Fix & improve keyboard and mousewheel flicking

TODO.md

@@ -1,6 +1,4 @@
-- make pageup/down not slippery again
 - better cancel for all boxes
-- get rid of all currentSpacing stuff
 
 - Media
   - Handle set avatar upload errors
@@ -24,6 +22,7 @@
 - Refactoring
   - Use a singleton for utils.js
   - Use HBox for Profile
+    - Get rid of all `currentSpacing` stuff
   - Banners
   - Composer
   - Try gel for the models and stop being lazy in python

src/qml/Base/HListView.qml

@@ -3,7 +3,7 @@ import QtQuick.Controls 2.12
 
 ListView {
     id: listView
-    interactive: enableFlicking
+    interactive: allowDragging
     currentIndex: -1
     keyNavigationWraps: true
     highlightMoveDuration: theme.animationDuration
@@ -15,18 +15,13 @@ ListView {
 
     maximumFlickVelocity: 4000
 
-    property bool enableFlicking: true
-
-    readonly property int currentItemHeight:
-        currentItem ? currentItem.height : 0
-
 
     highlight: Rectangle {
         color: theme.controls.listView.highlight
     }
 
     ScrollBar.vertical: ScrollBar {
-        visible: listView.interactive || ! listView.enableFlicking
+        visible: listView.interactive || ! listView.allowDragging
     }
 
     add: Transition {
@@ -52,4 +47,32 @@ ListView {
     }
 
     displaced: move
+
+
+    property bool allowDragging: true
+
+    property alias cursorShape: mouseArea.cursorShape
+
+    readonly property int currentItemHeight:
+        currentItem ? currentItem.height : 0
+
+
+    Connections {
+        target: listView
+        enabled: ! listView.allowDragging
+        // interactive gets temporarily set to true below to allow wheel scroll
+        onDraggingChanged: listView.interactive = false
+    }
+
+    MouseArea {
+        id: mouseArea
+        anchors.fill: parent
+        enabled: ! parent.allowDragging || cursorShape !== Qt.ArrowCursor
+        acceptedButtons: Qt.NoButton
+        onWheel: {
+            // Allow wheel usage, will be back to false on any drag attempt
+            parent.interactive = true
+            wheel.accepted = false
+        }
+    }
 }

src/qml/Chat/Timeline/EventList.qml

@@ -61,7 +61,7 @@ Rectangle {
         HListView {
             id: eventList
             clip: true
-            enableFlicking: false
+            allowDragging: false
 
             anchors.fill: parent
             anchors.leftMargin: theme.spacing
@@ -92,8 +92,6 @@ Rectangle {
             property bool ownEventsOnRight:
                 width < theme.chat.eventList.ownEventsOnRightUnderWidth
 
-            property alias cursorShape: mouseArea.cursorShape
-
 
             function canCombine(item, itemAfter) {
                 if (! item || ! itemAfter) return false
@@ -160,19 +158,6 @@ Rectangle {
             }
 
             delegate: EventDelegate {}
-
-            MouseArea {
-                id: mouseArea
-                anchors.fill: parent
-                acceptedButtons: Qt.NoButton
-
-                onWheel: Utils.smartVerticalFlick(
-                    eventList,
-                    200 * Qt.styleHints.wheelScrollLines *
-                    (wheel.angleDelta.y < 0 ? 1 : -1),
-                    2,
-                )
-            }
         }
     }
 

src/qml/Shortcuts.qml

@@ -72,32 +72,25 @@ Item {
     HShortcut {
         enabled: toFlick
         sequences: settings.keys.scrollUp
-        onActivated: Utils.smartVerticalFlick(toFlick, -335)
+        onActivated: Utils.flickPages(toFlick, -1 / 10)
     }
 
     HShortcut {
         enabled: toFlick
         sequences: settings.keys.scrollDown
-        onActivated: Utils.smartVerticalFlick(toFlick, 335)
+        onActivated: Utils.flickPages(toFlick, 1 / 10)
     }
 
     HShortcut {
         enabled: toFlick
         sequences: settings.keys.scrollPageUp
-        onActivated: Utils.smartVerticalFlick(
-            toFlick, -2.3 * toFlick.height, 8,
-        )
-        // Ensure only a slight slip after releasing the key
-        // onReleased: Utils.smartVerticalFlick(toFlick, -335)
+        onActivated: Utils.flickPages(toFlick, -1)
     }
 
     HShortcut {
         enabled: toFlick
         sequences: settings.keys.scrollPageDown
-        onActivated: Utils.smartVerticalFlick(
-            toFlick, 2.3 * toFlick.height, 8,
-        )
-        // onReleased: Utils.smartVerticalFlick(toFlick, 335)
+        onActivated: Utils.flickPages(toFlick, 1)
     }
 
     HShortcut {

src/qml/utils.js

@@ -229,20 +229,36 @@ function getItem(array, mainKey, value) {
 }
 
 
-function smartVerticalFlick(flickable, baseVelocity, fastMultiply=4) {
-    if (! flickable.interactive && flickable.enableFlicking) return
+function flickPages(flickable, pages) {
+    // Adapt velocity and deceleration for the number of pages to flick.
+    // If this is a repeated flicking, flick faster than a single flick.
+    if (! flickable.interactive && flickable.allowDragging) return
 
-    baseVelocity = -baseVelocity
-    let vel      = -flickable.verticalVelocity
-    let fast     = (baseVelocity < 0 && vel < baseVelocity / 2) ||
-                   (baseVelocity > 0 && vel > baseVelocity / 2)
+    const futureVelocity  = -flickable.height * pages
+    const currentVelocity = -flickable.verticalVelocity
+    const goFaster        =
+        (futureVelocity < 0 && currentVelocity < futureVelocity / 2) ||
+        (futureVelocity > 0 && currentVelocity > futureVelocity / 2)
 
-    flickable.flick(0, baseVelocity * (fast ? fastMultiply : 1))
+    const normalDecel  = flickable.flickDeceleration
+    const fastMultiply = pages && 8 / (1 - Math.log10(Math.abs(pages)))
+    const magicNumber  = 2.5
+
+    flickable.flickDeceleration = Math.max(
+        goFaster ? normalDecel : -Infinity,
+        Math.abs(normalDecel * magicNumber * pages),
+    )
+
+    flickable.flick(
+        0, futureVelocity * magicNumber * (goFaster ? fastMultiply : 1),
+    )
+
+    flickable.flickDeceleration = normalDecel
 }
 
 
 function flickToTop(flickable) {
-    if (! flickable.interactive && flickable.enableFlicking) return
+    if (! flickable.interactive && flickable.allowDragging) return
     if (flickable.visibleArea.yPosition < 0) return
 
     flickable.contentY -= flickable.contentHeight
@@ -252,7 +268,7 @@ function flickToTop(flickable) {
 
 
 function flickToBottom(flickable) {
-    if (! flickable.interactive && flickable.enableFlicking) return
+    if (! flickable.interactive && flickable.allowDragging) return
     if (flickable.visibleArea.yPosition < 0) return
 
     flickable.contentY = flickTarget.contentHeight - flickTarget.height