C# IDataObject类代码示例

        public override bool ItemDropped(IDataObject dragData)
        {
            if (IsValidDropTarget(dragData))
            {
                OutlinerNode[] droppedNodes = GetNodesFromDataObject(dragData);
                Int32[] droppedNodeHandles = new Int32[droppedNodes.Length];

                Tree.BeginTimedUpdate();
                Tree.BeginTimedSort();

                Int32 i = 0;
                foreach (OutlinerNode n in droppedNodes)
                {
                    //Tree.LinkObject((OutlinerObject)n, Data.Handle, false, false);

                    droppedNodeHandles[i] = ((OutlinerObject)n).Handle;
                    i++;
                }

                //Tree.RaiseObjectLinkedEvent(new NodeLinkedEventArgs(droppedNodeHandles, Data.Handle));
                Tree.RaiseObjectAddedToContainerEvent(new NodeGroupedEventArgs(droppedNodeHandles, Data.Handle, true, false));

                return true;
            }
            return false;
        }

        // Retrieves the text from the IDataObject instance.
        // Then create a textbox with the text data. 
        protected override void DoPaste(IDataObject dataObject) 
        {
            ElementList = new List<UIElement>(); 

            // Get the string from the data object.
            string text = dataObject.GetData(DataFormats.UnicodeText, true) as string;
 
            if ( String.IsNullOrEmpty(text) )
            { 
                // OemText can be retrieved as CF_TEXT. 
                text = dataObject.GetData(DataFormats.Text, true) as string;
            } 

            if ( !String.IsNullOrEmpty(text) )
            {
                // Now, create a text box and set the text to it. 
                TextBox textBox = new TextBox();
 
                textBox.Text = text; 
                textBox.TextWrapping = TextWrapping.Wrap;
 
                // Add the textbox to the internal array list.
                ElementList.Add(textBox);
            }
 
        }

 public static OutlinerNode[] GetNodesFromDataObject(IDataObject dragData)
 {
     if (dragData.GetDataPresent(typeof(OutlinerNode[])))
         return (OutlinerNode[])dragData.GetData(typeof(OutlinerNode[]));
     else
         return null;
 }

 public override DragDropEffects GetDragDropEffect(IDataObject dragData)
 {
     if (IsValidDropTarget(dragData))
         return DragDropEffects.Copy;
     else
         return Outliner.TreeView.DragDropEffectsNone;
 }

 public virtual UIElement ExtractElement(IDataObject obj)
 {
     string xamlString = obj.GetData(supportedFormat) as string;
     XmlReader reader = XmlReader.Create(new StringReader(xamlString));
     UIElement elt = XamlReader.Load(reader) as UIElement;
     return elt;
 }

		public override void Drop(IDataObject data, int index, DropEffect finalEffect)
		{
			try {
				string insertText = (data.GetData(typeof(string[])) as string[])
					.Aggregate((text, part) => text += part);
				ITextAnchor marker;
				int length = 0;
				if (index == this.Children.Count) {
					if (index == 0)
						marker = null;
					else
						marker = (this.Children[index - 1] as XamlOutlineNode).EndMarker;
					if (marker == null) {
						marker = this.EndMarker;
						length = -1; // move backwards
					} else {
						length = 2 + (this.Children[index - 1] as XamlOutlineNode).elementName.Length;
					}
				} else
					marker = (this.Children[index] as XamlOutlineNode).Marker;
				
				int offset = marker.Offset + length;
				Editor.Document.Insert(offset, insertText);
			} catch (Exception ex) {
				throw ex;
			}
		}

        public bool LimitDragDropOptions(IDataObject data)
        {
            var formats = data.GetFormats();
            if(!formats.Any())
            {
                return true;
            }


            var modelItemString = formats.FirstOrDefault(s => s.IndexOf("ModelItemsFormat", StringComparison.Ordinal) >= 0);
            if(!String.IsNullOrEmpty(modelItemString))
            {
                var innnerObjectData = data.GetData(modelItemString);
                var modelList = innnerObjectData as List<ModelItem>;
                if(modelList != null && modelList.Count > 1)
                {
                    if(modelList.FirstOrDefault(c => c.ItemType == typeof(FlowDecision) || c.ItemType == typeof(FlowSwitch<string>)) != null)
                    {
                        return false;
                    }
                }
            }

            modelItemString = formats.FirstOrDefault(s => s.IndexOf("ModelItemFormat", StringComparison.Ordinal) >= 0);
            if(String.IsNullOrEmpty(modelItemString))
            {
                modelItemString = formats.FirstOrDefault(s => s.IndexOf("WorkflowItemTypeNameFormat", StringComparison.Ordinal) >= 0);
                if(String.IsNullOrEmpty(modelItemString))
                {
                    return true;
                }
            }
            var objectData = data.GetData(modelItemString);
            return DropPointOnDragEnter(objectData);
        }

        public string Format(IDataObject obj)
        {
            if (obj == null) return string.Empty;

            var cls = _resolver.GetObjectClass(obj.Context.GetInterfaceType(obj));
            var allProps = cls.GetAllProperties();
            var result = new StringBuilder();

            foreach (var prop in allProps.OfType<StringProperty>().OrderBy(p => p.Name))
            {
                var txtVal = obj.GetPropertyValue<string>(prop.Name);
                if (!string.IsNullOrWhiteSpace(txtVal))
                {
                    result.AppendLine(txtVal);
                }
            }

            foreach (var prop in allProps.OfType<EnumerationProperty>().OrderBy(p => p.Name))
            {
                var enumVal = obj.GetPropertyValue<int>(prop.Name);
                var txtVal = prop.Enumeration.GetLabelByValue(enumVal);
                if (!string.IsNullOrWhiteSpace(txtVal))
                {
                    result.AppendLine(txtVal);
                }
            }

            return result.ToString();
        }

        private static void CheckRequiredProperties(IDataObject dataObj, ref DataObjectOperationResult result)
        {
            //Get Required Properties
            var requiredProperties = dataObj.GetType()
                                            .GetProperties()
                                            .Where(x => Attribute.IsDefined(x, typeof(RequiredValueAttribute)));

            //Check to Ensure Required Properties are not Null or empty
            foreach (var reqProp in requiredProperties)
            {
                var prop = dataObj.GetType().GetProperty(reqProp.Name);
                var propValue = prop.GetValue(dataObj, null);
                bool isNull = false;

                switch (prop.PropertyType.Name.ToLower())
                {
                    case "string":
                        isNull = string.IsNullOrEmpty((string)propValue);
                        break;
                    default:
                        isNull = propValue == null;
                        break;
                }

                if (isNull)
                {
                    RequiredValueAttribute reqAttrib = (RequiredValueAttribute)(prop.GetCustomAttributes(typeof(RequiredValueAttribute), false)[0]);
                    //var reqAttrib = prop.GetCustomAttribute<RequiredValueAttribute>();
                    result.Message = "A Required Value is Missing";
                    result.ErrorMessages.Add(reqProp.Name, reqAttrib.ErrorMessage);
                    result.Success = false;
                }
            }
        }

        public void AppendData(ref IDataObject data, MouseEventArgs e)
        {
            if (!(this.list.InputHitTest(e.GetPosition(e.OriginalSource as UIElement)) is ListBox)
                && !(this.list.InputHitTest(e.GetPosition(e.OriginalSource as UIElement)) is ScrollViewer)
                && !(e.OriginalSource is Thumb))
            {
                object o = this.list.SelectedItem;

                // This is cheating .. just for an example's sake..
                Debug.Assert(!data.GetDataPresent(DataFormats.Text));

                if (o.GetType() == typeof(XmlElement))
                {
                    data.SetData(DataFormats.Text, ((XmlElement)o).OuterXml);
                }
                else
                {
                    data.SetData(DataFormats.Text, o.ToString());
                }

                Debug.Assert(!data.GetDataPresent(o.GetType().ToString()));

                data.SetData(o.GetType().ToString(), o);
            }
            else
            {
                data = null;
            }
        }

        private IDataObject CloneClipboard(IDataObject obj)
        {
            if (obj == null)
                return null;

            string[] formats = obj.GetFormats();
            if (formats.Length == 0)
                return null;

            IDataObject newObj = new DataObject();
            
            foreach (string format in formats)
            {
				if (format.Contains("EnhancedMetafile")) //Ignore this. Cannot be processed in .NET
					continue;

				object o = obj.GetData(format);

                if (o != null)
                {
                    newObj.SetData(o);
                }
            }

            return newObj;
        }

        /// <summary>
        /// Create an OleDataObject from a .NET IDataObject.
        /// </summary>
        /// <param name="ido">IDataObject to extract OleDataObject from</param>
        /// <returns>A new instance of OleDataObject mapped to the inner
        /// OleDataObject of the specified IDataObject or null if unable
        /// to extract OleDataObject from IDataObject</returns>
        public static OleDataObject CreateFrom(IDataObject ido)
        {
            // initialize OleDataObject
            OleDataObject oleDataObject = new OleDataObject();

            // attempt to convert to concrete DataObject class
            DataObject dataObject = ido as DataObject;
            if (dataObject == null)
            {
                return null;
            }

            // To extract an OleDataObject from a DataObject, we first need to
            // get the "innerData" field of the DataObject. This field is of type
            // System.Windows.Forms.UnsafeNativeMethods.OleConverter. Next, we
            // need to get the "innerData" field of the OleConverter, which is of
            // type System.Windows.Forms.UnsafeNativeMethods.IOleDataObject
            const string INNER_DATA_FIELD = "innerData";
            object innerData = oleDataObject.GetField(dataObject, INNER_DATA_FIELD);
            object innerInnerData = oleDataObject.GetField(innerData, INNER_DATA_FIELD);

            // attempt to convert the 'private' ole data object contained in
            // innerData into an instance of our locally defined IOleDataObject
            oleDataObject.m_dataObject = innerInnerData as IOleDataObject;
            if (oleDataObject.m_dataObject != null)
            {
                return oleDataObject;
            }
            else
            {
                return null;
            }
        }

        public bool IsValidDataObject(IDataObject obj)
        {
            bool result = false;

            var elt = (FrameworkElement)this.TargetUI;

            var storeItemVM = elt.DataContext as StoreItemViewModelBase;
            //var channelVM = elt.DataContext as ChannelViewModel;

            if (storeItemVM != null)
            {
                if (obj.GetDataPresent(typeof(StoreItemViewModelBase[])))
                {
                    var data = (StoreItemViewModelBase[])obj.GetData(typeof(StoreItemViewModelBase[]));

                    result = data != null && data.Length > 0;
                    //.Any(droppedStoreItemVM => !channelListVM.Contains(droppedChannelVM));
                }
            }
            //else if (channelVM != null)
            //{
            //    if (obj.GetDataPresent(typeof(ChannelViewModel[])))
            //    {
            //        var data = (ChannelViewModel[])obj.GetData(typeof(ChannelViewModel[]));

            //        result = data
            //            .Any(droppedChannelVM => channelVM != droppedChannelVM);
            //    }
            //}

            return result;
        }

        /// <summary>
        /// Attempts to create a new HTMLData.  This can return null if the DataObject
        /// couldn't be created based upon the IDataObject.
        /// </summary>
        /// <param name="iDataObject">The IDataObject from which to create the HTML Data Object</param>
        /// <returns>The HTMLData, null if it couldn't be created.</returns>
        public static HTMLData Create(IDataObject iDataObject)
        {
            string[] loser = iDataObject.GetFormats();

            if (OleDataObjectHelper.GetDataPresentSafe(iDataObject, DataFormats.Html))
            {

                try
                {
                    HTMLData data = new HTMLData(iDataObject, null);
                    return string.IsNullOrEmpty(data.HTML) ? null : data;
                }
                catch (FormatException)
                {
                    // EML files with HTML inside of them report that they are HTML
                    // However, when we try to read the format, we have problems reading it
                    // So we will skip loading html that we cannot load
                    return null;
                }

            }
            else if (HtmlDocumentClassFormatPresent(iDataObject))
            {
                return new HTMLData(iDataObject, (IHTMLDocument2)iDataObject.GetData(typeof(HTMLDocumentClass)));
            }
            else
                return null;
        }

        protected override void DoCopy(IDataObject dataObject)
        {
            // samgeo - Presharp issue
            // Presharp gives a warning when local IDisposable variables are not closed
            // in this case, we can't call Dispose since it will also close the underlying stream
            // which needs to be open for consumers to read
#pragma warning disable 1634, 1691
#pragma warning disable 6518

            // Save the data in the data object.
            MemoryStream stream = new MemoryStream();
            Strokes.Save(stream);
            stream.Position = 0;
            (new UIPermission(UIPermissionClipboard.AllClipboard)).Assert();//BlessedAssert
            try
            {
                dataObject.SetData(StrokeCollection.InkSerializedFormat, stream);
            }
            finally
            {
                UIPermission.RevertAssert();
            }
#pragma warning restore 6518
#pragma warning restore 1634, 1691
        }