qml demo分析(clocks-时钟)

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

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 >= )
             return ListView.view.width / Math.floor(ListView.view.width / 200.0);
         else
             return ;
     }

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

     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 <  || hours >  )
         minutes = internationalTime ? date.getUTCMinutes() + ((clock.shift % ) * ) : date.getMinutes()
         seconds = date.getUTCSeconds();
     }

     Timer {
         interval: ; 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: ; height: 

         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:
             source: "hour.png"
             transform: Rotation {
                 id: hourRotation
                 origin.x: 7.5; origin.y: ;
                 angle: (clock.hours * ) + (clock.minutes * 0.5)
                 Behavior on angle {
                     SpringAnimation { spring: ; damping: 0.2; modulus:  }
                 }
             }
         }

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

         //秒针
         Image {
             x: 97.5; y:
             source: "second.png"
             transform: Rotation {
                 id: secondRotation
                 origin.x: 2.5; origin.y: ;
                 angle: clock.seconds *
                 Behavior on angle {
                     SpringAnimation { spring: ; damping: 0.2; modulus:  }
                 }
             }
         }
         //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: ; anchors.horizontalCenter: parent.horizontalCenter
             color: "white"
             font.family: "Helvetica"
             font.bold: true; font.pixelSize:
             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: ; height:
     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: //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: - }
             ListElement { cityName: "London"; timeShift:  }
             ListElement { cityName: "Oslo"; timeShift:  }
             ListElement { cityName: "Mumbai"; timeShift: 5.5 }
             ListElement { cityName: "Tokyo"; timeShift:  }
             ListElement { cityName: "Brisbane"; timeShift:  }
             ListElement { cityName: "Los Angeles"; timeShift: - }
         }
     }
     //左下角上一个箭头
     Image {
         anchors.left: parent.left
         anchors.bottom: parent.bottom
         anchors.margins:
         source: "content/arrow.png"
         rotation: -
         opacity: clockview.atXBeginning ?  : 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:  } }//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:
         source: "content/arrow.png"
         rotation:
         opacity: clockview.atXEnd ?  : 0.5
         Behavior on opacity { NumberAnimation { duration:  } }
     }
 }