QQuickTableView: change how tableview resolves column width and row height

The current solution of storing column widths as the user flicks around
turns out to not scale so well for huge data models. We basically don't
want to take on the responsibility of storing column widths and row
heights for e.g 100 000 rows/columns. Instead, we now choose to ask the
application for the sizes, whenever we need them. This way, the application
developer can optimize how to store/calculate/determine/persist row and
column sizes locally.

To implement this functionality, we add two new properties:
rowHeightProvider and columnWidthProvider. They both accept a javascript
function that takes one argument (row or column), and returns the
corresponing row height or column width.

If no function is assigned to the properties, TableView will calculate
the row height / column width based on the currently visible items, as
before.

Change-Id: I6e5552599f63c896531cf3963e8745658ba4d45a
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

1 files changed, 78 insertions, 0 deletions

diff --git a/tests/auto/quick/qquicktableview/data/alternatingrowheightcolumnwidth.qml b/tests/auto/quick/qquicktableview/data/alternatingrowheightcolumnwidth.qml
new file mode 100644
index 0000000000..c9fb1031dc
--- /dev/null
+++ b/tests/auto/quick/qquicktableview/data/alternatingrowheightcolumnwidth.qml
@@ -0,0 +1,78 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQuick module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+import QtQuick 2.12
+import QtQuick.Window 2.3
+import Qt.labs.tableview 1.0
+
+Item {
+    width: 640
+    height: 450
+
+    property alias tableView: tableView
+    property Component delegate: tableViewDelegate
+
+    TableView {
+        id: tableView
+        width: 600
+        height: 400
+        anchors.margins: 1
+        clip: true
+        delegate: tableViewDelegate
+        cacheBuffer: 0
+        columnSpacing: 1
+        rowSpacing: 1
+    }
+
+    Component {
+        id: tableViewDelegate
+        Rectangle {
+            objectName: "tableViewDelegate"
+            implicitWidth: column % 2 ? 30 : 40
+            implicitHeight: row % 2 ? 30 : 40
+            color: "lightgray"
+            border.width: 1
+            Text {
+                anchors.centerIn: parent
+                text: modelData
+            }
+        }
+    }
+
+}