'宣言 Protected Overrides Sub OnSubObjectPropChanged( _ ByVal propChange As Infragistics.Shared.PropChangeInfo _ )
protected override void OnSubObjectPropChanged( Infragistics.Shared.PropChangeInfo propChange )
Imports Infragistics.Shared Imports Infragistics.Win Public Class ExampleClass Inherits SubObjectBase Private appearanceHolder As appearanceHolder Private enabledValue As Boolean ' Listens for property change notifications of the object's sub objects. Protected Overrides Sub OnSubObjectPropChanged(ByVal pci As Infragistics.Shared.PropChangeInfo) ' Check if the source is our appearance object. If Not Me.appearanceHolder Is Nothing _ AndAlso pci.Source.Equals(Me.appearanceHolder.RootAppearance) Then ' Do what needs to be done (if anything) based on the ' nature of the change Dim propId As AppearancePropIds propId = pci.PropId If propId = AppearancePropIds.Image _ OrElse propId = AppearancePropIds.ImageHAlign _ OrElse propId = AppearancePropIds.ImageVAlign Then Me.DirtyImage() Else Me.DirtyText() End If ' Call NotifyPropChange with the appropriate property id ' and the PropChangeInfo instance that was passed into ' this method. Me.NotifyPropChange(StatusBarPropertyIds.Appearance, pci) ' Note: If there are any listeners to our 'SubObjectPropChanged' ' event, the event will be raised with a new PropChangeInfo ' event argument whose properties will be set as follows: ' 1. The Source property will refer to this object. ' 2. The PropId property will be StatusBarPropertyIds.Appearance. ' 3. The Trigger property will be the passed in PropChangeInfo. ' ' This will effectively create a chain of PropChangeInfo ' objects, with the new one at the head, that exposes ' complete context information regarding the change. Return End If ' There is an overload to the 'NotifyPropChange' method ' that just takes the passed in PropChangeInfo object. ' This is useful if you want to pass the notification ' along to this object's listeners 'as is'. In other words, ' without creating a new PropChangeInfo to add to the ' head of the chain (refer to above comments). Me.NotifyPropChange(pci) Dim sb As System.Text.StringBuilder ' The following code walks up the PropChangeInfo chain ' and writes out the source and property id of each ' object. While Not pci Is Nothing sb = New System.Text.StringBuilder() sb.Append("Property Id: ") sb.Append(pci.PropId.ToString()) sb.Append(", source: ") sb.Append(pci.Source.ToString()) sb.Append(". type: ") sb.Append(pci.Source.GetType().ToString()) Debug.WriteLine(sb.ToString()) Debug.Indent() End While ' Get the next PropChangeInfo object in the chain pci = pci.Trigger ' Reset the indent level of the Debug object Debug.IndentLevel = 0 ' Alternatively there are 'Find...' methods that ' will walk up the chain until they find the ' requested PropChangeInfo object to return or ' they will return null. pci = pci.FindPropId(AppearancePropIds.BackGradientStyle) pci = pci.FindTrigger(Me.appearanceHolder.RootAppearance) ' There is also a 'FindSource' method which will ' return the source object based on the passed ' in type. If no source object of that type is ' found in the chain this method will return null. Dim source As Object source = pci.FindSource(GetType(Infragistics.Win.Appearance)) End Sub Public Property Enabled() As Boolean Get Return Me.enabledValue End Get Set(ByVal Value As Boolean) If Not Me.enabledValue = Value Then Me.enabledValue = Value ' Call the overload to the 'NotifyPropChange' method ' that just takes a property id. Me.NotifyPropChange(StatusBarPropertyIds.Enabled) ' Note: If there are any listeners to our 'SubObjectPropChanged' ' event, the event will be raised with a PropChangeInfo ' event argument whose properties will be` set as follows: ' 1. The Source property will refer to this object. ' 2. The PropId property will be StatusBarPropertyIds.Enabled. ' 3. The Trigger property will be null. End If End Set End Property Public ReadOnly Property Appearance() As AppearanceBase Get ' Lazily create the appearance holder If Me.appearanceHolder Is Nothing Then Me.appearanceHolder = New AppearanceHolder() ' Listen in to property changes generated by the ' object. When one of its properties changes our ' 'OnSubObjectPropChanged' method will be called. AddHandler Me.appearanceHolder.SubObjectPropChanged, Me.SubObjectPropChangeHandler End If Return Me.appearanceHolder.Appearance End Get End Property Protected Overrides Sub OnDispose() If Not Me.appearanceHolder Is Nothing Then ' Remove ourselves as a listener RemoveHandler Me.appearanceHolder.SubObjectPropChanged, Me.SubObjectPropChangeHandler End If End Sub Private Sub DirtyImage() End Sub Private Sub DirtyText() End Sub End Class Public Enum StatusBarPropertyIds Appearance = 1 Enabled = 2 End Enum
using System; using System.Diagnostics; using Infragistics.Shared; using Infragistics.Win; namespace SharedSnippets { public class ExampleClass : SubObjectBase { private AppearanceHolder appearanceHolder = null; private bool enabled = true; // Listens for property change notifications of the object's sub objects. protected override void OnSubObjectPropChanged( PropChangeInfo pci ) { // Check if the source is our appearance object. if (this.appearanceHolder != null && pci.Source == this.appearanceHolder.RootAppearance) { // Do what needs to be done (if anything) based on the // nature of the change switch ( (AppearancePropIds)pci.PropId ) { case AppearancePropIds.Image: case AppearancePropIds.ImageHAlign: case AppearancePropIds.ImageVAlign: { this.DirtyImage(); break; } default: this.DirtyText(); break; } // Call NotifyPropChange with the appropriate property id // and the PropChangeInfo instance that was passed into // this method. this.NotifyPropChange( StatusBarPropertyIds.Appearance, pci ); // Note: If there are any listeners to our 'SubObjectPropChanged' // event, the event will be raised with a new PropChangeInfo // event argument whose properties will be set as follows: // 1. The Source property will refer to this object. // 2. The PropId property will be StatusBarPropertyIds.Appearance. // 3. The Trigger property will be the passed in PropChangeInfo. // // This will effectively create a chain of PropChangeInfo // objects, with the new one at the head, that exposes // complete context information regarding the change. return; } // There is an overload to the 'NotifyPropChange' method // that just takes the passed in PropChangeInfo object. // This is useful if you want to pass the notification // along to this object's listeners 'as is'. In other words, // without creating a new PropChangeInfo to add to the // head of the chain (refer to above comments). this.NotifyPropChange( pci ); // The following code walks up the PropChangeInfo chain // and writes out the source and property id of each // object. while ( pci != null ) { System.Text.StringBuilder sb = new System.Text.StringBuilder(); sb.Append("Property Id: "); sb.Append(pci.PropId.ToString()); sb.Append(", source: "); sb.Append(pci.Source.ToString()); sb.Append(". type: "); sb.Append(pci.Source.GetType().ToString()); Debug.WriteLine( sb.ToString() ); Debug.Indent(); // Get the next PropChangeInfo object in the chain pci = pci.Trigger; } // Reset the indent level of the Debug object Debug.IndentLevel = 0; // Alternatively there are 'Find...' methods that // will walk up the chain until they find the // requested PropChangeInfo object to return or // they will return null. pci = pci.FindPropId( AppearancePropIds.BackGradientStyle ); pci = pci.FindTrigger( this.appearanceHolder.RootAppearance ); // There is also a 'FindSource' method which will // return the source object based on the passed // in type. If no source object of that type is // found in the chain this method will return null. object source = pci.FindSource( typeof(Infragistics.Win.Appearance ) ); } public bool Enabled { get { return this.enabled; } set { if (this.enabled != value) { this.enabled = value; // Call the overload to the 'NotifyPropChange' method // that just takes a property id. this.NotifyPropChange( StatusBarPropertyIds.Enabled ); // Note: If there are any listeners to our 'SubObjectPropChanged' // event, the event will be raised with a PropChangeInfo // event argument whose properties will be` set as follows: // 1. The Source property will refer to this object. // 2. The PropId property will be StatusBarPropertyIds.Enabled. // 3. The Trigger property will be null. } } } public AppearanceBase Appearance { get { // Lazily create the appearance holder if (this.appearanceHolder == null) { this.appearanceHolder = new AppearanceHolder(); // Listen in to property changes generated by the // object. When one of its properties changes our // 'OnSubObjectPropChanged' method will be called. this.appearanceHolder.SubObjectPropChanged += this.SubObjectPropChangeHandler; } return this.appearanceHolder.Appearance; } } protected override void OnDispose() { if ( this.appearanceHolder != null ) { // Remove ourselves as a listener this.appearanceHolder.SubObjectPropChanged -= this.SubObjectPropChangeHandler; } } private void DirtyImage(){} private void DirtyText(){} } public enum StatusBarPropertyIds { Appearance = 1, Enabled = 2 } }