plasma-framework/declarativeimports/plasmacomponents/qml/SectionScroller.qml

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/**Documented API
Inherits:
        Item

Imports:
        QtQuick 1.1
        org.kde.plasma.core

Description:
        It's similar to a ScrollBar or a ScrollDecorator.
        It's interactive and works on ListViews that have section.property set,
        so its contents are categorized.
        An indicator will say to what category the user scrolled to.
        Useful for things like address books or things sorted by date.
        Don't use with models too big (thousands of items) because implies
        loading all the items to memory, as well loses precision.

Properties:
        ListView listView:
         As The ScrollBar, this is the listview the sectionScroller will operate on. This component doesn't work with simple Flickable or GridView.
**/

import QtQuick 1.1
import "private/SectionScroller.js" as Sections
import org.kde.plasma.core 0.1 as PlasmaCore

Item {
    id: root

    /*
     * The listview this scroll indicator will work on
     */
    property ListView listView

    onListViewChanged: {
        if (listView && listView.model)
            internal.initDirtyObserver();
    }

    Connections {
        target: listView
        onModelChanged: {
            if (listView && listView.model) {
                internal.initDirtyObserver()
            }
        }
    }

    width: 18
    Behavior on opacity {
        NumberAnimation {
            duration: 250
        }
    }

    anchors {
        right: listView.right
        top: listView.top
        bottom: listView.bottom
    }


    RangeModel {
        id: range

        minimumValue: 0
        maximumValue: Math.max(0, listView.contentHeight - listView.height)
        stepSize: 0
        //inverted: true
        positionAtMinimum: root.width*2
        positionAtMaximum: root.height - root.width*2
        value: listView.contentY
        onPositionChanged: sectionLabel.text = Sections.closestSection(position/listView.height)

    }

    ScrollBar {
        id: scrollBar
        flickableItem: listView
        anchors.fill: parent
        interactive: true
    }
    PlasmaCore.FrameSvgItem {
        id: tooltip
        imagePath: "widgets/tooltip"
        width: sectionLabel.width + margins.left + margins.right
        height: sectionLabel.height + margins.top + margins.bottom
        Label {
            id: sectionLabel
            x: parent.margins.left
            y: parent.margins.top
        }
        y: Math.min(root.height-height-scrollBar.width, Math.max(scrollBar.width, range.position - height/2))
        anchors {
            //verticalCenter: handle.verticalCenter
            right: parent.left
        }
        opacity: sectionLabel.text && scrollBar.pressed ? 1 : 0
        Behavior on opacity {
            NumberAnimation {
                duration: 250
            }
        }
    }


    Timer {
        id: dirtyTimer
        interval: 250
        onTriggered: {
            Sections.initSectionData(listView);
            internal.modelDirty = false;
            tooltip.visible = Sections._sections.length > 1
        }
    }
    QtObject {
        id: internal

        property bool modelDirty: false
        function initDirtyObserver() {
            Sections.initSectionData(listView);
            tooltip.visible = Sections._sections.length > 1
            function dirtyObserver() {
                if (!internal.modelDirty) {
                    internal.modelDirty = true;
                    dirtyTimer.running = true;
                }
            }

            if (listView.model.countChanged)
                listView.model.countChanged.connect(dirtyObserver);

            if (listView.model.itemsChanged)
                listView.model.itemsChanged.connect(dirtyObserver);

            if (listView.model.itemsInserted)
                listView.model.itemsInserted.connect(dirtyObserver);

            if (listView.model.itemsMoved)
                listView.model.itemsMoved.connect(dirtyObserver);

            if (listView.model.itemsRemoved)
                listView.model.itemsRemoved.connect(dirtyObserver);

            sectionsRepeater.model = Sections._sections.length
        }
    }
}