Init infinite scroll.

It constanatly crashes, TBD.

qml/form/RoomForm.qml

@@ -19,6 +19,23 @@ Item {
     MessageEventModel {
         id: messageEventModel
         room: currentRoom
+
+        onModelReset: {
+            if (currentRoom)
+            {
+                var lastScrollPosition = currentRoom.savedTopVisibleIndex()
+                if (lastScrollPosition === 0)
+                    messageListView.positionViewAtBeginning()
+                else
+                {
+                    console.log("Scrolling to position", lastScrollPosition)
+                    messageListView.positionViewAtIndex(lastScrollPosition, ListView.Contain)
+                }
+                if (messageListView.contentY < messageListView.originY + 10)
+                    currentRoom.getPreviousContent(100)
+            }
+            console.log("Model timeline reset")
+        }
     }
 
     RoomDrawer {
@@ -46,6 +63,8 @@ Item {
             Layout.fillWidth: true
             Layout.preferredHeight: 64
 
+            z: 10
+
             color: Material.accent
 
             ItemDelegate {
@@ -98,18 +117,10 @@ Item {
             }
         }
 
-        RowLayout {
-            Layout.fillWidth: true
-            Layout.fillHeight: true
-            Layout.leftMargin: 16
-
-            z: -10
-
-            spacing: 0
-
         ListView {
             Layout.fillWidth: true
             Layout.fillHeight: true
+            Layout.margins: 16
 
             id: messageListView
 
@@ -118,10 +129,25 @@ Item {
             verticalLayoutDirection: ListView.BottomToTop
             spacing: 8
 
-                boundsBehavior: Flickable.DragOverBounds
-                //                    flickDeceleration: 4096
+            flickDeceleration: 4096
 
-                //                    cacheBuffer: 200
+            boundsBehavior: Flickable.DragOverBounds
+
+            property int largestVisibleIndex: count > 0 ? indexAt(contentX, contentY + height - 1) : -1
+
+            onContentYChanged: {
+                // Check whether we're about to bump into the ceiling in 2 seconds
+                var curVelocity = verticalVelocity // Snapshot the current speed
+                if( curVelocity < 0 && contentY + curVelocity*2 < originY)
+                {
+                    // Request the amount of messages enough to scroll at this
+                    // rate for 3 more seconds
+                    var avgHeight = contentHeight / count
+                    currentRoom.getPreviousContent(-curVelocity*3 / avgHeight);
+                }
+            }
+
+            onMovementEnded: currentRoom.saveViewport(indexAt(contentX, contentY), largestVisibleIndex)
 
             model: SortFilterProxyModel {
                 id: sortedRoomListModel
@@ -195,11 +221,6 @@ Item {
                 }
             }
 
-                ScrollBar.vertical: messageListViewScrollBar
-
-                onAtYBeginningChanged: atYBeginning && currentRoom ? currentRoom.getPreviousContent(20) : {}
-                onAtYEndChanged: atYEnd && currentRoom ? currentRoom.markAllMessagesAsRead() : {}
-
             RoundButton {
                 width: 64
                 height: 64
@@ -308,14 +329,6 @@ Item {
             }
         }
 
-            ScrollBar {
-                Layout.preferredWidth: 16
-                Layout.fillHeight: true
-
-                id: messageListViewScrollBar
-            }
-        }
-
         Item {
             Layout.fillWidth: true
             Layout.preferredHeight: 40

src/spectralroom.cpp

@@ -147,3 +147,31 @@ QDateTime SpectralRoom::lastActiveTime() {
 }
 
 float SpectralRoom::orderForTag(QString name) { return tag(name).order; }
+
+int SpectralRoom::savedTopVisibleIndex() const {
+  return firstDisplayedMarker() == timelineEdge()
+             ? 0
+             : firstDisplayedMarker() - messageEvents().rbegin();
+}
+
+int SpectralRoom::savedBottomVisibleIndex() const {
+  return lastDisplayedMarker() == timelineEdge()
+             ? 0
+             : lastDisplayedMarker() - messageEvents().rbegin();
+}
+
+void SpectralRoom::saveViewport(int topIndex, int bottomIndex) {
+  if (topIndex == -1 || bottomIndex == -1 ||
+      (bottomIndex == savedBottomVisibleIndex() &&
+       (bottomIndex == 0 || topIndex == savedTopVisibleIndex())))
+    return;
+  if (bottomIndex == 0) {
+    qDebug() << "Saving viewport as the latest available";
+    setFirstDisplayedEventId({});
+    setLastDisplayedEventId({});
+    return;
+  }
+  qDebug() << "Saving viewport:" << topIndex << "thru" << bottomIndex;
+  setFirstDisplayedEvent(maxTimelineIndex() - topIndex);
+  setLastDisplayedEvent(maxTimelineIndex() - bottomIndex);
+}

src/spectralroom.h

@@ -38,6 +38,9 @@ class SpectralRoom : public Room {
   QDateTime lastActiveTime();
 
   Q_INVOKABLE float orderForTag(QString name);
+  Q_INVOKABLE int savedTopVisibleIndex() const;
+  Q_INVOKABLE int savedBottomVisibleIndex() const;
+  Q_INVOKABLE void saveViewport(int topIndex, int bottomIndex);
 
  private:
   QString m_cachedInput;