feat(StatusChatList): Add drag and drop support of list items

This implements drag and drop capabilities of chat items within a `StatusChatList`.
The commit introduces a `DelegateModal` to visually reorder chat items
when they're being dragged and dropped onto a `DropArea`.

To persist the new order of chat items, various signals have been introduced to chat
list related components:

```qml
StatusChatList {

    onChatItemReordered: function (id, from, to) {
        // ...
    }
}

StatusChatListAndCategories {

    onChatItemReordered: function (categoryId, chatId, from, to) {
        // ...
    }
}
```

There's no such API on the `StatusChatListCategory` type because that one already
exposes its underlying `StatusChatList` via `chatList`, which makes the signal available.

Dragging and dropping chat items is disabled by default and needs to be turned on
using the `draggableItems` property:

```qml
StatusChatList {
    draggableItems: true
    ...
}
```

Author: borismelnik

sandbox/DemoApp.qml

@@ -467,6 +467,7 @@ Rectangle {
                         width: leftPanel.width
                         height: implicitHeight > (leftPanel.height - 64) ? implicitHeight + 8 : leftPanel.height - 64
 
+                        draggableItems: true
                         chatList.model: models.demoCommunityChatListItems
                         categoryList.model: models.demoCommunityCategoryItems
 

sandbox/Models.qml

@@ -13,6 +13,7 @@ QtObject {
             unreadMessagesCount: 0
             mentionsCount: 0
             color: "blue"
+            position: 0
         }
         ListElement {
             chatId: "1"
@@ -22,6 +23,7 @@ QtObject {
             color: "red"
             unreadMessagesCount: 1
             mentionsCount: 1
+            position: 1
         }
         ListElement {
             chatId: "2"
@@ -32,6 +34,7 @@ QtObject {
             identicon: "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAADIAAAAyCAYAAAAeP4ixAAAAlklEQVR4nOzW0QmDQBAG4SSkl7SUQlJGCrElq9F3QdjjVhh/5nv3cFhY9vUIYQiNITSG0Bh
 CExPynn1gWf9bx498P7/nzPcxEzGExhBdJGYihtAYQlO+tUZvqrPbqeudo5iJGEJjCE15a3VtodH3q2ImYgiNITTlTdG1nUZ5a92VITQxITFiJmIIjSE0htAYQrMHAAD//+wwFVpz+yqXAAAAAElFTkSuQmCC"
             unreadMessagesCount: 0
+            position: 2
         }
         ListElement {
             chatId: "3"
@@ -40,6 +43,7 @@ CExPynn1gWf9bx498P7/nzPcxEzGExhBdJGYihtAYQlO+tUZvqrPbqeudo5iJGEJjCE15a3VtodH3q2I
             muted: false
             color: "purple"
             unreadMessagesCount: 0
+            position: 3
         }
         ListElement {
             chatId: "4"
@@ -48,6 +52,7 @@ CExPynn1gWf9bx498P7/nzPcxEzGExhBdJGYihtAYQlO+tUZvqrPbqeudo5iJGEJjCE15a3VtodH3q2I
             muted: true
             color: "Orange"
             unreadMessagesCount: 0
+            position: 4
         }
         ListElement {
             chatId: "5"
@@ -56,6 +61,7 @@ CExPynn1gWf9bx498P7/nzPcxEzGExhBdJGYihtAYQlO+tUZvqrPbqeudo5iJGEJjCE15a3VtodH3q2I
             muted: false
             color: "green"
             unreadMessagesCount: 0
+            position: 5
         }
     }
 
@@ -68,6 +74,7 @@ CExPynn1gWf9bx498P7/nzPcxEzGExhBdJGYihtAYQlO+tUZvqrPbqeudo5iJGEJjCE15a3VtodH3q2I
             muted: false
             unreadMessagesCount: 0
             color: "orange"
+            position: 0
         }
         ListElement {
             chatId: "1"
@@ -77,6 +84,7 @@ CExPynn1gWf9bx498P7/nzPcxEzGExhBdJGYihtAYQlO+tUZvqrPbqeudo5iJGEJjCE15a3VtodH3q2I
             unreadMessagesCount: 0
             color: "orange"
             categoryId: "public"
+            position: 0
         }
         ListElement {
             chatId: "2"
@@ -86,6 +94,7 @@ CExPynn1gWf9bx498P7/nzPcxEzGExhBdJGYihtAYQlO+tUZvqrPbqeudo5iJGEJjCE15a3VtodH3q2I
             unreadMessagesCount: 0
             color: "orange"
             categoryId: "public"
+            position: 1
         }
         ListElement {
             chatId: "3"
@@ -95,6 +104,7 @@ CExPynn1gWf9bx498P7/nzPcxEzGExhBdJGYihtAYQlO+tUZvqrPbqeudo5iJGEJjCE15a3VtodH3q2I
             unreadMessagesCount: 0
             color: "orange"
             categoryId: "dev"
+            position: 0
         }
     }
 

src/StatusQ/Components/StatusChatList.qml

@@ -1,4 +1,6 @@
 import QtQuick 2.13
+import QtQml.Models 2.14
+import QtQuick.Controls 2.13 as QC
 
 import StatusQ.Core 0.1
 import StatusQ.Core.Theme 0.1
@@ -13,7 +15,8 @@ Column {
 
     property string categoryId: ""
     property string selectedChatId: ""
-    property alias chatListItems: statusChatListItems
+    property alias chatListItems: delegateModel
+    property bool draggableItems: false
 
     property Component popupMenu
 
@@ -23,82 +26,209 @@ Column {
 
     signal chatItemSelected(string id)
     signal chatItemUnmuted(string id)
+    signal chatItemReordered(string id, int from, int to)
+
+    function getAbsolutePosition(node) {
+        var returnPos = {};
+        returnPos.x = 0;
+        returnPos.y = 0;
+        if (node !== undefined && node !== null) {
+            var parentValue = getAbsolutePosition(node.parent);
+            returnPos.x = parentValue.x + node.x;
+            returnPos.y = parentValue.y + node.y;
+        }
+        return returnPos;
+    }
 
     onPopupMenuChanged: {
         if (!!popupMenu) {
             popupMenuSlot.sourceComponent = popupMenu
         }
     }
 
-    Repeater {
-        id: statusChatListItems
-        delegate: StatusChatListItem {
+    DelegateModel {
+        id: delegateModel
 
-            id: statusChatListItem
+        delegate: Item {
+            id: draggable
+            width: statusChatListItem.width
+            height: statusChatListItem.height
 
-            property string profileImage: ""
+            property alias chatListItem: statusChatListItem
 
-            Component.onCompleted: {
-                if (typeof statusChatList.profileImageFn === "function") {
-                    profileImage = statusChatList.profileImageFn(model.chatId || model.id) || ""
+            visible: {
+                if (!!statusChatList.filterFn) {
+                    return statusChatList.filterFn(model, statusChatList.categoryId)
                 }
+                return true
             }
 
-            chatId: model.chatId || model.id
-            name: !!statusChatList.chatNameFn ? statusChatList.chatNameFn(model) : model.name
-            type: model.chatType
-            muted: !!model.muted
-            hasUnreadMessages: !!model.hasUnreadMessages || model.unviewedMessagesCount > 0
-            hasMention: model.mentionsCount > 0
-            badge.value: model.chatType === StatusChatListItem.Type.OneToOneChat ?
-                model.unviewedMessagesCount || 0 :
-                model.mentionsCount || 0
-            selected: (model.chatId || model.id) === statusChatList.selectedChatId
-
-            icon.color: model.color || ""
-            image.isIdenticon: !!!profileImage && !!!model.identityImage && !!model.identicon
-            image.source: profileImage || model.identityImage || model.identicon || ""
-
-            onClicked: {
-                if (mouse.button === Qt.RightButton && !!statusChatList.popupMenu) {
-                    statusChatListItem.highlighted = true
-
-                    let originalOpenHandler = popupMenuSlot.item.openHandler
-                    let originalCloseHandler = popupMenuSlot.item.closeHandler
-
-                    popupMenuSlot.item.openHandler = function () {
-                        if (!!originalOpenHandler) {
-                            originalOpenHandler((model.chatId || model.id))
-                        }
+            MouseArea {
+                id: dragSensor
+
+                anchors.fill: parent
+                cursorShape: active ? Qt.ClosedHandCursor : Qt.PointingHandCursor
+                hoverEnabled: true
+                pressAndHoldInterval: 150
+                enabled: statusChatList.draggableItems
+
+                property bool active: false
+                property real startY: 0
+                property real startX: 0
+
+                drag.target: draggedListItemLoader.item
+                drag.threshold: 0.1
+                drag.filterChildren: true
+
+                onPressed: {
+                    startY = mouseY
+                    startX = mouseX
+                }
+                onPressAndHold: active = true
+                onReleased: {
+                    if (active) {
+                        statusChatList.chatItemReordered(statusChatListItem.chatId, statusChatListItem.originalOrder, statusChatListItem.originalOrder)
+                    }
+                    active = false
+                }
+                onMouseYChanged: {
+                    if ((Math.abs(startY - mouseY) > 1) && pressed) {
+                        active = true
+                    }
+                }
+                onMouseXChanged: {
+                    if ((Math.abs(startX - mouseX) > 1) && pressed) {
+                        active = true
                     }
+                }
+
+                StatusChatListItem {
 
-                    popupMenuSlot.item.closeHandler = function () {
-                        if (statusChatListItem) {
-                            statusChatListItem.highlighted = false
+                    id: statusChatListItem
+
+                    property string profileImage: ""
+
+                    opacity: dragSensor.active ? 0.0 : 1.0
+                    Component.onCompleted: {
+                        if (typeof statusChatList.profileImageFn === "function") {
+                            profileImage = statusChatList.profileImageFn(model.chatId || model.id) || ""
                         }
-                        if (!!originalCloseHandler) {
-                            originalCloseHandler()
+                    }
+                    originalOrder: model.position
+                    chatId: model.chatId || model.id
+                    categoryId: model.categoryId || ""
+                    name: !!statusChatList.chatNameFn ? statusChatList.chatNameFn(model) : model.name
+                    type: model.chatType
+                    muted: !!model.muted
+                    hasUnreadMessages: !!model.hasUnreadMessages || model.unviewedMessagesCount > 0
+                    hasMention: model.mentionsCount > 0
+                    badge.value: model.chatType === StatusChatListItem.Type.OneToOneChat ?
+                        model.unviewedMessagesCount || 0 :
+                        model.mentionsCount || 0
+                    selected: (model.chatId || model.id) === statusChatList.selectedChatId
+
+                    icon.color: model.color || ""
+                    image.isIdenticon: !!!profileImage && !!!model.identityImage && !!model.identicon
+                    image.source: profileImage || model.identityImage || model.identicon || ""
+
+                    sensor.cursorShape: dragSensor.cursorShape
+                    onClicked: {
+                        if (mouse.button === Qt.RightButton && !!statusChatList.popupMenu) {
+                            statusChatListItem.highlighted = true
+
+                            let originalOpenHandler = popupMenuSlot.item.openHandler
+                            let originalCloseHandler = popupMenuSlot.item.closeHandler
+
+                            popupMenuSlot.item.openHandler = function () {
+                                if (!!originalOpenHandler) {
+                                    originalOpenHandler((model.chatId || model.id))
+                                }
+                            }
+
+                            popupMenuSlot.item.closeHandler = function () {
+                                if (statusChatListItem) {
+                                    statusChatListItem.highlighted = false
+                                }
+                                if (!!originalCloseHandler) {
+                                    originalCloseHandler()
+                                }
+                            }
+
+                            popupMenuSlot.item.popup(mouse.x + 4, statusChatListItem.y + mouse.y + 6)
+                            popupMenuSlot.item.openHandler = originalOpenHandler
+                            return
+                        }
+                        if (!statusChatListItem.selected) {
+                            statusChatList.chatItemSelected(model.chatId || model.id)
                         }
                     }
-
-                    popupMenuSlot.item.popup(mouse.x + 4, statusChatListItem.y + mouse.y + 6)
-                    popupMenuSlot.item.openHandler = originalOpenHandler
-                    return
+                    onUnmute: statusChatList.chatItemUnmuted(model.chatId || model.id)
                 }
-                if (!statusChatListItem.selected) {
-                    statusChatList.chatItemSelected(model.chatId || model.id)
+            }
+
+            DropArea {
+                id: dropArea
+                width: dragSensor.active ? 0 : parent.width
+                height: dragSensor.active ? 0 : parent.height
+                keys: ["chat-item-category-" + statusChatListItem.categoryId]
+
+                onEntered: reorderDelay.start()
+                onDropped: statusChatList.chatItemReordered(statusChatListItem.chatId, drag.source.originalOrder, statusChatListItem.DelegateModel.itemsIndex)
+
+                Timer {
+                    id: reorderDelay
+                    interval: 100
+                    repeat: false
+                    onTriggered: {
+                        if (dropArea.containsDrag) {
+                            dropArea.drag.source.chatListItem.originalOrder = statusChatListItem.originalOrder
+                            delegateModel.items.move(dropArea.drag.source.DelegateModel.itemsIndex, draggable.DelegateModel.itemsIndex)
+                        }
+                    }
                 }
             }
-            onUnmute: statusChatList.chatItemUnmuted(model.chatId || model.id)
-            visible: {
-                if (!!statusChatList.filterFn) {
-                    return statusChatList.filterFn(model, statusChatList.categoryId)
+
+            Loader {
+                id: draggedListItemLoader
+                active: dragSensor.active
+                sourceComponent: StatusChatListItem {
+                    property var globalPosition: statusChatList.getAbsolutePosition(draggable)
+                    parent: QC.Overlay.overlay
+                    sensor.cursorShape: dragSensor.cursorShape
+                    Drag.active: dragSensor.active
+                    Drag.hotSpot.x: width / 2
+                    Drag.hotSpot.y: height / 2
+                    Drag.keys: ["chat-item-category-" + categoryId]
+                    Drag.source: draggable
+
+                    Component.onCompleted: {
+                        x = globalPosition.x
+                        y = globalPosition.y
+                    }
+                    chatId: draggable.chatListItem.chatId
+                    categoryId: draggable.chatListItem.categoryId
+                    name: draggable.chatListItem.name
+                    type: draggable.chatListItem.type
+                    muted: draggable.chatListItem.muted
+                    dragged: true
+                    hasUnreadMessages: draggable.chatListItem.hasUnreadMessages
+                    hasMention: draggable.chatListItem.hasMention
+                    badge.value: draggable.chatListItem.badge.value
+                    selected: draggable.chatListItem.selected
+
+                    icon.color: draggable.chatListItem.icon.color
+                    image.isIdenticon: draggable.chatListItem.image.isIdenticon
+                    image.source: draggable.chatListItem.image.source
                 }
-                return true
             }
         }
     }
 
+    Repeater {
+        id: statusChatListItems
+        model: delegateModel
+    }
+
     Loader {
         id: popupMenuSlot
         active: !!statusChatList.popupMenu