darwin-external-dragndrop: implement external drag n' drop for darwin

Author: StarHack

app/os_macos.go

@@ -15,6 +15,7 @@ import (
 
 	"gioui.org/internal/f32"
 	"gioui.org/io/clipboard"
+	"gioui.org/io/externalDragDrop"
 	"gioui.org/io/key"
 	"gioui.org/io/pointer"
 	"gioui.org/io/system"
@@ -557,6 +558,13 @@ func gio_onMouse(view, evt C.CFTypeRef, cdir C.int, cbtn C.NSInteger, x, y, dx,
 	})
 }
 
+//export gio_onExternalDrop
+func gio_onExternalDrop(view C.CFTypeRef, pbrd *C.char) {
+	fileUrl := C.GoString(pbrd)
+	w := mustView(view)
+	w.w.Event(externalDragDrop.Event{Text: fileUrl})
+}
+
 //export gio_onDraw
 func gio_onDraw(view C.CFTypeRef) {
 	w := mustView(view)

app/os_macos.m

@@ -110,6 +110,27 @@ - (void)mouseMoved:(NSEvent *)event {
 - (void)mouseDragged:(NSEvent *)event {
 	handleMouse(self, event, MOUSE_MOVE, 0, 0);
 }
+-(NSDragOperation)draggingEntered:(id < NSDraggingInfo >)sender
+{
+    return NSDragOperationCopy; // NSDragOperationGeneric
+}
+- (void)draggingEnded:(id <NSDraggingInfo>)sender
+{
+	NSPasteboard* pbrd = [sender draggingPasteboard];
+
+	for (NSPasteboardItem *item in [pbrd pasteboardItems]) {
+		for (NSString *type in [item types]) {
+			if ([type isEqualToString:@"public.file-url"]) {
+				NSData* data = [item dataForType:type];
+				NSString *clipboard_url = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
+				NSURL *url = [[NSURL alloc] initWithString:clipboard_url];
+				NSString *real_path = url.path;
+				char* content = (char*)[real_path UTF8String];
+				gio_onExternalDrop((__bridge CFTypeRef)self, content);
+			}
+		}
+	}
+}
 - (void)scrollWheel:(NSEvent *)event {
 	CGFloat dx = -event.scrollingDeltaX;
 	CGFloat dy = -event.scrollingDeltaY;
@@ -366,6 +387,7 @@ CFTypeRef gio_createView(void) {
 	@autoreleasepool {
 		NSRect frame = NSMakeRect(0, 0, 0, 0);
 		GioView* view = [[GioView alloc] initWithFrame:frame];
+		[view registerForDraggedTypes: [NSArray arrayWithObjects:NSTIFFPboardType,NSFilenamesPboardType,nil]];
 		view.wantsLayer = YES;
 		view.layerContentsRedrawPolicy = NSViewLayerContentsRedrawDuringViewResize;
 		return CFBridgingRetain(view);

internal/ops/ops.go

@@ -76,6 +76,7 @@ const (
 	TypeSnippet
 	TypeSelection
 	TypeActionInput
+	TypeExternalDragDrop
 )
 
 type StackID struct {
@@ -160,6 +161,7 @@ const (
 	TypeSnippetLen          = 1 + 4 + 4
 	TypeSelectionLen        = 1 + 2*4 + 2*4 + 4 + 4
 	TypeActionInputLen      = 1 + 1
+	TypeExternalDragDropLen = 1
 )
 
 func (op *ClipOp) Decode(data []byte) {
@@ -417,6 +419,7 @@ var opProps = [0x100]opProp{
 	TypeSnippet:          {Size: TypeSnippetLen, NumRefs: 2},
 	TypeSelection:        {Size: TypeSelectionLen, NumRefs: 1},
 	TypeActionInput:      {Size: TypeActionInputLen, NumRefs: 0},
+	TypeExternalDragDrop: {Size: TypeExternalDragDropLen, NumRefs: 1},
 }
 
 func (t OpType) props() (size, numRefs int) {
@@ -498,6 +501,8 @@ func (t OpType) String() string {
 		return "Stroke"
 	case TypeSemanticLabel:
 		return "SemanticDescription"
+	case TypeExternalDragDrop:
+		return "ExternalDragDrop"
 	default:
 		panic("unknown OpType")
 	}

io/externalDragDrop/externalDragDrop.go

@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+package externalDragDrop
+
+import (
+	"gioui.org/internal/ops"
+	"gioui.org/io/event"
+	"gioui.org/op"
+)
+
+// Event is generated when the clipboard content is requested.
+type Event struct {
+	Text string
+}
+
+// ReadOp requests the text of the clipboard, delivered to
+// the current handler through an Event.
+type ReadOp struct {
+	Tag event.Tag
+}
+
+func (h ReadOp) Add(o *op.Ops) {
+	data := ops.Write1(&o.Internal, ops.TypeExternalDragDropLen, h.Tag)
+	data[0] = byte(ops.TypeExternalDragDrop)
+}
+
+func (Event) ImplementsEvent() {}

io/router/router.go

@@ -23,6 +23,7 @@ import (
 	"gioui.org/internal/ops"
 	"gioui.org/io/clipboard"
 	"gioui.org/io/event"
+	"gioui.org/io/externalDragDrop"
 	"gioui.org/io/key"
 	"gioui.org/io/pointer"
 	"gioui.org/io/profile"
@@ -182,6 +183,8 @@ func (q *Router) Queue(events ...event.Event) bool {
 			}
 		case clipboard.Event:
 			q.cqueue.Push(e, &q.handlers)
+		case externalDragDrop.Event:
+			q.handlers.Add(nil, e)
 		}
 	}
 	return q.handlers.HadEvents()