我们已经介绍使用canvas的api，并且做了刮刮卡实例的开发；我们知道canvas的操作必须通过js处理。
Canvas的介绍使用地址： http://my.oschina.net/u/2352644/blog/501231
我们在上面地址处理中做了简单刮刮卡的效果实现，下面我们有2件事要接着去做：
一.刮刮卡效果更贴切实际应用的修改升级
二.我们对svg进行初级了解
这里是对上面canvas的补充内容，请首先预览上篇博客！
一.刮刮卡效果更贴切实际应用的修改升级
1.最粗糙的刮刮卡实现代码
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<style type="text/css">
*{ margin:0; padding:0;}
.box{position: relative;; width: 300px;height: 200px;}
.box .chi{ position: absolute;; left: 0px;top: 0px;width: 300px;height: 200px;line-height: 200px;text-align: center;font-size: 50px;z-index: 9;}
.box #myCanvas{position: absolute;; left: 0px;top: 0px;z-index: 99;cursor: pointer;}
</style>
<title>demo</title>
</head>
<body>
<div class="box">
<canvas id="myCanvas" height="200" width="300"></canvas>
<div class="chi" id="conb"></div>
</div>
<div id="posi"></div>
</body>
<script type="text/javascript">
window.onload=function(){
var con=[‘一等奖‘,‘二等奖‘,‘三等奖‘,‘未中奖‘];
var conb= document.getElementById("conb");
conb.innerHTML=con[Math.floor(Math.random()*4)];
var arcr=10;
var canvas = document.getElementById("myCanvas"); //获取canvas
var context = canvas.getContext(‘2d‘); //canvas追加2d画图anvas = document.getElementById("canvas");
context.fillStyle="#000";
context.fillRect(0,0,300,200);
var posi = document.getElementById("posi");
var isdown=false;
canvas.onmousedown=function(event){
isdown=true;
};
context.fillStyle="#fff";
context.globalCompositeOperation ="destination-out";
canvas.onmousemove=function(event){
if(isdown){
posi.innerHTML="坐标x："+event.layerX+";"+"坐标u："+event.layerY;
context.arc(event.layerX,event.layerY,arcr,0,2*Math.PI);
context.fill();
};
};
canvas.onmouseup=function(event){
if(isdown){
isdown=false;
var imgdata=context.getImageData(0,0,300,200);
var len=imgdata.data.length;
var rgbaarr=[];
for(var i=0;i<len;i+=4){
var temp=imgdata.data[i]+" "+imgdata.data[i+1]+" "+imgdata.data[i+2]+" "+imgdata.data[i+3];
rgbaarr.push(temp);
};
if(percent("0 0 0 255",rgbaarr)/rgbaarr.length<0.2){
alert(con[Math.floor(Math.random()*4)]);
};
};
};
function percent(obj,arr){
var count=0;
for(var i=0;i<arr.length;i++){
if(arr[i]==obj){count+=1;}
};
return count;
};
};
</script>
</html>
2.实现更加灵活的可控性
哪些部分可以提取出变量的设置处理？
我们把整体修改，针对功能加入注释处理，然后针对可控实现做出下面自定义处理：
var arcr=10; var wcanvas=canvas.width; var hcanvas=canvas.height; var perc=0.4;
刮去的绘制圆形半径，canvas的宽高，参考百分比。
我们遮盖颜色是黑色，我们也在自定义设置：
var coverback="#000";
我们知道在分析数组返回的是rgba的数据，a就是透明度，我们这里不透明就是255，我们如果是黑色，那么16位颜色就是
#000，对应的rgba就是0 0 0；我们针对16位创建一个转化函数，得到rgba值：
function colorRgb(color16){
var reg = /^#([0-9a-fA-f]{3}|[0-9a-fA-f]{6})$/;
var sColor = color16.toLowerCase();
if(sColor && reg.test(sColor)){
if(sColor.length === 4){
var sColorNew = "#";
for(var i=1; i<4; i+=1){
sColorNew += sColor.slice(i,i+1).concat(sColor.slice(i,i+1));
}
sColor = sColorNew;
}
//处理六位的颜色值
var sColorChange = [];
for(var i=1; i<7; i+=2){
sColorChange.push(parseInt("0x"+sColor.slice(i,i+2)));
}
return sColorChange.join(" ")+" "+"255";
}else{
return sColor;
}
};
调用输出测试：
alert(colorRgb(coverback));
我们最后修改后，代码如下，对样式做了简单调整：
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<style type="text/css">
*{ margin:0; padding:0;}
.box{position: relative;; width: 200px;height: 100px;margin: 200px;}
.box .chi{ position: absolute;; left: 0px;top: 0px;width: 200px;height: 100px;line-height: 100px;text-align: center;font-size: 50px;z-index: 9;}
.box #myCanvas{position: absolute;; left: 0px;top: 0px;z-index: 99;cursor: pointer;}
</style>
<title>demo</title>
</head>
<body>
<div class="box">
<canvas id="myCanvas" height="100" width="200"></canvas>
<div class="chi" id="conb"></div>
</div>
<div id="posi"></div>
</body>
<script type="text/javascript">
window.onload=function(){
//获取对象
var conb= document.getElementById("conb");
var canvas = document.getElementById("myCanvas");
var posi = document.getElementById("posi");
//公共定义
var arcr=10;
var wcanvas=canvas.width;
var hcanvas=canvas.height;
var perc=0.4;
var coverback="#000";
var rgbareal=colorRgb(coverback);
//随机奖项
var con=[‘一等奖‘,‘二等奖‘,‘三等奖‘,‘未中奖‘];
conb.innerHTML=con[Math.floor(Math.random()*4)];
//基本画布获取和遮盖实现
var context = canvas.getContext(‘2d‘); //canvas追加2d画图anvas = document.getElementById("canvas");
context.fillStyle=coverback;
context.fillRect(0,0,wcanvas,hcanvas);
//刮去事件处理
var isdown=false;
canvas.onmousedown=function(event){
isdown=true;
};
context.fillStyle="#fff";
context.globalCompositeOperation ="destination-out";
canvas.onmousemove=function(event){
if(isdown){
posi.innerHTML="坐标x："+event.layerX+";"+"坐标u："+event.layerY;
context.arc(event.layerX,event.layerY,arcr,0,2*Math.PI);
context.fill();
};
};
canvas.onmouseup=function(event){
if(isdown){
isdown=false;
var imgdata=context.getImageData(0,0,wcanvas,hcanvas);
var len=imgdata.data.length;
var rgbaarr=[];
for(var i=0;i<len;i+=4){
var temp=imgdata.data[i]+" "+imgdata.data[i+1]+" "+imgdata.data[i+2]+" "+imgdata.data[i+3];
rgbaarr.push(temp);
};
if(percent(rgbareal,rgbaarr)/rgbaarr.length<perc){
alert(con[Math.floor(Math.random()*4)]);
};
};
};
//操作函数
function percent(obj,arr){
var count=0;
for(var i=0;i<arr.length;i++){
if(arr[i]==obj){count+=1;}
};
return count;
};
function colorRgb(color16){
var reg = /^#([0-9a-fA-f]{3}|[0-9a-fA-f]{6})$/;
var sColor = color16.toLowerCase();
if(sColor && reg.test(sColor)){
if(sColor.length === 4){
var sColorNew = "#";
for(var i=1; i<4; i+=1){
sColorNew += sColor.slice(i,i+1).concat(sColor.slice(i,i+1));
}
sColor = sColorNew;
}
//处理六位的颜色值
var sColorChange = [];
for(var i=1; i<7; i+=2){
sColorChange.push(parseInt("0x"+sColor.slice(i,i+2)));
}
return sColorChange.join(" ")+" "+"255";
}else{
return sColor;
}
};
};
</script>
</html>
3.随机奖项的可控处理
var con=[‘一等奖‘,‘二等奖‘,‘三等奖‘,‘未中奖‘]; conb.innerHTML=con[Math.floor(Math.random()*4)];
奖项设置，现在的出现比例格式25%；这样的话抽奖客户就乐坏了，我们要对奖项做几率处理，我们把一等奖出现概率设置为0.05；二等奖是0.1；三等奖0.15，未中奖0.7，为了简单我们就做这样简单模拟处理：
//随机奖项
var con=[‘一等奖‘,‘二等奖‘,‘三等奖‘,‘未中奖‘];
var percentcon=[0.05,0.1,0.15,0.7];
var all=100;
var allcon=[];
for(var i=0;i<percentcon.length;i++){
for(var j=0;j<percentcon[i]*all;j++){
allcon.push(con[i]);
};
};
conb.innerHTML=allcon[Math.floor(Math.random()*all)];
我们新的奖项存放数组长度变为100个，然后根据比例存入对应数量，同样获取值也会0-100之间，代码修改如下：
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<style type="text/css">
*{ margin:0; padding:0;}
.box{position: relative;; width: 200px;height: 100px;margin: 200px;}
.box .chi{ position: absolute;; left: 0px;top: 0px;width: 200px;height: 100px;line-height: 100px;text-align: center;font-size: 50px;z-index: 9;}
.box #myCanvas{position: absolute;; left: 0px;top: 0px;z-index: 99;cursor: pointer;}
</style>
<title>demo</title>
</head>
<body>
<div class="box">
<canvas id="myCanvas" height="100" width="200"></canvas>
<div class="chi" id="conb"></div>
</div>
<div id="posi"></div>
</body>
<script type="text/javascript">
window.onload=function(){
//获取对象
var conb= document.getElementById("conb");
var canvas = document.getElementById("myCanvas");
var posi = document.getElementById("posi");
//公共定义
var arcr=10;
var wcanvas=canvas.width;
var hcanvas=canvas.height;
var perc=0.4;
var coverback="#000";
var rgbareal=colorRgb(coverback);
//随机奖项
var con=[‘一等奖‘,‘二等奖‘,‘三等奖‘,‘未中奖‘];
var percentcon=[0.05,0.1,0.15,0.7];
var all=100;
var allcon=[];
for(var i=0;i<percentcon.length;i++){
for(var j=0;j<percentcon[i]*all;j++){
allcon.push(con[i]);
};
};
conb.innerHTML=allcon[Math.floor(Math.random()*all)];
//基本画布获取和遮盖实现
var context = canvas.getContext(‘2d‘); //canvas追加2d画图anvas = document.getElementById("canvas");
context.fillStyle=coverback;
context.fillRect(0,0,wcanvas,hcanvas);
//刮去事件处理
var isdown=false;
canvas.onmousedown=function(event){
isdown=true;
};
context.fillStyle="#fff";
context.globalCompositeOperation ="destination-out";
canvas.onmousemove=function(event){
if(isdown){
posi.innerHTML="坐标x："+event.layerX+";"+"坐标u："+event.layerY;
context.arc(event.layerX,event.layerY,arcr,0,2*Math.PI);
context.fill();
};
};
canvas.onmouseup=function(event){
if(isdown){
isdown=false;
var imgdata=context.getImageData(0,0,wcanvas,hcanvas);
var len=imgdata.data.length;
var rgbaarr=[];
for(var i=0;i<len;i+=4){
var temp=imgdata.data[i]+" "+imgdata.data[i+1]+" "+imgdata.data[i+2]+" "+imgdata.data[i+3];
rgbaarr.push(temp);
};
if(percent(rgbareal,rgbaarr)/rgbaarr.length<perc){
alert(allcon[Math.floor(Math.random()*all))]);
};
};
};
//操作函数
function percent(obj,arr){
var count=0;
for(var i=0;i<arr.length;i++){
if(arr[i]==obj){count+=1;}
};
return count;
};
function colorRgb(color16){
var reg = /^#([0-9a-fA-f]{3}|[0-9a-fA-f]{6})$/;
var sColor = color16.toLowerCase();
if(sColor && reg.test(sColor)){
if(sColor.length === 4){
var sColorNew = "#";
for(var i=1; i<4; i+=1){
sColorNew += sColor.slice(i,i+1).concat(sColor.slice(i,i+1));
}
sColor = sColorNew;
}
//处理六位的颜色值
var sColorChange = [];
for(var i=1; i<7; i+=2){
sColorChange.push(parseInt("0x"+sColor.slice(i,i+2)));
}
return sColorChange.join(" ")+" "+"255";
}else{
return sColor;
}
};
};
</script>
</html>
4.可用刮奖次数设定，实用完善处理
我们预设就设置为3次，刮完3次后提示次数用完。
原理：问题来了，既然有次数限制，那么就得触发次数减少，什么时候减少？就是弹出具体奖项的时候-1；同样如果次数减到0，就提示次数用完。
我们的次数处理都是抬起事件的alert部分添加：
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<style type="text/css">
*{ margin:0; padding:0;}
.box{position: relative;; width: 200px;height: 100px;margin: 200px;}
.box .chi{ position: absolute;; left: 0px;top: 0px;width: 200px;height: 100px;line-height: 100px;text-align: center;font-size: 50px;z-index: 9;}
.box #canvas{position: absolute;; left: 0px;top: 0px;z-index: 99;cursor: pointer;}
</style>
<title>demo</title>
</head>
<body>
<div class="box" id="box">
<!-- <canvas id="myCanvas" height="100" width="200"></canvas> -->
<div class="chi" id="conb"></div>
</div>
<div id="posi"></div>
</body>
<script type="text/javascript">
window.onload=function(){
//可用次数处理
var ablecount=3;
//获取对象
var box = document.getElementById("box");
var conb= document.getElementById("conb");
var posi = document.getElementById("posi");
var canvas;
var context;
//公共定义
var arcr=10;
var wcanvas;
var hcanvas;
var perc=0.4;
var coverback="#000";
var rgbareal=colorRgb(coverback);
//随机奖项
var con=[‘一等奖‘,‘二等奖‘,‘三等奖‘,‘未中奖‘];
var percentcon=[0.05,0.1,0.15,0.7];
var all=100;
var allcon=[];
for(var i=0;i<percentcon.length;i++){
for(var j=0;j<percentcon[i]*all;j++){
allcon.push(con[i]);
};
};
var realj="";
init();
function init(){
canvas=document.createElement("canvas");
canvas.id="canvas";
canvas.width=200;
canvas.height=100;
box.appendChild(canvas);
//基本画布获取和遮盖实现
context = canvas.getContext(‘2d‘); //canvas追加2d画图anvas = document.getElementById("canvas");
context.fillStyle=coverback;
wcanvas=canvas.width;
hcanvas=canvas.height;
conb.innerHTML=allcon[Math.floor(Math.random()*all)];
realj=conb.innerHTML;
context.clearRect(0,0,wcanvas,hcanvas);
context.fillRect(0,0,wcanvas,hcanvas);
context.fillStyle="#fff";
context.globalCompositeOperation ="destination-out";
//刮去事件处理
var isdown=false;
canvas.onmousedown=function(event){
isdown=true;
};
canvas.onmousemove=function(event){
if(isdown){
posi.innerHTML="坐标x："+event.layerX+";"+"坐标u："+event.layerY;
context.arc(event.layerX,event.layerY,arcr,0,2*Math.PI);
context.fill();
};
};
canvas.onmouseup=function(event){
if(isdown){
isdown=false;
var imgdata=context.getImageData(0,0,wcanvas,hcanvas);
var len=imgdata.data.length;
var rgbaarr=[];
for(var i=0;i<len;i+=4){
var temp=imgdata.data[i]+" "+imgdata.data[i+1]+" "+imgdata.data[i+2]+" "+imgdata.data[i+3];
rgbaarr.push(temp);
};
if(percent(rgbareal,rgbaarr)/rgbaarr.length<perc){
ablecount-=1;
if(ablecount<0){
alert("明日再战");
}else{
alert(realj);
var idcanvas= document.getElementById("canvas");
box.removeChild(idcanvas);
init();
};
};
};
};
};
//操作函数
function percent(obj,arr){
var count=0;
for(var i=0;i<arr.length;i++){
if(arr[i]==obj){count+=1;}
};
return count;
};
function colorRgb(color16){
var reg = /^#([0-9a-fA-f]{3}|[0-9a-fA-f]{6})$/;
var sColor = color16.toLowerCase();
if(sColor && reg.test(sColor)){
if(sColor.length === 4){
var sColorNew = "#";
for(var i=1; i<4; i+=1){
sColorNew += sColor.slice(i,i+1).concat(sColor.slice(i,i+1));
}
sColor = sColorNew;
}
//处理六位的颜色值
var sColorChange = [];
for(var i=1; i<7; i+=2){
sColorChange.push(parseInt("0x"+sColor.slice(i,i+2)));
}
return sColorChange.join(" ")+" "+"255";
}else{
return sColor;
}
};
};
</script>
</html>
我们对canvas做了动态插入处理，每次刮完就会删除已有，插入新的canvas，然后添加刮去事件和赋值新的奖项。
二.我们对svg进行初步了解
1.介绍
SVG是一种矢量图格式。SVG是Scalable Vector Graphics三个单词的首字母缩写。Adobe Illustrator是专门编辑、制作矢量图的软件工具。SVG是Adobe Illustrator的主要制作目标。你可以在轻松的网页上使用漂亮的SVG图，但SVG有很多的用法你可能还不知道。
我们通过AI可以制作svg，制作的矢量图在AI提供了直接生成svg文件的选择项，还有编辑svg文件的选项功能。
3.兼容及相关
ie9及其以上和其他主流浏览器
他是来自xml的扩展
canvas只能通过js控制绘制，svg通过标签想形式绘制
3.实用到html页面
--1.创建svg文件，后缀名是.svg，保存成svg.svg
<?xml version="1.0" standalone="no"?> <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd"> <svg width="100%" height="100%" version="1.1" xmlns="http://www.w3.org/2000/svg"> <circle cx="100" cy="50" r="40" stroke="black" stroke-width="2" fill="red"/> </svg> </svg>
其中
circle cx="100" cy="50" r="40" stroke="black" stroke-width="2" fill="red"/>
是绘制处理，我们看单词应该是一个红色圆形的绘制，半径40，描边宽度是2，和我们的canvas的dom api差不多名字
--2.embed标签引入外部svg文件
html结构如下：
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<style type="text/css">
*{ margin:0; padding:0;}
</style>
<title>demo</title>
</head>
<body>
<embed src="svg.svg" width="300" height="100" type="image/svg+xml" pluginspage="http://www.adobe.com/svg/viewer/install/" />
</body>
<script type="text/javascript">
window.onload=function(){
};
</script>
</html>
这是html5提供的新标签，作为外部内容和插件引入处理。
--3.object标签引入外部svg文件
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<style type="text/css">
*{ margin:0; padding:0;}
</style>
<title>demo</title>
</head>
<body>
<object data="svg.svg" width="300" height="100"
type="image/svg+xml"
codebase="http://www.adobe.com/svg/viewer/install/" />
</body>
<script type="text/javascript">
window.onload=function(){
};
</script>
</html>
object是以前就有的标签，还可以引入视频，音频等等文件。
--4.iframe标签引入外部svg文件
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<style type="text/css">
*{ margin:0; padding:0;}
</style>
<title>demo</title>
</head>
<body>
<iframe src="svg.svg" width="300" height="100">
</iframe>
</body>
<script type="text/javascript">
window.onload=function(){
};
</script>
</html>
浮动框架标签以前我们都是引入外部的html页面，同样可以引入svg。
--5.html页面内部写svg标签
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<style type="text/css">
*{ margin:0; padding:0;}
</style>
<title>demo</title>
</head>
<body>
<svg width="100%" height="100%" version="1.1"
xmlns="http://www.w3.org/2000/svg">
<circle cx="100" cy="50" r="40" stroke="black"
stroke-width="2" fill="red"/>
</body>
<script type="text/javascript">
window.onload=function(){
};
</script>
</html>
我们最喜欢的方式，写法确实不是很好，这样就会和我们的html标签交错。
--6.svg外部文件做图片引入
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<style type="text/css">
*{ margin:0; padding:0;}
</style>
<title>demo</title>
</head>
<body>
<img src="svg.svg" width="300" />
</body>
<script type="text/javascript">
window.onload=function(){
};
</script>
</html>
--7.svg外部文件做css背景引入
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<style type="text/css">
*{ margin:0; padding:0;}
.svg{background: url(‘svg.svg‘) no-repeat center;height: 300px;width: 300px;
}
</style>
<title>demo</title>
</head>
<body>
<div class="svg"></div>
</body>
<script type="text/javascript">
window.onload=function(){
};
</script>
</html>
总结：
svg页面可以做背景图
可以充当图片资源
可以作为外部对象被引用标签引入
可以在html页面内部以标签形式创建。
三.canvas的降级处理，兼容低级ie
采用的excanvas.js实现
excanvas.js 复制下载：
// Copyright 2006 Google Inc.
// Download by http://www.codefans.net
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Known Issues:
//
// * Patterns are not implemented.
// * Radial gradient are not implemented. The VML version of these look very
// different from the canvas one.
// * Clipping paths are not implemented.
// * Coordsize. The width and height attribute have higher priority than the
// width and height style values which isn‘t correct.
// * Painting mode isn‘t implemented.
// * Canvas width/height should is using content-box by default. IE in
// Quirks mode will draw the canvas using border-box. Either change your
// doctype to HTML5
// (http://www.whatwg.org/specs/web-apps/current-work/#the-doctype)
// or use Box Sizing Behavior from WebFX
// (http://webfx.eae.net/dhtml/boxsizing/boxsizing.html)
// * Optimize. There is always room for speed improvements.
// only add this code if we do not already have a canvas implementation
if (!window.CanvasRenderingContext2D) {
(function () {
// alias some functions to make (compiled) code shorter
var m = Math;
var mr = m.round;
var ms = m.sin;
var mc = m.cos;
// this is used for sub pixel precision
var Z = 10;
var Z2 = Z / 2;
var G_vmlCanvasManager_ = {
init: function (opt_doc) {
var doc = opt_doc || document;
if (/MSIE/.test(navigator.userAgent) && !window.opera) {
var self = this;
doc.attachEvent("onreadystatechange", function () {
self.init_(doc);
});
}
},
init_: function (doc) {
if (doc.readyState == "complete") {
// create xmlns
if (!doc.namespaces["g_vml_"]) {
doc.namespaces.add("g_vml_", "urn:schemas-microsoft-com:vml");
}
// setup default css
var ss = doc.createStyleSheet();
ss.cssText = "canvas{display:inline-block;overflow:hidden;" +
// default size is 300x150 in Gecko and Opera
"text-align:left;width:300px;height:150px}" +
"g_vml_\\:*{behavior:url(#default#VML)}";
// find all canvas elements
var els = doc.getElementsByTagName("canvas");
for (var i = 0; i < els.length; i++) {
if (!els[i].getContext) {
this.initElement(els[i]);
}
}
}
},
fixElement_: function (el) {
// in IE before version 5.5 we would need to add HTML: to the tag name
// but we do not care about IE before version 6
var outerHTML = el.outerHTML;
var newEl = el.ownerDocument.createElement(outerHTML);
// if the tag is still open IE has created the children as siblings and
// it has also created a tag with the name "/FOO"
if (outerHTML.slice(-2) != "/>") {
var tagName = "/" + el.tagName;
var ns;
// remove content
while ((ns = el.nextSibling) && ns.tagName != tagName) {
ns.removeNode();
}
// remove the incorrect closing tag
if (ns) {
ns.removeNode();
}
}
el.parentNode.replaceChild(newEl, el);
return newEl;
},
/**
* Public initializes a canvas element so that it can be used as canvas
* element from now on. This is called automatically before the page is
* loaded but if you are creating elements using createElement you need to
* make sure this is called on the element.
* @param {HTMLElement} el The canvas element to initialize.
* @return {HTMLElement} the element that was created.
*/
initElement: function (el) {
el = this.fixElement_(el);
el.getContext = function () {
if (this.context_) {
return this.context_;
}
return this.context_ = new CanvasRenderingContext2D_(this);
};
// do not use inline function because that will leak memory
el.attachEvent(‘onpropertychange‘, onPropertyChange);
el.attachEvent(‘onresize‘, onResize);
var attrs = el.attributes;
if (attrs.width && attrs.width.specified) {
// TODO: use runtimeStyle and coordsize
// el.getContext().setWidth_(attrs.width.nodeValue);
el.style.width = attrs.width.nodeValue + "px";
} else {
el.width = el.clientWidth;
}
if (attrs.height && attrs.height.specified) {
// TODO: use runtimeStyle and coordsize
// el.getContext().setHeight_(attrs.height.nodeValue);
el.style.height = attrs.height.nodeValue + "px";
} else {
el.height = el.clientHeight;
}
//el.getContext().setCoordsize_()
return el;
}
};
function onPropertyChange(e) {
var el = e.srcElement;
switch (e.propertyName) {
case ‘width‘:
el.style.width = el.attributes.width.nodeValue + "px";
el.getContext().clearRect();
break;
case ‘height‘:
el.style.height = el.attributes.height.nodeValue + "px";
el.getContext().clearRect();
break;
}
}
function onResize(e) {
var el = e.srcElement;
if (el.firstChild) {
el.firstChild.style.width = el.clientWidth + ‘px‘;
el.firstChild.style.height = el.clientHeight + ‘px‘;
}
}
G_vmlCanvasManager_.init();
// precompute "00" to "FF"
var dec2hex = [];
for (var i = 0; i < 16; i++) {
for (var j = 0; j < 16; j++) {
dec2hex[i * 16 + j] = i.toString(16) + j.toString(16);
}
}
function createMatrixIdentity() {
return [
[1, 0, 0],
[0, 1, 0],
[0, 0, 1]
];
}
function matrixMultiply(m1, m2) {
var result = createMatrixIdentity();
for (var x = 0; x < 3; x++) {
for (var y = 0; y < 3; y++) {
var sum = 0;
for (var z = 0; z < 3; z++) {
sum += m1[x][z] * m2[z][y];
}
result[x][y] = sum;
}
}
return result;
}
function copyState(o1, o2) {
o2.fillStyle = o1.fillStyle;
o2.lineCap = o1.lineCap;
o2.lineJoin = o1.lineJoin;
o2.lineWidth = o1.lineWidth;
o2.miterLimit = o1.miterLimit;
o2.shadowBlur = o1.shadowBlur;
o2.shadowColor = o1.shadowColor;
o2.shadowOffsetX = o1.shadowOffsetX;
o2.shadowOffsetY = o1.shadowOffsetY;
o2.strokeStyle = o1.strokeStyle;
o2.arcScaleX_ = o1.arcScaleX_;
o2.arcScaleY_ = o1.arcScaleY_;
}
function processStyle(styleString) {
var str, alpha = 1;
styleString = String(styleString);
if (styleString.substring(0, 3) == "rgb") {
var start = styleString.indexOf("(", 3);
var end = styleString.indexOf(")", start + 1);
var guts = styleString.substring(start + 1, end).split(",");
str = "#";
for (var i = 0; i < 3; i++) {
str += dec2hex[Number(guts[i])];
}
if ((guts.length == 4) && (styleString.substr(3, 1) == "a")) {
alpha = guts[3];
}
} else {
str = styleString;
}
return [str, alpha];
}
function processLineCap(lineCap) {
switch (lineCap) {
case "butt":
return "flat";
case "round":
return "round";
case "square":
default:
return "square";
}
}
/**
* This class implements CanvasRenderingContext2D interface as described by
* the WHATWG.
* @param {HTMLElement} surfaceElement The element that the 2D context should
* be associated with
*/
function CanvasRenderingContext2D_(surfaceElement) {
this.m_ = createMatrixIdentity();
this.mStack_ = [];
this.aStack_ = [];
this.currentPath_ = [];
// Canvas context properties
this.strokeStyle = "#000";
this.fillStyle = "#000";
this.lineWidth = 1;
this.lineJoin = "miter";
this.lineCap = "butt";
this.miterLimit = Z * 1;
this.globalAlpha = 1;
this.canvas = surfaceElement;
var el = surfaceElement.ownerDocument.createElement(‘div‘);
el.style.width = surfaceElement.clientWidth + ‘px‘;
el.style.height = surfaceElement.clientHeight + ‘px‘;
el.style.overflow = ‘hidden‘;
el.style.position = ‘absolute‘;
surfaceElement.appendChild(el);
this.element_ = el;
this.arcScaleX_ = 1;
this.arcScaleY_ = 1;
}
var contextPrototype = CanvasRenderingContext2D_.prototype;
contextPrototype.clearRect = function() {
this.element_.innerHTML = "";
this.currentPath_ = [];
};
contextPrototype.beginPath = function() {
// TODO: Branch current matrix so that save/restore has no effect
// as per safari docs.
this.currentPath_ = [];
};
contextPrototype.moveTo = function(aX, aY) {
this.currentPath_.push({type: "moveTo", x: aX, y: aY});
this.currentX_ = aX;
this.currentY_ = aY;
};
contextPrototype.lineTo = function(aX, aY) {
this.currentPath_.push({type: "lineTo", x: aX, y: aY});
this.currentX_ = aX;
this.currentY_ = aY;
};
contextPrototype.bezierCurveTo = function(aCP1x, aCP1y,
aCP2x, aCP2y,
aX, aY) {
this.currentPath_.push({type: "bezierCurveTo",
cp1x: aCP1x,
cp1y: aCP1y,
cp2x: aCP2x,
cp2y: aCP2y,
x: aX,
y: aY});
this.currentX_ = aX;
this.currentY_ = aY;
};
contextPrototype.quadraticCurveTo = function(aCPx, aCPy, aX, aY) {
// the following is lifted almost directly from
// http://developer.mozilla.org/en/docs/Canvas_tutorial:Drawing_shapes
var cp1x = this.currentX_ + 2.0 / 3.0 * (aCPx - this.currentX_);
var cp1y = this.currentY_ + 2.0 / 3.0 * (aCPy - this.currentY_);
var cp2x = cp1x + (aX - this.currentX_) / 3.0;
var cp2y = cp1y + (aY - this.currentY_) / 3.0;
this.bezierCurveTo(cp1x, cp1y, cp2x, cp2y, aX, aY);
};
contextPrototype.arc = function(aX, aY, aRadius,
aStartAngle, aEndAngle, aClockwise) {
aRadius *= Z;
var arcType = aClockwise ? "at" : "wa";
var xStart = aX + (mc(aStartAngle) * aRadius) - Z2;
var yStart = aY + (ms(aStartAngle) * aRadius) - Z2;
var xEnd = aX + (mc(aEndAngle) * aRadius) - Z2;
var yEnd = aY + (ms(aEndAngle) * aRadius) - Z2;
// IE won‘t render arches drawn counter clockwise if xStart == xEnd.
if (xStart == xEnd && !aClockwise) {
xStart += 0.125; // Offset xStart by 1/80 of a pixel. Use something
// that can be represented in binary
}
this.currentPath_.push({type: arcType,
x: aX,
y: aY,
radius: aRadius,
xStart: xStart,
yStart: yStart,
xEnd: xEnd,
yEnd: yEnd});
};
contextPrototype.rect = function(aX, aY, aWidth, aHeight) {
this.moveTo(aX, aY);
this.lineTo(aX + aWidth, aY);
this.lineTo(aX + aWidth, aY + aHeight);
this.lineTo(aX, aY + aHeight);
this.closePath();
};
contextPrototype.strokeRect = function(aX, aY, aWidth, aHeight) {
// Will destroy any existing path (same as FF behaviour)
this.beginPath();
this.moveTo(aX, aY);
this.lineTo(aX + aWidth, aY);
this.lineTo(aX + aWidth, aY + aHeight);
this.lineTo(aX, aY + aHeight);
this.closePath();
this.stroke();
};
contextPrototype.fillRect = function(aX, aY, aWidth, aHeight) {
// Will destroy any existing path (same as FF behaviour)
this.beginPath();
this.moveTo(aX, aY);
this.lineTo(aX + aWidth, aY);
this.lineTo(aX + aWidth, aY + aHeight);
this.lineTo(aX, aY + aHeight);
this.closePath();
this.fill();
};
contextPrototype.createLinearGradient = function(aX0, aY0, aX1, aY1) {
var gradient = new CanvasGradient_("gradient");
return gradient;
};
contextPrototype.createRadialGradient = function(aX0, aY0,
aR0, aX1,
aY1, aR1) {
var gradient = new CanvasGradient_("gradientradial");
gradient.radius1_ = aR0;
gradient.radius2_ = aR1;
gradient.focus_.x = aX0;
gradient.focus_.y = aY0;
return gradient;
};
contextPrototype.drawImage = function (image, var_args) {
var dx, dy, dw, dh, sx, sy, sw, sh;
// to find the original width we overide the width and height
var oldRuntimeWidth = image.runtimeStyle.width;
var oldRuntimeHeight = image.runtimeStyle.height;
image.runtimeStyle.width = ‘auto‘;
image.runtimeStyle.height = ‘auto‘;
// get the original size
var w = image.width;
var h = image.height;
// and remove overides
image.runtimeStyle.width = oldRuntimeWidth;
image.runtimeStyle.height = oldRuntimeHeight;
if (arguments.length == 3) {
dx = arguments[1];
dy = arguments[2];
sx = sy = 0;
sw = dw = w;
sh = dh = h;
} else if (arguments.length == 5) {
dx = arguments[1];
dy = arguments[2];
dw = arguments[3];
dh = arguments[4];
sx = sy = 0;
sw = w;
sh = h;
} else if (arguments.length == 9) {
sx = arguments[1];
sy = arguments[2];
sw = arguments[3];
sh = arguments[4];
dx = arguments[5];
dy = arguments[6];
dw = arguments[7];
dh = arguments[8];
} else {
throw "Invalid number of arguments";
}
var d = this.getCoords_(dx, dy);
var w2 = sw / 2;
var h2 = sh / 2;
var vmlStr = [];
var W = 10;
var H = 10;
// For some reason that I‘ve now forgotten, using divs didn‘t work
vmlStr.push(‘ <g_vml_:group‘,
‘ coordsize="‘, Z * W, ‘,‘, Z * H, ‘"‘,
‘ coordorigin="0,0"‘ ,
‘ style="width:‘, W, ‘;height:‘, H, ‘;position:absolute;‘);
// If filters are necessary (rotation exists), create them
// filters are bog-slow, so only create them if abbsolutely necessary
// The following check doesn‘t account for skews (which don‘t exist
// in the canvas spec (yet) anyway.
if (this.m_[0][0] != 1 || this.m_[0][1]) {
var filter = [];
// Note the 12/21 reversal
filter.push("M11=‘", this.m_[0][0], "‘,",
"M12=‘", this.m_[1][0], "‘,",
"M21=‘", this.m_[0][1], "‘,",
"M22=‘", this.m_[1][1], "‘,",
"Dx=‘", mr(d.x / Z), "‘,",
"Dy=‘", mr(d.y / Z), "‘");
// Bounding box calculation (need to minimize displayed area so that
// filters don‘t waste time on unused pixels.
var max = d;
var c2 = this.getCoords_(dx + dw, dy);
var c3 = this.getCoords_(dx, dy + dh);
var c4 = this.getCoords_(dx + dw, dy + dh);
max.x = Math.max(max.x, c2.x, c3.x, c4.x);
max.y = Math.max(max.y, c2.y, c3.y, c4.y);
vmlStr.push("padding:0 ", mr(max.x / Z), "px ", mr(max.y / Z),
"px 0;filter:progid:DXImageTransform.Microsoft.Matrix(",
filter.join(""), ", sizingmethod=‘clip‘);");
} else {
vmlStr.push("top:", mr(d.y / Z), "px;left:", mr(d.x / Z), "px;");
}
vmlStr.push(‘ ">‘ ,
‘<g_vml_:image src="‘, image.src, ‘"‘,
‘ style="width:‘, Z * dw, ‘;‘,
‘ height:‘, Z * dh, ‘;"‘,
‘ cropleft="‘, sx / w, ‘"‘,
‘ croptop="‘, sy / h, ‘"‘,
‘ cropright="‘, (w - sx - sw) / w, ‘"‘,
‘ cropbottom="‘, (h - sy - sh) / h, ‘"‘,
‘ />‘,
‘</g_vml_:group>‘);
this.element_.insertAdjacentHTML("BeforeEnd",
vmlStr.join(""));
};
contextPrototype.stroke = function(aFill) {
var lineStr = [];
var lineOpen = false;
var a = processStyle(aFill ? this.fillStyle : this.strokeStyle);
var color = a[0];
var opacity = a[1] * this.globalAlpha;
var W = 10;
var H = 10;
lineStr.push(‘<g_vml_:shape‘,
‘ fillcolor="‘, color, ‘"‘,
‘ filled="‘, Boolean(aFill), ‘"‘,
‘ style="position:absolute;width:‘, W, ‘;height:‘, H, ‘;"‘,
‘ coordorigin="0 0" coordsize="‘, Z * W, ‘ ‘, Z * H, ‘"‘,
‘ stroked="‘, !aFill, ‘"‘,
‘ strokeweight="‘, this.lineWidth, ‘"‘,
‘ strokecolor="‘, color, ‘"‘,
‘ path="‘);
var newSeq = false;
var min = {x: null, y: null};
var max = {x: null, y: null};
for (var i = 0; i < this.currentPath_.length; i++) {
var p = this.currentPath_[i];
if (p.type == "moveTo") {
lineStr.push(" m ");
var c = this.getCoords_(p.x, p.y);
lineStr.push(mr(c.x), ",", mr(c.y));
} else if (p.type == "lineTo") {
lineStr.push(" l ");
var c = this.getCoords_(p.x, p.y);
lineStr.push(mr(c.x), ",", mr(c.y));
} else if (p.type == "close") {
lineStr.push(" x ");
} else if (p.type == "bezierCurveTo") {
lineStr.push(" c ");
var c = this.getCoords_(p.x, p.y);
var c1 = this.getCoords_(p.cp1x, p.cp1y);
var c2 = this.getCoords_(p.cp2x, p.cp2y);
lineStr.push(mr(c1.x), ",", mr(c1.y), ",",
mr(c2.x), ",", mr(c2.y), ",",
mr(c.x), ",", mr(c.y));
} else if (p.type == "at" || p.type == "wa") {
lineStr.push(" ", p.type, " ");
var c = this.getCoords_(p.x, p.y);
var cStart = this.getCoords_(p.xStart, p.yStart);
var cEnd = this.getCoords_(p.xEnd, p.yEnd);
lineStr.push(mr(c.x - this.arcScaleX_ * p.radius), ",",
mr(c.y - this.arcScaleY_ * p.radius), " ",
mr(c.x + this.arcScaleX_ * p.radius), ",",
mr(c.y + this.arcScaleY_ * p.radius), " ",
mr(cStart.x), ",", mr(cStart.y), " ",
mr(cEnd.x), ",", mr(cEnd.y));
}
// TODO: Following is broken for curves due to
// move to proper paths.
// Figure out dimensions so we can do gradient fills
// properly
if(c) {
if (min.x == null || c.x < min.x) {
min.x = c.x;
}
if (max.x == null || c.x > max.x) {
max.x = c.x;
}
if (min.y == null || c.y < min.y) {
min.y = c.y;
}
if (max.y == null || c.y > max.y) {
max.y = c.y;
}
}
}
lineStr.push(‘ ">‘);
if (typeof this.fillStyle == "object") {
var focus = {x: "50%", y: "50%"};
var width = (max.x - min.x);
var height = (max.y - min.y);
var dimension = (width > height) ? width : height;
focus.x = mr((this.fillStyle.focus_.x / width) * 100 + 50) + "%";
focus.y = mr((this.fillStyle.focus_.y / height) * 100 + 50) + "%";
var colors = [];
// inside radius (%)
if (this.fillStyle.type_ == "gradientradial") {
var inside = (this.fillStyle.radius1_ / dimension * 100);
// percentage that outside radius exceeds inside radius
var expansion = (this.fillStyle.radius2_ / dimension * 100) - inside;
} else {
var inside = 0;
var expansion = 100;
}
var insidecolor = {offset: null, color: null};
var outsidecolor = {offset: null, color: null};
// We need to sort ‘colors‘ by percentage, from 0 > 100 otherwise ie
// won‘t interpret it correctly
this.fillStyle.colors_.sort(function (cs1, cs2) {
return cs1.offset - cs2.offset;
});
for (var i = 0; i < this.fillStyle.colors_.length; i++) {
var fs = this.fillStyle.colors_[i];
colors.push( (fs.offset * expansion) + inside, "% ", fs.color, ",");
if (fs.offset > insidecolor.offset || insidecolor.offset == null) {
insidecolor.offset = fs.offset;
insidecolor.color = fs.color;
}
if (fs.offset < outsidecolor.offset || outsidecolor.offset == null) {
outsidecolor.offset = fs.offset;
outsidecolor.color = fs.color;
}
}
colors.pop();
lineStr.push(‘<g_vml_:fill‘,
‘ color="‘, outsidecolor.color, ‘"‘,
‘ color2="‘, insidecolor.color, ‘"‘,
‘ type="‘, this.fillStyle.type_, ‘"‘,
‘ focusposition="‘, focus.x, ‘, ‘, focus.y, ‘"‘,
‘ colors="‘, colors.join(""), ‘"‘,
‘ opacity="‘, opacity, ‘" />‘);
} else if (aFill) {
lineStr.push(‘<g_vml_:fill color="‘, color, ‘" opacity="‘, opacity, ‘" />‘);
} else {
lineStr.push(
‘<g_vml_:stroke‘,
‘ opacity="‘, opacity,‘"‘,
‘ joinstyle="‘, this.lineJoin, ‘"‘,
‘ miterlimit="‘, this.miterLimit, ‘"‘,
‘ endcap="‘, processLineCap(this.lineCap) ,‘"‘,
‘ weight="‘, this.lineWidth, ‘px"‘,
‘ color="‘, color,‘" />‘
);
}
lineStr.push("</g_vml_:shape>");
this.element_.insertAdjacentHTML("beforeEnd", lineStr.join(""));
//this.currentPath_ = [];
};
contextPrototype.fill = function() {
this.stroke(true);
};
contextPrototype.closePath = function() {
this.currentPath_.push({type: "close"});
};
/**
* @private
*/
contextPrototype.getCoords_ = function(aX, aY) {
return {
x: Z * (aX * this.m_[0][0] + aY * this.m_[1][0] + this.m_[2][0]) - Z2,
y: Z * (aX * this.m_[0][1] + aY * this.m_[1][1] + this.m_[2][1]) - Z2
}
};
contextPrototype.save = function() {
var o = {};
copyState(this, o);
this.aStack_.push(o);
this.mStack_.push(this.m_);
this.m_ = matrixMultiply(createMatrixIdentity(), this.m_);
};
contextPrototype.restore = function() {
copyState(this.aStack_.pop(), this);
this.m_ = this.mStack_.pop();
};
contextPrototype.translate = function(aX, aY) {
var m1 = [
[1, 0, 0],
[0, 1, 0],
[aX, aY, 1]
];
this.m_ = matrixMultiply(m1, this.m_);
};
contextPrototype.rotate = function(aRot) {
var c = mc(aRot);
var s = ms(aRot);
var m1 = [
[c, s, 0],
[-s, c, 0],
[0, 0, 1]
];
this.m_ = matrixMultiply(m1, this.m_);
};
contextPrototype.scale = function(aX, aY) {
this.arcScaleX_ *= aX;
this.arcScaleY_ *= aY;
var m1 = [
[aX, 0, 0],
[0, aY, 0],
[0, 0, 1]
];
this.m_ = matrixMultiply(m1, this.m_);
};
/******** STUBS ********/
contextPrototype.clip = function() {
// TODO: Implement
};
contextPrototype.arcTo = function() {
// TODO: Implement
};
contextPrototype.createPattern = function() {
return new CanvasPattern_;
};
// Gradient / Pattern Stubs
function CanvasGradient_(aType) {
this.type_ = aType;
this.radius1_ = 0;
this.radius2_ = 0;
this.colors_ = [];
this.focus_ = {x: 0, y: 0};
}
CanvasGradient_.prototype.addColorStop = function(aOffset, aColor) {
aColor = processStyle(aColor);
this.colors_.push({offset: 1-aOffset, color: aColor});
};
function CanvasPattern_() {}
// set up externs
G_vmlCanvasManager = G_vmlCanvasManager_;
CanvasRenderingContext2D = CanvasRenderingContext2D_;
CanvasGradient = CanvasGradient_;
CanvasPattern = CanvasPattern_;
})();
} // if
原文：http://my.oschina.net/u/2352644/blog/501260