From 03b3d93bfce8ae638656ff7a1d7d3d0baac6290c Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Mon, 29 May 2017 13:19:38 +0530
Subject: [PATCH] Fix pinch to change font size not working on Safari

---
 src/pyj/read_book/touch.pyj | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/pyj/read_book/touch.pyj b/src/pyj/read_book/touch.pyj
index f522833026..176a4be4e1 100644
--- a/src/pyj/read_book/touch.pyj
+++ b/src/pyj/read_book/touch.pyj
@@ -109,6 +109,11 @@ def tap_on_link(gesture):
     return False
 
 
+def touch_id(touch):
+    # On Safari using touch.identifier as dict key yields a key of "NaN" for some reason
+    return touch.identifier + ''
+
+
 class TouchHandler:
 
     def __init__(self):
@@ -162,7 +167,7 @@ class TouchHandler:
         ev.preventDefault(), ev.stopPropagation()
         self.prune_expired_touches()
         for touch in ev.changedTouches:
-            self.ongoing_touches[touch.identifier] = copy_touch(touch)
+            self.ongoing_touches[touch_id(touch)] = copy_touch(touch)
             if self.gesture_id is None:
                 nonlocal gesture_id
                 gesture_id += 1
@@ -180,7 +185,7 @@ class TouchHandler:
     def handle_touchmove(self, ev):
         ev.preventDefault(), ev.stopPropagation()
         for touch in ev.changedTouches:
-            t = self.ongoing_touches[touch.identifier]
+            t = self.ongoing_touches[touch_id(touch)]
             if t:
                 self.update_touch(t, touch)
                 self.dispatch_gesture()
@@ -188,7 +193,7 @@ class TouchHandler:
     def handle_touchend(self, ev):
         ev.preventDefault(), ev.stopPropagation()
         for touch in ev.changedTouches:
-            t = self.ongoing_touches[touch.identifier]
+            t = self.ongoing_touches[touch_id(touch)]
             if t:
                 t.active = False
                 self.update_touch(t, touch)