1.得到一個canvas元素 2.用canvas元素去得到一個html5內置內置的工具getContext("2d")
3.常用的方法，fillStyle屬性指明填充的顏色樣式，fillRect(x,y,width,height)畫矩形
4.畫直線moveTo(x,y) lineTo(x,y) closePath() stroke() 屬性：lineJoin 默認是平角round是圓角 lineCap有3個值：butt（平，默認）,round（圓）,square（方） lineWidth線條寬度 stokeStyle線條的顏色樣式 學習http://www.jb51.net/html5/70307.html
5畫圓形cxt2.arc(100,100,100,0,Math.PI*2,true);cxt2.closePath();cxt2.fill();
arc（x,y,r,0,Math.PI*2,true）x，y圓心 r半徑
6.漸變填充
var grd=cxt3.createLinearGradient(0,0,180,100);grd.addColorStop(0,"#FF0000");
grd.addColorStop(1,"#00FF00");cxt3.fillStyle=grd;cxt3.fillRect(0,0,180,100);
addColorStop(x,color) 0=《x《=1 開始和技術時的顏色
7.圖像填充var can4 = document.getElementById('can4');
var cxt4 = can4.getContext("2d");
var img = new Image();
img.src ="22.gif";
console.log(img);
cxt4.drawImage(img,0,0);這樣的結果並不會顯示出來圖像
因爲img沒有加載進來，解決辦法img.onload = function () {
cxt4.drawImage(img, 50, 50,100,100);
}
代碼：1.html
<style>
#can1{border:solid 1px blue;}
</style>
</head>
<body>
<canvas id="can1" width="200" height="200"></canvas>
<script>
var can1 = document.getElementById('can1');
var cxt = can1.getContext("2d");
cxt.fillStyle="blue";
cxt.fillRect(0,0,50,50);
cxt.moveTo(60,60);
cxt.lineTo(150,60);
//cxt.moveTo(150,60);
cxt.lineTo(150,150);
cxt.lineTo(60,150);
cxt.lineTo(60,60);
//cxt.lineJoin="round";
//cxt.closePath();
cxt.lineCap="square";
cxt.lineWidth=20;
cxt.strokeStyle = 'rgba(255,0,0,0.5)';
cxt.stroke();
</script>
代碼2.html
<canvas id="can2" width="200" height="200"></canvas>
<canvas id="can3" width="200" height="200"></canvas>
<canvas id="can4" width="200" height="200"></canvas>
<script>
//
var can2 = document.getElementById('can2');
var cxt2 = can2.getContext("2d");
cxt2.fillStyle="#FF0000";
cxt2.arc(100,100,100,0,Math.PI*2,true);
cxt2.closePath();
cxt2.fill();
var can3 = document.getElementById('can3');
var cxt3 = can3.getContext("2d");
var grd=cxt3.createLinearGradient(0,0,180,100);
grd.addColorStop(0,"#FF0000");
grd.addColorStop(1,"#00FF00");
cxt3.fillStyle=grd;
cxt3.fillRect(0,0,180,100);
var can4 = document.getElementById('can4');
var cxt4 = can4.getContext("2d");
var img = new Image();
img.src ="22.gif";
console.log(img);
//cxt4.drawImage(img,0,0);
img.onload = function () {
cxt4.drawImage(img, 50, 50,100,100);
}
</script>