Start work on gesture support for viewer

src/pyj/read_book/iframe.pyj

@@ -18,6 +18,7 @@ from read_book.paged_mode import (
     jump_to_cfi as paged_jump_to_cfi
 )
 from read_book.settings import apply_settings
+from read_book.touch import create_handlers as create_touch_handlers
 from utils import debounce
 
 FORCE_FLOW_MODE = False
@@ -70,6 +71,7 @@ class IframeBoss:
         if data.translations:
             install(data.translations)
         window.onerror = self.onerror
+        create_touch_handlers()
 
     def onerror(self, msg, script_url, line_number, column_number, error_object):
         console.log(error_object)

src/pyj/read_book/touch.pyj

@@ -0,0 +1,72 @@
+# vim:fileencoding=utf-8
+# License: GPL v3 Copyright: 2016, Kovid Goyal <kovid at kovidgoyal.net>
+from __python__ import hash_literals, bound_methods
+
+
+def copy_touch(t):
+    return {'identifier':t.identifier, 'page_x':v'[t.pageX]', 'page_y':v'[t.pageY]', 'viewport_x':v'[t.clientX]', 'viewport_y':v'[t.clientY]',
+            'active':True, 'mtime':window.performance.now()}
+
+class TouchHandler:
+
+    def __init__(self):
+        self.ongoing_touches = {}
+
+    @property
+    def has_active_touches(self):
+        now = window.performance.now()
+        expired = v'[]'
+        ans = False
+        for t in self.ongoing_touches:
+            if t.active:
+                if now - t.mtime > 3000:
+                    expired.push(t.identifier)
+                ans = True
+                break
+        for tid in expired:
+            v'delete self.ongoing_touches[tid]'
+        return ans
+
+    def handle_touchstart(self, ev):
+        ev.preventDefault(), ev.stopPropagation()
+        for touch in ev.changedTouches:
+            self.ongoing_touches[touch.identifier] = copy_touch(touch)
+
+    def update_touch(self, t, touch):
+        t.mtime = window.performance.now()
+        t.page_x.push(touch.pageX), t.page_y.push(touch.pageY)
+        t.viewport_x.push(touch.clientX), t.viewport_y.push(touch.clientY)
+
+    def handle_touchmove(self, ev):
+        ev.preventDefault(), ev.stopPropagation()
+        for touch in ev.changedTouches:
+            t = self.ongoing_touches[touch.identifier]
+            if t:
+                self.update_touch(t, touch)
+
+    def handle_touchend(self, ev):
+        ev.preventDefault(), ev.stopPropagation()
+        for touch in ev.changedTouches:
+            t = self.ongoing_touches[touch.identifier]
+            if t:
+                t.active = False
+                self.update_touch(t, touch)
+        if not self.has_active_touches:
+            touches, self.ongoing_touches = self.ongoing_touches, {}
+            self.interpret_gesture(touches)
+
+    def handle_touchcancel(self, ev):
+        ev.preventDefault(), ev.stopPropagation()
+        for touch in ev.changedTouches:
+            v'delete self.ongoing_touches[touch.identifier]'
+
+    def interpret_gesture(self, touches):
+        print(1111111, touches)
+
+touch_handler = TouchHandler()
+
+def create_handlers():
+    document.body.addEventListener('touchstart', touch_handler.handle_touchstart, True)
+    document.body.addEventListener('touchmove', touch_handler.handle_touchmove, True)
+    document.body.addEventListener('touchend', touch_handler.handle_touchend, True)
+    document.body.addEventListener('touchcancel', touch_handler.handle_touchcancel, True)