DragAndDropOverlay.iOS.cs

using System;
using CoreGraphics;
using Foundation;
using ObjCRuntime;
using UIKit;

namespace DrasticOverlay.Overlays
{
    public partial class DragAndDropOverlay
    {
        DragAndDropView dragAndDropView;

        public override bool Initialize()
        {
            if (dragAndDropOverlayNativeElementsInitialized)
                return true;

            base.Initialize();

            var nativeLayer = Window?.GetNative(true);
            if (nativeLayer is not UIWindow nativeWindow)
                return false;

            if (nativeWindow?.RootViewController?.View == null)
                return false;

            // We're going to create a new view.
            // This will handle the "drop" events, and nothing else.
            dragAndDropView = new DragAndDropView(this, nativeWindow.RootViewController.View.Frame);
            dragAndDropView.UserInteractionEnabled = true;
            nativeWindow?.RootViewController.View.AddSubview(dragAndDropView);
            nativeWindow?.RootViewController.View.BringSubviewToFront(dragAndDropView);
            return dragAndDropOverlayNativeElementsInitialized = true;
        }

        public override bool Deinitialize()
        {
            if (this.dragAndDropView != null)
            {
                this.dragAndDropView.RemoveFromSuperview();
                this.dragAndDropView.Dispose();
            }
            return base.Deinitialize();
        }


        class DragAndDropView : UIView, IUIDropInteractionDelegate
		{
            DragAndDropOverlay overlay;

            public DragAndDropView(DragAndDropOverlay overlay, CGRect frame)
				: base(frame)
			{
                this.overlay = overlay;
                this.AddInteraction(new UIDropInteraction(this));
			}

            // The following are all of the sessions we can handle.

            [Export("dropInteraction:canHandleSession:")]
            public bool CanHandleSession(UIDropInteraction interaction, IUIDropSession session)
            {
                Console.WriteLine($"CanHandleSession ({interaction}, {session})");

                return session.CanLoadObjects(new Class(typeof(UIImage)));
            }

            [Export("dropInteraction:sessionDidEnter:")]
            public void SessionDidEnter(UIDropInteraction interaction, IUIDropSession session)
            {
                Console.WriteLine($"SessionDidEnter ({interaction}, {session})");
                this.overlay.IsDragging = true;
            }

            [Export("dropInteraction:sessionDidExit:")]
            public void SessionDidExit(UIDropInteraction interaction, IUIDropSession session)
            {
                Console.WriteLine($"SessionDidExit ({interaction}, {session})");
                this.overlay.IsDragging = false;
            }

            [Export("dropInteraction:sessionDidUpdate:")]
            public UIDropProposal SessionDidUpdate(UIDropInteraction interaction, IUIDropSession session)
            {
                Console.WriteLine($"sessionDidUpdate ({interaction}, {session})");
                if (session.LocalDragSession == null && session.CanLoadObjects(typeof(UIImage)))
                {
                    return new UIDropProposal(UIDropOperation.Copy);
                }
                return new UIDropProposal(UIDropOperation.Cancel);
            }

            [Export("dropInteraction:performDrop:")]
            public void PerformDrop(UIDropInteraction interaction, IUIDropSession session)
            {
                Console.WriteLine($"performDrop ({interaction}, {session})");
                session.ProgressIndicatorStyle = UIDropSessionProgressIndicatorStyle.None;

                foreach (UIDragItem item in session.Items)
                {
                    if (item.ItemProvider.CanLoadObject(typeof(UIImage)))
                    {
                        item.ItemProvider.LoadObject<UIImage>((img, err) => {
                            using (NSData imageData = img.AsPNG())
                            {
                                Byte[] barray = new Byte[imageData.Length];
                                System.Runtime.InteropServices.Marshal.Copy(imageData.Bytes, barray, 0, Convert.ToInt32(imageData.Length));
                                this.overlay.Drop?.Invoke(this.overlay, new DragAndDropOverlayTappedEventArgs("test", barray));
                            }
                        });
                    }
                }
            }

            [Export("dropInteraction:concludeDrop:")]
            public void ConcludeDrop(UIDropInteraction interaction, IUIDropSession session)
            {
                Console.WriteLine($"concludeDrop ({interaction}, {session})");
                this.overlay.IsDragging = false;
            }

            public override bool PointInside(CGPoint point, UIEvent? uievent)
            {
                if (uievent != null && (long)uievent.Type == 9)
                {
                    return true;
                }

                return false;
            }
        }
    }
}