qt-everywhere-src-5.14.1/qtdoc/examples/demos/rssnews/content/ScrollBar.qml

/****************************************************************************
**
** Copyright (C) 2017 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** 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.
**
** BSD License Usage
** Alternatively, you may use this file under the terms of the BSD license
** as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
**   * Redistributions of source code must retain the above copyright
**     notice, this list of conditions and the following disclaimer.
**   * Redistributions in binary form must reproduce the above copyright
**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
**   * Neither the name of The Qt Company Ltd nor the names of its
**     contributors may be used to endorse or promote products derived
**     from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/

import QtQuick 2.2

Item {
    id: container

    property variant scrollArea
    property int orientation: Qt.Vertical

    opacity: 0

    function position()
    {
        var ny = 0;
        if (container.orientation == Qt.Vertical)
            ny = scrollArea.visibleArea.yPosition * container.height;
        else
            ny = scrollArea.visibleArea.xPosition * container.width;

        if (ny > 2)
            return ny;
        else
            return 2;
    }

    function size()
    {
        var nh, ny;

        if (container.orientation == Qt.Vertical)
            nh = scrollArea.visibleArea.heightRatio * container.height;
        else
            nh = scrollArea.visibleArea.widthRatio * container.width;

        if (container.orientation == Qt.Vertical)
            ny = scrollArea.visibleArea.yPosition * container.height;
        else
            ny = scrollArea.visibleArea.xPosition * container.width;

        if (ny > 3) {
            var t;
            if (container.orientation == Qt.Vertical)
                t = Math.ceil(container.height - 3 - ny);
            else
                t = Math.ceil(container.width - 3 - ny);
            if (nh > t)
                return t;
            else
                return nh;
        } else
            return nh + ny;
    }

    Rectangle { anchors.fill: parent; color: "Black"; opacity: 0.3 }

    BorderImage {
        source: "images/scrollbar.png"
        border { left: 1; right: 1; top: 1; bottom: 1 }
        x: container.orientation == Qt.Vertical ? 2 : position()
        y: container.orientation == Qt.Vertical ? position() : 2
        width: container.orientation == Qt.Vertical ? container.width - 4 : size()
        height: container.orientation == Qt.Vertical ? size() : container.height - 4
    }

    states: State {
        name: "visible"
        when: container.orientation == Qt.Vertical ?
                  scrollArea.movingVertically :
                  scrollArea.movingHorizontally
        PropertyChanges { target: container; opacity: 1.0 }
    }

    transitions: Transition {
        from: "visible"; to: ""
        NumberAnimation { properties: "opacity"; duration: 600 }
    }
}