TabBarLayout.qml

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/****************************************************************************
**
** Copyright 2011 Marco Martin <mart@kde.org>
**
** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the Qt Components project.
**
** $QT_BEGIN_LICENSE:BSD$
** You may use this file under the terms of the BSD license as follows:
**
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** 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.
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**     the documentation and/or other materials provided with the
**     distribution.
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**     the names of its contributors may be used to endorse or promote
**     products derived from this software without specific prior written
**     permission.
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import QtQuick 1.1
import org.kde.qtextracomponents 0.1
import "AppManager.js" as Utils

Item {
    id: root

    Component.onCompleted: priv.layoutChildren()
    onChildrenChanged: priv.layoutChildren()
    onWidthChanged: priv.layoutChildren()
    onHeightChanged: priv.layoutChildren()


    Keys.onPressed: {
        if (event.key == Qt.Key_Right || event.key == Qt.Key_Left) {
            
            if (event.key == Qt.Key_Right || priv.mirrored) {
                priv.goNextTab()
                event.accepted = true
            } else if (event.key == Qt.Key_Left || priv.mirrored) {
                priv.goPreviousTab()
                event.accepted = true
            }
        }
    }

    focus: true

    MouseEventListener {
        anchors.fill: parent
        onWheelMoved: {
            if (wheel.delta < 0) {
                goNextTab()
            } else {
                goPreviousTab()
            }
        }

        id: priv
        property Item firstButton: root.children.length > 1 ? root.children[1] : null
        property Item firstTab: firstButton ? (firstButton.tab != null ? firstButton.tab : null) : null
        property Item tabGroup: firstTab ? Utils.findParent(firstTab, "currentTab") : null
        property bool mirrored: root.LayoutMirroring.enabled
        property Item tabBar: Utils.findParent(root, "currentTab")

        onMirroredChanged: layoutChildren()

        function goNextTab() {
            var oldIndex = priv.currentButtonIndex();
            while (oldIndex < root.children.length) {
                ++oldIndex

                if (oldIndex > root.children.length - 1) {
                    oldIndex = 1
                }

                //anything with a checked property may act as tabbutton
                if (root.children[oldIndex].checked === undefined) {
                    continue
                }


                if (root.children[oldIndex].visible) {
                    priv.setCurrentButtonIndex(oldIndex)
                    break
                }
            }
        }

        function goPreviousTab() {
            var oldIndex = priv.currentButtonIndex();
            while (oldIndex > 0) {
                --oldIndex

                if (oldIndex <= 0) {
                    oldIndex = root.children.length - 1
                }

                //anything with a checked property may act as tabbutton
                if (root.children[oldIndex].checked === undefined) {
                    continue
                }

                if (root.children[oldIndex].visible) {
                    priv.setCurrentButtonIndex(oldIndex)
                    break
                }
            }
        }

        function currentButtonIndex() {
            for (var i = 0; i < root.children.length; ++i) {
                if (root.children[i] == priv.tabBar.currentTab)
                    return i
            }
            return -1
        }

        function setCurrentButtonIndex(index) {
            if (tabGroup) {
                tabGroup.currentTab = root.children[index].tab
            }
            
            priv.tabBar.currentTab = root.children[index]
        }

        function layoutChildren() {
            priv.tabBar = Utils.findParent(root, "currentTab")
            var childCount = root.children.length
            var visibleChildCount = childCount
            var contentWidth = 0
            var contentHeight = 0
            var maxChildWidth = 0
            if (childCount != 0) {
                //not too much efficient but the loop over children needs to be done two times to get the proper child width
                for (var i = 0; i < childCount; ++i) {
                    if (!root.children[i].visible || root.children[i].text === undefined) {
                        --visibleChildCount
                    }
                }

                var maxAllowedWidth = theme.defaultFont.mSize.width * 14
                var itemWidth = (root.width - (visibleChildCount-1)*10) / visibleChildCount

                var itemIndex = mirrored ? childCount - 1 : 0
                var increment = mirrored ? - 1 : 1
                var visibleIndex = 0

                for (var i = 0; i < childCount; ++i, itemIndex += increment) {
                    var child = root.children[itemIndex]
                    if (!child.visible || root.children[i].text === undefined) {
                        continue
                    }

                    child.x = visibleIndex * itemWidth + visibleIndex*10
                    ++visibleIndex
                    child.y = 0
                    child.width = itemWidth
                    child.height = root.height

                    if (child.implicitWidth != undefined) {
                        maxChildWidth = Math.max(maxChildWidth, Math.min(maxAllowedWidth, child.implicitWidth))
                        contentWidth = Math.max(contentWidth, (maxChildWidth + buttonFrame.margins.left + buttonFrame.margins.right) * childCount)
                        contentHeight = Math.max(contentHeight, (child.implicitHeight + buttonFrame.margins.top + buttonFrame.margins.bottom))
                    }
                }
            }
            root.implicitWidth = contentWidth
            root.implicitHeight = contentHeight
            if ( priv.tabBar.currentTab === null) {
                //99% of the cases this loop will be length 1 but a tabbar can also have other children, such as Repeater
                for (var i = 0; i < tabBarLayout.children.length; ++i) {
                    //anything with a checked property may act as tabbutton
                    if (tabBarLayout.children[i].checked !== undefined) {
                        priv.tabBar.currentTab = tabBarLayout.children[i]
                        break;
                    }
                }
            }
        }
    }
}