canvas畫動態時鐘

時間 2019-11-09

標籤 canvas 動態時鐘简体版

原文原文鏈接

用canvas畫動態時鐘

HTML代碼css

<body>
  <div class="box">
    <span id="hour"></span>:
    <span id="minute"></span>:
    <span id="second"></span>
  </div>
  <div>
    <canvas id="clock" width="200px" height="200px"></canvas>
  </div>
</body>

css：canvas

*{margin: 0;padding: 0;}
div{
  text-align: center;
}
div.box{
  margin: 50px auto;
  text-align: center;
  font-size: 30px;
  display: flex;
  align-content: center;
  justify-content: center;
}
span{
  display: inline-block;
  width: 50px;
  height: 50px;
  line-height: 50px;
  border:2px solid #ccc;
  font-size: 20px;
  margin: 0px 20px;
}

js代碼dom

var hourspan =document.getElementById("hour");
  var minutespan =document.getElementById("minute");
  var secondspan =document.getElementById("second");
  var dom = document.getElementById("clock");
  var ctx = dom.getContext("2d");
  var width = ctx.canvas.width;
  var height = ctx.canvas.height;
  var r = width/2;
  

  function drawBackground(){
    ctx.save(); //保存當前畫布樣式
    ctx.translate(r,r);//切換中心點
//畫外圓
    ctx.beginPath();
    ctx.lineWidth=10;
    ctx.arc(0,0,r-5,0,2*Math.PI,false);
    ctx.stroke();
//畫數字
    var hourNumber = [3,4,5,6,7,8,9,10,11,12,1,2];
    ctx.textAlign = "center";
    ctx.textBaseline = "middle";
    hourNumber.forEach(function(item,index){
      var rad = 2*Math.PI/12*index;
      var x = Math.cos(rad)*(r-30);
      var y = Math.sin(rad)*(r-30);
      ctx.fillText(item,x,y);
    })
//畫時刻
    for(var i=0;i<60;i++){
      var rad = 2*Math.PI/60*i;
      var x = Math.cos(rad)*(r-15);
      var y = Math.sin(rad)*(r-15);
      ctx.beginPath();
      ctx.arc(x,y,2,0,Math.PI*2,false);
      if(i%5 == 0){
        ctx.fillStyle = "#000";
        ctx.fill();
      }else{
        ctx.fillStyle = "#ccc";
        ctx.fill();
      }
    }
  }
//畫時針，分針，秒針
  function drawHour(hour,minute,second){
    ctx.save();
    ctx.beginPath();
    var rad = 2*Math.PI/12*hour+((2*Math.PI/12)*(minute+second/60)/60);//將分，秒換算成小時
    ctx.rotate(rad);
    ctx.strokeStyle = "#000";
    ctx.lineWidth = 4;
    ctx.lineCap = "round";
    ctx.moveTo(0,10);
    ctx.lineTo(0,-r/2);
    ctx.stroke();
    ctx.restore();//返回上一個畫布樣式
  }
  function drawMinute(minute,second){
    ctx.save();
    ctx.beginPath();
    var rad = 2*Math.PI/60*minute+(2*Math.PI/60)*(second/60);//將秒換算成分
    ctx.rotate(rad);
    ctx.strokeStyle = "#000";
    ctx.lineWidth = 6;
    ctx.lineCap = "round";
    ctx.moveTo(0,15);
    ctx.lineTo(0,-(r-25));
    ctx.stroke();
    ctx.restore();
  }
  function drawSecond(second){
    ctx.save();
    ctx.beginPath();
    ctx.strokeStyle = "red";
    var rad = 2*Math.PI/60*second;
    ctx.rotate(rad);
    ctx.lineWidth = 3;
    ctx.lineCap = "round";
    ctx.moveTo(0,20);
    ctx.lineTo(0,-(r-15));
    ctx.stroke();
    ctx.restore();
  }
//畫圓心
  function drawCicle(){
    ctx.save();
    ctx.beginPath();
    ctx.fillStyle ="#fff";
    ctx.arc(0,0,2,0,Math.PI*2,false);
    ctx.fill();
    ctx.restore();
  }
  
  
  //將全部事件封裝在一個函數中，爲製做成動態時鐘作準備
  function timeActive(){
    ctx.clearRect(0,0,width,height);//清空整個畫布
    var date = new Date();
    var hour = date.getHours();
    var minute = date.getMinutes();
    var second = date.getSeconds();
    hourspan.innerText = hour;
    minutespan.innerText = minute;
    secondspan.innerText = second;
    drawBackground();
    drawHour(hour,minute,second);
    drawMinute(minute,second);
    drawSecond(second);
    drawCicle();
    ctx.restore();
  }
  timeActive();//初始化畫布
  setInterval('timeActive()',1000);

小生初出茅廬，但願各位海涵，看見網上的教學視頻後，感受挺有意思的，手敲了一遍。函數

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