From 8504d41db3fa30c392da9b0813e9c6791f546b2a Mon Sep 17 00:00:00 2001
From: Florian Bruhin <git@the-compiler.org>
Date: Fri, 20 Oct 2017 08:58:28 +0200
Subject: [PATCH] Use Qt API for QtWebEngine scrolling

See #2233
Fixes #2822
---
 qutebrowser/browser/webengine/webenginetab.py | 50 ++++++++-----------
 qutebrowser/javascript/scroll.js              | 27 ----------
 2 files changed, 20 insertions(+), 57 deletions(-)

diff --git a/qutebrowser/browser/webengine/webenginetab.py b/qutebrowser/browser/webengine/webenginetab.py
index 1e625d93c..2decf3599 100644
--- a/qutebrowser/browser/webengine/webenginetab.py
+++ b/qutebrowser/browser/webengine/webenginetab.py
@@ -24,7 +24,7 @@ import functools
 import html as html_utils
 
 import sip
-from PyQt5.QtCore import pyqtSlot, Qt, QEvent, QPoint, QUrl, QTimer
+from PyQt5.QtCore import pyqtSlot, Qt, QEvent, QPoint, QPointF, QUrl, QTimer
 from PyQt5.QtGui import QKeyEvent
 from PyQt5.QtNetwork import QAuthenticator
 from PyQt5.QtWidgets import QApplication
@@ -308,40 +308,30 @@ class WebEngineScroller(browsertab.AbstractScroller):
         for _ in range(min(count, 5000)):
             self._tab.key_press(key, modifier)
 
-    @pyqtSlot()
-    def _update_pos(self):
+    @pyqtSlot(QPointF)
+    def _update_pos(self, pos):
         """Update the scroll position attributes when it changed."""
-        def update_pos_cb(jsret):
-            """Callback after getting scroll position via JS."""
-            if jsret is None:
-                # This can happen when the callback would get called after
-                # shutting down a tab
-                return
-            log.webview.vdebug(jsret)
-            assert isinstance(jsret, dict), jsret
-            self._pos_px = QPoint(jsret['px']['x'], jsret['px']['y'])
+        self._pos_px = pos.toPoint()
+        contents_size = self._widget.page().contentsSize()
 
-            dx = jsret['scroll']['width'] - jsret['inner']['width']
-            if dx == 0:
-                perc_x = 0
-            else:
-                perc_x = min(100, round(100 / dx * jsret['px']['x']))
+        scrollable_x = contents_size.width() - self._widget.width()
+        if scrollable_x == 0:
+            perc_x = 0
+        else:
+            perc_x = min(100, round(100 / scrollable_x * pos.x()))
 
-            dy = jsret['scroll']['height'] - jsret['inner']['height']
-            if dy == 0:
-                perc_y = 0
-            else:
-                perc_y = min(100, round(100 / dy * jsret['px']['y']))
+        scrollable_y = contents_size.height() - self._widget.height()
+        if scrollable_y == 0:
+            perc_y = 0
+        else:
+            perc_y = min(100, round(100 / scrollable_y * pos.y()))
 
-            self._at_bottom = math.ceil(jsret['px']['y']) >= dy
+        self._at_bottom = math.ceil(pos.y()) >= scrollable_y
 
-            if (self._pos_perc != (perc_x, perc_y) or
-                    'no-scroll-filtering' in self._args.debug_flags):
-                self._pos_perc = perc_x, perc_y
-                self.perc_changed.emit(*self._pos_perc)
-
-        js_code = javascript.assemble('scroll', 'pos')
-        self._tab.run_js_async(js_code, update_pos_cb)
+        if (self._pos_perc != (perc_x, perc_y) or
+                'no-scroll-filtering' in self._args.debug_flags):
+            self._pos_perc = perc_x, perc_y
+            self.perc_changed.emit(*self._pos_perc)
 
     def pos_px(self):
         return self._pos_px
diff --git a/qutebrowser/javascript/scroll.js b/qutebrowser/javascript/scroll.js
index 35f412783..188320f11 100644
--- a/qutebrowser/javascript/scroll.js
+++ b/qutebrowser/javascript/scroll.js
@@ -71,32 +71,5 @@ window._qutebrowser.scroll = (function() {
         window.scrollBy(dx, dy);
     };
 
-    funcs.pos = function() {
-        var pos = {
-            "px": {"x": window.scrollX, "y": window.scrollY},
-            "scroll": {
-                "width": Math.max(
-                    document.body.scrollWidth,
-                    document.body.offsetWidth,
-                    document.documentElement.scrollWidth,
-                    document.documentElement.offsetWidth
-                ),
-                "height": Math.max(
-                    document.body.scrollHeight,
-                    document.body.offsetHeight,
-                    document.documentElement.scrollHeight,
-                    document.documentElement.offsetHeight
-                ),
-            },
-            "inner": {
-                "width": window.innerWidth,
-                "height": window.innerHeight,
-            },
-        };
-
-        // console.log(JSON.stringify(pos));
-        return pos;
-    };
-
     return funcs;
 })();