Revert "Remove ScrollHelper. Scrolling is fixed in Qt upstream."

This reverts commit 059d8da6b2

imports/Spectral/Component/AutoListView.qml

@@ -0,0 +1,11 @@
+import QtQuick 2.12
+
+ListView {
+    pixelAligned: true
+
+    ScrollHelper {
+        anchors.fill: parent
+
+        flickable: parent
+    }
+}

imports/Spectral/Component/ScrollHelper.qml

@@ -0,0 +1,105 @@
+/*
+ *  Copyright (C) 2016 Michael Bohlender, <michael.bohlender@kdemail.net>
+ *  Copyright (C) 2017 Christian Mollekopf, <mollekopf@kolabsystems.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+import QtQuick 2.12
+import QtQuick.Controls 2.12
+
+/*
+* The MouseArea + interactive: false + maximumFlickVelocity are required
+* to fix scrolling for desktop systems where we don't want flicking behaviour.
+*
+* See also:
+* ScrollView.qml in qtquickcontrols
+* qquickwheelarea.cpp in qtquickcontrols
+*/
+MouseArea {
+    id: root
+    propagateComposedEvents: true
+
+    property Flickable flickable
+    property alias enabled: root.enabled
+
+    //Place the mouse area under the flickable
+    z: -1
+    onFlickableChanged: {
+        if (enabled) {
+            flickable.interactive = false
+            flickable.maximumFlickVelocity = 100000
+            flickable.boundsBehavior = Flickable.StopAtBounds
+            root.parent = flickable
+        }
+    }
+
+    function calculateNewPosition(flickableItem, wheel) {
+        //Nothing to scroll
+        if (flickableItem.contentHeight < flickableItem.height) {
+            return flickableItem.contentY;
+        }
+        //Ignore 0 events (happens at least with Christians trackpad)
+        if (wheel.pixelDelta.y == 0 && wheel.angleDelta.y == 0) {
+            return flickableItem.contentY;
+        }
+        //pixelDelta seems to be the same as angleDelta/8
+        var pixelDelta = 0
+        //The pixelDelta is a smaller number if both are provided, so pixelDelta can be 0 while angleDelta is still something. So we check the angleDelta
+        if (wheel.angleDelta.y) {
+            var wheelScrollLines = 3 //Default value of QApplication wheelScrollLines property
+            var pixelPerLine = 20 //Default value in Qt, originally comes from QTextEdit
+            var ticks = (wheel.angleDelta.y / 8) / 15.0 //Divide by 8 gives us pixels typically come in 15pixel steps.
+            pixelDelta =  ticks * pixelPerLine * wheelScrollLines
+        } else {
+            pixelDelta = wheel.pixelDelta.y
+        }
+
+        if (!pixelDelta) {
+            return flickableItem.contentY;
+        }
+
+        var minYExtent = flickableItem.originY + flickableItem.topMargin;
+        var maxYExtent = (flickableItem.contentHeight + flickableItem.bottomMargin + flickableItem.originY) - flickableItem.height;
+
+        if (typeof(flickableItem.headerItem) !== "undefined" && flickableItem.headerItem) {
+            minYExtent += flickableItem.headerItem.height
+        }
+
+        //Avoid overscrolling
+        return Math.max(minYExtent, Math.min(maxYExtent, flickableItem.contentY - pixelDelta));
+    }
+
+    onWheel: {
+        var newPos = calculateNewPosition(flickable, wheel);
+        // console.warn("Delta: ", wheel.pixelDelta.y);
+        // console.warn("Old position: ", flickable.contentY);
+        // console.warn("New position: ", newPos);
+
+        // Show the scrollbars
+        flickable.flick(0, 0);
+        flickable.contentY = newPos;
+        cancelFlickStateTimer.start()
+    }
+
+
+    Timer {
+        id: cancelFlickStateTimer
+        //How long the scrollbar will remain visible
+        interval: 500
+        // Hide the scrollbars
+        onTriggered: flickable.cancelFlick();
+    }
+}

imports/Spectral/Component/qmldir

@@ -2,6 +2,8 @@ module Spectral.Component
 AutoMouseArea 2.0 AutoMouseArea.qml
 MaterialIcon 2.0 MaterialIcon.qml
 SideNavButton 2.0 SideNavButton.qml
+ScrollHelper 2.0 ScrollHelper.qml
+AutoListView 2.0 AutoListView.qml
 AutoTextField 2.0 AutoTextField.qml
 Avatar 2.0 Avatar.qml
 FullScreenImage 2.0 FullScreenImage.qml

imports/Spectral/Panel/RoomDrawer.qml

@@ -172,7 +172,7 @@ Drawer {
             }
         }
 
-        ListView {
+        AutoListView {
             Layout.fillWidth: true
             Layout.fillHeight: true
 
@@ -180,8 +180,6 @@ Drawer {
 
             clip: true
 
-            pixelAligned: true
-
             boundsBehavior: Flickable.DragOverBounds
 
             model: UserListModel {

imports/Spectral/Panel/RoomListPanel.qml

@@ -185,7 +185,7 @@ Item {
             }
         }
 
-        ListView {
+        AutoListView {
             Layout.fillWidth: true
             Layout.fillHeight: true
 
@@ -197,8 +197,6 @@ Item {
 
             model: sortedRoomListModel
 
-            pixelAligned: true
-
             boundsBehavior: Flickable.DragOverBounds
 
             ScrollBar.vertical: ScrollBar {}

imports/Spectral/Panel/RoomPanel.qml

@@ -223,7 +223,7 @@ Item {
 
             spacing: 16
 
-            ListView {
+            AutoListView {
                 readonly property int largestVisibleIndex: count > 0 ? indexAt(contentX + (width / 2), contentY + height - 1) : -1
                 readonly property bool noNeedMoreContent: !currentRoom || currentRoom.eventsHistoryJob || currentRoom.allHistoryLoaded
 
@@ -241,8 +241,6 @@ Item {
 
                 boundsBehavior: Flickable.DragOverBounds
 
-                pixelAligned: true
-
                 model: SortFilterProxyModel {
                     id: sortedMessageEventModel
 
@@ -256,10 +254,16 @@ Item {
 
                     onModelReset: {
                         movingTimer.stop()
-                        messageListView.positionViewAtBeginning()
                         if (currentRoom) {
                             movingTimer.restart()
 
+                            var lastScrollPosition = sortedMessageEventModel.mapFromSource(currentRoom.savedTopVisibleIndex())
+                            if (lastScrollPosition === 0) {
+                                messageListView.positionViewAtBeginning()
+                            } else {
+                                messageListView.currentIndex = lastScrollPosition
+                            }
+
                             if (messageListView.contentY < messageListView.originY + 10 || currentRoom.timelineSize < 20)
                                 currentRoom.getPreviousContent(50)
                         }

res.qrc

@@ -26,6 +26,8 @@
         <file>imports/Spectral/Panel/RoomListPanel.qml</file>
         <file>imports/Spectral/Panel/RoomPanel.qml</file>
         <file>imports/Spectral/Panel/RoomHeader.qml</file>
+        <file>imports/Spectral/Component/ScrollHelper.qml</file>
+        <file>imports/Spectral/Component/AutoListView.qml</file>
         <file>imports/Spectral/Component/AutoTextField.qml</file>
         <file>imports/Spectral/Panel/RoomPanelInput.qml</file>
         <file>imports/Spectral/Component/Timeline/SectionDelegate.qml</file>