我正在使用html2canvas来获取网页的屏幕截图并将其渲染为缩略图(好吧,400×300,不完全是缩略图).
基于Screenshot console code,除缩略图部分外,一切都很好.
如何将图像大小设置为400×300？在firebug中,我将属性定位为：< canvas style =“width：973px; height：2184px;” width =“973”height =“2184”>< / canvas>.但是,我无法弄清楚我的代码(下面)或html2canvas.js中硬编码400×300参数的位置.
screenshot.html：
<html>
<head>
<title>Screenshot</title>
<!--[if lt IE 9]>
<script src="//html5shim.googlecode.com/svn/trunk/html5.js">
</script>
<![endif]-->
</head>
<body>
<div class=container> </div>
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
<script type="text/javascript" src="js/html2canvas.js"></script>
<script type="text/javascript">
var date=new Date();
var message,timeoutTimer,timer;
var proxyUrl="http://html2canvas.appspot.com";
function addRow(a,c,d){var b=$("<tr />").appendTo($(a));b.append($("<td />").css("font-weight","bold").text(c)).append($("<td />").text(d))}function throwMessage(b,a){window.clearTimeout(timeoutTimer);timeoutTimer=window.setTimeout(function(){message.fadeOut(function(){message.remove()})},a||2000);$(message).remove();message=$("<div />").html(b).css({margin:0,padding:10,background:"#000",opacity:0.7,position:"fixed",top:10,right:10,fontFamily:"Tahoma",color:"#fff",fontSize:12,borderRadius:12,width:"auto",height:"auto",textAlign:"center",textDecoration:"none"}).hide().fadeIn().appendTo("body")}$(function(){$("#recommended a").click(function(c){c.preventDefault();$("#url").val(this.href);$("button").click()});var a,b;$('input[type="button"]').click(function(){$(a.contentWindow).unbind("load");$(a).contents().find("body").html2canvas({canvasHeight:b.body.scrollHeight,canvasWidth:b.body.scrollWidth,logging:true})});$("#getscreenshot").click(function(d){d.preventDefault();$(this).prop("disabled",true);var c=$("#url").val();$("#content").append($("<img />").attr("src","loading.gif").css("margin-top",40));var f=document.createElement("a");f.href=c;$.ajax({data:{xhr2:false,url:f.href},url:proxyUrl,dataType:"jsonp",success:function(e){a=document.createElement("iframe");$(a).css({visibility:"hidden"}).width($(window).width()/2).height($(window).height()/2);$("#content").append(a);b=a.contentWindow.document;b.open();$(a.contentWindow).load(function(){var g=$(a).contents().find("body"),h={onrendered:function(j){$("#content").empty().append(j);$("#getscreenshot").prop("disabled",false);$("base").attr("href","")},allowTaint:true,taintTest:false,flashcanvas:"src/flashcanvas.min.js"},i=html2canvas(g,h)});$("base").attr("href",f.protocol+"//"+f.hostname+"/"+f.pathname);e=e.replace("<head>","<head><base href='"+f.protocol+"//"+f.hostname+"/"+f.pathname+"' />");if($("#disablejs").prop("checked")){e=e.replace(/\<script/gi,"<!--<script");e=e.replace(/\<\/script\>/gi,"<\/script>-->")}b.write(e);b.close()}})})});
</script>
<form class="well form-search">
<label for=url>Website URL:</label>
<input type=url id=url value="http://www.yahoo.com" class="input-medium search-query"/>
<button class=btn id=getscreenshot>Get screenshot!</button>
</form>
<div id=content></div>
</body>
</html>
解决方法:
您可以创建其他新的< canvas>缩略图尺寸并使用drawImage()在这个新的< canvas>上缩小它.
drawImage()可以读取< canvas>作为图像源,您可以设置目标宽度和高度.
https://developer.mozilla.org/en-US/docs/Web/Guide/HTML/Canvas_tutorial/Using_images