WebBrowser：拖放
我想拦截WebBrowser控件上的拖放操作。 更确切地说，我希望能够基于文件扩展名取消或批准拖放事件（并在WebBrowser外部处理该文件），并且我想使拖放图标看起来像常规图标： http ： //snag.gy/DUjMc。 jpg ，不像这个： http ： //snag.gy/ExX19.jpg 。
我相信我需要实现自定义IDocHostUIHandler并拦截GetDropTarget。 不幸的是，我没有成功。 我使用此代码作为我的“基本”代码： https ： //stackoverflow.com/a/19739699/2758677和我做的这部分： http ： //pastebin.com/Ux947Eck 。 永远不会调用GetDropTarget。
这是一个完整的基于WinForms的示例， IDocHostUIHandler.GetDropTarget确实被调用。
using System; using System.Diagnostics; using System.Linq; using System.Runtime.InteropServices; using System.Windows.Forms; namespace CustomWebBrowser { public partial class MainForm : Form { public MainForm() { InitializeComponent(); } private void MainForm_Load(object sender, EventArgs e) { var wb = new ImprovedWebBrowser(); wb.Dock = DockStyle.Fill; this.Controls.Add(wb); wb.Visible = true; wb.DocumentText = "Hello from ImprovedWebBrowser!"; } } public class ImprovedWebBrowser : WebBrowser { /// /// provide custom WebBrowserSite, /// where we override IDocHostUIHandler and call the base implementation /// More info: http://stackoverflow.com/a/19739699/1768303 /// protected override WebBrowserSiteBase CreateWebBrowserSiteBase() { return new ImprovedWebBrowserSite(this); } #region ImprovedWebBrowserSite [ClassInterface(ClassInterfaceType.None)] protected class ImprovedWebBrowserSite : WebBrowserSite, NativeMethods.IDocHostUIHandler, IDisposable, ICustomQueryInterface { ImprovedWebBrowser _host; NativeMethods.IDocHostUIHandler _baseIDocHostUIHandler; IntPtr _unkInnerAggregated; IntPtr _unkOuter; Inner _inner; // constructor public ImprovedWebBrowserSite(WebBrowser host) : base(host) { _host = (ImprovedWebBrowser)host; // get the CCW object for this _unkOuter = Marshal.GetIUnknownForObject(this); Marshal.AddRef(_unkOuter); try { // aggregate the CCW object with the helper Inner object _inner = new Inner(this); _unkInnerAggregated = Marshal.CreateAggregatedObject(_unkOuter, _inner); // obtain private WebBrowserSite COM interfaces _baseIDocHostUIHandler = (NativeMethods.IDocHostUIHandler)Marshal.GetTypedObjectForIUnknown(_unkInnerAggregated, typeof(NativeMethods.IDocHostUIHandler)); } finally { Marshal.Release(_unkOuter); } } ~ImprovedWebBrowserSite() { // need to work out the reference counting for GC to work correctly Debug.Print("ImprovedWebBrowserSite object finalized."); } void IDisposable.Dispose() { base.Dispose(); _baseIDocHostUIHandler = null; if (_unkInnerAggregated != IntPtr.Zero) { Marshal.Release(_unkInnerAggregated); _unkInnerAggregated = IntPtr.Zero; } if (_unkOuter != IntPtr.Zero) { Marshal.Release(_unkOuter); _unkOuter = IntPtr.Zero; } } #region Inner // Inner as aggregated object class Inner : ICustomQueryInterface, IDisposable { object _outer; Type[] _interfaces; public Inner(object outer) { _outer = outer; _interfaces = _outer.GetType().BaseType.GetInterfaces(); } public CustomQueryInterfaceResult GetInterface(ref Guid iid, out IntPtr ppv) { if (_outer != null) { var guid = iid; var iface = _interfaces.FirstOrDefault((t) => t.GUID == guid); if (iface != null) { var unk = Marshal.GetComInterfaceForObject(_outer, iface, CustomQueryInterfaceMode.Ignore); if (unk != IntPtr.Zero) { ppv = unk; return CustomQueryInterfaceResult.Handled; } } } ppv = IntPtr.Zero; return CustomQueryInterfaceResult.Failed; } ~Inner() { // need to work out the reference counting for GC to work correctly Debug.Print("Inner object finalized."); } public void Dispose() { _outer = null; _interfaces = null; } } #endregion #region ICustomQueryInterface public CustomQueryInterfaceResult GetInterface(ref Guid iid, out IntPtr ppv) { // CustomQueryInterfaceMode.Ignore is to avoid infinite loop during QI. if (iid == typeof(NativeMethods.IDocHostUIHandler).GUID) { ppv = Marshal.GetComInterfaceForObject(this, typeof(NativeMethods.IDocHostUIHandler), CustomQueryInterfaceMode.Ignore); } else { ppv = IntPtr.Zero; return CustomQueryInterfaceResult.NotHandled; } return CustomQueryInterfaceResult.Handled; } #endregion #region IDocHostUIHandler int NativeMethods.IDocHostUIHandler.ShowContextMenu(int dwID, ref NativeMethods.POINT pt, IntPtr pcmdtReserved, IntPtr pdispReserved) { return _baseIDocHostUIHandler.ShowContextMenu(dwID, ref pt, pcmdtReserved, pdispReserved); } int NativeMethods.IDocHostUIHandler.GetHostInfo(ref NativeMethods.DOCHOSTUIINFO info) { Debug.Print("IDocHostUIHandler.GetHostInfo"); return _baseIDocHostUIHandler.GetHostInfo(ref info); } int NativeMethods.IDocHostUIHandler.ShowUI(int dwID, IntPtr activeObject, IntPtr commandTarget, IntPtr frame, IntPtr doc) { return _baseIDocHostUIHandler.ShowUI(dwID, activeObject, commandTarget, frame, doc); } int NativeMethods.IDocHostUIHandler.HideUI() { return _baseIDocHostUIHandler.HideUI(); } int NativeMethods.IDocHostUIHandler.UpdateUI() { return _baseIDocHostUIHandler.UpdateUI(); } int NativeMethods.IDocHostUIHandler.EnableModeless(bool fEnable) { return _baseIDocHostUIHandler.EnableModeless(fEnable); } int NativeMethods.IDocHostUIHandler.OnDocWindowActivate(bool fActivate) { return _baseIDocHostUIHandler.OnDocWindowActivate(fActivate); } int NativeMethods.IDocHostUIHandler.OnFrameWindowActivate(bool fActivate) { return _baseIDocHostUIHandler.OnFrameWindowActivate(fActivate); } int NativeMethods.IDocHostUIHandler.ResizeBorder(ref NativeMethods.COMRECT rect, IntPtr doc, bool fFrameWindow) { return _baseIDocHostUIHandler.ResizeBorder(ref rect, doc, fFrameWindow); } int NativeMethods.IDocHostUIHandler.TranslateAccelerator(ref NativeMethods.MSG msg, ref Guid group, int nCmdID) { return _baseIDocHostUIHandler.TranslateAccelerator(ref msg, ref group, nCmdID); } int NativeMethods.IDocHostUIHandler.GetOptionKeyPath(string[] pbstrKey, int dw) { return _baseIDocHostUIHandler.GetOptionKeyPath(pbstrKey, dw); } int NativeMethods.IDocHostUIHandler.GetDropTarget(IntPtr pDropTarget, out IntPtr ppDropTarget) { Debug.Print("IDocHostUIHandler.GetDropTarget"); return _baseIDocHostUIHandler.GetDropTarget(pDropTarget, out ppDropTarget); } int NativeMethods.IDocHostUIHandler.GetExternal(out object ppDispatch) { return _baseIDocHostUIHandler.GetExternal(out ppDispatch); } int NativeMethods.IDocHostUIHandler.TranslateUrl(int dwTranslate, string strURLIn, out string pstrURLOut) { return _baseIDocHostUIHandler.TranslateUrl(dwTranslate, strURLIn, out pstrURLOut); } int NativeMethods.IDocHostUIHandler.FilterDataObject(IntPtr pDO, out IntPtr ppDORet) { return _baseIDocHostUIHandler.FilterDataObject(pDO, out ppDORet); } #endregion } #endregion } public static class NativeMethods { #region IDocHostUIHandler public enum DOCHOSTUIDBLCLICK { DEFAULT = 0x0, SHOWPROPERTIES = 0x1, SHOWCODE = 0x2 } public enum DOCHOSTUIFLAG { DIALOG = 0x1, DISABLE_HELP_MENU = 0x2, NO3DBORDER = 0x4, SCROLL_NO = 0x8, DISABLE_SCRIPT_INACTIVE = 0x10, OPENNEWWIN = 0x20, DISABLE_OFFSCREEN = 0x40, FLAT_SCROLLBAR = 0x80, DIV_BLOCKDEFAULT = 0x100, ACTIVATE_CLIENTHIT_ONLY = 0x200, NO3DOUTERBORDER = 0x00200000, THEME = 0x00040000, NOTHEME = 0x80000, DISABLE_COOKIE = 0x400 } [StructLayout(LayoutKind.Sequential)] public struct DOCHOSTUIINFO { [MarshalAs(UnmanagedType.U4)] public int cbSize; [MarshalAs(UnmanagedType.I4)] public int dwFlags; [MarshalAs(UnmanagedType.I4)] public int dwDoubleClick; [MarshalAs(UnmanagedType.I4)] public int dwReserved1; [MarshalAs(UnmanagedType.I4)] public int dwReserved2; } [StructLayout(LayoutKind.Sequential)] public struct COMRECT { public int left; public int top; public int right; public int bottom; } [StructLayout(LayoutKind.Sequential)] public struct POINT { public int x; public int y; } [StructLayout(LayoutKind.Sequential)] public struct MSG { public IntPtr hwnd; public int message; public IntPtr wParam; public IntPtr lParam; public int time; POINT pt; } [ComImport(), Guid("BD3F23C0-D43E-11CF-893B-00AA00BDCE1A"), InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIUnknown)] public interface IDocHostUIHandler { [return: MarshalAs(UnmanagedType.I4)] [PreserveSig] int ShowContextMenu( [In, MarshalAs(UnmanagedType.U4)] int dwID, [In] ref POINT pt, [In] IntPtr pcmdtReserved, [In] IntPtr pdispReserved); [return: MarshalAs(UnmanagedType.I4)] [PreserveSig] int GetHostInfo( [In, Out] ref DOCHOSTUIINFO info); [return: MarshalAs(UnmanagedType.I4)] [PreserveSig] int ShowUI( [In, MarshalAs(UnmanagedType.I4)] int dwID, [In] IntPtr activeObject, [In] IntPtr commandTarget, [In] IntPtr frame, [In] IntPtr doc); [return: MarshalAs(UnmanagedType.I4)] [PreserveSig] int HideUI(); [return: MarshalAs(UnmanagedType.I4)] [PreserveSig] int UpdateUI(); [return: MarshalAs(UnmanagedType.I4)] [PreserveSig] int EnableModeless( [In, MarshalAs(UnmanagedType.Bool)] bool fEnable); [return: MarshalAs(UnmanagedType.I4)] [PreserveSig] int OnDocWindowActivate( [In, MarshalAs(UnmanagedType.Bool)] bool fActivate); [return: MarshalAs(UnmanagedType.I4)] [PreserveSig] int OnFrameWindowActivate( [In, MarshalAs(UnmanagedType.Bool)] bool fActivate); [return: MarshalAs(UnmanagedType.I4)] [PreserveSig] int ResizeBorder( [In] ref COMRECT rect, [In] IntPtr doc, bool fFrameWindow); [return: MarshalAs(UnmanagedType.I4)] [PreserveSig] int TranslateAccelerator( [In] ref MSG msg, [In] ref Guid group, [In, MarshalAs(UnmanagedType.I4)] int nCmdID); [return: MarshalAs(UnmanagedType.I4)] [PreserveSig] int GetOptionKeyPath( [Out, MarshalAs(UnmanagedType.LPArray)] String[] pbstrKey, [In, MarshalAs(UnmanagedType.U4)] int dw); [return: MarshalAs(UnmanagedType.I4)] [PreserveSig] int GetDropTarget( [In] IntPtr pDropTarget, [Out] out IntPtr ppDropTarget); [return: MarshalAs(UnmanagedType.I4)] [PreserveSig] int GetExternal( [Out, MarshalAs(UnmanagedType.IDispatch)] out object ppDispatch); [return: MarshalAs(UnmanagedType.I4)] [PreserveSig] int TranslateUrl( [In, MarshalAs(UnmanagedType.U4)] int dwTranslate, [In, MarshalAs(UnmanagedType.LPWStr)] string strURLIn, [Out, MarshalAs(UnmanagedType.LPWStr)] out string pstrURLOut); [return: MarshalAs(UnmanagedType.I4)] [PreserveSig] int FilterDataObject( [In] IntPtr pDO, [Out] out IntPtr ppDORet); } #endregion } }