Drag and drop animated GIFs rendered in NSImageView Swift MacOS application - swift

Question

I am trying to build a Mac OSX application that renders several gifs and allows the users to drag and drop them for copying the gifs into some other app. I am using a DragDropImageView (code below) that conforms to an NSImageView to render a gif that is drag-n-drop enabled.
It works fine, except that when I drag and drop the gif into another application, it copies only a single image frame of the gif. My intention is to copy the entire gif file and not just a single image.
I am pretty new to iOS/MacOS development in general, and I am not sure if my approach to building this draggable gif component is correct.
I am building the app using swiftUI, and I use a custom view called GifImageView that converts the DragDropImageView to a swiftUI view.
DragDropImageView.swift
import Cocoa
class DragDropImageView: NSImageView, NSDraggingSource {
/// Holds the last mouse down event, to track the drag distance.
var mouseDownEvent: NSEvent?
override init(frame frameRect: NSRect) {
super.init(frame: frameRect)
isEditable = false
}
required init?(coder: NSCoder) {
super.init(coder: coder)
// Assure editable is set to true, to enable drop capabilities.
isEditable = true
}
override func draw(_ dirtyRect: NSRect) {
super.draw(dirtyRect)
}
// MARK: - NSDraggingSource
// Since we only want to copy the current image we register
// for .Copy operation.
func draggingSession(_: NSDraggingSession,
sourceOperationMaskFor _: NSDraggingContext) -> NSDragOperation {
return NSDragOperation.copy
}
// // Clear the ImageView on delete operation; e.g. the image gets
// // dropped on the trash can in the dock.
// func draggingSession(_: NSDraggingSession, endedAt _: NSPoint,
// operation: NSDragOperation) {
// if operation == .delete {
// image = nil
// }
// }
// Track mouse down events and safe the to the poperty.
override func mouseDown(with theEvent: NSEvent) {
mouseDownEvent = theEvent
}
// Track mouse dragged events to handle dragging sessions.
override func mouseDragged(with event: NSEvent) {
// Calculate the dragging distance...
let mouseDown = mouseDownEvent!.locationInWindow
let dragPoint = event.locationInWindow
let dragDistance = hypot(mouseDown.x - dragPoint.x, mouseDown.y - dragPoint.y)
// Cancel the dragging session in case of an accidental drag.
if dragDistance < 3 {
return
}
guard let image = self.image else {
return
}
let draggingImage = image
// Create a new NSDraggingItem with the image as content.
let draggingItem = NSDraggingItem(pasteboardWriter: image)
// Calculate the mouseDown location from the window's coordinate system to the
// ImageView's coordinate system, to use it as origin for the dragging frame.
let draggingFrameOrigin = convert(mouseDown, from: nil)
// Build the dragging frame and offset it by half the image size on each axis
// to center the mouse cursor within the dragging frame.
let draggingFrame = NSRect(origin: draggingFrameOrigin, size: draggingImage.size)
.offsetBy(dx: -draggingImage.size.width / 2, dy: -draggingImage.size.height / 2)
// Assign the dragging frame to the draggingFrame property of our dragging item.
draggingItem.draggingFrame = draggingFrame
// Provide the components of the dragging image.
draggingItem.imageComponentsProvider = {
let component = NSDraggingImageComponent(key: NSDraggingItem.ImageComponentKey.icon)
component.contents = image
component.frame = NSRect(origin: NSPoint(), size: draggingFrame.size)
return [component]
}
// Begin actual dragging session. Woohow!
beginDraggingSession(with: [draggingItem], event: mouseDownEvent!, source: self)
}
}
GifImageView.swift
import AppKit;
import SwiftUI;
struct GifImageView: NSViewRepresentable {
var image: NSImage
func makeNSView(context: Context) -> DragDropImageView {
let view = DragDropImageView()
view.image = self.image
// view.allowsCutCopyPaste = true
return view
}
func updateNSView(_ view: DragDropImageView, context: Context) {
}
}
struct GifImageView_Previews: PreviewProvider {
static var previews: some View {
GifImageView(image: NSImage(data: (NSDataAsset(name: "tenor")?.data)!)!)
}
}
in my ContentView.swift, I use my GifImageView something like this:
GifImageView(image: *some NSImage*)