Add support for drag images and drop descriptions

src/System.Windows.Forms.Primitives/src/Interop/Interop.CLSID.cs

@@ -9,6 +9,9 @@ internal static class CLSID
         // 00BB2763-6A77-11D0-A535-00C04FD7D062
         internal static Guid AutoComplete = new Guid(0x00BB2763, 0x6A77, 0x11D0, 0xA5, 0x35, 0x00, 0xC0, 0x4F, 0xD7, 0xD0, 0x62);
 
+        // 4657278A-411B-11D2-839A-00C04FD918D0
+        internal static Guid DragDropHelper = new Guid(0x4657278A, 0x411B, 0x11D2, 0x83, 0x9A, 0x0, 0xC0, 0x4F, 0xD9, 0x18, 0xD0);
+
         // C0B4E2F3-BA21-4773-8DBA-335EC946EB8B
         internal static Guid FileSaveDialog = new Guid(0xC0B4E2F3, 0xBA21, 0x4773, 0x8D, 0xBA, 0x33, 0x5E, 0xC9, 0x46, 0xEB, 0x8B);
 

src/System.Windows.Forms.Primitives/src/Interop/Interop.IID.cs

@@ -18,6 +18,9 @@ internal static class IID
         // 00000121-0000-0000-C000-000000000046
         public static Guid IDropSource { get; } = new(0x00000121, 0x0000, 0x0000, 0xC0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x46);
 
+        // 0000012B-0000-0000-C000-000000000046
+        public static Guid IDropSourceNotify { get; } = new(0x0000012B, 0x000, 0x000, 0xC0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x46);
+
         // 00000122-0000-0000-C000-000000000046
         public static Guid IDropTarget { get; } = new(0x00000122, 0x0000, 0x0000, 0xC0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x46);
 

src/System.Windows.Forms.Primitives/src/Interop/Ole32/Interop.IDropSourceNotify.cs

@@ -0,0 +1,24 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Runtime.InteropServices;
+
+internal partial class Interop
+{
+    internal static partial class Ole32
+    {
+        [ComImport]
+        [Guid("0000012B-0000-0000-C000-000000000046")]
+        [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
+        public interface IDropSourceNotify
+        {
+            [PreserveSig]
+            HRESULT DragEnterTarget(
+                IntPtr hwndTarget);
+
+            [PreserveSig]
+            HRESULT DragLeaveTarget();
+        }
+    }
+}

src/System.Windows.Forms.Primitives/src/Interop/Ole32/Interop.OleDuplicateData.cs

@@ -0,0 +1,15 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Runtime.InteropServices;
+using static Interop.Kernel32;
+
+internal static partial class Interop
+{
+    internal static partial class Ole32
+    {
+        [DllImport(Libraries.Ole32, ExactSpelling = true)]
+        public static extern IntPtr OleDuplicateData(IntPtr hSrc, short cfFormat, GMEM uiFlags);
+    }
+}

src/System.Windows.Forms.Primitives/src/Interop/Shell32/Interop.DROPDESCRIPTION.cs

@@ -0,0 +1,41 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Runtime.InteropServices;
+
+internal partial class Interop
+{
+    internal static partial class Shell32
+    {
+        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
+        public unsafe struct DROPDESCRIPTION
+        {
+            public DROPIMAGETYPE type;
+            private fixed char _szMessage[Kernel32.MAX_PATH];
+            private fixed char _szInsert[Kernel32.MAX_PATH];
+
+            private Span<char> szMessage
+            {
+                get { fixed (char* c = _szMessage) { return new Span<char>(c, Kernel32.MAX_PATH); } }
+            }
+
+            private Span<char> szInsert
+            {
+                get { fixed (char* c = _szInsert) { return new Span<char>(c, Kernel32.MAX_PATH); } }
+            }
+
+            public ReadOnlySpan<char> Message
+            {
+                get => szMessage.SliceAtFirstNull();
+                set => SpanHelpers.CopyAndTerminate(value, szMessage);
+            }
+
+            public ReadOnlySpan<char> Insert
+            {
+                get => szInsert.SliceAtFirstNull();
+                set => SpanHelpers.CopyAndTerminate(value, szInsert);
+            }
+        }
+    }
+}

src/System.Windows.Forms.Primitives/src/Interop/Shell32/Interop.DROPIMAGETYPE.cs

@@ -0,0 +1,21 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+internal partial class Interop
+{
+    internal static partial class Shell32
+    {
+        public enum DROPIMAGETYPE
+        {
+            DROPIMAGE_INVALID = -1,
+            DROPIMAGE_NONE = 0,
+            DROPIMAGE_COPY = 1,
+            DROPIMAGE_MOVE = 2,
+            DROPIMAGE_LINK = 4,
+            DROPIMAGE_LABEL = 6,
+            DROPIMAGE_WARNING = 7,
+            DROPIMAGE_NOIMAGE = 8
+        }
+    }
+}

src/System.Windows.Forms.Primitives/src/Interop/Shell32/Interop.IDragSourceHelper2.cs

@@ -0,0 +1,31 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Drawing;
+using System.Runtime.InteropServices;
+using System.Runtime.InteropServices.ComTypes;
+
+internal static partial class Interop
+{
+    internal static partial class Shell32
+    {
+        [ComImport]
+        [Guid("DE5BF786-477A-11D2-839D-00C04FD918D0")]
+        [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
+        public interface IDragSourceHelper2
+        {
+            HRESULT InitializeFromBitmap(
+                in SHDRAGIMAGE pshdi,
+                IDataObject dataObject);
+
+            HRESULT InitializeFromWindow(
+                IntPtr hwnd,
+                in Point ppt,
+                IDataObject dataObject);
+
+            HRESULT SetFlags(
+                int dwFlags);
+        }
+    }
+}

src/System.Windows.Forms.Primitives/src/Interop/Shell32/Interop.IDropTargetHelper.cs

@@ -0,0 +1,44 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Drawing;
+using System.Runtime.InteropServices;
+using IComDataObject = System.Runtime.InteropServices.ComTypes.IDataObject;
+
+internal static partial class Interop
+{
+    internal static partial class Shell32
+    {
+        [ComImport]
+        [Guid("4657278B-411B-11D2-839A-00C04FD918D0")]
+        [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
+        public interface IDropTargetHelper
+        {
+            [PreserveSig]
+            HRESULT DragEnter(
+                IntPtr hwndTarget,
+                IComDataObject pDataObj,
+                ref Point ppt,
+                Ole32.DROPEFFECT dwEffect);
+
+            [PreserveSig]
+            HRESULT DragLeave();
+
+            [PreserveSig]
+            HRESULT DragOver(
+                ref Point ppt,
+                Ole32.DROPEFFECT dwEffect);
+
+            [PreserveSig]
+            HRESULT Drop(
+                IComDataObject pDataObj,
+                ref Point ppt,
+                Ole32.DROPEFFECT dwEffect);
+
+            [PreserveSig]
+            HRESULT Show(
+                BOOL fShow);
+        }
+    }
+}

src/System.Windows.Forms.Primitives/src/Interop/Shell32/Interop.SHDRAGIMAGE.cs

@@ -0,0 +1,22 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Drawing;
+using System.Runtime.InteropServices;
+using static Interop.Gdi32;
+
+internal partial class Interop
+{
+    internal static partial class Shell32
+    {
+        [StructLayout(LayoutKind.Sequential)]
+        public struct SHDRAGIMAGE
+        {
+            public Size sizeDragImage;
+            public Point ptOffset;
+            public HBITMAP hbmpDragImage;
+            public COLORREF crColorKey;
+        }
+    }
+}

src/System.Windows.Forms.Primitives/src/Interop/WinFormsComWrappers.IDropSourceNotifyVtbl.cs

@@ -0,0 +1,55 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+
+internal partial class Interop
+{
+    internal unsafe partial class WinFormsComWrappers
+    {
+        internal static class IDropSourceNotifyVtbl
+        {
+            public static IntPtr Create(IntPtr fpQueryInterface, IntPtr fpAddRef, IntPtr fpRelease)
+            {
+                IntPtr* vtblRaw = (IntPtr*)RuntimeHelpers.AllocateTypeAssociatedMemory(typeof(IDropSourceNotifyVtbl), IntPtr.Size * 5);
+                vtblRaw[0] = fpQueryInterface;
+                vtblRaw[1] = fpAddRef;
+                vtblRaw[2] = fpRelease;
+                vtblRaw[3] = (IntPtr)(delegate* unmanaged<IntPtr, IntPtr, HRESULT>)&DragEnterTarget;
+                vtblRaw[4] = (IntPtr)(delegate* unmanaged<IntPtr, HRESULT>)&DragLeaveTarget;
+
+                return (IntPtr)vtblRaw;
+            }
+
+            [UnmanagedCallersOnly]
+            private static HRESULT DragEnterTarget(IntPtr thisPtr, IntPtr hwndTarget)
+            {
+                try
+                {
+                    var instance = ComInterfaceDispatch.GetInstance<Ole32.IDropSourceNotify>((ComInterfaceDispatch*)thisPtr);
+                    return instance.DragEnterTarget(hwndTarget);
+                }
+                catch (Exception ex)
+                {
+                    return (HRESULT)ex.HResult;
+                }
+            }
+
+            [UnmanagedCallersOnly]
+            private static HRESULT DragLeaveTarget(IntPtr thisPtr)
+            {
+                try
+                {
+                    var instance = ComInterfaceDispatch.GetInstance<Ole32.IDropSourceNotify>((ComInterfaceDispatch*)thisPtr);
+                    return instance.DragLeaveTarget();
+                }
+                catch (Exception ex)
+                {
+                    return (HRESULT)ex.HResult;
+                }
+            }
+        }
+    }
+}

src/System.Windows.Forms.Primitives/src/Interop/WinFormsComWrappers.cs

@@ -83,10 +83,13 @@ private WinFormsComWrappers() { }
             GetIUnknownImpl(out IntPtr fpQueryInterface, out IntPtr fpAddRef, out IntPtr fpRelease);
 
             IntPtr iDropSourceVtbl = IDropSourceVtbl.Create(fpQueryInterface, fpAddRef, fpRelease);
+            IntPtr iDropSourceNotifyVtbl = IDropSourceNotifyVtbl.Create(fpQueryInterface, fpAddRef, fpRelease);
 
-            ComInterfaceEntry* wrapperEntry = (ComInterfaceEntry*)RuntimeHelpers.AllocateTypeAssociatedMemory(typeof(WinFormsComWrappers), sizeof(ComInterfaceEntry));
-            wrapperEntry->IID = IID.IDropSource;
-            wrapperEntry->Vtable = iDropSourceVtbl;
+            ComInterfaceEntry* wrapperEntry = (ComInterfaceEntry*)RuntimeHelpers.AllocateTypeAssociatedMemory(typeof(WinFormsComWrappers), sizeof(ComInterfaceEntry) * 2);
+            wrapperEntry[0].IID = IID.IDropSource;
+            wrapperEntry[0].Vtable = iDropSourceVtbl;
+            wrapperEntry[1].IID = IID.IDropSourceNotify;
+            wrapperEntry[1].Vtable = iDropSourceNotifyVtbl;
             return wrapperEntry;
         }
 
@@ -130,7 +133,7 @@ private WinFormsComWrappers() { }
 
             if (obj is Ole32.IDropSource)
             {
-                count = 1;
+                count = 2;
                 return s_dropSourceEntry;
             }
 

src/System.Windows.Forms/src/PublicAPI.Unshipped.txt

@@ -1 +1,26 @@
-~override System.Windows.Forms.WebBrowser.CreateAccessibilityInstance() -> System.Windows.Forms.AccessibleObject
+System.Windows.Forms.DropImageType
+System.Windows.Forms.DropImageType.Invalid = -1 -> System.Windows.Forms.DropImageType
+System.Windows.Forms.DropImageType.None = 0 -> System.Windows.Forms.DropImageType
+System.Windows.Forms.DropImageType.Copy = 1 -> System.Windows.Forms.DropImageType
+System.Windows.Forms.DropImageType.Move = 2 -> System.Windows.Forms.DropImageType
+System.Windows.Forms.DropImageType.Link = 4 -> System.Windows.Forms.DropImageType
+System.Windows.Forms.DropImageType.Label = 6 -> System.Windows.Forms.DropImageType
+System.Windows.Forms.DropImageType.Warning = 7 -> System.Windows.Forms.DropImageType
+System.Windows.Forms.DropImageType.NoImage = 8 -> System.Windows.Forms.DropImageType
+~System.Windows.Forms.Control.DoDragDrop(object data, System.Windows.Forms.DragDropEffects allowedEffects, System.Drawing.Bitmap dragImage, System.Drawing.Point cursorOffset, bool useDefaultDragImage) -> System.Windows.Forms.DragDropEffects
+~System.Windows.Forms.ToolStripItem.DoDragDrop(object data, System.Windows.Forms.DragDropEffects allowedEffects, System.Drawing.Bitmap dragImage, System.Drawing.Point cursorOffset, bool useDefaultDragImage) -> System.Windows.Forms.DragDropEffects
+System.Windows.Forms.DragEventArgs.DragEventArgs(System.Windows.Forms.IDataObject? data, int keyState, int x, int y, System.Windows.Forms.DragDropEffects allowedEffect, System.Windows.Forms.DragDropEffects effect, System.Windows.Forms.DropImageType dropImageType, string! message, string! messageReplacementToken) -> void
+System.Windows.Forms.DragEventArgs.DropImageType.get -> System.Windows.Forms.DropImageType
+System.Windows.Forms.DragEventArgs.DropImageType.set -> void
+System.Windows.Forms.DragEventArgs.Message.get -> string?
+System.Windows.Forms.DragEventArgs.Message.set -> void
+System.Windows.Forms.DragEventArgs.MessageReplacementToken.get -> string?
+System.Windows.Forms.DragEventArgs.MessageReplacementToken.set -> void
+System.Windows.Forms.GiveFeedbackEventArgs.GiveFeedbackEventArgs(System.Windows.Forms.DragDropEffects effect, bool useDefaultCursors, System.Drawing.Bitmap? dragImage, System.Drawing.Point cursorOffset, bool useDefaultDragImage) -> void
+System.Windows.Forms.GiveFeedbackEventArgs.CursorOffset.get -> System.Drawing.Point
+System.Windows.Forms.GiveFeedbackEventArgs.CursorOffset.set -> void
+System.Windows.Forms.GiveFeedbackEventArgs.DragImage.get -> System.Drawing.Bitmap?
+System.Windows.Forms.GiveFeedbackEventArgs.DragImage.set -> void
+System.Windows.Forms.GiveFeedbackEventArgs.UseDefaultDragImage.get -> bool
+System.Windows.Forms.GiveFeedbackEventArgs.UseDefaultDragImage.set -> void
+~override System.Windows.Forms.WebBrowser.CreateAccessibilityInstance() -> System.Windows.Forms.AccessibleObject

src/System.Windows.Forms/src/System/Windows/Forms/Control.cs

@@ -5285,8 +5285,34 @@ internal virtual void DisposeAxControls()
         /// </summary>
         public DragDropEffects DoDragDrop(object data, DragDropEffects allowedEffects)
         {
-            Ole32.IDropSource dropSource = new DropSource(this);
+            return DoDragDrop(data, allowedEffects, dragImage: null, cursorOffset: default, useDefaultDragImage: false);
+        }
 
+        /// <summary>
+        ///  Begins a drag operation. The <paramref name="allowedEffects"/> determine which drag operations can occur. If the drag operation
+        ///  needs to interop with applications in another process, <paramref name="data"/> should either be a base managed class
+        ///  (<see cref="string"/>, <see cref="Bitmap"/>, or <see cref="Drawing.Imaging.Metafile"/>) or some <see cref="object"/> that implements
+        ///  <see cref="Runtime.Serialization.ISerializable"/>. <paramref name="data"/> can also be any <see cref="object"/> that implements
+        ///  <see cref="IDataObject"/>. <paramref name="dragImage"/> is the bitmap that will be displayed during the  drag operation and
+        ///  <paramref name="cursorOffset"/> specifies the location of the cursor within <paramref name="dragImage"/>, which is an offset from the
+        ///  upper-left corner. Specify <see langword="true"/> for <paramref name="useDefaultDragImage"/> to use a layered window drag image with a
+        ///  size of 96x96; otherwise <see langword="false"/>. Note the outer edges of <paramref name="dragImage"/> are blended out if the image width
+        ///  or height exceeds 300 pixels.
+        /// </summary>
+        /// <returns>
+        ///  A value from the <see cref="DragDropEffects"/> enumeration that represents the final effect that was performed during the drag-and-drop
+        ///  operation.
+        /// </returns>
+        /// <remarks>
+        ///  <para>
+        ///   Because <see cref="DoDragDrop(object, DragDropEffects, Bitmap, Point, bool)"/> always performs the RGB multiplication step in calculating
+        ///   the alpha value, you should always pass a <see cref="Bitmap"/> without premultiplied alpha blending. Note that no error will result from
+        ///   passing a <see cref="Bitmap"/> with premultiplied alpha blending, but this method will multiply it again, doubling the resulting alpha
+        ///   value.
+        ///  </para>
+        /// </remarks>
+        public DragDropEffects DoDragDrop(object data, DragDropEffects allowedEffects, Bitmap dragImage, Point cursorOffset, bool useDefaultDragImage)
+        {
             IComDataObject dataObject = null;
 
             if (data is IComDataObject)
@@ -5309,10 +5335,23 @@ public DragDropEffects DoDragDrop(object data, DragDropEffects allowedEffects)
                 dataObject = (IComDataObject)iwdata;
             }
 
-            HRESULT hr = Ole32.DoDragDrop(dataObject, dropSource, (Ole32.DROPEFFECT)allowedEffects, out Ole32.DROPEFFECT finalEffect);
-            if (!hr.Succeeded())
+            Ole32.DROPEFFECT finalEffect;
+
+            try
             {
-                return DragDropEffects.None;
+                Ole32.IDropSource dropSource = new DropSource(this, dataObject, dragImage, cursorOffset, useDefaultDragImage);
+                HRESULT hr = Ole32.DoDragDrop(dataObject, dropSource, (Ole32.DROPEFFECT)allowedEffects, out finalEffect);
+                if (!hr.Succeeded())
+                {
+                    return DragDropEffects.None;
+                }
+            }
+            finally
+            {
+                if (DragDropHelper.IsInDragLoop(dataObject))
+                {
+                    DragDropHelper.SetInDragLoop(dataObject, inDragLoop: false);
+                }
             }
 
             return (DragDropEffects)finalEffect;