HTML5 Canvans(3) 调整Canvas画布大小和擦除

//得到2D渲染上下文

var cancans = document.getElementById("myCanvas");



var width = cancans.getAttribute("width");

var height = cancans.getAttribute("height");

var context = document.getElementById("myCanvas").getContext("2d");



var x = 40, y = 40;

context.fillStyle = "blue"; //设置填充色

context.fillRect(x, y, 55, 55);

  context.clearRect(x, y, 45, 45);



var timeoutlRst;

var resizeCavans = function () {

    //节流，防止频繁调用

    clearTimeout(timeoutlRst);

    setTimeout(SetCanvansSize, 500);

}

var SetCanvansSize = function () {

    var width = document.body.clientWidth;

    var height = $(window).get(0).innerHeight;//这里使用jquery的封装的方法得到高度

    cancans.width = width;

    cancans.height = height;

    context.fillStyle = "blue"; //设置填充色

    context.fillRect(0, 0, width, height);

}

window.onresize = resizeCavans;

// cancans.setAttribute("width", 500); //设置canvans大小后所有设置样式会重置