Merge pull request #261 from matrix-org/rav/issue_1151

Fix an issue where the scroll stopped working.

karma.conf.js

@@ -1,6 +1,7 @@
 // karma.conf.js - the config file for karma, which runs our tests.
 
 var path = require('path');
+var fs = require('fs');
 
 /*
  * We use webpack to build our tests. It's a pain to have to wait for webpack
@@ -17,6 +18,21 @@ var path = require('path');
 
 process.env.PHANTOMJS_BIN = 'node_modules/.bin/phantomjs';
 
+function fileExists(name) {
+    try {
+        fs.statSync(gsCss);
+        return true;
+    } catch (e) {
+        return false;
+    }
+}
+
+// try find the gemini-scrollbar css in an npm-version-agnostic way
+var gsCss = 'node_modules/gemini-scrollbar/gemini-scrollbar.css';
+if (!fileExists(gsCss)) {
+    gsCss = 'node_modules/react-gemini-scrollbar/'+gsCss;
+}
+
 module.exports = function (config) {
     config.set({
         // frameworks to use
@@ -26,6 +42,7 @@ module.exports = function (config) {
         // list of files / patterns to load in the browser
         files: [
             'test/tests.js',
+            gsCss,
         ],
 
         // list of files to exclude

src/components/structures/ScrollPanel.js

@@ -20,6 +20,7 @@ var GeminiScrollbar = require('react-gemini-scrollbar');
 var q = require("q");
 
 var DEBUG_SCROLL = false;
+// var DEBUG_SCROLL = true;
 
 if (DEBUG_SCROLL) {
     // using bind means that we get to keep useful line numbers in the console
@@ -144,7 +145,8 @@ module.exports = React.createClass({
 
     onScroll: function(ev) {
         var sn = this._getScrollNode();
-        debuglog("Scroll event: offset now:", sn.scrollTop, "recentEventScroll:", this.recentEventScroll);
+        debuglog("Scroll event: offset now:", sn.scrollTop,
+                 "_lastSetScroll:", this._lastSetScroll);
 
         // Sometimes we see attempts to write to scrollTop essentially being
         // ignored. (Or rather, it is successfully written, but on the next
@@ -158,13 +160,10 @@ module.exports = React.createClass({
         // By way of a workaround, we detect this situation and just keep
         // resetting scrollTop until we see the scroll node have the right
         // value.
-        if (this.recentEventScroll !== undefined) {
+        if (this._lastSetScroll !== undefined && sn.scrollTop < this._lastSetScroll-200) {
-            if(sn.scrollTop < this.recentEventScroll-200) {
+            console.log("Working around vector-im/vector-web#528");
-                console.log("Working around vector-im/vector-web#528");
+            this._restoreSavedScrollState();
-                this._restoreSavedScrollState();
+            return;
-                return;
-            }
-            this.recentEventScroll = undefined;
         }
 
         // If there weren't enough children to fill the viewport, the scroll we
@@ -395,17 +394,14 @@ module.exports = React.createClass({
         var wrapperRect = ReactDOM.findDOMNode(this).getBoundingClientRect();
         var boundingRect = node.getBoundingClientRect();
         var scrollDelta = boundingRect.bottom + pixelOffset - wrapperRect.bottom;
+
+        debuglog("Scrolling to token '" + node.dataset.scrollToken + "'+" +
+                 pixelOffset + " (delta: "+scrollDelta+")");
+
         if(scrollDelta != 0) {
             this._setScrollTop(scrollNode.scrollTop + scrollDelta);
-
-            // see the comments in onScroll regarding recentEventScroll
-            this.recentEventScroll = scrollNode.scrollTop;
         }
 
-        debuglog("Scrolled to token", node.dataset.scrollToken, "+",
-                 pixelOffset+":", scrollNode.scrollTop, 
-                 "(delta: "+scrollDelta+")");
-        debuglog("recentEventScroll now "+this.recentEventScroll);
     },
 
     _saveScrollState: function() {

test/components/structures/ScrollPanel-test.js

@@ -0,0 +1,275 @@
+/*
+Copyright 2016 OpenMarket Ltd
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+var React = require('react');
+var ReactDOM = require("react-dom");
+var ReactTestUtils = require('react-addons-test-utils');
+var expect = require('expect');
+var q = require('q');
+
+var sdk = require('matrix-react-sdk');
+
+var ScrollPanel = sdk.getComponent('structures.ScrollPanel');
+var test_utils = require('test-utils');
+
+var Tester = React.createClass({
+    getInitialState: function() {
+        return {
+            tileKeys: [],
+        };
+    },
+
+    componentWillMount: function() {
+        this.fillCounts = {'b': 0, 'f': 0};
+        this._fillHandlers = {'b': null, 'f': null};
+        this._fillDefers = {'b': null, 'f': null};
+        this._scrollDefer = null;
+
+        // scrollTop at the last scroll event
+        this.lastScrollEvent = null;
+    },
+
+    _onFillRequest: function(back) {
+        var dir = back ? 'b': 'f';
+        console.log("FillRequest: " + dir);
+        this.fillCounts[dir]++;
+
+        var handler = this._fillHandlers[dir];
+        var defer = this._fillDefers[dir];
+
+        // don't use the same handler twice
+        this._fillHandlers[dir] = null;
+        this._fillDefers[dir] = null;
+
+        var res;
+        if (handler) {
+            res = handler();
+        } else {
+            res = q(false);
+        }
+
+        if (defer) {
+            defer.resolve();
+        }
+        return res;
+    },
+
+    addFillHandler: function(dir, handler) {
+        this._fillHandlers[dir] = handler;
+    },
+
+    /* returns a promise which will resolve when the fill happens */
+    awaitFill: function(dir) {
+        var defer = q.defer();
+        this._fillDefers[dir] = defer;
+        return defer.promise;
+    },
+
+    _onScroll: function(ev) {
+        var st = ev.target.scrollTop;
+        console.log("Scroll event; scrollTop: " + st);
+        this.lastScrollEvent = st;
+
+        var d = this._scrollDefer;
+        if (d) {
+            this._scrollDefer = null;
+            d.resolve();
+        }
+    },
+
+    /* returns a promise which will resolve when a scroll event happens */
+    awaitScroll: function() {
+        console.log("Awaiting scroll");
+        this._scrollDefer = q.defer();
+        return this._scrollDefer.promise;
+    },
+
+    setTileKeys: function(keys) {
+        console.log("Updating keys: len=" + keys.length);
+        this.setState({tileKeys: keys.slice()});
+    },
+
+    scrollPanel: function() {
+        return this.refs.sp;
+    },
+
+    _mkTile: function(key) {
+        // each tile is 150 pixels high:
+        // 98 pixels of body
+        // 2 pixels of border
+        // 50 pixels of margin
+        //
+        // there is an extra 50 pixels of margin at the bottom.
+        return (
+            <li key={key} data-scroll-token={key}>
+                <div style={{height: '98px', margin: '50px', border: '1px solid black',
+                             backgroundColor: '#fff8dc' }}>
+                   {key}
+                </div>
+             </li>
+         );
+    },
+
+    render: function() {
+        var tiles = this.state.tileKeys.map(this._mkTile);
+        console.log("rendering with " + tiles.length + " tiles");
+        return (
+            <ScrollPanel ref="sp"
+                onScroll={ this._onScroll }
+                onFillRequest={ this._onFillRequest }>
+                    {tiles}
+            </ScrollPanel>
+        );
+    },
+});
+
+describe('ScrollPanel', function() {
+    var parentDiv;
+    var tester;
+    var scrollingDiv;
+
+    beforeEach(function(done) {
+        test_utils.beforeEach(this);
+
+        // create a div of a useful size to put our panel in, and attach it to
+        // the document so that we can interact with it properly.
+        parentDiv = document.createElement('div');
+        parentDiv.style.width = '800px';
+        parentDiv.style.height = '600px';
+        parentDiv.style.overflow = 'hidden';
+        document.body.appendChild(parentDiv);
+
+        tester = ReactDOM.render(<Tester/>, parentDiv);
+        expect(tester.fillCounts.b).toEqual(1);
+        expect(tester.fillCounts.f).toEqual(1);
+
+        scrollingDiv = ReactTestUtils.findRenderedDOMComponentWithClass(
+            tester, "gm-scroll-view");
+
+        // wait for a browser tick to let the initial paginates complete
+        setTimeout(function() {
+            done();
+        }, 0);
+    });
+
+    afterEach(function() {
+        if (parentDiv) {
+            document.body.removeChild(parentDiv);
+            parentDiv = null;
+        }
+    });
+
+    it('should handle scrollEvent strangeness', function(done) {
+        var events = [];
+
+        q().then(() => {
+            // initialise with a few events
+            for (var i = 0; i < 10; i++) {
+                events.push(i+90);
+            }
+            tester.setTileKeys(events);
+            expect(tester.fillCounts.b).toEqual(1);
+            expect(tester.fillCounts.f).toEqual(2);
+            expect(scrollingDiv.scrollHeight).toEqual(1550) // 10*150 + 50
+            expect(scrollingDiv.scrollTop).toEqual(1550 - 600);
+            return tester.awaitScroll();
+        }).then(() => {
+            expect(tester.lastScrollEvent).toBe(950);
+
+            // we want to simulate back-filling as we scroll up
+            tester.addFillHandler('b', function() {
+                var newEvents = [];
+                for (var i = 0; i < 10; i++) {
+                    newEvents.push(i+80);
+                }
+                events.unshift.apply(events, newEvents);
+                tester.setTileKeys(events);
+                return q(true);
+            });
+
+            // simulate scrolling up; this should trigger the backfill
+            scrollingDiv.scrollTop = 200;
+
+            return tester.awaitFill('b');
+        }).then(() => {
+            console.log('filled');
+
+            // at this point, ScrollPanel will have updated scrollTop, but
+            // the event hasn't fired. Stamp over the scrollTop.
+            expect(tester.lastScrollEvent).toEqual(200);
+            expect(scrollingDiv.scrollTop).toEqual(10*150 + 200);
+            scrollingDiv.scrollTop = 500;
+
+            return tester.awaitScroll();
+        }).then(() => {
+            expect(tester.lastScrollEvent).toBe(10*150 + 200);
+            expect(scrollingDiv.scrollTop).toEqual(10*150 + 200);
+        }).done(done);
+    });
+
+    it('should not get stuck in #528 workaround', function(done) {
+        var events = [];
+        q().then(() => {
+            // initialise with a bunch of events
+            for (var i = 0; i < 40; i++) {
+                events.push(i);
+            }
+            tester.setTileKeys(events);
+            expect(tester.fillCounts.b).toEqual(1);
+            expect(tester.fillCounts.f).toEqual(2);
+            expect(scrollingDiv.scrollHeight).toEqual(6050) // 40*150 + 50
+            expect(scrollingDiv.scrollTop).toEqual(6050 - 600);
+
+            // try to scroll up, to a non-integer offset.
+            tester.scrollPanel().scrollToToken("30", -101/3);
+
+            expect(scrollingDiv.scrollTop).toEqual(4616); // 31*150 - 34
+
+            // wait for the scroll event to land
+            return tester.awaitScroll(); // fails
+        }).then(() => {
+            expect(tester.lastScrollEvent).toEqual(4616);
+
+            // Now one more event; this will make it reset the scroll, but
+            // because the delta will be less than 1, will not trigger a
+            // scroll event, this leaving recentEventScroll defined.
+            console.log("Adding event 50");
+            events.push(50);
+            tester.setTileKeys(events);
+
+            // wait for the scrollpanel to stop trying to paginate
+        }).then(() => {
+            // Now, simulate hitting "scroll to bottom".
+            events = [];
+            for (var i = 100; i < 120; i++) {
+                events.push(i);
+            }
+            tester.setTileKeys(events);
+            tester.scrollPanel().scrollToBottom();
+
+            // wait for the scroll event to land
+            return tester.awaitScroll(); // fails
+        }).then(() => {
+            expect(scrollingDiv.scrollTop).toEqual(20*150 + 50 - 600);
+
+            // simulate a user-initiated scroll on the div
+            scrollingDiv.scrollTop = 1200;
+            return tester.awaitScroll();
+        }).then(() => {
+            expect(scrollingDiv.scrollTop).toEqual(1200);
+        }).done(done);
+    });
+});

test/test-utils.js

@@ -5,6 +5,18 @@ var jssdk = require('matrix-js-sdk');
 var MatrixEvent = jssdk.MatrixEvent;
 var sinon = require('sinon');
 
+/**
+ * Perform common actions before each test case, e.g. printing the test case
+ * name to stdout.
+ * @param {Mocha.Context} context  The test context
+ */
+module.exports.beforeEach = function(context) {
+    var desc = context.currentTest.fullTitle();
+    console.log();
+    console.log(desc);
+    console.log(new Array(1 + desc.length).join("="));
+};
+
 
 /**
  * Stub out the MatrixClient, and configure the MatrixClientPeg object to
@@ -128,22 +140,3 @@ module.exports.mkMessage = function(opts) {
     };
     return module.exports.mkEvent(opts);
 };
-
-/**
- * make the test fail, with the given exception
- *
- * <p>This is useful for use with integration tests which use asyncronous
- * methods: it can be added as a 'catch' handler in a promise chain.
- *
- * @param {Error} error   exception to be reported
- *
- * @example
- * it("should not throw", function(done) {
- *    asynchronousMethod().then(function() {
- *       // some tests
- *    }).catch(utils.failTest).done(done);
- * });
- */
-module.exports.failTest = function(error) {
-    expect(error.stack).toBe(null);
-};