controls: add TreeViewDelegate

This patch adds TreeViewDelegate to Controls.
TreeViewDelegate is a ready-made delegate that can be
assigned to TreeView. It takes care of drawing the
tree using the style, and can be used directly
without the need for customization.

It implements all the required properties set
by TreeView, and offers in addition a small API that
lets the developer change the indicator and the label.

[ChangeLog][Controls] New delegate added: TreeViewDelegate

Change-Id: I50fbc059afbc2b896d23d9d59717c8571e94bae6
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

1 files changed, 59 insertions, 0 deletions

diff --git a/tests/auto/quickcontrols2/qquicktreeviewdelegate/data/unmodified.qml b/tests/auto/quickcontrols2/qquicktreeviewdelegate/data/unmodified.qml
new file mode 100644
index 0000000000..ffa3b81cbd
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+++ b/tests/auto/quickcontrols2/qquicktreeviewdelegate/data/unmodified.qml
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+/****************************************************************************
+**
+** Copyright (C) 2021 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
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+** 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
+import TestModel
+import QtQuick.Controls
+
+Item {
+    width: 800
+    height: 600
+
+    property alias treeView: treeView
+
+    TreeView {
+        id: treeView
+        anchors.fill:parent
+        anchors.margins: 10
+        model: TestModel {}
+        clip: true
+
+        delegate: TreeViewDelegate {}
+    }
+}