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--- swdev:dotnet:wpf:dependency_properties [2011/03/15 16:49]
smayr [Dependency Properties]
+++ swdev:dotnet:wpf:dependency_properties [2013/01/25 09:16] (current)
smayr [Example 1]
@@ Line 55: / Line 55: @@
   // A property changed callback (not must)
   private static void OnIsCancelPropertyChanged(
-    DependencyObject o, DependencyPropertyChangedEventArgs e)
+    DependencyObject source, DependencyPropertyChangedEventArgs e)
   {
-       ...
+       Button control = source as Button;
+       // Put some update logic here...
+       control.IsCancel = (bool)e.NewValue;
+       if (control.IsCancel == true)
+       {
+           // do something
+       }
   }
@@ Line 71: / Line 78: @@
 IMPORTANT: The accessor property is fine to use, but the XAML code will only call the SetValue() and GetValue() methods directly, so make sure that no other code gets added to the accessor property, to make sure both work the same.
-=== Example ===
+=== Example 1 ===
 <code csharp>
 public class Employee : DependencyObject
@@ Line 92: / Line 99: @@
     // If employee id is greater than 1000 then make it 1000
-    static void EmpIdCallBack(DependencyObject d,
+    static void EmpIdCallBack(DependencyObject d, DependencyPropertyChangedEventArgs args)
-        DependencyPropertyChangedEventArgs args)
     {
         Employee emp = (Employee)d;
@@ Line 142: / Line 148: @@
 Source: [[http://zamjad.wordpress.com/2009/07/13/dependency-property-metadata|Zeeshan Amjad: Dependency Property Metadata]]
+=== Example 2 ===
+A user control that requires a Dependency Property in order to set the ''SelectedIndex'' in a ''ListBox'' using Data Binding.
+XAML:
+<code xml>
+<UserControl x:Class="ACME.Controls.ucActiveInstrument". . .>
+. . .
+<Grid>
+        <ListBox Name="lstOptions" Width="110" Height="40" SelectedIndex="1"
+                 SelectionChanged="lstOptions_SelectionChanged">
+            <ListBoxItem>
+                <ListBoxItem.Content>
+                    <Image Source="/images/icons/icon-device-right.png" Height="25" />
+                </ListBoxItem.Content>
+            </ListBoxItem>
+            <ListBoxItem>
+                <ListBoxItem.Content>
+                    <Image Source="/images/icons/icon-device-both.png" Height="25" />
+                </ListBoxItem.Content>
+            </ListBoxItem>
+            <ListBoxItem>
+                <ListBoxItem.Content>
+                    <Image Source="/images/icons/icon-device-left.png" Height="25" />
+                </ListBoxItem.Content>
+            </ListBoxItem>
+        </ListBox>
+    </Grid>
+</UserControl>
+</code>
+C# code:
+<code csharp>
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Data;
+using System.Windows.Documents;
+using System.Windows.Input;
+using System.Windows.Media;
+using System.Windows.Media.Imaging;
+using System.Windows.Navigation;
+using System.Windows.Shapes;
+namespace ACME.Controls
+{
+    public partial class ucActiveInstrument : UserControl
+    {
+        #region DependencyProperty SelectedItemIndex
+        //-----------------------------------
+        // SelectedItemIndex
+        //-----------------------------------
+        // Dependency Property
+        public static readonly DependencyProperty SelectedItemIndexProperty =
+          DependencyProperty.Register(
+              "SelectedItemIndex",
+              typeof(int),
+              typeof(ucActiveInstrument),
+              new FrameworkPropertyMetadata(
+                    new int(),
+                    OnSelectedItemIndexPropertyChanged
+              )
+          );
+        // .NET Property Wrapper
+        public int SelectedItemIndex
+        {
+            // Important: Do not add any logic to these properties, because they are only
+            // called when you set the property from code. If you set the property from XAML
+            // the SetValue() method is called directly.
+            get { return (int)GetValue(SelectedItemIndexProperty); }
+            set { SetValue(SelectedItemIndexProperty, value); }
+        }
+        // Alias
+        public int SelectedItemIdx
+        {
+            get { return SelectedItemIndex; }
+        }
+        ///----------------------------------------------------------------------------------------
+        /// <summary>
+        /// OnPropertyChanged event handler for fitting view model.
+        /// </summary>
+        /// <param name="source">Source control</param>
+        /// <param name="e">Event Arguments</param>
+        ///----------------------------------------------------------------------------------------
+        private static void OnSelectedItemIndexPropertyChanged(
+          DependencyObject source,
+          DependencyPropertyChangedEventArgs e)
+        {
+            ucActiveInstrument control = source as ucActiveInstrument;
+            //DateTime time = (DateTime)e.NewValue;
+            //-----------------------------------------
+            // Put some update logic here...
+            //-----------------------------------------
+            //SetDataBinding((TFittingViewModel)e.NewValue, control);
+            //SetBinauralView(control);
+            control.lstOptions.SelectedIndex = (int)e.NewValue;
+        }
+        #endregion
+        //-----------------------------------------------------------------------------------------
+        /// <summary>
+        /// Constructor.
+        /// </summary>
+        //-----------------------------------------------------------------------------------------
+        public ucActiveInstrument()
+        {
+            InitializeComponent();
+        }
+        //-----------------------------------------------------------------------------------------
+        /// <summary>
+        /// SelectionChange event handler for lstOptions.
+        /// </summary>
+        /// <param name="sender"></param>
+        /// <param name="e"></param>
+        //-----------------------------------------------------------------------------------------
+        private void lstOptions_SelectionChanged(object sender, SelectionChangedEventArgs e)
+        {
+            this.SelectedItemIndex = lstOptions.SelectedIndex;
+        }
+    }
+}
+</code>
 == See Also ==
   * [[swdev:dotnet:wpf:implementing_mvvm|Implementing M-V-VM]]
   * [[http://zamjad.wordpress.com/2009/07/13/dependency-property-metadata/|Zeeshan Amjad: Dependency Property Metadata]]