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.NET Shell Extensions - Shell Drop Handlers

, 19 Jan 2013 CPOL
Rapidly create Shell Drop Handler Extensions using .NET
SharpShell_Core_Library.zip
SharpShell.dll
SharpShell_Source_Code.zip
SharpShell Source Code
Dependencies
Apex
Apex.WinForms.dll
SharpShell
packages
Apex.1.5.0
Apex.1.5.0.nupkg
lib
net35
Apex.dll
net40
Apex.dll
sl30
Apex.Silverlight.dll
sl3-wp
Apex.WP7.dll
sl40
Apex.Silverlight4.dll
sl4-wp71
Apex.WP7.dll
sl50
Apex.Silverlight.dll
NUnit.2.6.2
lib
nunit.framework.dll
NUnit.2.6.2.nupkg
Samples
ContextMenu
CountLinesExtension
CountLinesExtension.csproj.vspscc
Key.snk
Properties
Resources
CountLines.bmp
DropHandler
XsdDropHandler
ExampleFiles
Key.snk
Properties
XsdDropHandler.csproj.vspscc
IconHandler
DllIconHandler
DllIconHandler.csproj.vspscc
Key.snk
Properties
Resources
ManagedDll.ico
NativeDll.ico
IconOverlayHandler
ReadOnlyFileIconOverlayHandler
Key.snk
Properties
ReadOnlyFileIconOverlayHandler.csproj.vspscc
Resources
ReadOnly.ico
InfoTipHandler
FolderInfoTipHandler
FolderInfoTipHandler.csproj.vspscc
Key.snk
Properties
PropertySheet
DrivePropertySheet
DrivePropertySheet.csproj.vspscc
Key.snk
Properties
TextFilePropertySheet
Key.snk
Properties
TextFilePropertySheet.csproj.vspscc
SharpShell
Attributes
Diagnostics
Extensions
Interop
Key.snk
NativeBridge
SharpShellNativeBridge32.dll
SharpShellNativeBridge64.dll
Properties
ServerRegistration
SharpContextMenu
SharpDropHandler
SharpIconHandler
SharpIconOverlayHandler
SharpInfoTipHandler
SharpPropertySheet
SharpShell.csproj.vspscc
SharpShellNativeBridge
SharpShellNativeBridge.vcxproj.filters
SharpShellNativeBridge.vcxproj.user
SharpShellNativeBridge.vcxproj.vspscc
Tools
ServerInspector
Properties
Settings.settings
ServerInspector.csproj.vspscc
Servers
ServerManager
About
LogView
Properties
Settings.settings
Resources
ChangeYourView.png
ContextMenu.png
Icon.png
openHS.png
PlayHS.png
PropertySheet.png
View_Details.png
View_LargeIcons.png
View_List.png
View_SmallIcons.png
View_Tiles.png
ServerDetails
ServerManager.csproj.vspscc
SharpShell.ico
TestShell
ShellExtensionManager
Properties
Settings.settings
ShellExtensionManager.csproj.vspscc
SharpShell_Tools.zip
SharpShell Tools
Apex.dll
Apex.WinForms.dll
ServerInspector.exe
ServerManager.exe
SharpShell.dll
System.Windows.Interactivity.dll
using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using SharpShell.Attributes;
using SharpShell.Extensions;
using SharpShell.Interop;
using IDataObject = System.Runtime.InteropServices.ComTypes.IDataObject;
using IDropTarget = SharpShell.Interop.IDropTarget;

namespace SharpShell.SharpDropHandler
{
    /// <summary>
    /// The SharpIconHandler is the base class for SharpShell servers that provide
    /// custom Icon Handlers.
    /// </summary>
    [ServerType(ServerType.ShellDropHandler)]
    public abstract class SharpDropHandler : PersistFileServer, IDropTarget
    {
        #region Implementation of IDropTarget

        /// <summary>
        /// Indicates whether a drop can be accepted, and, if so, the effect of the drop.
        /// </summary>
        /// <param name="pDataObj">A pointer to the IDataObject interface on the data object. This data object contains the data being transferred in the drag-and-drop operation. If the drop occurs, this data object will be incorporated into the target.</param>
        /// <param name="grfKeyState">The current state of the keyboard modifier keys on the keyboard. Possible values can be a combination of any of the flags MK_CONTROL, MK_SHIFT, MK_ALT, MK_BUTTON, MK_LBUTTON, MK_MBUTTON, and MK_RBUTTON.</param>
        /// <param name="pt">A POINTL structure containing the current cursor coordinates in screen coordinates.</param>
        /// <param name="pdwEffect">On input, pointer to the value of the pdwEffect parameter of the DoDragDrop function. On return, must contain one of the DROPEFFECT flags, which indicates what the result of the drop operation would be.</param>
        /// <returns>
        /// This method returns S_OK on success.
        /// </returns>
        int IDropTarget.DragEnter(IDataObject pDataObj, uint grfKeyState, POINT pt, ref uint pdwEffect)
        {
            //  Log this key event.
            Log(string.Format("Drag Enter for item {0}", SelectedItemPath));

            //  Get the drag items.
            try
            {
                dragItems = pDataObj.GetFileList();
            }
            catch (Exception exception)
            {
                //  Log the error.
                LogError("An exception occured when getting the file list from the data object.", exception);
                return WinError.E_UNEXPECTED;
            }

            //  Create drag event args, which store the provided parameters.
            var dragEventArgs = new DragEventArgs(null, (int) grfKeyState, pt.X, pt.Y, (DragDropEffects) pdwEffect, DragDropEffects.None);

            try
            {
                //  Call the main drag enter function.
                DragEnter(dragEventArgs);
            }
            catch (Exception exception)
            {
                //  Log the exception.
                LogError("An exception occured during a drag enter event.", exception);

                //  Don't allow any drag effect.
                dragEventArgs.Effect = DragDropEffects.None;
            }

            //  Set the effect.
            pdwEffect = (uint)dragEventArgs.Effect;

            //  Return success.
            return WinError.S_OK;
        }

        /// <summary>
        /// Provides target feedback to the user and communicates the drop's effect to the DoDragDrop function so it can communicate the effect of the drop back to the source.
        /// </summary>
        /// <param name="grfKeyState">The current state of the keyboard modifier keys on the keyboard. Valid values can be a combination of any of the flags MK_CONTROL, MK_SHIFT, MK_ALT, MK_BUTTON, MK_LBUTTON, MK_MBUTTON, and MK_RBUTTON.</param>
        /// <param name="pt">A POINTL structure containing the current cursor coordinates in screen coordinates.</param>
        /// <param name="pdwEffect">On input, pointer to the value of the pdwEffect parameter of the DoDragDrop function. On return, must contain one of the DROPEFFECT flags, which indicates what the result of the drop operation would be.</param>
        /// <returns>
        /// This method returns S_OK on success.
        /// </returns>
        int IDropTarget.DragOver(uint grfKeyState, POINT pt, ref uint pdwEffect)
        {
            //  Not called for shell extensions.
            return WinError.S_OK;
        }

        /// <summary>
        /// Removes target feedback and releases the data object.
        /// </summary>
        /// <returns>
        /// This method returns S_OK on success.
        /// </returns>
        int IDropTarget.DragLeave()
        {
            //  We don't have cleanup tasks in this case.
            return WinError.S_OK;
        }

        /// <summary>
        /// Incorporates the source data into the target window, removes target feedback, and releases the data object.
        /// </summary>
        /// <param name="pDataObj">A pointer to the IDataObject interface on the data object being transferred in the drag-and-drop operation.</param>
        /// <param name="grfKeyState">The current state of the keyboard modifier keys on the keyboard. Possible values can be a combination of any of the flags MK_CONTROL, MK_SHIFT, MK_ALT, MK_BUTTON, MK_LBUTTON, MK_MBUTTON, and MK_RBUTTON.</param>
        /// <param name="pt">A POINTL structure containing the current cursor coordinates in screen coordinates.</param>
        /// <param name="pdwEffect">On input, pointer to the value of the pdwEffect parameter of the DoDragDrop function. On return, must contain one of the DROPEFFECT flags, which indicates what the result of the drop operation would be.</param>
        /// <returns>
        /// This method returns S_OK on success.
        /// </returns>
        int IDropTarget.Drop(IDataObject pDataObj, uint grfKeyState, POINT pt, ref uint pdwEffect)
        {
            //  Log this key event.
            Log(string.Format("Drop for item {0}", SelectedItemPath));

            //  Create drag event args, which store the provided parameters.
            var dragEventArgs = new DragEventArgs(null, (int)grfKeyState, pt.X, pt.Y, (DragDropEffects)pdwEffect, DragDropEffects.None);

            try
            {
                //  Perform the drop.
                Drop(dragEventArgs);
            }
            catch (Exception exception)
            {
                //  Log the exception.
                LogError("An exception occured during the drop event.", exception);
            }

            //  Return success.
            return WinError.S_OK;
        }

        #endregion

        /// <summary>
        /// Checks what operations are available for dragging onto the target with the drag files.
        /// </summary>
        /// <param name="dragEventArgs">The <see cref="System.Windows.Forms.DragEventArgs"/> instance containing the event data.</param>
        protected abstract void DragEnter(DragEventArgs dragEventArgs);

        /// <summary>
        /// Performs the drop.
        /// </summary>
        /// <param name="dragEventArgs">The <see cref="System.Windows.Forms.DragEventArgs"/> instance containing the event data.</param>
        protected abstract void Drop(DragEventArgs dragEventArgs);

        /// <summary>
        /// The set of items being dragged.
        /// </summary>
        private List<string> dragItems = new List<string>();

        /// <summary>
        /// Gets the drag items.
        /// </summary>
        public IEnumerable<string> DragItems { get { return dragItems; } } 
    }
}

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This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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Dave Kerr
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United Kingdom United Kingdom
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