Page turn gestures in paged mode

src/pyj/read_book/flow_mode.pyj

@@ -99,3 +99,5 @@ def flow_onkeydown(evt):
 def layout(is_single_page):
     set_css(document.body, margin='0', border_width='0', padding='0')
 
+def handle_gesture(gesture):
+    pass

src/pyj/read_book/iframe.pyj

@@ -10,12 +10,12 @@ from read_book.globals import set_boss, set_current_spine_item, current_layout_m
 from read_book.mathjax import apply_mathjax
 from read_book.resources import finalize_resources, unserialize_html
 from read_book.flow_mode import (
-    flow_to_scroll_fraction, flow_onwheel, flow_onkeydown, layout as flow_layout
+    flow_to_scroll_fraction, flow_onwheel, flow_onkeydown, layout as flow_layout, handle_gesture as flow_handle_gesture
 )
 from read_book.paged_mode import (
     layout as paged_layout, scroll_to_fraction as paged_scroll_to_fraction,
     onwheel as paged_onwheel, onkeydown as paged_onkeydown, scroll_to_elem,
-    jump_to_cfi as paged_jump_to_cfi
+    jump_to_cfi as paged_jump_to_cfi, handle_gesture as paged_handle_gesture
 )
 from read_book.settings import apply_settings
 from read_book.touch import create_handlers as create_touch_handlers
@@ -94,6 +94,7 @@ class IframeBoss:
             self.do_layout = flow_layout
             self.handle_wheel = flow_onwheel
             self.handle_keydown = flow_onkeydown
+            self.handle_gesture = flow_handle_gesture
             self.to_scroll_fraction = flow_to_scroll_fraction
             self.jump_to_cfi = scroll_to_cfi
         else:
@@ -102,6 +103,7 @@ class IframeBoss:
             self.handle_keydown = paged_onkeydown
             self.to_scroll_fraction = paged_scroll_to_fraction
             self.jump_to_cfi = paged_jump_to_cfi
+            self.handle_gesture = paged_handle_gesture
         apply_settings(data.settings)
         set_current_spine_item({'name':data.name, 'is_first':index is 0, 'is_last':index is spine.length - 1, 'initial_position':data.initial_position})
         self.last_cfi = None

src/pyj/read_book/paged_mode.pyj

@@ -492,3 +492,11 @@ def onkeydown(evt):
         scroll_by_page(key is 'pageup', True)
     if handled:
         evt.preventDefault()
+
+def handle_gesture(gesture):
+    if gesture.type is 'swipe':
+        if not gesture.active:
+            if gesture.axis is 'vertical':
+                pass  # TODO: next/prev section
+            else:
+                scroll_by_page(gesture.direction is 'right', False)

src/pyj/read_book/touch.pyj

@@ -2,10 +2,44 @@
 # License: GPL v3 Copyright: 2016, Kovid Goyal <kovid at kovidgoyal.net>
 from __python__ import hash_literals, bound_methods
 
+from read_book.globals import get_boss
 
 def copy_touch(t):
+    now = window.performance.now()
     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()}
+            'active':True, 'mtime':now, 'ctime':now}
+
+def max_displacement(points):
+    ans = 0
+    first = points[0]
+    if not first?:
+        return ans
+    for p in points:
+        delta = abs(p - first)
+        if delta > ans:
+            ans = delta
+    return ans
+
+def interpret_single_gesture(touch):
+    max_x_displacement = max_displacement(touch.viewport_x)
+    max_y_displacement = max_displacement(touch.viewport_y)
+    if max(max_x_displacement, max_y_displacement) < 25:
+        return {'type':'tap'}
+    if touch.viewport_y.length < 2:
+        return {}
+    delta_x = abs(touch.viewport_x[-1] - touch.viewport_x[0])
+    delta_y = abs(touch.viewport_y[-1] - touch.viewport_y[0])
+    if max(delta_y, delta_x) > 30 and min(delta_x, delta_y)/max(delta_y, delta_x) < 0.35:
+        ans = {'type':'swipe'}
+        ans.axis = 'vertical' if delta_y > delta_x else 'horizontal'
+        pts = touch.viewport_y if ans.axis is 'vertical' else touch.viewport_x
+        positive = pts[-1] > pts[0]
+        if ans.axis is 'vertical':
+            ans.direction = 'down' if positive else 'up'
+        else:
+            ans.direction = 'right' if positive else 'left'
+        return ans
+    return {}
 
 class TouchHandler:
 
@@ -43,6 +77,12 @@ class TouchHandler:
             t = self.ongoing_touches[touch.identifier]
             if t:
                 self.update_touch(t, touch)
+                if len(self.ongoing_touches) is 1:
+                    gesture = interpret_single_gesture(t)
+                    if gesture?.type is 'swipe':
+                        gesture.active = True
+                        get_boss().handle_gesture(gesture)
+
 
     def handle_touchend(self, ev):
         ev.preventDefault(), ev.stopPropagation()
@@ -61,7 +101,18 @@ class TouchHandler:
             v'delete self.ongoing_touches[touch.identifier]'
 
     def interpret_gesture(self, touches):
-        print(1111111, touches)
+        num = len(touches)
+        gesture = {}
+        if num is 1:
+            gesture = interpret_single_gesture(touches[Object.keys(touches)[0]])
+        if not gesture?.type:
+            return
+        if gesture.type is 'tap':
+            # TODO: Check for tap on link. Also convert the tap gesture into
+            # semantic gestures based on position of tap (next page/previous
+            # page/show ui) as these are common to both paged and flow mode.
+            pass
+        get_boss().handle_gesture(gesture)
 
 touch_handler = TouchHandler()