QML定时器

QML中的定时器能够周期性的触发一个事件，其使用非常简单、方便。这里给出一个示例：

 import QtQuick 2.4
 import QtQuick.Controls 1.3
 import QtQuick.Window 2.2
 import QtQuick.Dialogs 1.2

 Rectangle{
     id: root
     width:  512
     height: 512
     color: "gray"

     QtObject {
         id: attrs
         property int count;
         Component.onCompleted: {
             attrs.count = 10;
         }
     }

     Text {
         id: countShow
         color: "blue"
         font.pixelSize: 30
         anchors.centerIn: parent
     }

     Timer {
         id: countDown
         interval: 1000
         repeat: true
         triggeredOnStart: true
         onTriggered: {
             countShow.text = attrs.count;
             attrs.count -= 1;
             if (attrs.count < 0){
                 countDown.stop();
                 countShow.text = "Clap Now!";
                 startBtn.text = "Start"
             }
         }
     }

     Button {
         id: startBtn
         text: "Start"
         onClicked: {
             attrs.count = 10;
             countDown.start();
             startBtn.text = "Restart"
         }

         anchors.horizontalCenter: parent.horizontalCenter
         anchors.bottom: parent.bottom
         anchors.bottomMargin: 20
     }
 }