From 8463c01123635050bce13f738e38dd9891438558 Mon Sep 17 00:00:00 2001
From: Lea Anthony <lea.anthony@gmail.com>
Date: Sat, 21 Oct 2023 11:21:10 +1100
Subject: [PATCH] [windows] Drag-n-drop support

---
 v3/examples/drag-n-drop/assets/index.html     |  11 ++
 v3/examples/drag-n-drop/main.go               |   4 +-
 v3/go.mod                                     |   4 +-
 v3/go.sum                                     |   6 +-
 .../runtime/desktop/api/event_types.js        |   5 +
 v3/pkg/application/application.go             |   7 +
 .../application/context_application_event.go  |   1 -
 v3/pkg/application/context_window_event.go    |   1 -
 .../application/options_webview_window_win.go |  22 ++-
 v3/pkg/application/webview_window.go          |   2 +-
 v3/pkg/application/webview_window_windows.go  | 118 ++++++++++++
 v3/pkg/events/events.go                       |  95 +++++-----
 v3/pkg/events/events.txt                      |   5 +
 v3/pkg/w32/com.go                             |  55 ++++++
 v3/pkg/w32/idataobject.go                     | 168 ++++++++++++++++++
 v3/pkg/w32/idroptarget.go                     | 129 ++++++++++++++
 v3/pkg/w32/iunknown.go                        |  29 ---
 v3/pkg/w32/ole32.go                           |  20 +++
 v3/pkg/w32/shell32.go                         |   6 +-
 v3/pkg/w32/utils.go                           |   6 +-
 v3/tasks/events/generate.go                   |   4 -
 21 files changed, 608 insertions(+), 90 deletions(-)
 create mode 100644 v3/pkg/w32/com.go
 create mode 100644 v3/pkg/w32/idataobject.go
 create mode 100644 v3/pkg/w32/idroptarget.go
 delete mode 100644 v3/pkg/w32/iunknown.go

diff --git a/v3/examples/drag-n-drop/assets/index.html b/v3/examples/drag-n-drop/assets/index.html
index c5ac43d9..6e7e2dd5 100644
--- a/v3/examples/drag-n-drop/assets/index.html
+++ b/v3/examples/drag-n-drop/assets/index.html
@@ -13,6 +13,17 @@ Drop Files onto this window...
 </body>
 
 <script>
+    document.body.addEventListener('drop', function(e) {
+        // Note that postMessageWithAdditionalObjects does not accept a single object,
+        // but only accepts an ArrayLike object.
+        // However, input.files is type FileList, which is already an ArrayLike object so
+        // no conversion to array is needed.
+        const currentFiles = input.files;
+        chrome.webview.postMessageWithAdditionalObjects("FilesDropped", currentFiles);
+        e.preventDefault();
+        e.stopPropagation();
+        return false;
+    });
     wails.Events.On("files", function(event) {
         let resultsHTML = "";
         event.data.forEach(function(file) {
diff --git a/v3/examples/drag-n-drop/main.go b/v3/examples/drag-n-drop/main.go
index 10b64c96..a0feae58 100644
--- a/v3/examples/drag-n-drop/main.go
+++ b/v3/examples/drag-n-drop/main.go
@@ -35,13 +35,13 @@ func main() {
 		EnableDragAndDrop: true,
 	})
 
-	window.On(events.FilesDropped, func(event *application.WindowEvent) {
+	window.On(events.Common.WindowFilesDropped, func(event *application.WindowEvent) {
 		files := event.Context().DroppedFiles()
 		app.Events.Emit(&application.WailsEvent{
 			Name: "files",
 			Data: files,
 		})
-		log.Printf("[Go] FilesDropped received: %+v\n", files)
+		app.Logger.Info("Files Dropped!", "files", files)
 	})
 
 	err := app.Run()
diff --git a/v3/go.mod b/v3/go.mod
index d4f8cb7a..4ae5c50c 100644
--- a/v3/go.mod
+++ b/v3/go.mod
@@ -28,9 +28,10 @@ require (
 	github.com/pkg/browser v0.0.0-20210911075715-681adbf594b8
 	github.com/pkg/errors v0.9.1
 	github.com/pterm/pterm v0.12.51
+	github.com/rodrigocfd/windigo v0.0.0-20230809154420-8faa606d9f5f
 	github.com/samber/lo v1.38.1
 	github.com/tc-hib/winres v0.1.6
-	github.com/wailsapp/go-webview2 v1.0.8
+	github.com/wailsapp/go-webview2 v1.0.9-0.20231016103125-072d9d56c9b2
 	github.com/wailsapp/mimetype v1.4.1
 	golang.org/x/net v0.10.0
 	golang.org/x/sys v0.13.0
@@ -108,3 +109,4 @@ require (
 )
 
 replace github.com/ebitengine/purego v0.4.0-alpha.4 => github.com/tmclane/purego v0.0.0-20230818202843-0b72c8c9140f
+replace github.com/wailsapp/go-webview2 v1.0.9-0.20231016103125-072d9d56c9b2 => ..\..\go-webview2
\ No newline at end of file
diff --git a/v3/go.sum b/v3/go.sum
index 7be6e76e..4e1fb37c 100644
--- a/v3/go.sum
+++ b/v3/go.sum
@@ -314,6 +314,8 @@ github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec/go.mod h1:qq
 github.com/rivo/uniseg v0.2.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJtxc=
 github.com/rivo/uniseg v0.4.4 h1:8TfxU8dW6PdqD27gjM8MVNuicgxIjxpm4K7x4jp8sis=
 github.com/rivo/uniseg v0.4.4/go.mod h1:FN3SvrM+Zdj16jyLfmOkMNblXMcoc8DfTHruCPUcx88=
+github.com/rodrigocfd/windigo v0.0.0-20230809154420-8faa606d9f5f h1:jIXpgDE/hOglaKyTP5ZRqe6rhcJx2dtCan2ncR66qhU=
+github.com/rodrigocfd/windigo v0.0.0-20230809154420-8faa606d9f5f/go.mod h1:Vw0QLpSedVsbAFWYIVE/Zb1pa6XPIgwIMTUQQoUG8Wo=
 github.com/rogpeppe/go-internal v1.3.0/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFRclV5y23lUDJ4=
 github.com/rogpeppe/go-internal v1.10.1-0.20230524175051-ec119421bb97 h1:3RPlVWzZ/PDqmVuf/FKHARG5EMid/tl7cv54Sw/QRVY=
 github.com/rogpeppe/go-internal v1.10.1-0.20230524175051-ec119421bb97/go.mod h1:ddIwULY96R17DhadqLgMfk9H9tvdUzkipdSkR5nkCZA=
@@ -346,8 +348,8 @@ github.com/tc-hib/winres v0.1.6 h1:qgsYHze+BxQPEYilxIz/KCQGaClvI2+yLBAZs+3+0B8=
 github.com/tc-hib/winres v0.1.6/go.mod h1:pe6dOR40VOrGz8PkzreVKNvEKnlE8t4yR8A8naL+t7A=
 github.com/tmclane/purego v0.0.0-20230818202843-0b72c8c9140f h1:/HXk9aFXP97CJRzOIphm4pzySmJLqIMhKu1kD5usz1E=
 github.com/tmclane/purego v0.0.0-20230818202843-0b72c8c9140f/go.mod h1:ah1In8AOtksoNK6yk5z1HTJeUkC1Ez4Wk2idgGslMwQ=
-github.com/wailsapp/go-webview2 v1.0.8 h1:hyoFPlMSfb/NM64wuVbgBaq1MASJjqsSUYhN+Rbcr9Y=
-github.com/wailsapp/go-webview2 v1.0.8/go.mod h1:Uk2BePfCRzttBBjFrBmqKGJd41P6QIHeV9kTgIeOZNo=
+github.com/wailsapp/go-webview2 v1.0.9-0.20231016103125-072d9d56c9b2 h1:FDoMl9tSWP2bjfhARy8zaH2gRxq98TIleMmCHq6YuNo=
+github.com/wailsapp/go-webview2 v1.0.9-0.20231016103125-072d9d56c9b2/go.mod h1:Uk2BePfCRzttBBjFrBmqKGJd41P6QIHeV9kTgIeOZNo=
 github.com/wailsapp/mimetype v1.4.1 h1:pQN9ycO7uo4vsUUuPeHEYoUkLVkaRntMnHJxVwYhwHs=
 github.com/wailsapp/mimetype v1.4.1/go.mod h1:9aV5k31bBOv5z6u+QP8TltzvNGJPmNJD4XlAL3U+j3o=
 github.com/xanzy/ssh-agent v0.3.0 h1:wUMzuKtKilRgBAD1sUb8gOwwRr2FGoBVumcjoOACClI=
diff --git a/v3/internal/runtime/desktop/api/event_types.js b/v3/internal/runtime/desktop/api/event_types.js
index 5fc44e71..d6344aa6 100644
--- a/v3/internal/runtime/desktop/api/event_types.js
+++ b/v3/internal/runtime/desktop/api/event_types.js
@@ -22,6 +22,10 @@ export const EventTypes = {
 		WindowClose: "windows:WindowClose",
 		WindowSetFocus: "windows:WindowSetFocus",
 		WindowKillFocus: "windows:WindowKillFocus",
+		WindowDragDrop: "windows:WindowDragDrop",
+		WindowDragEnter: "windows:WindowDragEnter",
+		WindowDragLeave: "windows:WindowDragLeave",
+		WindowDragOver: "windows:WindowDragOver",
 	},
 	Mac: {
 		ApplicationDidBecomeActive: "mac:ApplicationDidBecomeActive",
@@ -167,6 +171,7 @@ export const EventTypes = {
 		WindowShow: "common:WindowShow",
 		WindowHide: "common:WindowHide",
 		WindowDPIChanged: "common:WindowDPIChanged",
+		WindowFilesDropped: "common:WindowFilesDropped",
 		ThemeChanged: "common:ThemeChanged",
 	},
 };
diff --git a/v3/pkg/application/application.go b/v3/pkg/application/application.go
index faf3954a..8ffea808 100644
--- a/v3/pkg/application/application.go
+++ b/v3/pkg/application/application.go
@@ -191,6 +191,13 @@ type dragAndDropMessage struct {
 
 var windowDragAndDropBuffer = make(chan *dragAndDropMessage)
 
+func addDragAndDropMessage(windowId uint, filenames []string) {
+	windowDragAndDropBuffer <- &dragAndDropMessage{
+		windowId:  windowId,
+		filenames: filenames,
+	}
+}
+
 var _ webview.Request = &webViewAssetRequest{}
 
 const webViewRequestHeaderWindowId = "x-wails-window-id"
diff --git a/v3/pkg/application/context_application_event.go b/v3/pkg/application/context_application_event.go
index ba455fb3..27d539d0 100644
--- a/v3/pkg/application/context_application_event.go
+++ b/v3/pkg/application/context_application_event.go
@@ -3,7 +3,6 @@ package application
 var blankApplicationEventContext = &ApplicationEventContext{}
 
 const (
-	// FilesDropped is the event name for when files are dropped on the window
 	openedFiles = "openedFiles"
 )
 
diff --git a/v3/pkg/application/context_window_event.go b/v3/pkg/application/context_window_event.go
index f9895fbd..f5063b19 100644
--- a/v3/pkg/application/context_window_event.go
+++ b/v3/pkg/application/context_window_event.go
@@ -3,7 +3,6 @@ package application
 var blankWindowEventContext = &WindowEventContext{}
 
 const (
-	// FilesDropped is the event name for when files are dropped on the window
 	droppedFiles = "droppedFiles"
 )
 
diff --git a/v3/pkg/application/options_webview_window_win.go b/v3/pkg/application/options_webview_window_win.go
index 1e8a10d4..4ebec538 100644
--- a/v3/pkg/application/options_webview_window_win.go
+++ b/v3/pkg/application/options_webview_window_win.go
@@ -1,8 +1,24 @@
 package application
 
-import "github.com/wailsapp/wails/v3/pkg/events"
+import (
+	"github.com/wailsapp/wails/v3/pkg/events"
+)
 
 type BackdropType int32
+type DragEffect int32
+
+const (
+	// DragEffectNone is used to indicate that the drop target cannot accept the data.
+	DragEffectNone DragEffect = 1
+	// DragEffectCopy is used to indicate that the data is copied to the drop target.
+	DragEffectCopy DragEffect = 2
+	// DragEffectMove is used to indicate that the data is removed from the drag source.
+	DragEffectMove DragEffect = 3
+	// DragEffectLink is used to indicate that a link to the original data is established.
+	DragEffectLink DragEffect = 4
+	// DragEffectScroll is used to indicate that the target can be scrolled while dragging to locate a drop position that is not currently visible in the target.
+
+)
 
 const (
 	Auto    BackdropType = 0
@@ -74,6 +90,10 @@ type WindowsWindow struct {
 
 	// Menu is the menu to use for the window.
 	Menu *Menu
+
+	// Drag Cursor Effects
+	OnEnterEffect DragEffect
+	OnOverEffect  DragEffect
 }
 
 type Theme int
diff --git a/v3/pkg/application/webview_window.go b/v3/pkg/application/webview_window.go
index 800bc493..a074b607 100644
--- a/v3/pkg/application/webview_window.go
+++ b/v3/pkg/application/webview_window.go
@@ -1010,7 +1010,7 @@ func (w *WebviewWindow) HandleDragAndDropMessage(filenames []string) {
 	ctx := newWindowEventContext()
 	ctx.setDroppedFiles(filenames)
 	thisEvent.ctx = ctx
-	for _, listener := range w.eventListeners[uint(events.FilesDropped)] {
+	for _, listener := range w.eventListeners[uint(events.Common.WindowFilesDropped)] {
 		listener.callback(thisEvent)
 	}
 }
diff --git a/v3/pkg/application/webview_window_windows.go b/v3/pkg/application/webview_window_windows.go
index 5a70d465..e4249fb9 100644
--- a/v3/pkg/application/webview_window_windows.go
+++ b/v3/pkg/application/webview_window_windows.go
@@ -14,6 +14,7 @@ import (
 	"path"
 	"strconv"
 	"strings"
+	"sync"
 	"time"
 	"unicode/utf16"
 	"unsafe"
@@ -60,6 +61,8 @@ type windowsWebviewWindow struct {
 	resizeBorderWidth  int32
 	resizeBorderHeight int32
 	focusingChromium   bool
+	dropTarget         *w32.DropTarget
+	onceDo             sync.Once
 }
 
 func (w *windowsWebviewWindow) handleKeyEvent(_ string) {
@@ -391,6 +394,9 @@ func (w *windowsWebviewWindow) relativePosition() (int, int) {
 
 func (w *windowsWebviewWindow) destroy() {
 	// Not sure if we have anything to destroy...
+	if w.dropTarget != nil {
+		w.dropTarget.Release()
+	}
 }
 
 func (w *windowsWebviewWindow) reload() {
@@ -915,6 +921,7 @@ func (w *windowsWebviewWindow) isActive() bool {
 }
 
 func (w *windowsWebviewWindow) WndProc(msg uint32, wparam, lparam uintptr) uintptr {
+	w.onceDo.Do(w.onCreate)
 	switch msg {
 	case w32.WM_ACTIVATE:
 		if int(wparam&0xffff) == w32.WA_INACTIVE {
@@ -1006,6 +1013,7 @@ func (w *windowsWebviewWindow) WndProc(msg uint32, wparam, lparam uintptr) uintp
 		if hasConstraints {
 			return 0
 		}
+
 	case w32.WM_DPICHANGED:
 		newWindowSize := (*w32.RECT)(unsafe.Pointer(lparam))
 		w32.SetWindowPos(w.hwnd,
@@ -1299,6 +1307,7 @@ func (w *windowsWebviewWindow) setupChromium() {
 	}
 
 	chromium.MessageCallback = w.processMessage
+	chromium.MessageWithAdditionalObjectsCallback = w.processMessageWithAdditionalObjects
 	chromium.WebResourceRequestedCallback = w.processRequest
 	chromium.NavigationCompletedCallback = w.navigationCompleted
 	chromium.AcceleratorKeyCallback = func(vkey uint) bool {
@@ -1318,6 +1327,49 @@ func (w *windowsWebviewWindow) setupChromium() {
 		}
 	}
 
+	if chromium.HasCapability(edge.AllowExternalDrop) {
+		err := chromium.AllowExternalDrag(false)
+		if err != nil {
+			globalApplication.fatal(err.Error())
+		}
+		if opts.OnEnterEffect != 0 {
+			w.dropTarget.OnEnterEffect = convertEffect(opts.OnEnterEffect)
+		}
+		if opts.OnOverEffect != 0 {
+			w.dropTarget.OnOverEffect = convertEffect(opts.OnOverEffect)
+		}
+		if w.parent.options.EnableDragAndDrop {
+			w.dropTarget = w32.NewDropTarget()
+			w.dropTarget.OnDrop = func(files []string) {
+				w.parent.emit(events.Windows.WindowDragDrop)
+				windowDragAndDropBuffer <- &dragAndDropMessage{
+					windowId:  windowID,
+					filenames: files,
+				}
+			}
+			w.dropTarget.OnEnter = func() {
+				w.parent.emit(events.Windows.WindowDragEnter)
+			}
+			w.dropTarget.OnLeave = func() {
+				w.parent.emit(events.Windows.WindowDragLeave)
+			}
+			w.dropTarget.OnOver = func() {
+				w.parent.emit(events.Windows.WindowDragOver)
+			}
+		}
+	}
+
+	// We will get round to this
+	//if chromium.HasCapability(edge.AllowExternalDrop) {
+	//	err := chromium.AllowExternalDrag(w.parent.options.EnableDragAndDrop)
+	//	if err != nil {
+	//		globalApplication.fatal(err.Error())
+	//	}
+	//	if w.parent.options.EnableDragAndDrop {
+	//		chromium.MessageWithAdditionalObjectsCallback = w.processMessageWithAdditionalObjects
+	//	}
+	//}
+
 	chromium.Resize()
 	settings, err := chromium.GetSettings()
 	if err != nil {
@@ -1408,6 +1460,19 @@ func (w *windowsWebviewWindow) setupChromium() {
 
 }
 
+func convertEffect(effect DragEffect) w32.DWORD {
+	switch effect {
+	case DragEffectCopy:
+		return w32.DROPEFFECT_COPY
+	case DragEffectMove:
+		return w32.DROPEFFECT_MOVE
+	case DragEffectLink:
+		return w32.DROPEFFECT_LINK
+	default:
+		return w32.DROPEFFECT_NONE
+	}
+}
+
 func (w *windowsWebviewWindow) flash(enabled bool) {
 	w32.FlashWindow(w.hwnd, enabled)
 }
@@ -1484,6 +1549,59 @@ func (w *windowsWebviewWindow) processKeyBinding(vkey uint) bool {
 
 }
 
+func (w *windowsWebviewWindow) processMessageWithAdditionalObjects(message string, sender *edge.ICoreWebView2, args *edge.ICoreWebView2WebMessageReceivedEventArgs) {
+	if strings.HasPrefix(message, "FilesDropped") {
+		objs, err := args.GetAdditionalObjects()
+		if err != nil {
+			globalApplication.error(err.Error())
+			return
+		}
+
+		defer objs.Release()
+
+		count, err := objs.GetCount()
+		if err != nil {
+			globalApplication.error(err.Error())
+			return
+		}
+
+		var filenames []string
+		for i := uint32(0); i < count; i++ {
+			_file, err := objs.GetValueAtIndex(i)
+			if err != nil {
+				globalApplication.error("cannot get value at %d : %s", i, err.Error())
+				return
+			}
+
+			file := (*edge.ICoreWebView2File)(unsafe.Pointer(_file))
+			defer file.Release()
+
+			filepath, err := file.GetPath()
+			if err != nil {
+				globalApplication.error("cannot get path for object at %d : %s", i, err.Error())
+				return
+			}
+
+			filenames = append(filenames, filepath)
+		}
+
+		addDragAndDropMessage(w.parent.id, filenames)
+		return
+	}
+}
+
+func (w *windowsWebviewWindow) onCreate() {
+	// Register DnD
+	InvokeSync(func() {
+		if w.parent.options.EnableDragAndDrop {
+			err := w32.RegisterDragDrop(w.hwnd, w.dropTarget)
+			if err != nil {
+				globalApplication.error("Error registering drag and drop: " + err.Error())
+			}
+		}
+	})
+}
+
 func ScaleWithDPI(pixels int, dpi uint) int {
 	return (pixels * int(dpi)) / 96
 }
diff --git a/v3/pkg/events/events.go b/v3/pkg/events/events.go
index 5bfb66b9..8cf2f44f 100644
--- a/v3/pkg/events/events.go
+++ b/v3/pkg/events/events.go
@@ -3,10 +3,6 @@ package events
 type ApplicationEventType uint
 type WindowEventType uint
 
-const (
-	FilesDropped WindowEventType = iota
-)
-
 var Common = newCommonEvents()
 
 type commonEvents struct {
@@ -28,30 +24,32 @@ type commonEvents struct {
 	WindowShow         WindowEventType
 	WindowHide         WindowEventType
 	WindowDPIChanged   WindowEventType
+	WindowFilesDropped WindowEventType
 	ThemeChanged       ApplicationEventType
 }
 
 func newCommonEvents() commonEvents {
 	return commonEvents{
-		ApplicationStarted: 1168,
-		WindowMaximise:     1169,
-		WindowUnMaximise:   1170,
-		WindowFullscreen:   1171,
-		WindowUnFullscreen: 1172,
-		WindowRestore:      1173,
-		WindowMinimise:     1174,
-		WindowUnMinimise:   1175,
-		WindowClosing:      1176,
-		WindowZoom:         1177,
-		WindowZoomIn:       1178,
-		WindowZoomOut:      1179,
-		WindowZoomReset:    1180,
-		WindowFocus:        1181,
-		WindowLostFocus:    1182,
-		WindowShow:         1183,
-		WindowHide:         1184,
-		WindowDPIChanged:   1185,
-		ThemeChanged:       1186,
+		ApplicationStarted: 1172,
+		WindowMaximise:     1173,
+		WindowUnMaximise:   1174,
+		WindowFullscreen:   1175,
+		WindowUnFullscreen: 1176,
+		WindowRestore:      1177,
+		WindowMinimise:     1178,
+		WindowUnMinimise:   1179,
+		WindowClosing:      1180,
+		WindowZoom:         1181,
+		WindowZoomIn:       1182,
+		WindowZoomOut:      1183,
+		WindowZoomReset:    1184,
+		WindowFocus:        1185,
+		WindowLostFocus:    1186,
+		WindowShow:         1187,
+		WindowHide:         1188,
+		WindowDPIChanged:   1189,
+		WindowFilesDropped: 1190,
+		ThemeChanged:       1191,
 	}
 }
 
@@ -335,6 +333,10 @@ type windowsEvents struct {
 	WindowClose                WindowEventType
 	WindowSetFocus             WindowEventType
 	WindowKillFocus            WindowEventType
+	WindowDragDrop             WindowEventType
+	WindowDragEnter            WindowEventType
+	WindowDragLeave            WindowEventType
+	WindowDragOver             WindowEventType
 }
 
 func newWindowsEvents() windowsEvents {
@@ -360,6 +362,10 @@ func newWindowsEvents() windowsEvents {
 		WindowClose:                1165,
 		WindowSetFocus:             1166,
 		WindowKillFocus:            1167,
+		WindowDragDrop:             1168,
+		WindowDragEnter:            1169,
+		WindowDragLeave:            1170,
+		WindowDragOver:             1171,
 	}
 }
 
@@ -512,23 +518,28 @@ var eventToJS = map[uint]string{
 	1165: "windows:WindowClose",
 	1166: "windows:WindowSetFocus",
 	1167: "windows:WindowKillFocus",
-	1168: "common:ApplicationStarted",
-	1169: "common:WindowMaximise",
-	1170: "common:WindowUnMaximise",
-	1171: "common:WindowFullscreen",
-	1172: "common:WindowUnFullscreen",
-	1173: "common:WindowRestore",
-	1174: "common:WindowMinimise",
-	1175: "common:WindowUnMinimise",
-	1176: "common:WindowClosing",
-	1177: "common:WindowZoom",
-	1178: "common:WindowZoomIn",
-	1179: "common:WindowZoomOut",
-	1180: "common:WindowZoomReset",
-	1181: "common:WindowFocus",
-	1182: "common:WindowLostFocus",
-	1183: "common:WindowShow",
-	1184: "common:WindowHide",
-	1185: "common:WindowDPIChanged",
-	1186: "common:ThemeChanged",
+	1168: "windows:WindowDragDrop",
+	1169: "windows:WindowDragEnter",
+	1170: "windows:WindowDragLeave",
+	1171: "windows:WindowDragOver",
+	1172: "common:ApplicationStarted",
+	1173: "common:WindowMaximise",
+	1174: "common:WindowUnMaximise",
+	1175: "common:WindowFullscreen",
+	1176: "common:WindowUnFullscreen",
+	1177: "common:WindowRestore",
+	1178: "common:WindowMinimise",
+	1179: "common:WindowUnMinimise",
+	1180: "common:WindowClosing",
+	1181: "common:WindowZoom",
+	1182: "common:WindowZoomIn",
+	1183: "common:WindowZoomOut",
+	1184: "common:WindowZoomReset",
+	1185: "common:WindowFocus",
+	1186: "common:WindowLostFocus",
+	1187: "common:WindowShow",
+	1188: "common:WindowHide",
+	1189: "common:WindowDPIChanged",
+	1190: "common:WindowFilesDropped",
+	1191: "common:ThemeChanged",
 }
diff --git a/v3/pkg/events/events.txt b/v3/pkg/events/events.txt
index 5df968e0..9b22a3c4 100644
--- a/v3/pkg/events/events.txt
+++ b/v3/pkg/events/events.txt
@@ -142,6 +142,10 @@ windows:WindowUnMinimise
 windows:WindowClose
 windows:WindowSetFocus
 windows:WindowKillFocus
+windows:WindowDragDrop
+windows:WindowDragEnter
+windows:WindowDragLeave
+windows:WindowDragOver
 common:ApplicationStarted
 common:WindowMaximise
 common:WindowUnMaximise
@@ -160,4 +164,5 @@ common:WindowLostFocus
 common:WindowShow
 common:WindowHide
 common:WindowDPIChanged
+common:WindowFilesDropped
 common:ThemeChanged
diff --git a/v3/pkg/w32/com.go b/v3/pkg/w32/com.go
new file mode 100644
index 00000000..35b79e53
--- /dev/null
+++ b/v3/pkg/w32/com.go
@@ -0,0 +1,55 @@
+//go:build windows
+
+package w32
+
+import (
+	"golang.org/x/sys/windows"
+	"syscall"
+	"unsafe"
+)
+
+// ComProc stores a COM procedure.
+type ComProc uintptr
+
+// NewComProc creates a new COM proc from a Go function.
+func NewComProc(fn interface{}) ComProc {
+	return ComProc(windows.NewCallback(fn))
+}
+
+type EventRegistrationToken struct {
+	value int64
+}
+
+// IUnknown
+type IUnknown struct {
+	Vtbl *IUnknownVtbl
+}
+
+type IUnknownVtbl struct {
+	QueryInterface ComProc
+	AddRef         ComProc
+	Release        ComProc
+}
+
+func (i *IUnknownVtbl) CallRelease(this unsafe.Pointer) error {
+	_, _, err := i.Release.Call(
+		uintptr(this),
+	)
+	if err != windows.ERROR_SUCCESS {
+		return err
+	}
+	return nil
+}
+
+type IUnknownImpl interface {
+	QueryInterface(refiid, object uintptr) uintptr
+	AddRef() uintptr
+	Release() uintptr
+}
+
+// Call calls a COM procedure.
+//
+//go:uintptrescapes
+func (p ComProc) Call(a ...uintptr) (r1, r2 uintptr, lastErr error) {
+	return syscall.SyscallN(uintptr(p), a...)
+}
diff --git a/v3/pkg/w32/idataobject.go b/v3/pkg/w32/idataobject.go
new file mode 100644
index 00000000..cf56d093
--- /dev/null
+++ b/v3/pkg/w32/idataobject.go
@@ -0,0 +1,168 @@
+//go:build windows
+
+package w32
+
+import (
+	"golang.org/x/sys/windows"
+	"syscall"
+	"unsafe"
+)
+
+type IDataObjectVtbl struct {
+	IUnknownVtbl
+	GetData               ComProc
+	GetDataHere           ComProc
+	QueryGetData          ComProc
+	GetCanonicalFormatEtc ComProc
+	SetData               ComProc
+	EnumFormatEtc         ComProc
+	DAdvise               ComProc
+}
+
+type IDataObject struct {
+	Vtbl *IDataObjectVtbl
+}
+
+func (i *IDataObject) AddRef() uintptr {
+	refCounter, _, _ := i.Vtbl.AddRef.Call(uintptr(unsafe.Pointer(i)))
+	return refCounter
+}
+
+func (i *IDataObject) GetData(formatEtc *FORMATETC, medium *STGMEDIUM) error {
+	hr, _, err := i.Vtbl.GetData.Call(
+		uintptr(unsafe.Pointer(i)),
+		uintptr(unsafe.Pointer(formatEtc)),
+		uintptr(unsafe.Pointer(medium)),
+	)
+	if windows.Handle(hr) != windows.S_OK {
+		return syscall.Errno(hr)
+	}
+	return err
+}
+
+func (i *IDataObject) GetDataHere(formatEtc *FORMATETC, medium *STGMEDIUM) error {
+	hr, _, err := i.Vtbl.GetDataHere.Call(
+		uintptr(unsafe.Pointer(i)),
+		uintptr(unsafe.Pointer(formatEtc)),
+		uintptr(unsafe.Pointer(medium)),
+	)
+	if windows.Handle(hr) != windows.S_OK {
+		return syscall.Errno(hr)
+	}
+	return err
+}
+
+func (i *IDataObject) QueryGetData(formatEtc *FORMATETC) error {
+	hr, _, err := i.Vtbl.QueryGetData.Call(
+		uintptr(unsafe.Pointer(i)),
+		uintptr(unsafe.Pointer(formatEtc)),
+	)
+	if windows.Handle(hr) != windows.S_OK {
+		return syscall.Errno(hr)
+	}
+	return err
+}
+
+func (i *IDataObject) GetCanonicalFormatEtc(inputFormatEtc *FORMATETC, outputFormatEtc *FORMATETC) error {
+	hr, _, err := i.Vtbl.GetCanonicalFormatEtc.Call(
+		uintptr(unsafe.Pointer(i)),
+		uintptr(unsafe.Pointer(inputFormatEtc)),
+		uintptr(unsafe.Pointer(outputFormatEtc)),
+	)
+	if windows.Handle(hr) != windows.S_OK {
+		return syscall.Errno(hr)
+	}
+	return err
+}
+
+func (i *IDataObject) SetData(formatEtc *FORMATETC, medium *STGMEDIUM, release bool) error {
+	hr, _, err := i.Vtbl.SetData.Call(
+		uintptr(unsafe.Pointer(i)),
+		uintptr(unsafe.Pointer(formatEtc)),
+		uintptr(unsafe.Pointer(medium)),
+		uintptr(BoolToBOOL(release)),
+	)
+	if windows.Handle(hr) != windows.S_OK {
+		return syscall.Errno(hr)
+	}
+	return err
+}
+
+func (i *IDataObject) EnumFormatEtc(dwDirection uint32, enumFormatEtc **IEnumFORMATETC) error {
+	hr, _, err := i.Vtbl.EnumFormatEtc.Call(
+		uintptr(unsafe.Pointer(i)),
+		uintptr(dwDirection),
+		uintptr(unsafe.Pointer(enumFormatEtc)),
+	)
+	if windows.Handle(hr) != windows.S_OK {
+		return syscall.Errno(hr)
+	}
+	return err
+}
+
+func (i *IDataObject) DAdvise(formatEtc *FORMATETC, advf uint32, adviseSink *IAdviseSink, pdwConnection *uint32) error {
+	hr, _, err := i.Vtbl.DAdvise.Call(
+		uintptr(unsafe.Pointer(i)),
+		uintptr(unsafe.Pointer(formatEtc)),
+		uintptr(advf),
+		uintptr(unsafe.Pointer(adviseSink)),
+		uintptr(unsafe.Pointer(pdwConnection)),
+	)
+	if windows.Handle(hr) != windows.S_OK {
+		return syscall.Errno(hr)
+	}
+	return err
+}
+
+type DVTargetDevice struct {
+	TdSize             uint32
+	TdDriverNameOffset uint16
+	TdDeviceNameOffset uint16
+	TdPortNameOffset   uint16
+	TdExtDevmodeOffset uint16
+	TdData             [1]byte
+}
+
+type FORMATETC struct {
+	CfFormat uint16
+	Ptd      *DVTargetDevice
+	DwAspect uint32
+	Lindex   int32
+	Tymed    Tymed
+}
+
+type Tymed uint32
+
+const (
+	TYMED_HGLOBAL  Tymed = 1
+	TYMED_FILE     Tymed = 2
+	TYMED_ISTREAM  Tymed = 4
+	TYMED_ISTORAGE Tymed = 8
+	TYMED_GDI      Tymed = 16
+	TYMED_MFPICT   Tymed = 32
+	TYMED_ENHMF    Tymed = 64
+	TYMED_NULL     Tymed = 0
+)
+
+type STGMEDIUM struct {
+	Tymed          Tymed
+	Union          uintptr
+	PUnkForRelease IUnknownImpl
+}
+
+func (s STGMEDIUM) FileName() string {
+	if s.Tymed != TYMED_FILE {
+		return ""
+	}
+	return windows.UTF16PtrToString((*uint16)(unsafe.Pointer(s.Union)))
+}
+
+func (s STGMEDIUM) Release() {
+	if s.PUnkForRelease != nil {
+		s.PUnkForRelease.Release()
+	}
+}
+
+type IEnumFORMATETC struct{}
+type IAdviseSink struct{}
+type IEnumStatData struct{}
diff --git a/v3/pkg/w32/idroptarget.go b/v3/pkg/w32/idroptarget.go
new file mode 100644
index 00000000..19621d1e
--- /dev/null
+++ b/v3/pkg/w32/idroptarget.go
@@ -0,0 +1,129 @@
+//go:build windows
+
+package w32
+
+import (
+	"github.com/wailsapp/go-webview2/pkg/combridge"
+	"golang.org/x/sys/windows"
+)
+
+const (
+	DROPEFFECT_NONE = 0
+	DROPEFFECT_COPY = 1
+	DROPEFFECT_MOVE = 2
+	DROPEFFECT_LINK = 4
+)
+
+func _NOP(_ uintptr) uintptr {
+	return uintptr(windows.S_FALSE)
+}
+
+func init() {
+	combridge.RegisterVTable[combridge.IUnknown, iDropTarget](
+		"{00000122-0000-0000-C000-000000000046}",
+		_iDropTargetDragEnter,
+		_iDropTargetDragOver,
+		_iDropTargetDragLeave,
+		_iDropTargetDrop,
+		_NOP,
+	)
+}
+
+func _iDropTargetDragEnter(this uintptr, dataObject *IDataObject, grfKeyState DWORD, point POINT, pdfEffect *DWORD) uintptr {
+	return combridge.Resolve[iDropTarget](this).DragEnter(dataObject, grfKeyState, point, pdfEffect)
+}
+
+func _iDropTargetDragOver(this uintptr, grfKeyState DWORD, point POINT, pdfEffect *DWORD) uintptr {
+	return combridge.Resolve[iDropTarget](this).DragOver(grfKeyState, point, pdfEffect)
+}
+
+func _iDropTargetDragLeave(this uintptr) uintptr {
+	return combridge.Resolve[iDropTarget](this).DragLeave()
+}
+
+func _iDropTargetDrop(this uintptr, dataObject *IDataObject, grfKeyState DWORD, point POINT, pdfEffect *DWORD) uintptr {
+	return combridge.Resolve[iDropTarget](this).Drop(dataObject, grfKeyState, point, pdfEffect)
+}
+
+type iDropTarget interface {
+	combridge.IUnknown
+
+	DragEnter(dataObject *IDataObject, grfKeyState DWORD, point POINT, pdfEffect *DWORD) uintptr
+	DragOver(grfKeyState DWORD, point POINT, pdfEffect *DWORD) uintptr
+	DragLeave() uintptr
+	Drop(dataObject *IDataObject, grfKeyState DWORD, point POINT, pdfEffect *DWORD) uintptr
+}
+
+var _ iDropTarget = &DropTarget{}
+
+type DropTarget struct {
+	combridge.IUnknownImpl
+	OnEnterEffect DWORD
+	OnOverEffect  DWORD
+	OnEnter       func()
+	OnLeave       func()
+	OnOver        func()
+	OnDrop        func(filenames []string)
+}
+
+func NewDropTarget() *DropTarget {
+	return &DropTarget{
+		OnEnterEffect: DROPEFFECT_COPY,
+		OnOverEffect:  DROPEFFECT_COPY,
+	}
+}
+
+func (d *DropTarget) DragEnter(dataObject *IDataObject, grfKeyState DWORD, point POINT, pdfEffect *DWORD) uintptr {
+	*pdfEffect = d.OnEnterEffect
+	if d.OnEnter != nil {
+		d.OnEnter()
+	}
+	return uintptr(windows.S_OK)
+}
+
+func (d *DropTarget) DragOver(grfKeyState DWORD, point POINT, pdfEffect *DWORD) uintptr {
+	*pdfEffect = d.OnOverEffect
+	if d.OnOver != nil {
+		d.OnOver()
+	}
+	return uintptr(windows.S_OK)
+}
+
+func (d *DropTarget) DragLeave() uintptr {
+	if d.OnLeave != nil {
+		d.OnLeave()
+	}
+	return uintptr(windows.S_OK)
+}
+
+func (d *DropTarget) Drop(dataObject *IDataObject, grfKeyState DWORD, point POINT, pdfEffect *DWORD) uintptr {
+
+	if d.OnDrop == nil {
+		return uintptr(windows.S_OK)
+	}
+
+	// Extract filenames from dataObject
+	var filenames []string
+	var formatETC = FORMATETC{
+		CfFormat: CF_HDROP,
+		Tymed:    TYMED_HGLOBAL,
+	}
+
+	var stgMedium STGMEDIUM
+
+	err := dataObject.GetData(&formatETC, &stgMedium)
+	if err != nil && err != windows.ERROR_SUCCESS {
+		return uintptr(windows.S_FALSE)
+	}
+	defer stgMedium.Release()
+	hDrop := stgMedium.Union
+	_, numFiles := DragQueryFile(hDrop, 0xFFFFFFFF)
+	for i := uint(0); i < numFiles; i++ {
+		filename, _ := DragQueryFile(hDrop, i)
+		filenames = append(filenames, filename)
+	}
+
+	d.OnDrop(filenames)
+
+	return uintptr(windows.S_OK)
+}
diff --git a/v3/pkg/w32/iunknown.go b/v3/pkg/w32/iunknown.go
deleted file mode 100644
index 8ddc605c..00000000
--- a/v3/pkg/w32/iunknown.go
+++ /dev/null
@@ -1,29 +0,0 @@
-//go:build windows
-
-/*
- * Copyright (C) 2019 Tad Vizbaras. All Rights Reserved.
- * Copyright (C) 2010-2012 The W32 Authors. All Rights Reserved.
- */
-package w32
-
-type pIUnknownVtbl struct {
-	pQueryInterface uintptr
-	pAddRef         uintptr
-	pRelease        uintptr
-}
-
-type IUnknown struct {
-	lpVtbl *pIUnknownVtbl
-}
-
-func (this *IUnknown) QueryInterface(id *GUID) *IDispatch {
-	return ComQueryInterface(this, id)
-}
-
-func (this *IUnknown) AddRef() int32 {
-	return ComAddRef(this)
-}
-
-func (this *IUnknown) Release() int32 {
-	return ComRelease(this)
-}
diff --git a/v3/pkg/w32/ole32.go b/v3/pkg/w32/ole32.go
index 00409931..8eb2c3b6 100644
--- a/v3/pkg/w32/ole32.go
+++ b/v3/pkg/w32/ole32.go
@@ -7,6 +7,7 @@
 package w32
 
 import (
+	"github.com/wailsapp/go-webview2/pkg/combridge"
 	"syscall"
 	"unsafe"
 )
@@ -16,8 +17,10 @@ var (
 
 	procCoInitializeEx        = modole32.NewProc("CoInitializeEx")
 	procCoInitialize          = modole32.NewProc("CoInitialize")
+	procOleInitialize         = modole32.NewProc("OleInitialize")
 	procCoUninitialize        = modole32.NewProc("CoUninitialize")
 	procCreateStreamOnHGlobal = modole32.NewProc("CreateStreamOnHGlobal")
+	procRegisterDragDrop      = modole32.NewProc("RegisterDragDrop")
 )
 
 func CoInitializeEx(coInit uintptr) HRESULT {
@@ -63,3 +66,20 @@ func CreateStreamOnHGlobal(hGlobal HGLOBAL, fDeleteOnRelease bool) *IStream {
 
 	return stream
 }
+func OleInitialise() {
+	procOleInitialize.Call()
+}
+
+func RegisterDragDrop(hwnd HWND, dropTarget *DropTarget) error {
+
+	dt := combridge.New[iDropTarget](dropTarget)
+	hr, _, _ := procRegisterDragDrop.Call(
+		hwnd,
+		dt.Ref(),
+	)
+
+	if hr != S_OK {
+		return syscall.Errno(hr)
+	}
+	return nil
+}
diff --git a/v3/pkg/w32/shell32.go b/v3/pkg/w32/shell32.go
index 4c213cc6..33cb72bc 100644
--- a/v3/pkg/w32/shell32.go
+++ b/v3/pkg/w32/shell32.go
@@ -259,13 +259,13 @@ func SHGetPathFromIDList(idl uintptr) string {
 
 func DragAcceptFiles(hwnd HWND, accept bool) {
 	procDragAcceptFiles.Call(
-		uintptr(hwnd),
+		hwnd,
 		uintptr(BoolToBOOL(accept)))
 }
 
 func DragQueryFile(hDrop HDROP, iFile uint) (fileName string, fileCount uint) {
 	ret, _, _ := procDragQueryFile.Call(
-		uintptr(hDrop),
+		hDrop,
 		uintptr(iFile),
 		0,
 		0)
@@ -276,7 +276,7 @@ func DragQueryFile(hDrop HDROP, iFile uint) (fileName string, fileCount uint) {
 		buf := make([]uint16, fileCount+1)
 
 		ret, _, _ := procDragQueryFile.Call(
-			uintptr(hDrop),
+			hDrop,
 			uintptr(iFile),
 			uintptr(unsafe.Pointer(&buf[0])),
 			uintptr(fileCount+1))
diff --git a/v3/pkg/w32/utils.go b/v3/pkg/w32/utils.go
index fb6612e2..1f36480c 100644
--- a/v3/pkg/w32/utils.go
+++ b/v3/pkg/w32/utils.go
@@ -79,7 +79,7 @@ func UTF16PtrToString(cstr *uint16) string {
 }
 
 func ComAddRef(unknown *IUnknown) int32 {
-	ret, _, _ := syscall.Syscall(unknown.lpVtbl.pAddRef, 1,
+	ret, _, _ := syscall.Syscall(uintptr(unknown.Vtbl.AddRef), 1,
 		uintptr(unsafe.Pointer(unknown)),
 		0,
 		0)
@@ -87,7 +87,7 @@ func ComAddRef(unknown *IUnknown) int32 {
 }
 
 func ComRelease(unknown *IUnknown) int32 {
-	ret, _, _ := syscall.Syscall(unknown.lpVtbl.pRelease, 1,
+	ret, _, _ := syscall.Syscall(uintptr(unknown.Vtbl.Release), 1,
 		uintptr(unsafe.Pointer(unknown)),
 		0,
 		0)
@@ -96,7 +96,7 @@ func ComRelease(unknown *IUnknown) int32 {
 
 func ComQueryInterface(unknown *IUnknown, id *GUID) *IDispatch {
 	var disp *IDispatch
-	hr, _, _ := syscall.Syscall(unknown.lpVtbl.pQueryInterface, 3,
+	hr, _, _ := syscall.Syscall(uintptr(unknown.Vtbl.QueryInterface), 3,
 		uintptr(unsafe.Pointer(unknown)),
 		uintptr(unsafe.Pointer(id)),
 		uintptr(unsafe.Pointer(&disp)))
diff --git a/v3/tasks/events/generate.go b/v3/tasks/events/generate.go
index 970f8b3a..aade6d26 100644
--- a/v3/tasks/events/generate.go
+++ b/v3/tasks/events/generate.go
@@ -12,10 +12,6 @@ var eventsGo = `package events
 type ApplicationEventType uint
 type WindowEventType      uint
 
-const (
-	FilesDropped WindowEventType = iota
-)
-
 var Common = newCommonEvents()
 
 type commonEvents struct {