browserdropwrappers.cs

C#界面编程

using System;
using System.Collections.Generic;
using System.Text;
using ShellDll;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using System.Drawing;

namespace FileBrowser
{
    /// <summary>
    /// This class takes care of every drop operation in a BrowserTreeView
    /// </summary>
    internal class BrowserTVDropWrapper : ShellDll.IDropTarget, IDisposable
    {
        #region Fields

        // The browser for which to do the drop work
        private Browser br;

        private IntPtr treeViewHandle;

        // The current IDropTarget the cursor is over and the pointers to the target and dataobject
        private ShellDll.IDropTarget dropTarget;
        private IntPtr dropTargetPtr;
        private IntPtr dropDataObject;

        private IDropTargetHelper dropHelper;
        private IntPtr dropHelperPtr;

        // The current node the cursor is over to drop on
        private TreeNode dropNode;

        // The last selected node from the browser
        // This is to remember which node to select after drop has completed
        private TreeNode lastSelectedNode;

        // The parent ShellItems of the drop- and dragitem
        private ShellItem parentDropItem, parentDragItem;

        // The mouse and keys state when a drag enter occurs
        private ShellAPI.MK mouseButtons;

        // A bool to indicate whether this class has been disposed
        private bool disposed = false;

        // The event for when a drop is occuring
        public event DropEventHandler Drop;

        #endregion

        /// <summary>
        /// Registers the TreeView for drag/drop operations and uses this class as the IDropTarget
        /// </summary>
        /// <param name="br">The browser for which to support the drop</param>
        public BrowserTVDropWrapper(Browser br)
        {
            this.br = br;

            treeViewHandle = br.FolderView.Handle;
            ShellAPI.RegisterDragDrop(treeViewHandle, this);

            br.FolderView.HandleCreated += new EventHandler(FolderView_HandleCreated);
            br.FolderView.HandleDestroyed += new EventHandler(FolderView_HandleDestroyed);

            ShellHelper.GetIDropTargetHelper(out dropHelperPtr, out dropHelper);
        }

        ~BrowserTVDropWrapper()
        {
            ((IDisposable)this).Dispose();
        }

        #region Handle Changes

        void FolderView_HandleCreated(object sender, EventArgs e)
        {
            treeViewHandle = br.FolderView.Handle;
            ShellAPI.RegisterDragDrop(treeViewHandle, this);
        }

        void FolderView_HandleDestroyed(object sender, EventArgs e)
        {
            ShellAPI.RevokeDragDrop(br.FolderView.Handle);
        }

        #endregion

        #region Public

        /// <summary>
        /// This ShellItem is the parent item of the item being currently dragged. This field is used
        /// to check whether an item is being moved to it's original folder. If this is the case, we don't
        /// have to do anything, cause the item is allready there.
        /// </summary>
        public ShellItem ParentDragItem
        {
            get { return parentDragItem; }
            set { parentDragItem = value; }
        }

        #endregion

        #region Generated Events

        /// <summary>
        /// This event will be raised whenever a drop occurs on the TreeView.
        /// </summary>
        /// <param name="e">The DropEventArgs for the event</param>
        private void OnDrop(DropEventArgs e)
        {
            if (Drop != null)
                Drop(this, e);
        }

        #endregion

        #region IDropTarget Members

        public int DragEnter(IntPtr pDataObj, ShellAPI.MK grfKeyState, ShellAPI.POINT pt, ref DragDropEffects pdwEffect)
        {
            mouseButtons = grfKeyState;

            br.FolderView.Focus();
            br.SelectionChange = false;
            lastSelectedNode = br.FolderView.SelectedNode;

            ReleaseCom();

            dropDataObject = pDataObj;

            #region Get DropItem

            Point point = br.FolderView.PointToClient(new Point(pt.x, pt.y));
            TreeViewHitTestInfo hitTest = br.FolderView.HitTest(point);

            dropNode = hitTest.Node;
            br.FolderView.SelectedNode = dropNode;

            if (dropNode != null)
            {
                ShellItem item = (ShellItem)dropNode.Tag;
                parentDropItem = item;

                if (ShellHelper.GetIDropTarget(item, out dropTargetPtr, out dropTarget))
                {
                    dropTarget.DragEnter(pDataObj, grfKeyState, pt, ref pdwEffect);
                }
            }

            #endregion

            if (dropHelper != null)
                dropHelper.DragEnter(br.Handle, pDataObj, ref pt, pdwEffect);

            return ShellAPI.S_OK;
        }

        public int DragOver(ShellAPI.MK grfKeyState, ShellAPI.POINT pt, ref DragDropEffects pdwEffect)
        {
            bool reset = false;

            #region Get DropItem

            Point point = br.FolderView.PointToClient(new Point(pt.x, pt.y));
            TreeViewHitTestInfo hitTest = br.FolderView.HitTest(point);
            if (!TreeNode.Equals(dropNode, hitTest.Node))
            {
                if (dropTarget != null)
                    dropTarget.DragLeave();

                ReleaseCom();

                dropNode = hitTest.Node;
                br.FolderView.SelectedNode = dropNode;
                
                if (dropNode == null)
                {
                    pdwEffect = DragDropEffects.None;

                    if (dropHelper != null)
                        dropHelper.DragOver(ref pt, pdwEffect);

                    return ShellAPI.S_OK;
                }
                else
                {
                    ShellItem item = (ShellItem)dropNode.Tag;
                    parentDropItem = item;

                    ShellHelper.GetIDropTarget(item, out dropTargetPtr, out dropTarget);
                    reset = true;
                }
            }
            else if (dropNode == null)
            {
                if (dropTarget != null)
                    dropTarget.DragLeave();

                ReleaseCom();

                dropNode = null;
                br.SelectedNode = null;

                pdwEffect = DragDropEffects.None;

                if (dropHelper != null)
                    dropHelper.DragOver(ref pt, pdwEffect);

                return ShellAPI.S_OK;
            }

            #endregion

            if (dropTarget != null)
            {
                if (reset)
                    dropTarget.DragEnter(dropDataObject, grfKeyState, pt, ref pdwEffect);
                else
                    dropTarget.DragOver(grfKeyState, pt, ref pdwEffect);
            }
            else
                pdwEffect = DragDropEffects.None;

            if (dropHelper != null)
                dropHelper.DragOver(ref pt, pdwEffect);

            return ShellAPI.S_OK;
        }

        public int DragLeave()
        {
            ResetDrop();
            if (dropTarget != null)
            {
                dropTarget.DragLeave();

                ReleaseCom();
                dropDataObject = IntPtr.Zero;
            }

            if (dropHelper != null)
                dropHelper.DragLeave();

            return ShellAPI.S_OK;
        }

        public int DragDrop(IntPtr pDataObj, ShellAPI.MK grfKeyState, ShellAPI.POINT pt, ref DragDropEffects pdwEffect)
        {
            OnDrop(new DropEventArgs(mouseButtons, br.FolderView));

            if (!((mouseButtons & ShellAPI.MK.RBUTTON) != 0 ||
                  grfKeyState == ShellAPI.MK.CONTROL || 
                  grfKeyState == ShellAPI.MK.ALT || 
                  grfKeyState == (ShellAPI.MK.CONTROL | ShellAPI.MK.SHIFT)) && ShellItem.Equals(parentDragItem, parentDropItem))
            {
                ResetDrop();                
                ReleaseCom();
                pdwEffect = DragDropEffects.None;

                if (dropHelper != null)
                    dropHelper.DragLeave();

                return ShellAPI.S_OK;
            }

            ResetDrop();
            if (dropTarget != null)
            {
                dropTarget.DragDrop(pDataObj, grfKeyState, pt, ref pdwEffect);

                ReleaseCom();
                dropDataObject = IntPtr.Zero;
            }

            if (dropHelper != null)
                dropHelper.Drop(pDataObj, ref pt, pdwEffect);

            return ShellAPI.S_OK;
        }

        /// <summary>
        /// Reset all fields to the default values and release the IDropTarget
        /// </summary>
        private void ResetDrop()
        {
            if (dropNode != null)
            {
                dropNode = null;
                parentDropItem = null;
            }

            if (lastSelectedNode != null)
                br.FolderView.SelectedNode = lastSelectedNode;

            br.SelectionChange = true;
        }

        #endregion

        #region IDisposable Members

        /// <summary>
        /// If not disposed, dispose the class
        /// </summary>
        public void Dispose()
        {
            if (!disposed)
            {
                DisposeDropWrapper();
                GC.SuppressFinalize(this);

                disposed = true;
            }
        }

        /// <summary>
        /// Revokes the TreeView from getting drop messages and releases the IDropTarget
        /// </summary>
        private void DisposeDropWrapper()
        {
            ReleaseCom();

            if (dropHelper != null)
            {
                Marshal.ReleaseComObject(dropHelper);
            }
        }

        /// <summary>
        /// Release the IDropTarget and free's the allocated memory
        /// </summary>
        private void ReleaseCom()
        {
            if (dropTarget != null)
            {
                Marshal.ReleaseComObject(dropTarget);

                dropTarget = null;
                dropHelperPtr = IntPtr.Zero;
            }
        }

        #endregion
    }

    /// <summary>
    /// This class takes care of every drop operation in a BrowserListView
    /// </summary>
    internal class BrowserLVDropWrapper : ShellDll.IDropTarget, IDisposable
    {
        #region Fields

        // The browser for which to do the drop work
        private Browser br;