeof(Button), new FrameworkPropertyMetadata(new PropertyChangedCallback(OnIsEnabledChanged))); 
            }
        } 

        /// 
        ///     Default Button constructor
        ///  
        /// 
        ///     Automatic determination of current Dispatcher. Use alternative constructor 
        ///     that accepts a Dispatcher for best performance. 
        /// 
        public Button() : base() 
        {
        }

        #endregion 

        #region Properties 
 
        #region IsDefault
 
        /// 
        ///     The DependencyProperty for the IsDefault property.
        ///     Flags:              None
        ///     Default Value:      false 
        /// 
        public static readonly DependencyProperty IsDefaultProperty 
            = DependencyProperty.Register("IsDefault", typeof(bool), typeof(Button), 
                                          new FrameworkPropertyMetadata(BooleanBoxes.FalseBox,
                                                                        new PropertyChangedCallback(OnIsDefaultChanged))); 

        /// 
        /// Specifies whether or not this button is the default button.
        ///  
        /// 
        public bool IsDefault 
        { 
            get { return (bool) GetValue(IsDefaultProperty); }
            set { SetValue(IsDefaultProperty, BooleanBoxes.Box(value)); } 
        }

        private static void OnIsDefaultChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        { 
            Button b = d as Button;
            KeyboardFocusChangedEventHandler focusChangedEventHandler = FocusChangedEventHandlerField.GetValue(b); 
            if (focusChangedEventHandler == null) 
            {
                focusChangedEventHandler = new KeyboardFocusChangedEventHandler(b.OnFocusChanged); 
                FocusChangedEventHandlerField.SetValue(b, focusChangedEventHandler);
            }

            if ((bool) e.NewValue) 
            {
                AccessKeyManager.Register("\x000D", b); 
                KeyboardNavigation.Current.FocusChanged += focusChangedEventHandler; 
                b.UpdateIsDefaulted(Keyboard.FocusedElement);
            } 
            else
            {
                AccessKeyManager.Unregister("\x000D", b);
                KeyboardNavigation.Current.FocusChanged -= focusChangedEventHandler; 
                b.UpdateIsDefaulted(null);
            } 
        } 

        private static void OnIsEnabledChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
        {
            // This value is cached in FE, so all we have to do here is look at the new value
            Button b = ((Button)d);
 
            // If it's not a default button we don't need to update the IsDefaulted property
            if (b.IsDefault) 
            { 
                b.UpdateIsDefaulted(Keyboard.FocusedElement);
            } 
        }

        #endregion
 
        #region IsCancel
 
        ///  
        ///     The DependencyProperty for the IsCancel property.
        ///     Flags:              None 
        ///     Default Value:      false
        /// 
        public static readonly DependencyProperty IsCancelProperty =
                DependencyProperty.Register( 
                        "IsCancel",
                        typeof(bool), 
                        typeof(Button), 
                        new FrameworkPropertyMetadata(
                                BooleanBoxes.FalseBox, 
                                new PropertyChangedCallback(OnIsCancelChanged)));

        /// 
        /// Specifies whether or not this button is the cancel button. 
        /// 
        ///  
        public bool IsCancel 
        {
            get { return (bool) GetValue(IsCancelProperty); } 
            set { SetValue(IsCancelProperty, BooleanBoxes.Box(value)); }
        }

        private static void OnIsCancelChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
        {
            Button b = d as Button; 
            if ((bool) e.NewValue) 
            {
                AccessKeyManager.Register("\x001B", b); 
            }
            else
            {
                AccessKeyManager.Unregister("\x001B", b); 
            }
        } 
 
        #endregion
 
        #region IsDefaulted

        /// 
        ///     The key needed set a read-only property. 
        /// 
        private static readonly DependencyPropertyKey IsDefaultedPropertyKey 
            = DependencyProperty.RegisterReadOnly("IsDefaulted", typeof(bool), typeof(Button), 
                                          new FrameworkPropertyMetadata(BooleanBoxes.FalseBox));
 
        /// 
        ///     The DependencyProperty for the IsDefaulted property.
        ///     Flags:              None
        ///     Default Value:      false 
        /// 
        public static readonly DependencyProperty IsDefaultedProperty 
            = IsDefaultedPropertyKey.DependencyProperty; 

        ///  
        /// Specifies whether or not this button is the button that would be invoked when Enter is pressed.
        /// 
        /// 
        public bool IsDefaulted 
        {
            get 
            { 
                return (bool)GetValue(IsDefaultedProperty);
            } 
        }

        #endregion
 
        #endregion
 
        #region Private helpers 

        private void OnFocusChanged(object sender, KeyboardFocusChangedEventArgs e) 
        {
            UpdateIsDefaulted(Keyboard.FocusedElement);
        }
 
        private void UpdateIsDefaulted(IInputElement focus)
        { 
            // If it's not a default button, or nothing is focused, or it's disabled then it's not defaulted. 
            if (!IsDefault || focus == null || !IsEnabled)
            { 
                SetValue(IsDefaultedPropertyKey, BooleanBoxes.FalseBox);
                return;
            }
 
            DependencyObject focusDO = focus as DependencyObject;
            object thisScope, focusScope; 
 
            // If the focused thing is not in this scope then IsDefaulted = false
            AccessKeyPressedEventArgs e; 

            object isDefaulted = BooleanBoxes.FalseBox;
            try
            { 
                // Step 1: Determine the AccessKey scope from currently focused element
                e = new AccessKeyPressedEventArgs(); 
                focus.RaiseEvent(e); 
                focusScope = e.Scope;
 
                // Step 2: Determine the AccessKey scope from this button
                e = new AccessKeyPressedEventArgs();
                this.RaiseEvent(e);
                thisScope = e.Scope; 

                // Step 3: Compare scopes 
                if (thisScope == focusScope && (focusDO == null || (bool)focusDO.GetValue(KeyboardNavigation.AcceptsReturnProperty) == false)) 
                {
                    isDefaulted = BooleanBoxes.TrueBox; 
                }
            }
            finally
            { 
                SetValue(IsDefaultedPropertyKey, isDefaulted);
            } 
 
        }
 
        #endregion Private helpers

        #region Override methods
 
        /// 
        /// Creates AutomationPeer () 
        ///  
        protected override System.Windows.Automation.Peers.AutomationPeer OnCreateAutomationPeer()
        { 
            return new System.Windows.Automation.Peers.ButtonAutomationPeer(this);
        }

        ///  
        /// This method is called when button is clicked.
        ///  
        protected override void OnClick() 
        {
            if (AutomationPeer.ListenerExists(AutomationEvents.InvokePatternOnInvoked)) 
            {
                AutomationPeer peer = UIElementAutomationPeer.CreatePeerForElement(this);
                if (peer != null)
                    peer.RaiseAutomationEvent(AutomationEvents.InvokePatternOnInvoked); 
            }
 
            // base.OnClick should be called first. 
            // Our default command for Cancel Button to close dialog should happen
            // after Button's click event handler has been called. 
            // If there is excption and it's a Cancel button and RoutedCommand is null,
            // We will raise Window.DialogCancelCommand.
            try
            { 
                base.OnClick();
            } 
            finally 
            {
                // When the Button RoutedCommand is null, if it's a Cancel Button, Window.DialogCancelCommand will 
                // be the default command. Do not assign Window.DialogCancelCommand to Button.Command.
                // If in Button click handler user nulls the Command, we still want to provide the default behavior.
                if ((Command == null) && IsCancel)
                { 
                    // Can't invoke Window.DialogCancelCommand directly. Have to raise event.
                    // Filed bug 936090: Commanding perf issue: can't directly invoke a command. 
                    MS.Internal.Commands.CommandHelpers.ExecuteCommand(Window.DialogCancelCommand, null, this); 
                }
            } 
        }

        //
        //  This property 
        //  1. Finds the correct initial size for the _effectiveValues store on the current DependencyObject
        //  2. This is a performance optimization 
        // 
        internal override int EffectiveValuesInitialSize
        { 
            get { return 42; }
        }

        #endregion 

        #region Data 
 
        // This field is used to hang on to the event handler that we
        // hand out to KeyboardNavigation.  On the KeyNav side it's tracked 
        // as a WeakReference so when we hand it out we need to make sure
        // that we hold a strong reference ourselves.  We only need this
        // handler when we are a Default button (very uncommon).
        private static readonly UncommonField FocusChangedEventHandlerField = new UncommonField(); 

        #endregion 
 
        #region DTypeThemeStyleKey
 
        // Returns the DependencyObjectType for the registered ThemeStyleKey's default
        // value. Controls will override this method to return approriate types.
        internal override DependencyObjectType DTypeThemeStyleKey
        { 
            get { return _dType; }
        } 
 
        private static DependencyObjectType _dType;
 
        #endregion DTypeThemeStyleKey

    }
} 

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

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