Improve message delegate code, fix multiple issues

- Fix the ListView not auto-scrolling like it should when message
  delegates changed height, such as when images were loaded

- Fix messed up delegate positions overlapping each others when
  movements happen

- Fix previous/nextItem binding broken due to imperative modification

- Fix "messageBodyWidth" binding loop

TODO.md

@@ -49,18 +49,15 @@
 
 ## Issues
 
+- Room pane slightly overlaps chat at small width
 - invisible uploaded mxc images?
 - first undecryptable message
 - Join button 502
 - Leave box button focus
 
-- two upload delegates height bug
 - Pausing uploads doesn't work well, servers end up dropping the connection 
 - Pause upload, switch to other room, then come back, wrong state displayed
 
-- Messed up message delegates position
-- Event delegates changing height don't scroll the list
-
 - In the "Leave me" room, "join > Hi > left" aren't combined
 - When selecting text and scrolling up, selection stops working after a while
   - Ensure all the text that should be copied is copied

src/qml/Base/HNoticePage.qml

@@ -18,17 +18,16 @@ HRowLayout {
         leftPadding: theme.spacing
         rightPadding: leftPadding
 
-        Layout.margins: theme.spacing
-        Layout.alignment: Qt.AlignCenter
-        Layout.maximumWidth:
-            parent.width - Layout.leftMargin - Layout.rightMargin
-
-        opacity: width > Layout.leftMargin + Layout.rightMargin ? 1 : 0
+        opacity: width > 16 * theme.uiScale ? 1 : 0
 
         background: Rectangle {
             id: noticeLabelBackground
             color: theme.controls.box.background
             radius: theme.controls.box.radius
         }
+
+        Layout.alignment: Qt.AlignCenter
+        Layout.preferredWidth: implicitWidth
+        Layout.maximumWidth: parent.width
     }
 }

src/qml/Chat/Timeline/EventContent.qml

@@ -27,16 +27,15 @@ HRowLayout {
     readonly property string hoveredLink: contentLabel.hoveredLink
     readonly property bool hoveredSelectable: contentHover.hovered
 
-    readonly property int messageBodyWidth:
-        width - (avatarWrapper.visible ? avatarWrapper.width : 0) -
-        spacing * Math.max(0, (visibleChildren.length - 1))
-
     readonly property int xOffset:
         onRight ?
         contentLabel.width - contentLabel.paintedWidth -
         contentLabel.leftPadding - contentLabel.rightPadding :
         0
 
+    // 600px max with a 16px font
+    readonly property int maxMessageWidth: theme.fontSize.normal * 0.5 * 75
+
 
     TapHandler {
         enabled: debugMode
@@ -116,11 +115,8 @@ HRowLayout {
 
             transform: Translate { x: xOffset }
 
-            Layout.maximumWidth: Math.min(
-                // 600px with 16px font
-                theme.fontSize.normal * 0.5 * 75,
-                messageBodyWidth - leftPadding - rightPadding,
-            )
+            Layout.maximumWidth: eventContent.maxMessageWidth
+            Layout.fillWidth: true
 
             function selectAllText() {
                 // Select the message body without the date or name
@@ -162,10 +158,10 @@ HRowLayout {
 
         HRepeater {
             id: linksRepeater
-            model: eventDelegate.currentItem.links
+            model: eventDelegate.currentModel.links
 
             EventMediaLoader {
-                singleMediaInfo: eventDelegate.currentItem
+                singleMediaInfo: eventDelegate.currentModel
                 mediaUrl: modelData
                 showSender: pureMedia ? senderText : ""
                 showDate: pureMedia ? timeText : ""

src/qml/Chat/Timeline/EventDelegate.qml

@@ -3,15 +3,9 @@ import QtQuick.Layouts 1.12
 import "../../Base"
 import "../../utils.js" as Utils
 
-Column {
+HColumnLayout {
     id: eventDelegate
     width: eventList.width
-    topPadding:
-        model.event_type === "RoomCreateEvent" ? 0 :
-        dayBreak  ? theme.spacing * 4 :
-        talkBreak ? theme.spacing * 6 :
-        combine   ? theme.spacing / 2 :
-        theme.spacing * 2
 
 
     enum Media { Page, File, Image, Video, Audio }
@@ -19,23 +13,18 @@ Column {
     property var hoveredMediaTypeUrl: []
 
     // Remember timeline goes from newest message at index 0 to oldest
-    property var previousItem: eventList.model.get(model.index + 1)
-    property var nextItem: eventList.model.get(model.index - 1)
-    readonly property QtObject currentItem: model
-    property int modelIndex: model.index
-    onModelIndexChanged: {
-        previousItem = eventList.model.get(model.index + 1)
-        nextItem     = eventList.model.get(model.index - 1)
-    }
+    readonly property var previousModel: eventList.model.get(model.index + 1)
+    readonly property var nextModel: eventList.model.get(model.index - 1)
+    readonly property QtObject currentModel: model
 
     property bool isOwn: chat.userId === model.sender_id
     property bool onRight: eventList.ownEventsOnRight && isOwn
-    property bool combine: eventList.canCombine(previousItem, model)
-    property bool talkBreak: eventList.canTalkBreak(previousItem, model)
-    property bool dayBreak: eventList.canDayBreak(previousItem, model)
+    property bool combine: eventList.canCombine(previousModel, model)
+    property bool talkBreak: eventList.canTalkBreak(previousModel, model)
+    property bool dayBreak: eventList.canDayBreak(previousModel, model)
 
     readonly property bool smallAvatar:
-        eventList.canCombine(model, nextItem) &&
+        eventList.canCombine(model, nextModel) &&
         (model.event_type === "RoomMessageEmote" ||
          ! (model.event_type.startsWith("RoomMessage") ||
             model.event_type.startsWith("RoomEncrypted")))
@@ -60,6 +49,12 @@ Column {
 
         Qt.ArrowCursor
 
+    readonly property int separationSpacing:
+            dayBreak  ? theme.spacing * 4 :
+            talkBreak ? theme.spacing * 6 :
+            combine   ? theme.spacing / 2 :
+            theme.spacing * 2
+
     // Needed because of eventList's MouseArea which steals the
     // HSelectableLabel's MouseArea hover events
     onCursorShapeChanged: eventList.cursorShape = cursorShape
@@ -87,20 +82,31 @@ Column {
     }
 
 
+    Item {
+
+        Layout.fillWidth: true
+        Layout.preferredHeight:
+            model.event_type === "RoomCreateEvent" ? 0 : separationSpacing
+    }
+
     Daybreak {
         visible: dayBreak
-        width: eventDelegate.width
+
+        Layout.fillWidth: true
+        Layout.minimumWidth: parent.width
     }
 
     Item {
         visible: dayBreak
-        width: parent.width
-        height: topPadding
+
+        Layout.fillWidth: true
+        Layout.preferredHeight: separationSpacing
     }
 
     EventContent {
         id: eventContent
-        width: parent.width
+
+        Layout.fillWidth: true
 
         Behavior on x { HNumberAnimation {} }
     }

src/qml/Chat/Timeline/EventFile.qml

@@ -5,10 +5,10 @@ import "../../utils.js" as Utils
 
 HTile {
     id: file
-    width: Math.max(
-        Math.min(eventContent.messageBodyWidth,
-                 theme.chat.message.fileMinWidth),
-        Math.min(eventContent.messageBodyWidth, implicitWidth),
+    width: Math.min(
+        eventDelegate.width,
+        eventContent.maxMessageWidth,
+        Math.max(theme.chat.message.fileMinWidth, implicitWidth),
     )
     height: Math.max(theme.chat.message.avatarSize, implicitHeight)
 

src/qml/Chat/Timeline/EventImage.qml

@@ -49,7 +49,7 @@ HMxcImage {
         // Maximum display size
         Math.min(
             eventList.height * maxHeight,
-            eventContent.messageBodyWidth * Math.min(1, theme.uiScale),
+            eventContent.maxMessageWidth * Math.min(1, theme.uiScale), // XXX
         ),
         eventList.height * maxHeight,
     )