ComboBoxItem.cs source code in C# .NET

                        Code:
                         / DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Framework / System / Windows / Controls / ComboBoxItem.cs / 2 / ComboBoxItem.cs
                        
                        
                            //---------------------------------------------------------------------------- 
//
// Copyright (C) Microsoft Corporation.  All rights reserved.
//
// File: ComboBoxItem.cs 
//
//--------------------------------------------------------------------------- 
using MS.Internal; 
using MS.Internal.KnownBoxes;
using System; 
using System.ComponentModel;

using System.Diagnostics;
using System.Windows.Threading; 

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

namespace System.Windows.Controls 
{
    ///  
    ///     Control that implements a selectable item inside a ComboBox. 
    /// 
    [Localizability(LocalizationCategory.ComboBox)] 
#if OLD_AUTOMATION
    [Automation(AccessibilityControlType = "ListItem")]
#endif
    public class ComboBoxItem : ListBoxItem 
    {
        //------------------------------------------------------------------- 
        // 
        //  Constructors
        // 
        //-------------------------------------------------------------------

        #region Constructors
 
        /// 
        ///     Default DependencyObject constructor 
        ///  
        /// 
        ///     Automatic determination of current Dispatcher. Use alternative constructor 
        ///     that accepts a Dispatcher for best performance.
        /// 
        public ComboBoxItem() : base()
        { 
        }
 
        static ComboBoxItem() 
        {
            DefaultStyleKeyProperty.OverrideMetadata(typeof(ComboBoxItem), new FrameworkPropertyMetadata(typeof(ComboBoxItem))); 
            _dType = DependencyObjectType.FromSystemTypeInternal(typeof(ComboBoxItem));
        }

        #endregion 

        #region Public Properties 
 
        /// 
        ///     The key needed set a read-only property. 
        /// 
        private static readonly DependencyPropertyKey IsHighlightedPropertyKey =
            DependencyProperty.RegisterReadOnly("IsHighlighted", typeof(bool), typeof(ComboBoxItem),
                                        new FrameworkPropertyMetadata(BooleanBoxes.FalseBox)); 

        ///  
        /// DependencyProperty for the IsHighlighted property 
        /// 
        public static readonly DependencyProperty IsHighlightedProperty = 
            IsHighlightedPropertyKey.DependencyProperty;

        /// 
        /// Indicates if the item is highlighted or not.  Styles that want to 
        /// show a highlight for selection should trigger off of this value.
        ///  
        ///  
        public bool IsHighlighted
        { 
            get
            {
                return (bool)GetValue(IsHighlightedProperty);
            } 
            protected set
            { 
                SetValue(IsHighlightedPropertyKey, BooleanBoxes.Box(value)); 
            }
        } 

        #endregion

        //-------------------------------------------------------------------- 
        //
        //  Protected Methods 
        // 
        //-------------------------------------------------------------------
 
        #region Protected Methods

        /// 
        ///     This is the method that responds to the MouseButtonEvent event. 
        /// 
        /// Event arguments 
        protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e) 
        {
            e.Handled = true; 

            ComboBox parent = ParentComboBox;

            if (parent != null) 
            {
                parent.NotifyComboBoxItemMouseDown(this); 
            } 

            base.OnMouseLeftButtonDown(e); 
        }

        /// 
        /// 
        /// 
        ///  
        protected override void OnMouseLeftButtonUp(MouseButtonEventArgs e) 
        {
            e.Handled = true; 

            ComboBox parent = ParentComboBox;

            if (parent != null) 
            {
                parent.NotifyComboBoxItemMouseUp(this); 
            } 

            base.OnMouseLeftButtonUp(e); 
        }

        /// 
        /// 
        /// 
        ///  
        protected override void OnMouseEnter(MouseEventArgs e) 
        {
            e.Handled = true; 

            ComboBox parent = ParentComboBox;

            if (parent != null) 
            {
                parent.NotifyComboBoxItemEnter(this); 
            } 

            base.OnMouseEnter(e); 

        }

        ///  
        /// Called when Content property has been changed.
        ///  
        ///  
        /// 
        protected override void OnContentChanged(object oldContent, object newContent) 
        {
            base.OnContentChanged(oldContent, newContent);

            // If this is selected, we need to update ParentComboBox.Text 
            // Scenario:
            //       
            //          item1 
            //          Item2
            //          item3 
            //      
            // In this case ComboBox will try to update Text property as soon as it get
            // SelectionChanged event. However, at that time ComboBoxItem.Content is not
            // parse yet. So, Content is null. This causes ComboBox.Text to be "". 
            //
            ComboBox parent; 
            if (IsSelected && (null != (parent = ParentComboBox))) 
            {
                parent.SelectedItemUpdated(); 
            }

            // When the content of the combobox item is a UIElement,
            // combobox will create a visual clone of the item which needs 
            // to update even when the combobox is closed
            SetFlags(newContent is UIElement, VisualFlags.IsLayoutIslandRoot); 
        } 

        ///  
        ///     Called when this element gets focus.
        /// 
        /// 
        protected override void OnGotKeyboardFocus(KeyboardFocusChangedEventArgs e) 
        {
            e.Handled = true; 
 
            ComboBox parent = ParentComboBox;
 
            if (parent != null)
            {
                parent.NotifyComboBoxItemEnter(this);
            } 

            base.OnGotKeyboardFocus(e); 
        } 

        #endregion 

        //--------------------------------------------------------------------
        //
        //  Implementation 
        //
        //-------------------------------------------------------------------- 
 
        #region Implementation
 
        private ComboBox ParentComboBox
        {
            get
            { 
                return ParentSelector as ComboBox;
            } 
        } 

        internal void SetIsHighlighted(bool isHighlighted) 
        {
            IsHighlighted = isHighlighted;
        }
 
        #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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ComboBoxItem.cs source code in C# .NET

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