canvas實(shí)現(xiàn)粒子時(shí)鐘效果

更新時(shí)間：2017年02月06日 09:59:16 作者：小火柴的藍(lán)色理想

本文將使用canvas實(shí)現(xiàn)粒子時(shí)鐘效果，具有一定的參考價(jià)值，下面跟著小編一起來看下吧

前面的話

本文將使用canvas實(shí)現(xiàn)粒子時(shí)鐘效果

效果展示

點(diǎn)陣數(shù)字

digit.js是一個(gè)三維數(shù)組，包含的是0到9以及冒號(hào)(digit[10])的二維點(diǎn)陣。每個(gè)數(shù)字的點(diǎn)陣表示是7*10大小的二維數(shù)組

通過遍歷數(shù)字點(diǎn)陣的二維數(shù)組，當(dāng)該位置的值為1時(shí)，則繪制一個(gè)粒子，否則不繪制

將繪制數(shù)字的函數(shù)命名為renderDigit()。在該函數(shù)中，將粒子繪制為一個(gè)小圓。小圓的半徑為R，小圓所占據(jù)的矩形寬(高)為2(R+1)。由于數(shù)字點(diǎn)陣是10*7的二維數(shù)組，所以一個(gè)數(shù)字的寬度為14(R+1)，高度為20(R+1)

假設(shè)數(shù)字的高度為100px，則小圓的半徑R=4

<div id="test">
 <button>1</button>
 <button>2</button>
 <button>3</button>
 <button>4</button>
 <button>5</button>
 <button>6</button>
 <button>7</button>
 <button>8</button>
 <button>9</button>
 <button>10</button>
</div>
<canvas id="canvas">當(dāng)前瀏覽器不支持canvas，請更換瀏覽器后再試</canvas>
<script src="http://files.cnblogs.com/files/xiaohuochai/digit.js"></script> 
<script>var canvas = document.getElementById('canvas');
 if(canvas.getContext){
  var cxt = canvas.getContext('2d');
 }
 function renderDigit(num){
  //重置畫布寬度，達(dá)到清空畫布的效果
  canvas.height = 100;
  var R = canvas.height/20-1;
  for(var i = 0; i < digit[num].length; i++){
   for(var j = 0; j < digit[num][i].length; j++){
    if(digit[num][i][j] == 1){
     cxt.beginPath();
     cxt.arc(j*2*(R+1)+(R+1),i*2*(R+1)+(R+1),R,0,2*Math.PI);
     cxt.closePath();
     cxt.fill();
    }
   }
  }  
 }
 var test = document.getElementById('test');
 test.onclick = function(e){
  e = e || event;
  var target = e.target || e.srcElement;
  if(!isNaN(target.innerHTML)){
   renderDigit(target.innerHTML);
  } 
 }
</script>

時(shí)鐘實(shí)現(xiàn)

在上一步的點(diǎn)陣數(shù)字的基礎(chǔ)上，實(shí)現(xiàn)一個(gè)粒子時(shí)鐘。將時(shí)鐘實(shí)現(xiàn)的函數(shù)命名為digitTime()，時(shí)鐘實(shí)現(xiàn)由獲取時(shí)間數(shù)據(jù)和渲染時(shí)鐘兩部分組成

【時(shí)間數(shù)據(jù)】

　最簡單的時(shí)鐘形式由兩位的小時(shí)、兩位的分鐘和兩位的秒鐘組成，中間用冒號(hào)隔開。通過日期對象Date來獲取當(dāng)前時(shí)間，以及當(dāng)前的小時(shí)、分鐘和秒鐘。但是，最終需要得到的是數(shù)字表示的時(shí)鐘

　比如12:02:36的時(shí)間數(shù)據(jù)的表示形式為data[1,2,10,0,2,10,3,6]

【渲染時(shí)鐘】

獲取到時(shí)間數(shù)據(jù)后，通過循環(huán)使用renderDigit()來渲染時(shí)鐘中的每一個(gè)數(shù)字。此時(shí)，有一個(gè)需要改變的地方是arc()函數(shù)中的x坐標(biāo)，否則它們將疊加在一起

為了將時(shí)鐘數(shù)字表示更加清晰在每個(gè)數(shù)字之間增加一定的間距。每個(gè)數(shù)字的寬度是14(R+1)，假設(shè)data數(shù)組中7個(gè)數(shù)字的索引為index，則每個(gè)數(shù)字的起始X坐標(biāo)可以等于14(R+2)*index

最后通過定時(shí)器每間隔一段時(shí)間后更新時(shí)間

<canvas id="canvas" style="width:400px;">當(dāng)前瀏覽器不支持canvas，請更換瀏覽器后再試</canvas>
<script src="http://files.cnblogs.com/files/xiaohuochai/digit.js"></script> 
<script>
 var canvas = document.getElementById('canvas');
 if(canvas.getContext){
  var cxt = canvas.getContext('2d');
 }
 canvas.height = 100;
 canvas.width = 700;
 function renderDigit(index,num){
  var R = canvas.height/20-1;
  for(var i = 0; i < digit[num].length; i++){
   for(var j = 0; j < digit[num][i].length; j++){
    if(digit[num][i][j] == 1){
     cxt.beginPath();
     cxt.arc(14*(R+2)*index + j*2*(R+1)+(R+1),i*2*(R+1)+(R+1),R,0,2*Math.PI);
     cxt.closePath();
     cxt.fill();
    }
   }
  }  
 }
 function digitTime(){
  /*獲取時(shí)間數(shù)據(jù)*/
  var temp = /(\d)(\d):(\d)(\d):(\d)(\d)/.exec(new Date());
  //存儲(chǔ)時(shí)間數(shù)字，由十位小時(shí)、個(gè)位小時(shí)、冒號(hào)、十位分鐘、個(gè)位分鐘、冒號(hào)、十位秒鐘、個(gè)位秒鐘這7個(gè)數(shù)字組成
  var data = [];
  data.push(temp[1],temp[2],10,temp[3],temp[4],10,temp[5],temp[6]);
  /*渲染時(shí)鐘*/
  //重置畫布寬度，達(dá)到清空畫布的效果
  canvas.height = 100;
  for(var i = 0; i < data.length; i++){
   renderDigit(i,data[i]);
  }
 }
 digitTime();
 clearInterval(oTimer);
 var oTimer = setInterval(function(){
  digitTime();
 },500);
</script>

隨機(jī)拋物線

這節(jié)的隨機(jī)拋物線運(yùn)動(dòng)是下節(jié)粒子動(dòng)畫的預(yù)備節(jié)。以DOM節(jié)點(diǎn)的投擲碰壁為基礎(chǔ)，利用canvas實(shí)現(xiàn)一個(gè)小球的隨機(jī)拋物線運(yùn)動(dòng)

將小球的運(yùn)動(dòng)拆分為x軸和y軸運(yùn)動(dòng)。x軸做勻速運(yùn)動(dòng)，y軸先做向上的減速運(yùn)動(dòng)，再做向下的加速運(yùn)動(dòng)。當(dāng)小球離開畫布區(qū)域時(shí)，停止定時(shí)器

<button id="btn">按鈕</button>
<canvas id="canvas" style="border:1px solid black">當(dāng)前瀏覽器不支持canvas，請更換瀏覽器后再試</canvas>
<script>
 var canvas = document.getElementById('canvas');
 if(canvas.getContext){
  var cxt = canvas.getContext('2d');
 }
 //聲明canvas的寬高
 var H = 100,W = 200;
 canvas.height = H;
 canvas.width = W; 
 var R = canvas.height/20-1;
 var numArray = [1,2,3,4];
 var colorArray = ["#3BE","#09C","#A6C","#93C","#9C0","#690","#FB3","#F80","#F44","#C00"];
 btn.onclick = function(){
  //聲明x、y軸坐標(biāo)
  var x=Math.floor(Math.random() * 60 + 10);
  var y=Math.floor(Math.random() * 60 + 10);
  //聲明x、y軸的步長值
  var stepY = -3*numArray[Math.floor(Math.random()*numArray.length)];
  var stepX = Math.floor(Math.random() * 10 -5);
  //聲明y軸變化值
  var disY = numArray[Math.floor(Math.random()*numArray.length)];
  var color =colorArray[Math.floor(Math.random()*colorArray.length)];
  clearInterval(oTimer);
  var oTimer = setInterval(function(){
   stepY += disY;
   x += stepX;
   y += stepY;
   canvas.height = 100;
   cxt.beginPath();
   cxt.arc(x,y,R,0,2*Math.PI);
   cxt.fillStyle = color;
   cxt.closePath();
   cxt.fill(); 
   if(x > W + R || y > H + R){
    clearInterval(oTimer);
   } 
  },50);
 }
</script>

粒子動(dòng)畫

下面來實(shí)現(xiàn)粒子動(dòng)畫。在時(shí)間數(shù)字變化的瞬間，由眾多的粒子組成的新數(shù)字上重復(fù)生成相同的粒子，并且新生成的粒子做隨機(jī)的拋物線運(yùn)動(dòng)

所以，第一步是先要判斷是哪個(gè)或哪些數(shù)字在時(shí)間更新時(shí)發(fā)生了變化。然后，通過這些變化信息，生成要運(yùn)動(dòng)的小球。在定時(shí)器的運(yùn)行間隔內(nèi)，對運(yùn)動(dòng)小球的狀態(tài)進(jìn)行更新。最后，對時(shí)鐘和運(yùn)行的小球進(jìn)行統(tǒng)一渲染

<canvas id="canvas" style="width:500px;">當(dāng)前瀏覽器不支持canvas，請更換瀏覽器后再試</canvas>
<script src="http://files.cnblogs.com/files/xiaohuochai/digit.js"></script> 
<script>
 var canvas = document.getElementById('canvas');
 if(canvas.getContext){
  var cxt = canvas.getContext('2d');
 }
 //聲明canvas的寬高
 var H = 100,W = 700;
 canvas.height = H;
 canvas.width = W;
 //存儲(chǔ)時(shí)間數(shù)據(jù)
 var data = [];
 //存儲(chǔ)運(yùn)動(dòng)的小球
 var balls = [];
 //設(shè)置粒子半徑
 var R = canvas.height/20-1;
 (function(){
  var temp = /(\d)(\d):(\d)(\d):(\d)(\d)/.exec(new Date());
  //存儲(chǔ)時(shí)間數(shù)字，由十位小時(shí)、個(gè)位小時(shí)、冒號(hào)、十位分鐘、個(gè)位分鐘、冒號(hào)、十位秒鐘、個(gè)位秒鐘這7個(gè)數(shù)字組成
  data.push(temp[1],temp[2],10,temp[3],temp[4],10,temp[5],temp[6]); 
 })();
 /*生成點(diǎn)陣數(shù)字*/
 function renderDigit(index,num){
  for(var i = 0; i < digit[num].length; i++){
   for(var j = 0; j < digit[num][i].length; j++){
    if(digit[num][i][j] == 1){
     cxt.beginPath();
     cxt.arc(14*(R+2)*index + j*2*(R+1)+(R+1),i*2*(R+1)+(R+1),R,0,2*Math.PI);
     cxt.closePath();
     cxt.fill();
    }
   }
  }  
 }
 /*更新時(shí)鐘*/
 function updateDigitTime(){
  var changeNumArray = [];
  var temp = /(\d)(\d):(\d)(\d):(\d)(\d)/.exec(new Date());
  var NewData = [];
  NewData.push(temp[1],temp[2],10,temp[3],temp[4],10,temp[5],temp[6]);
  for(var i = data.length-1; i >=0 ; i--){
   //時(shí)間發(fā)生變化 
   if(NewData[i] !== data[i]){
    //將變化的數(shù)字值和在data數(shù)組中的索引存儲(chǔ)在changeNumArray數(shù)組中
    changeNumArray.push(i+'_'+(Number(data[i])+1)%10);
   }
  }
  //增加小球
  for(var i = 0; i< changeNumArray.length; i++){
   addBalls.apply(this,changeNumArray[i].split('_'));
  } 
  data = NewData.concat();
 }
 /*更新小球狀態(tài)*/
 function updateBalls(){
  for(var i = 0; i < balls.length; i++){
   balls[i].stepY += balls[i].disY;
   balls[i].x += balls[i].stepX;
   balls[i].y += balls[i].stepY; 
   if(balls[i].x > W + R || balls[i].y > H + R){
    balls.splice(i,1);
    i--;
   }    
  }
 }
 /*增加要運(yùn)動(dòng)的小球*/
 function addBalls(index,num){
  var numArray = [1,2,3];
  var colorArray = ["#3BE","#09C","#A6C","#93C","#9C0","#690","#FB3","#F80","#F44","#C00"];
  for(var i = 0; i < digit[num].length; i++){
   for(var j = 0; j < digit[num][i].length; j++){
    if(digit[num][i][j] == 1){
     var ball = {
      x:14*(R+2)*index + j*2*(R+1)+(R+1),
      y:i*2*(R+1)+(R+1),
      stepX:Math.floor(Math.random() * 4 -2),
      stepY:-2*numArray[Math.floor(Math.random()*numArray.length)],
      color:colorArray[Math.floor(Math.random()*colorArray.length)],
      disY:1
     };
     balls.push(ball);   
    }
   }
  } 
 }
 /*渲染*/
 function render(){
  //重置畫布寬度，達(dá)到清空畫布的效果
  canvas.height = 100;
  //渲染時(shí)鐘
  for(var i = 0; i < data.length; i++){
   renderDigit(i,data[i]);
  }  
  //渲染小球
  for(var i = 0; i < balls.length; i++){
   cxt.beginPath();
   cxt.arc(balls[i].x,balls[i].y,R,0,2*Math.PI);
   cxt.fillStyle = balls[i].color;
   cxt.closePath();
   cxt.fill();    
  }
 }
 clearInterval(oTimer);
 var oTimer = setInterval(function(){
  //更新時(shí)鐘
  updateDigitTime();
  //更新小球狀態(tài)
  updateBalls();
  //渲染
  render();
 },50);
</script>

源碼查看

公告欄擴(kuò)展

將canvas粒子時(shí)鐘js部分封裝為canvasTime.js，在公告欄添加如下代碼，即可以實(shí)現(xiàn)在公告欄插入時(shí)鐘的效果

<canvas id="canvas" style="width:100%;">當(dāng)前瀏覽器不支持canvas，請更換瀏覽器后再試</canvas>
<script src="http://files.cnblogs.com/files/xiaohuochai/canvasTime.js"></script>