qml demo分析(clocks-时钟)

原文：http://www.cnblogs.com/swarmbees/p/6344837.html

一、效果展示

　　效果如图1所示，时钟列表支持鼠标左右拖动，带有黑色背景的是晚上时钟，无黑色背景的是白天时钟

 

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二、源码分析

1、main.cpp文件中只包含了一个宏，该宏的具体解释请看qml 示例中的关键宏文章

2、时钟项

Item {
    id : clock
    width: {
        if (ListView.view && ListView.view.width >= 200)
            return ListView.view.width / Math.floor(ListView.view.width / 200.0);
        else
            return 200;
    }

    height: {
        if (ListView.view && ListView.view.height >= 240)
            return ListView.view.height;
        else
            return 240;
    }

    property alias city: cityLabel.text//属性别名，方便在外部使用
    property int hours//自定义属性
    property int minutes
    property int seconds
    property real shift
    property bool night: false//是否是晚上  来决定是否显示黑色实心圈
    property bool internationalTime: true //Unset for local time

    //js函数
    function timeChanged() {
        var date = new Date;
        hours = internationalTime ? date.getUTCHours() + Math.floor(clock.shift) : date.getHours()
        night = ( hours < 7 || hours > 19 )
        minutes = internationalTime ? date.getUTCMinutes() + ((clock.shift % 1) * 60) : date.getMinutes()
        seconds = date.getUTCSeconds();
    }

    Timer {
        interval: 100; running: true; repeat: true;//一个每隔100ms重复执行的定时器，默认启动
        onTriggered: clock.timeChanged()//定时器槽函数
    }

    Item {
        anchors.centerIn: parent
        width: 200; height: 240

        Image { id: background; source: "clock.png"; visible: clock.night == false }//最外层白色圈
        Image { source: "clock-night.png"; visible: clock.night == true }//黑色实心圈，带有白色实心圆球的刻度点

        //时针
        Image {
            x: 92.5; y: 27
            source: "hour.png"
            transform: Rotation {
                id: hourRotation
                origin.x: 7.5; origin.y: 73;
                angle: (clock.hours * 30) + (clock.minutes * 0.5)
                Behavior on angle {
                    SpringAnimation { spring: 2; damping: 0.2; modulus: 360 }
                }
            }
        }

        //分针
        Image {
            x: 93.5; y: 17
            source: "minute.png"
            transform: Rotation {
                id: minuteRotation
                origin.x: 6.5; origin.y: 83;
                angle: clock.minutes * 6
                Behavior on angle {
                    SpringAnimation { spring: 2; damping: 0.2; modulus: 360 }
                }
            }
        }

        //秒针
        Image {
            x: 97.5; y: 20
            source: "second.png"
            transform: Rotation {
                id: secondRotation
                origin.x: 2.5; origin.y: 80;
                angle: clock.seconds * 6
                Behavior on angle {
                    SpringAnimation { spring: 2; damping: 0.2; modulus: 360 }
                }
            }
        }
        //中心白色圆圈
        Image {
            anchors.centerIn: background; source: "center.png"
        }

        Text {
            id: cityLabel//该属性已经被导出，在clocks.qml文件中指定该属性值
            y: 210; anchors.horizontalCenter: parent.horizontalCenter
            color: "white"
            font.family: "Helvetica"
            font.bold: true; font.pixelSize: 16
            style: Text.Raised; styleColor: "black"
        }
    }
}

3、时钟列表

import "content" as Content //导入目录  该目录底下的所有qml自定义控件均可以直接使用

Rectangle {
    id: root
    width: 640; height: 320
    color: "#646464"

    ListView {//列表视图
        id: clockview//唯一id
        anchors.fill: parent//填充整个父窗口
        orientation: ListView.Horizontal//列表朝向为水平方向
        cacheBuffer: 2000//左右2000个像素以内的委托项都不会被析构
        snapMode: ListView.SnapOneItem//拖拽模式
        highlightRangeMode: ListView.ApplyRange//高亮模式，高亮尽可能在可是区间内

        delegate: Content.Clock { city: cityName; shift: timeShift }//设置Clock控件的导出属性值
        model: ListModel {//静态model
            ListElement { cityName: "New York"; timeShift: -4 }
            ListElement { cityName: "London"; timeShift: 0 }
            ListElement { cityName: "Oslo"; timeShift: 1 }
            ListElement { cityName: "Mumbai"; timeShift: 5.5 }
            ListElement { cityName: "Tokyo"; timeShift: 9 }
            ListElement { cityName: "Brisbane"; timeShift: 10 }
            ListElement { cityName: "Los Angeles"; timeShift: -8 }
        }
    }
    //左下角上一个箭头
    Image {
        anchors.left: parent.left
        anchors.bottom: parent.bottom
        anchors.margins: 10
        source: "content/arrow.png"
        rotation: -90
        opacity: clockview.atXBeginning ? 0 : 0.5//当视图滚动到第一个时透明度为0(使用行为动画)
        Behavior on opacity { NumberAnimation { duration: 500 } }//在透明度属性上添加动画(数字动画)
    }
    //右下角下一个箭头
    Image {
        anchors.right: parent.right
        anchors.bottom: parent.bottom
        anchors.margins: 10
        source: "content/arrow.png"
        rotation: 90
        opacity: clockview.atXEnd ? 0 : 0.5
        Behavior on opacity { NumberAnimation { duration: 500 } }
    }
}