标签：rgba net margin 绘制 baseline als 绘制矩形 div base
Canvas绘制矩形
//html（在html的canvas元素中为其制定高和宽）
<canvas id="drawing" width="200" height="200">A Drawing Of Somothing.</canvas>
//js
var drawing = document.getElementById("drawing");
//判断浏览器是否支持canvas
if (drawing.getContext) {
var context = drawing.getContext("2d");
//制定填充的样式（css中的颜色）
context.fillStyle = "red";
//填充绘制矩形
context.fillRect(10,10,50,50);
context.fillStyle = "rgba(0,0,255,0.5)";
context.fillRect(30,30,50,50);
//清除其中一小块矩形
context.clearRect(30,30,30,30);
Canvas绘制表盘
var context = drawing.getContext("2d");
//开始路径
context.beginPath();
context.arc(100,100,99,0,2*Math.PI,false);
context.moveTo(194,100);
context.arc(100,100,94,0,2*Math.PI,false);
context.moveTo(100,100);
context.lineTo(100,25);
context.moveTo(100,100);
context.lineTo(35,100);
context.stroke();
context.font = "bold 14px Arial";
context.textAlign = "center";
context.textBaseline = "middle";
context.fillText("12",100,20);
Canvas
标签：rgba net margin 绘制 baseline als 绘制矩形 div base
原文地址：http://www.cnblogs.com/lisir-eason/p/7683891.html
