/****************************************************************************
**
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the Qt Quick Controls module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** 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 Digia Plc and its Subsidiary(-ies) 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
import QtQuick.Controls 1.2
import QtQuick.Controls.Private 1.0

/*!
    \qmltype ScrollViewStyle
    \inqmlmodule QtQuick.Controls.Styles
    \since 5.1
    \ingroup viewsstyling
    \brief Provides custom styling for ScrollView
*/
Style {
    id: root

    /*! The \l ScrollView this style is attached to. */
    readonly property ScrollView control: __control

    /*! This property controls the frame border padding of the scrollView. */
    padding {left: 1; top: 1; right: 1; bottom: 1}

    /*! This Component paints the corner area between scroll bars */
    property Component corner: Rectangle { color: "#ccc" }

    /*! This component determines if the flickable should reposition itself at the
    mouse location when clicked. */
    property bool scrollToClickedPosition: true

    /*! This property holds whether the scroll bars are transient. Transient scroll bars
        appear when the content is scrolled and disappear when they are no longer needed.

        The default value is platform dependent. */
    property bool transientScrollBars: Settings.hasTouchScreen

    /*! This Component paints the frame around scroll bars. */
    property Component frame: Rectangle {
        color: control["backgroundVisible"] ? "white": "transparent"
        border.color: "#999"
        border.width: 1
        radius: 1
        visible: control.frameVisible
    }

    /*! This is the minimum extent of the scroll bar handle.

        The default value is \c 30.
    */

    property int minimumHandleLength: 30

    /*! This property controls the edge overlap
        between the handle and the increment/decrement buttons.

        The default value is \c 30.
    */

    property int handleOverlap: 1

    /*! This component controls the appearance of the
        scroll bar background.

        You can access the following state properties:

        \table
            \row \li property bool \b styleData.hovered
            \row \li property bool \b styleData.horizontal
        \endtable
    */

    property Component scrollBarBackground: Item {
        property bool sticky: false
        property bool hovered: styleData.hovered
        implicitWidth: Math.round(TextSingleton.implicitHeight)
        implicitHeight: Math.round(TextSingleton.implicitHeight)
        clip: true
        opacity: transientScrollBars ? 0.5 : 1.0
        visible: !Settings.hasTouchScreen && (!transientScrollBars || sticky)
        Rectangle {
            anchors.fill: parent
            color: "#ddd"
            border.color: "#aaa"
            anchors.rightMargin: styleData.horizontal ? -2 : -1
            anchors.leftMargin: styleData.horizontal ? -2 : 0
            anchors.topMargin: styleData.horizontal ? 0 : -2
            anchors.bottomMargin: styleData.horizontal ? -1 : -2
        }
        onHoveredChanged: if (hovered) sticky = true
        onVisibleChanged: if (!visible) sticky = false
    }

    /*! This component controls the appearance of the
        scroll bar handle.

        You can access the following state properties:

        \table
            \row \li property bool \b styleData.hovered
            \row \li property bool \b styleData.pressed
            \row \li property bool \b styleData.horizontal
        \endtable
    */

    property Component handle: Item {
        property bool sticky: false
        property bool hovered: __activeControl !== "none"
        implicitWidth: Math.round(TextSingleton.implicitHeight) + 1
        implicitHeight: Math.round(TextSingleton.implicitHeight) + 1
        BorderImage {
            id: img
            opacity: styleData.pressed && !transientScrollBars ? 0.5 : styleData.hovered ? 1 : 0.8
            source: "images/scrollbar-handle-" + (transientScrollBars ? "transient" : styleData.horizontal ? "horizontal" : "vertical") + ".png"
            border.left: transientScrollBars ? 5 : 2
            border.top: transientScrollBars ? 5 : 2
            border.right: transientScrollBars ? 5 : 2
            border.bottom: transientScrollBars ? 5 : 2
            anchors.top: !styleData.horizontal ? parent.top : undefined
            anchors.margins: transientScrollBars ? 2 : 0
            anchors.bottom: parent.bottom
            anchors.right: parent.right
            anchors.left: styleData.horizontal ? parent.left : undefined
            width: !styleData.horizontal && transientScrollBars ? sticky ? 13 : 10 : parent.width
            height: styleData.horizontal && transientScrollBars ? sticky ? 13 : 10 : parent.height
            Behavior on width { enabled: !styleData.horizontal && transientScrollBars; NumberAnimation { duration: 100 } }
            Behavior on height { enabled: styleData.horizontal && transientScrollBars; NumberAnimation { duration: 100 } }
        }
        onHoveredChanged: if (hovered) sticky = true
        onVisibleChanged: if (!visible) sticky = false
    }

    /*! This component controls the appearance of the
        scroll bar increment button.

        You can access the following state properties:

        \table
            \row \li property bool \b styleData.hovered
            \row \li property bool \b styleData.pressed
            \row \li property bool \b styleData.horizontal
        \endtable
    */
    property Component incrementControl: Rectangle {
        visible: !transientScrollBars
        implicitWidth: transientScrollBars ? 0 : Math.round(TextSingleton.implicitHeight)
        implicitHeight: transientScrollBars ? 0 : Math.round(TextSingleton.implicitHeight)
        Rectangle {
            anchors.fill: parent
            anchors.bottomMargin: -1
            anchors.rightMargin: -1
            border.color: "#aaa"
            Rectangle {
                anchors.fill: parent
                anchors.margins: 1
                color: "transparent"
                border.color: "#44ffffff"
            }
            Image {
                source: styleData.horizontal ? "images/arrow-right.png" : "images/arrow-down.png"
                anchors.centerIn: parent
                opacity: control.enabled ? 0.6 : 0.5
            }
            gradient: Gradient {
                GradientStop {color: styleData.pressed ? "lightgray" : "white" ; position: 0}
                GradientStop {color: styleData.pressed ? "lightgray" : "lightgray" ; position: 1}
            }
        }
    }

    /*! This component controls the appearance of the
        scroll bar decrement button.

        You can access the following state properties:

        \table
            \row \li property bool \b styleData.hovered
            \row \li property bool \b styleData.pressed
            \row \li property bool \b styleData.horizontal
        \endtable
    */
    property Component decrementControl: Rectangle {
        visible: !transientScrollBars
        implicitWidth: transientScrollBars ? 0 : Math.round(TextSingleton.implicitHeight)
        implicitHeight: transientScrollBars ? 0 : Math.round(TextSingleton.implicitHeight)
        Rectangle {
            anchors.fill: parent
            anchors.topMargin: styleData.horizontal ? 0 : -1
            anchors.leftMargin:  styleData.horizontal ? -1 : 0
            anchors.bottomMargin: styleData.horizontal ? -1 : 0
            anchors.rightMargin: styleData.horizontal ? 0 : -1
            color: "lightgray"
            Rectangle {
                anchors.fill: parent
                anchors.margins: 1
                color: "transparent"
                border.color: "#44ffffff"
            }
            Image {
                source: styleData.horizontal ? "images/arrow-left.png" : "images/arrow-up.png"
                anchors.centerIn: parent
                anchors.verticalCenterOffset: styleData.horizontal ? 0 : -1
                anchors.horizontalCenterOffset: styleData.horizontal ? -1 : 0
                opacity: control.enabled ? 0.6 : 0.5
            }
            gradient: Gradient {
                GradientStop {color: styleData.pressed ? "lightgray" : "white" ; position: 0}
                GradientStop {color: styleData.pressed ? "lightgray" : "lightgray" ; position: 1}
            }
            border.color: "#aaa"
        }
    }

    /*! \internal */
    property Component __scrollbar: Item {
        id: panel
        property string activeControl: "none"
        property bool scrollToClickPosition: true
        property bool isTransient: transientScrollBars

        property bool on: false
        property bool raised: false
        property bool sunken: __styleData.upPressed | __styleData.downPressed | __styleData.handlePressed

        states: State {
            name: "out"
            when: isTransient
                  && (!__stickyScrollbars || !flickableItem.moving)
                  && panel.activeControl === "none"
                  && !panel.on
                  && !panel.raised
            PropertyChanges { target: panel; opacity: 0 }
        }

        transitions: Transition {
            to: "out"
            SequentialAnimation {
                PauseAnimation { duration: root.__scrollBarFadeDelay }
                NumberAnimation { properties: "opacity"; duration: root.__scrollBarFadeDuration }
                PropertyAction { target: panel; property: "visible"; value: false }
            }
        }

        implicitWidth: __styleData.horizontal ? 200 : bg.implicitWidth
        implicitHeight: __styleData.horizontal ? bg.implicitHeight : 200

        function pixelMetric(arg) {
            if (arg === "scrollbarExtent")
                return (__styleData.horizontal ? bg.height : bg.width);
            return 0;
        }

        function styleHint(arg) {
            return false;
        }

        function hitTest(argX, argY) {
            if (itemIsHit(handleControl, argX, argY))
                return "handle"
            else if (itemIsHit(incrementLoader, argX, argY))
                return "up";
            else if (itemIsHit(decrementLoader, argX, argY))
                return "down";
            else if (itemIsHit(bg, argX, argY)) {
                if (__styleData.horizontal && argX < handleControl.x || !__styleData.horizontal && argY < handleControl.y)
                    return "upPage"
                else
                    return "downPage"
            }

            return "none";
        }

        function subControlRect(arg) {
            if (arg === "handle") {
                return Qt.rect(handleControl.x, handleControl.y, handleControl.width, handleControl.height);
            } else if (arg === "groove") {
                if (__styleData.horizontal) {
                    return Qt.rect(incrementLoader.width - handleOverlap,
                                   0,
                                   __control.width - (incrementLoader.width + decrementLoader.width - handleOverlap * 2),
                                   __control.height);
                } else {
                    return Qt.rect(0,
                                   incrementLoader.height - handleOverlap,
                                   __control.width,
                                   __control.height - (incrementLoader.height + decrementLoader.height - handleOverlap * 2));
                }
            }
            return Qt.rect(0,0,0,0);
        }

        function itemIsHit(argItem, argX, argY) {
            var pos = argItem.mapFromItem(__control, argX, argY);
            return (pos.x >= 0 && pos.x <= argItem.width && pos.y >= 0 && pos.y <= argItem.height);
        }

        Loader {
            id: incrementLoader
            anchors.top: parent.top
            anchors.left: parent.left
            sourceComponent: decrementControl
            property QtObject styleData: QtObject {
                readonly property bool hovered: activeControl === "up"
                readonly property bool pressed: __styleData.upPressed
                readonly property bool horizontal: __styleData.horizontal
            }
        }

        Loader {
            id: bg
            anchors.top: __styleData.horizontal ? undefined : incrementLoader.bottom
            anchors.bottom: __styleData.horizontal ? undefined : decrementLoader.top
            anchors.left:  __styleData.horizontal ? incrementLoader.right : undefined
            anchors.right: __styleData.horizontal ? decrementLoader.left : undefined
            sourceComponent: scrollBarBackground
            property QtObject styleData: QtObject {
                readonly property bool horizontal: __styleData.horizontal
                readonly property bool hovered: activeControl !== "none"
            }
        }

        Loader {
            id: decrementLoader
            anchors.bottom: __styleData.horizontal ? undefined : parent.bottom
            anchors.right: __styleData.horizontal ? parent.right : undefined
            sourceComponent: incrementControl
            property QtObject styleData: QtObject {
                readonly property bool hovered: activeControl === "down"
                readonly property bool pressed: __styleData.downPressed
                readonly property bool horizontal: __styleData.horizontal
            }
        }

        property var flickableItem: control.flickableItem
        property int extent: Math.max(minimumHandleLength, __styleData.horizontal ?
                                          (flickableItem ? flickableItem.width/flickableItem.contentWidth : 0 ) * bg.width :
                                          (flickableItem ? flickableItem.height/flickableItem.contentHeight : 0) * bg.height)
        readonly property real range: __control.maximumValue - __control.minimumValue
        readonly property real begin: __control.value - __control.minimumValue

        Loader {
            id: handleControl
            height: __styleData.horizontal ? implicitHeight : extent
            width: __styleData.horizontal ? extent : implicitWidth
            anchors.top: bg.top
            anchors.left: bg.left
            anchors.topMargin: __styleData.horizontal ? 0 : -handleOverlap + (2 * begin * (bg.height + (2 * handleOverlap) - extent) + range) / (2 * range)
            anchors.leftMargin: __styleData.horizontal ? -handleOverlap + (2 * begin * (bg.width + (2 * handleOverlap) - extent) + range) / (2 * range) : 0
            sourceComponent: handle
            property QtObject styleData: QtObject {
                readonly property bool hovered: activeControl === "handle"
                readonly property bool pressed: __styleData.handlePressed
                readonly property bool horizontal: __styleData.horizontal
            }
            readonly property alias __activeControl: panel.activeControl
        }
    }

    /*! \internal */
    property bool __externalScrollBars: false
    /*! \internal */
    property int __scrollBarSpacing: 4
    /*! \internal */
    property int __scrollBarFadeDelay: 450
    /*! \internal */
    property int __scrollBarFadeDuration: 200
    /*! \internal */
    property bool __stickyScrollbars: false
}