mirror of https://github.com/dahall/Vanara.git
178 lines
8.1 KiB
C#
178 lines
8.1 KiB
C#
using System;
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using System.Drawing;
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using System.Windows.Forms;
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using Vanara.PInvoke;
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using static Vanara.PInvoke.Ole32;
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using static Vanara.PInvoke.Shell32;
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using IDataObject = System.Runtime.InteropServices.ComTypes.IDataObject;
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using IDropTarget = Vanara.PInvoke.Ole32.IDropTarget;
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namespace Vanara.Windows.Shell
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{
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/// <summary>
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/// COM object that implements IDropTarget. Solves race problem on drop and simplifies interface calls. All IDropTarget methods call
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/// their equivalent On[MethodName] equivalents. To specialize their handling, simply override the On[MethodName] method or hook an event
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/// to the corresponding event.
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/// </summary>
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/// <remarks>
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/// This class provides an easy means of creating a COM based out-of-process DropTarget.
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/// <list type="number">
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/// <item>Create a .NET application project.</item>
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/// <item>Delete the Program.cs file that includes the Main method.</item>
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/// <item>Create a new class and derive it from <see cref="ShellDropTarget"/> with the attributes in the example below.</item>
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/// <item>Ensure the project is built as "X86".</item>
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/// </list>
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/// <code title="Example" lang="cs">[Guid("<Your GUID here>"), ClassInterface(ClassInterfaceType.None)]
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///public class MyDropTarget : ShellDropTarget
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///{
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/// // In your constructor, be sure to override the DragEnter and DragDrop events and set the effect you desire.
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/// public MyDropTarget() : base()
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/// {
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/// // Setting the effect to Copy here ensure we continue to get drag/drop messages
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/// DragEnter += (s, e) => e.Effect = DragDropEffects.Copy;
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///
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/// DragDrop += MyDragDrop;
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/// }
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///
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/// // This event handler for DragDrop should never hold up the shell. To accommodate a non-blocking response,
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/// // use the 'QueueNonBlockingCallback' method which uses PostThreadMessage to run a delegate as shown below.
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/// private void MyDragDrop(object sender, DragEventArgs e)
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/// {
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/// // Setting the effect to None here ends drag/drop messages
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/// e.Effect = DragDropEffects.None;
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/// // Notice we're passing in the DragEventArgs.Data property that contains the shell item array from the Shell.
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/// QueueNonBlockingCallback(DisplayData, e.Data);
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/// }
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///
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/// // This delegate will get run outside of the Shell's calling path and can display a UI or perform any other
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/// // function on the list of shell items passed to it.
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/// private void DisplayData(object ido)
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/// {
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/// // *** Replace with your functionality ***
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/// using (var shia = ShellItemArray.FromDataObject(ido as DataObject))
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/// {
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/// var szMsg = $"Found {shia.Count} item(s): " + string.Join(", ", shia.Select(i => i.Name));
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/// MessageBox.Show(szMsg, "MyDropTarget");
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/// }
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/// // Don't fail to call QuitMessageLoop once you're done processing the Shell call.
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/// QuitMessageLoop();
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/// }
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///
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/// // This is the main thread of the application. When called from the Shell, it will append the -embedding argument to indicate that
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/// // a message loop needs to start running and the COM server registered. All that is accomplished by calling the 'Run' method
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/// // on your new class.
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/// [STAThread]
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/// private static void Main(string[] args)
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/// {
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/// // *** Replace with your ProgID, name and display name ***
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/// const string progID = "txtfile";
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/// const string verbDisplayName = "DropTarget Verb Sample";
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/// const string verbName = "DropTargetVerb";
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///
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/// var arg = args.Length > 0 ? args[0].TrimStart('-', '/').ToLowerInvariant() : null;
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/// switch (arg)
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/// {
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/// // Handle a call from the Shell launching this out-of-proc server
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/// case "embedding":
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/// new MyDropTarget().Run(TimeSpan.FromSeconds(30));
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/// break;
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///
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/// // Unregister this out-of-proc server from handling the DropTarget. This can be omitted if done by an installer.
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/// case "unregister":
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/// using (var progid = new ProgId(progID, false))
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/// progid.Verbs.Remove(verbName);
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/// ShellRegistrar.UnregisterLocalServer<MyDropTarget>(false);
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/// break;
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///
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/// // Register this out-of-proc server to handle the DropTarget. This can be omitted if done by an installer.
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/// default:
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/// ShellRegistrar.RegisterLocalServer<MyDropTarget>("MyTestDropTarget", systemWide: false);
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/// using (var progid = new ProgId(progID, false))
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/// using (var verb = progid.Verbs.Add(verbName, verbDisplayName))
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/// {
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/// verb.DropTarget = Marshal.GenerateGuidForType(typeof(MyDropTarget));
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/// verb.NeverDefault = true;
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/// }
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/// break;
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/// }
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/// }
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///}</code></remarks>
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/// <seealso cref="Vanara.Windows.Shell.ComObject"/>
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/// <seealso cref="Vanara.PInvoke.Ole32.IDropTarget"/>
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public abstract class ShellDropTarget : ShellCommand, IDropTarget, IInitializeCommand
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{
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private DataObject lastDataObject;
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private DROPEFFECT lastEffect = DROPEFFECT.DROPEFFECT_NONE;
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/// <summary>Initializes a new instance of the <see cref="ShellDropTarget"/> class.</summary>
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protected ShellDropTarget() : base() { }
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/// <summary>Initializes a new instance of the <see cref="ShellDropTarget"/> class.</summary>
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/// <param name="classContext">The context within which the COM object is to be run.</param>
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/// <param name="classUse">Indicates how connections are made to the class object.</param>
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protected ShellDropTarget(CLSCTX classContext, REGCLS classUse) : base(classContext, classUse) { }
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/// <summary>Occurs when a drag-and-drop operation is started. All calls from this event must be non-blocking.</summary>
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public event DragEventHandler DragDrop;
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/// <summary>Occurs to request whether a drop can be accepted, and, if so, the effect of the drop.</summary>
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public event DragEventHandler DragEnter;
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/// <summary>Occurs when the object is told to remove target feedback and releases the data object.</summary>
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public event EventHandler DragLeave;
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/// <summary>
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/// Occurs so target can provide feedback to the user and communicate the drop's effect to the DoDragDrop function so it can
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/// communicate the effect of the drop back to the source.
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/// </summary>
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public event DragEventHandler DragOver;
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/// <inheritdoc/>
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HRESULT IDropTarget.DragEnter(IDataObject pDataObj, uint grfKeyState, Point pt, ref DROPEFFECT pdwEffect)
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{
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System.Diagnostics.Debug.WriteLine($"IDropTarget.DragEnter: effect={pdwEffect}");
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var drgevent = CreateDragEventArgs(pDataObj, grfKeyState, pt, pdwEffect);
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DragEnter?.Invoke(this, drgevent);
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lastEffect = pdwEffect = (DROPEFFECT)drgevent.Effect;
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return HRESULT.S_OK;
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}
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/// <inheritdoc/>
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HRESULT IDropTarget.DragLeave()
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{
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System.Diagnostics.Debug.WriteLine("IDropTarget.DragLeave");
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DragLeave?.Invoke(this, EventArgs.Empty);
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lastDataObject = null;
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return HRESULT.S_OK;
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}
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/// <inheritdoc/>
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HRESULT IDropTarget.DragOver(uint grfKeyState, Point pt, ref DROPEFFECT pdwEffect)
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{
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System.Diagnostics.Debug.WriteLine($"IDropTarget.DragOver: effect={pdwEffect}");
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var drgevent = CreateDragEventArgs(null, grfKeyState, pt, pdwEffect);
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DragOver?.Invoke(this, drgevent);
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lastEffect = pdwEffect = (DROPEFFECT)drgevent.Effect;
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return HRESULT.S_OK;
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}
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/// <inheritdoc/>
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HRESULT IDropTarget.Drop(IDataObject pDataObj, uint grfKeyState, Point pt, ref DROPEFFECT pdwEffect)
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{
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System.Diagnostics.Debug.WriteLine($"IDropTarget.Drop: effect={pdwEffect}");
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var drgevent = CreateDragEventArgs(pDataObj, grfKeyState, pt, pdwEffect);
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DragDrop?.Invoke(this, drgevent);
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pdwEffect = (DROPEFFECT)drgevent.Effect;
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CancelTimeout();
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return HRESULT.S_OK;
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}
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private DragEventArgs CreateDragEventArgs(IDataObject pDataObj, uint grfKeyState, Point pt, DROPEFFECT pdwEffect)
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{
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var data = pDataObj == null ? lastDataObject : new DataObject(pDataObj);
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var drgevent = new DragEventArgs(data, (int)grfKeyState, pt.X, pt.Y, (DragDropEffects)pdwEffect, (DragDropEffects)lastEffect);
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lastDataObject = data;
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return drgevent;
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}
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}
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} |