Start work on time left display for browser viewer

src/pyj/read_book/iframe.pyj

@@ -170,6 +170,9 @@ class IframeBoss:
     def gesture_from_margin(self, data):
         self.handle_gesture(data.gesture)
 
+    def report_human_scroll(self, scrolled_by_frac, is_large_scroll):
+        self.send_message('human_scroll', scrolled_by_frac=scrolled_by_frac or None, is_large_scroll=v'!!is_large_scroll')
+
     def on_scroll_to_anchor(self, data):
         frag = data.frag
         if frag:

src/pyj/read_book/paged_mode.pyj

@@ -56,13 +56,13 @@ def create_page_div(elem):
 _in_paged_mode = False
 def in_paged_mode():
     return _in_paged_mode
-col_width = screen_width = screen_height = cols_per_screen = gap = col_and_gap = 0
+col_width = screen_width = screen_height = cols_per_screen = gap = col_and_gap = number_of_cols = 0
 is_full_screen_layout = False
 
 def reset_paged_mode_globals():
-    nonlocal _in_paged_mode, col_width, col_and_gap, screen_height, gap, screen_width, is_full_screen_layout, cols_per_screen
+    nonlocal _in_paged_mode, col_width, col_and_gap, screen_height, gap, screen_width, is_full_screen_layout, cols_per_screen, number_of_cols
     scroll_viewport.reset_globals()
-    col_width = screen_width = screen_height = cols_per_screen = gap = col_and_gap = 0
+    col_width = screen_width = screen_height = cols_per_screen = gap = col_and_gap = number_of_cols = 0
     is_full_screen_layout = _in_paged_mode = False
 
 def column_at(xpos):
@@ -216,12 +216,14 @@ def layout(is_single_page):
     # themselves, unless the container width is an exact multiple, so we check
     # for that and manually set the container widths.
     def check_column_widths():
-        ncols = (scroll_viewport.paged_content_width() + gap) / col_and_gap
+        nonlocal number_of_cols
+        ncols = number_of_cols = (scroll_viewport.paged_content_width() + gap) / col_and_gap
         if ncols is not Math.floor(ncols):
-            n = Math.floor(ncols)
+            n = number_of_cols = Math.floor(ncols)
             dw = n*col_width + (n-1)*gap
             data = {'col_width':col_width, 'gap':gap, 'scrollWidth':scroll_viewport.paged_content_width(), 'ncols':ncols, 'desired_width':dw}
             return data
+
     data = check_column_widths()
     if data:
         dw = data.desired_width
@@ -459,11 +461,19 @@ def onwheel(evt):
 def scroll_by_page(backward, by_screen):
     if by_screen:
         pos = previous_screen_location() if backward else next_screen_location()
+        pages = cols_per_screen
     else:
         pos = previous_col_location() if backward else next_col_location()
+        pages = 1
     if pos is -1:
+        get_boss().report_human_scroll()
         get_boss().send_message('next_spine_item', previous=backward)
     else:
+        if not backward:
+            scrolled_frac = (pages / number_of_cols) if number_of_cols > 0 else 0
+            get_boss().report_human_scroll(scrolled_frac, True)
+        else:
+            get_boss().report_human_scroll()
         scroll_to_xpos(pos)
 
 def onkeydown(evt):
@@ -472,21 +482,25 @@ def onkeydown(evt):
     if key is 'up' or key is 'down':
         handled = True
         if evt.ctrlKey:
+            get_boss().report_human_scroll()
             scroll_to_offset(0 if key is 'left' else document_width())
         else:
             scroll_by_page(key is 'up', True)
     elif (key is 'left' or key is 'right') and not evt.altKey:
         handled = True
         if evt.ctrlKey:
+            get_boss().report_human_scroll()
             scroll_to_offset(0 if key is 'left' else document_width())
         else:
             scroll_by_page(key is 'left', False)
     elif key is 'home' or key is 'end':
         handled = True
         if evt.ctrlKey:
+            get_boss().report_human_scroll()
             get_boss().send_message('goto_doc_boundary', start=key is 'home')
         else:
             if key is 'home':
+                get_boss().report_human_scroll()
                 scroll_to_offset(0)
             else:
                 scroll_to_offset(document_width())

src/pyj/read_book/timers.pyj

@@ -0,0 +1,56 @@
+# vim:fileencoding=utf-8
+# License: GPL v3 Copyright: 2018, Kovid Goyal <kovid at kovidgoyal.net>
+from __python__ import bound_methods, hash_literals
+
+THRESHOLD = 5
+FILTER_THRESHOLD = 25
+MAX_SAMPLES = 256
+
+class Timers:
+
+    def __init__(self):
+        self.reset_read_timer()
+        self.rates = v'[]'
+        self.average = self.stddev = 0
+
+    def start_book(self, book):
+        self.reset_read_timer()
+        self.rates = v'[]'
+
+    def reset_read_timer(self):
+        self.last_scroll_at = None
+
+    def calculate(self):
+        rates = self.rates
+        rlen = rates.length
+        if rlen >= THRESHOLD:
+            avg = 0
+            for v'var i = 0; i < rlen; i++':
+                avg += rates[i]
+            avg /= rlen
+            self.average = avg
+            sq = 0
+            for v'var i = 0; i < rlen; i++':
+                x = rates[i]
+                sq += (x - avg) * (x - avg)
+            self.stddev = Math.sqrt(sq / (rlen - 1))
+        else:
+            self.average = self.stddev = 0
+
+    def on_human_scroll(self, amt_scrolled, is_large_scroll):
+        last_scroll_at = self.last_scroll_at
+        self.last_scroll_at = now = window.performance.now()
+        if last_scroll_at is None:
+            return
+        time_since_last_scroll = now - last_scroll_at
+        if time_since_last_scroll <= 0 or time_since_last_scroll >= 300:
+            return
+        if is_large_scroll and time_since_last_scroll < 2:
+            return
+        rate = amt_scrolled / time_since_last_scroll
+        if self.rates.length >= FILTER_THRESHOLD and Math.abs(rate - self.average) > 2 * self.stddev:
+            return
+        if self.rates.length >= MAX_SAMPLES:
+            self.rates.shift()
+        self.rates.push(rate)
+        self.calculate()

src/pyj/read_book/view.pyj

@@ -23,6 +23,7 @@ from read_book.prefs.font_size import change_font_size_by
 from read_book.prefs.head_foot import render_head_foot
 from read_book.resources import load_resources
 from read_book.search import SearchOverlay, find_in_spine
+from read_book.timers import Timers
 from read_book.toc import get_current_toc_nodes, update_visible_toc_nodes
 from read_book.touch import set_left_margin_handler, set_right_margin_handler
 from session import get_device_uuid, get_interface_data
@@ -116,6 +117,7 @@ class View:
 
     def __init__(self, container, ui):
         self.ui = ui
+        self.timers = Timers()
         self.loaded_resources = {}
         self.current_progress_frac = 0
         self.current_toc_node = self.current_toc_toplevel_node = None
@@ -163,6 +165,7 @@ class View:
             'request_size': self.on_request_size,
             'show_footnote': self.on_show_footnote,
             'print': self.on_print,
+            'human_scroll': self.on_human_scroll,
         }
         self.iframe_wrapper = IframeWrapper(handlers, document.getElementById(iframe_id), 'read_book.iframe', _('Bootstrapping book reader...'))
         self.search_overlay = SearchOverlay(self)
@@ -214,6 +217,16 @@ class View:
     def on_print(self, data):
         print(data.string)
 
+    def on_human_scroll(self, data):
+        if data.scrolled_by_frac is None:
+            self.timers.reset_read_timer()
+        else:
+            name = self.currently_showing.name
+            length = self.book.manifest.files[name]?.length
+            if length:
+                amt_scrolled = data.scrolled_by_frac * length
+                self.timers.on_human_scroll(amt_scrolled, data.is_large_scroll)
+
     def find(self, text, backwards):
         self.iframe_wrapper.send_message('find', text=text, backwards=backwards, searched_in_spine=False)
 
@@ -361,6 +374,7 @@ class View:
             self.content_popup_overlay.iframe_wrapper.reset()
             self.loaded_resources = {}
             self.content_popup_overlay.loaded_resources = {}
+            self.timers.start_book(book)
         self.book = current_book.book = book
         self.ui.db.update_last_read_time(book)
         pos = {'replace_history':True}