Revise TableView API for managing the columns

Replace "property list<TableViewColumn> columns" with:
- addColumn(column)
- insertColumn(index, column)
- moveColumn(from, to)
- removeColumn(index)
- getColumn(index)

Exposing list<TableViewColumn> type of property in the public API was
problematic for several reasons. First of all, it limited the internal
implementation too much. Secondly, modifying the list programmatically
did not work as expected, and it also threw nasty warnings while
reordering the columns interactively.

Task-number: QTBUG-30319
Task-number: QTBUG-31028
Change-Id: I0039f7e4be2d6ee9303a4118bdf84146b6a96a05
Reviewed-by: Jens Bache-Wiig <jens.bache-wiig@digia.com>

2 files changed, 90 insertions, 24 deletions

diff --git a/src/controls/TableView.qml b/src/controls/TableView.qml
index 4cde5d3e..93d75e92 100644
--- a/src/controls/TableView.qml
+++ b/src/controls/TableView.qml
@@ -200,9 +200,8 @@ ScrollView {
     */
     property int sortIndicatorOrder: Qt.AscendingOrder
 
-    /*! \qmlproperty list<TableViewColumn> TableView::columns
-    This property contains the TableViewColumn items */
-    default property alias columns: listView.columnheader
+    /*! \internal */
+    default property alias __columns: root.data
 
     /*! \qmlproperty Component TableView::contentHeader
     This is the content header of the TableView */
@@ -216,8 +215,9 @@ ScrollView {
     The current number of rows */
     readonly property alias rowCount: listView.count
 
-    /*! The current number of columns */
-    readonly property int columnCount: columns.length
+    /*! \qmlproperty int TableView::columnCount
+    The current number of columns */
+    readonly property alias columnCount: columnModel.count
 
     /*! \qmlproperty string TableView::section.property
         \qmlproperty enumeration TableView::section.criteria
@@ -288,6 +288,73 @@ ScrollView {
         return listView.indexAt(obj.x, obj.y)
     }
 
+    /*! Adds a \a column and returns the added column.
+
+        The \a column argument can be an instance of TableViewColumn,
+        or a Component. The component has to contain a TableViewColumn.
+        Otherwise  \c null is returned.
+    */
+    function addColumn(column) {
+        return insertColumn(columnCount, column)
+    }
+
+    /*! Inserts a \a column at the given \a index and returns the inserted column.
+
+        The \a column argument can be an instance of TableViewColumn,
+        or a Component. The component has to contain a TableViewColumn.
+        Otherwise  \c null is returned.
+    */
+    function insertColumn(index, column) {
+        var object = column
+        if (typeof column['createObject'] === 'function')
+            object = column.createObject(root)
+
+        if (index >= 0 && index <= columnCount && object.Accessible.role === Accessible.ColumnHeader) {
+            columnModel.insert(index, {columnItem: object})
+            return object
+        }
+
+        if (object !== column)
+            object.destroy()
+        console.warn("TableView::insertColumn(): invalid argument")
+        return null
+    }
+
+    /*! Removes and destroys a column at the given \a index. */
+    function removeColumn(index) {
+        if (index < 0 || index >= columnCount) {
+            console.warn("TableView::removeColumn(): invalid argument")
+            return
+        }
+        var column = columnModel.get(index).columnItem
+        columnModel.remove(index, 1)
+        column.destroy()
+    }
+
+    /*! Moves a column \a from index \a to another. */
+    function moveColumn(from, to) {
+        if (from < 0 || from >= columnCount || to < 0 || to >= columnCount) {
+            console.warn("TableView::moveColumn(): invalid argument")
+            return
+        }
+        columnModel.move(from, to, 1)
+    }
+
+    /*! Returns the column at the given \a index
+        or \c null if the \a index is invalid. */
+    function getColumn(index) {
+        if (index < 0 || index >= columnCount)
+            return null
+        return columnModel.get(index).columnItem
+    }
+
+    Component.onCompleted: {
+        for (var i = 0; i < __columns.length; ++i) {
+            var column = __columns[i]
+            if (column.Accessible.role === Accessible.ColumnHeader)
+                addColumn(column)
+        }
+    }
 
     style: Qt.createComponent(Settings.style + "/TableViewStyle.qml", root)
 
@@ -429,7 +496,10 @@ ScrollView {
             }
         }
 
-        property list<TableViewColumn> columnheader
+        ListModel {
+            id: columnModel
+        }
+
         highlightFollowsCurrentItem: true
         model: root.model
 
@@ -483,7 +553,7 @@ ScrollView {
                 height: parent.height
                 Repeater {
                     id: repeater
-                    model: root.columnCount
+                    model: columnModel
 
                     Loader {
                         id: itemDelegateLoader
@@ -509,7 +579,7 @@ ScrollView {
                             readonly property string role: __column.role
                         }
 
-                        readonly property TableViewColumn __column: columns[index]
+                        readonly property TableViewColumn __column: columnItem
                         readonly property bool __hasModelRole: styleData.role && itemModel.hasOwnProperty(styleData.role)
                         readonly property bool __hasModelDataRole: styleData.role && modelData && modelData.hasOwnProperty(styleData.role)
                     }
@@ -548,12 +618,12 @@ ScrollView {
                     property int targetIndex: -1
                     property int dragIndex: -1
 
-                    model: columnCount
+                    model: columnModel
 
                     delegate: Item {
                         z:-index
-                        width: columns[index].width
-                        visible: columns[index].visible
+                        width: modelData.width
+                        visible: modelData.visible
                         height: headerVisible ? headerStyle.height : 0
 
                         Loader {
@@ -562,7 +632,7 @@ ScrollView {
                             anchors.left: parent.left
                             anchors.right: parent.right
                             property QtObject styleData: QtObject {
-                                readonly property string value: columns[index].title
+                                readonly property string value: modelData.title
                                 readonly property bool pressed: headerClickArea.pressed
                                 readonly property bool containsMouse: headerClickArea.containsMouse
                                 readonly property int column: index
@@ -608,13 +678,7 @@ ScrollView {
 
                             onReleased: {
                                 if (repeater.targetIndex >= 0 && repeater.targetIndex != index ) {
-                                    // Rearrange the header sections
-                                    var items = new Array
-                                    for (var i = 0 ; i< columnCount ; ++i)
-                                        items.push(columns[i])
-                                    items.splice(index, 1);
-                                    items.splice(repeater.targetIndex, 0, columns[index]);
-                                    columns = items
+                                    columnModel.move(index, repeater.targetIndex, 1)
                                     if (sortIndicatorColumn == index)
                                         sortIndicatorColumn = repeater.targetIndex
                                 }
@@ -628,14 +692,14 @@ ScrollView {
                         Loader {
                             id: draghandle
                             property QtObject styleData: QtObject{
-                                readonly property string value: columns[index].title
+                                readonly property string value: modelData.title
                                 readonly property bool pressed: headerClickArea.pressed
                                 readonly property bool containsMouse: headerClickArea.containsMouse
                                 readonly property int column: index
                             }
 
                             parent: tableHeader
-                            width: columns[index].width
+                            width: modelData.width
                             height: parent.height
                             sourceComponent: root.headerDelegate
                             visible: headerClickArea.pressed
@@ -651,8 +715,8 @@ ScrollView {
                             width: 16 ; height: parent.height
                             anchors.right: parent.right
                             onPositionChanged:  {
-                                var newHeaderWidth = columns[index].width + (mouseX - offset)
-                                columns[index].width = Math.max(minimumSize, newHeaderWidth)
+                                var newHeaderWidth = modelData.width + (mouseX - offset)
+                                modelData.width = Math.max(minimumSize, newHeaderWidth)
                             }
                             property bool found:false
 
@@ -667,7 +731,7 @@ ScrollView {
                                         minWidth = Math.max(minWidth, item.children[1].children[index].children[0].implicitWidth)
                                 }
                                 if (minWidth)
-                                    columns[index].width = minWidth
+                                    modelData.width = minWidth
                             }
                             onPressedChanged: if (pressed) offset=mouseX
                             cursorShape: Qt.SplitHCursor
diff --git a/src/controls/TableViewColumn.qml b/src/controls/TableViewColumn.qml
index 919f30de..2c629dfb 100644
--- a/src/controls/TableViewColumn.qml
+++ b/src/controls/TableViewColumn.qml
@@ -89,4 +89,6 @@ QtObject {
     /*! The delegate of the column. This can be used to set the
     \l TableView::itemDelegate for a specific column. */
     property Component delegate
+
+    Accessible.role: Accessible.ColumnHeader
 }