[macdoc] Implement swipe gesture for navigation

1 files changed, 122 insertions, 0 deletions

diff --git a/WebViewExtraordinaire.cs b/WebViewExtraordinaire.cs
new file mode 100644
index 0000000..260f75f
--- /dev/null
+++ b/WebViewExtraordinaire.cs
@@ -0,0 +1,122 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using MonoMac.Foundation;
+using MonoMac.AppKit;
+using MonoMac.WebKit;
+using MonoMac.ObjCRuntime;
+
+namespace macdoc
+{
+
+	public enum SwipeSide
+	{
+		None,
+		Left,
+		Right
+	}
+	
+	public class SwipeEventArgs : EventArgs
+	{
+		public SwipeSide Side { get; set; }
+	}
+	
+	public partial class WebViewExtraordinaire : WebView
+	{
+		public event EventHandler<SwipeEventArgs> SwipeEvent;
+		public event EventHandler<SwipeEventArgs> OngoingSwipeEvent;
+		
+		public WebViewExtraordinaire (IntPtr handle) : base (handle)
+		{
+			Initialize ();
+		}
+		
+		[Export ("initWithCoder:")]
+		public WebViewExtraordinaire (NSCoder coder) : base (coder)
+		{
+			Initialize ();
+		}
+		
+		void Initialize ()
+		{
+			IsSwipeEnabled = NSEvent.IsSwipeTrackingFromScrollEventsEnabled;
+			//FinishedLoad += (sender, e) => MainFrame.FrameView.DocumentView.EnclosingScrollView.HorizontalScrollElasticity = NSScrollElasticity.Allowed;
+		}
+		
+		public bool IsSwipeEnabled { get; set; }
+		
+		public override void ScrollWheel (NSEvent theEvent)
+		{
+			if (theEvent.Phase != NSEventPhase.Began)
+				return;
+			if (theEvent.DeltaX == 0 || Math.Abs (theEvent.DeltaX) <= Math.Abs (theEvent.DeltaY) * 8)
+				return;
+			if (Math.Abs (theEvent.DeltaX) < 1f)
+				return;
+			
+			FireSwipeEvent (theEvent.DeltaX > 0 ? SwipeSide.Left : SwipeSide.Right);
+			
+			// The following scroll event to swipe event translation is mostly inspired from the following Firefox patch
+			// https://bugzilla.mozilla.org/attachment.cgi?id=553654&action=diff
+			// Although it's not working fine for us, let's do our own sauce
+			/*
+			// We only take pure swipe event into account that is only
+			// when the swipe is initiated at the beginning of the touch process
+			// (put differently a swipe can't happen after a normal scroll and user need,
+			// to first stop whatever scroll he was doing before attempting a swipe)
+			if (theEvent.Phase != NSEventPhase.Began)
+				return;
+			
+			// Bit of heuristic to avoid triggering accidental swipes
+			if (theEvent.DeltaX == 0 || Math.Abs (theEvent.DeltaX) <= Math.Abs (theEvent.DeltaY) * 8)
+				return;
+			
+			NSEventTrackHandler swipeBlock = delegate (float gestureAmount, NSEventPhase eventPhase, bool isComplete, ref bool stop) {
+				Console.WriteLine ("[{0}] {1} {2} {3}", theEvent.Timestamp, gestureAmount, eventPhase, isComplete);
+				if (isComplete && gestureAmount != 0) {
+					FireSwipeEvent (gestureAmount > 0 ? SwipeSide.Left : SwipeSide.Right);
+				}
+			};
+			
+			Console.WriteLine ("Tracking {0}", theEvent.Timestamp.ToString ());
+			theEvent.TrackSwipeEvent ((NSEventSwipeTrackingOptions)0,
+			                          -1,
+			                           1,
+			                          swipeBlock);
+			*/
+		}
+
+		public override void SwipeWithEvent (NSEvent theEvent)
+		{
+			// We are only interested in horizontal swipe
+			if (theEvent.DeltaX == 0)
+				return;
+			FireSwipeEvent (theEvent.DeltaX > 0 ? SwipeSide.Left : SwipeSide.Right);
+		}
+		
+		public override bool WantsForwardedScrollEventsForAxis (NSEventGestureAxis axis)
+		{
+			return axis == NSEventGestureAxis.Horizontal && IsSwipeEnabled;
+		}
+	
+		public override bool AcceptsFirstResponder ()
+		{
+			return true;
+		}
+		
+		void FireSwipeEvent (SwipeSide side)
+		{
+			var temp = SwipeEvent;
+			if (temp != null)
+				temp (this, new SwipeEventArgs { Side = side });
+		}
+		
+		void FireOngoingSwipeEvent (SwipeSide status)
+		{
+			var temp = OngoingSwipeEvent;
+			if (temp != null)
+				temp (this, new SwipeEventArgs { Side = status });
+		}
+	}
+}
+