In canvas, when writing width and height on canvas, it is the actual artboard size of canvas. By default, width is 300px and height is 150px.
When writing css style in style, widht and height are the actual display size.
Now use canvas to draw a diagonal line as an example:
canvas</title> ; <br /><script type='text/javascript'> <br>window.onload = function(){ <br>getCanvas(); <br>}; <br>//canvase drawing<br>function getCanvas(){ <br>//Get the canvas element and its drawing context <br>var canvas = document.getElementById('canvasId'); <br>var context = canvas.getContext('2d'); <br>/ /Use absolute landmarks to create a path <br>context.beginPath(); <br>context.moveTo(0,200); <br>context.lineTo(200,0); <br>//Draw this first to On canvas <br>context.stroke(); <br>} <br></script> <br></head> <br><body> <br><canvas id='canvasId' width ="200px" height='200px' style='width:400px;height:200px;' ></canvas> <br></body> <br></html> <br>
</div> <br>The display effect is as follows: <br><img src="http://files.jb51.net/file_images/article/201301/201316172320955.png" alt=""> <br>As you can see, the canvas drawing board is a square of 200*200, and the drawing uses the diagonal display from (0, 200) to (200, 0). <br>But the graph is displayed as a 400*200 rectangle, and it also displays diagonals.</div><div class="nphpQianMsg"><div class="clear"></div></div><div class="nphpQianSheng"><span>Statement：</span><div>The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn</div></div></div><div class="nphpSytBox"><span>Previous article：<a class="dBlack" title="Implementation of new tags using HTML5 in old browsers such as IE6 series_html5 tutorial tips" href="http://m.php.cn/faq/6515.html">Implementation of new tags using HTML5 in old browsers such as IE6 series_html5 tutorial tips</a></span><span>Next article：<a class="dBlack" title="Implementation of new tags using HTML5 in old browsers such as IE6 series_html5 tutorial tips" href="http://m.php.cn/faq/6519.html">Implementation of new tags using HTML5 in old browsers such as IE6 series_html5 tutorial tips</a></span></div><div class="nphpSytBox2"><div class="nphpZbktTitle"><h2>Related articles</h2><em><a href="http://m.php.cn/article.html" class="bBlack"><i>See more</i><b></b></a></em><div class="clear"></div></div><ul class="nphpXgwzList"><li><b></b><a href="http://m.php.cn/faq/348281.html" title="AlloyTouch full-screen scrolling plug-in creates a smooth H5 page in 30 seconds" class="aBlack">AlloyTouch full-screen scrolling plug-in creates a smooth H5 page in 30 seconds</a><div class="clear"></div></li><li><b></b><a href="http://m.php.cn/faq/348372.html" title="HTML5 actual combat and analysis of touch events (touchstart, touchmove and touchend)" class="aBlack">HTML5 actual combat and analysis of touch events (touchstart, touchmove and touchend)</a><div class="clear"></div></li><li><b></b><a href="http://m.php.cn/faq/348373.html" title="Detailed explanation of image drawing examples in HTML5 canvas 9" class="aBlack">Detailed explanation of image drawing examples in HTML5 canvas 9</a><div class="clear"></div></li><li><b></b><a href="http://m.php.cn/faq/348374.html" title="Regular expressions and new HTML5 elements" class="aBlack">Regular expressions and new HTML5 elements</a><div class="clear"></div></li><li><b></b><a href="http://m.php.cn/faq/348469.html" title="How to combine NodeJS and HTML5 to drag and drop multiple files to upload to the server" class="aBlack">How to combine NodeJS and HTML5 to drag and drop multiple files to upload to the server</a><div class="clear"></div></li></ul></div></div><div class="nphpFoot"><div class="nphpFootBg"><ul class="nphpFootMenu"><li><a href="http://m.php.cn/"><b class="icon1"></b><p>Home</p></a></li><li><a href="http://m.php.cn/course.html"><b class="icon2"></b><p>Course</p></a></li><li><a href="http://m.php.cn/wenda.html"><b class="icon4"></b><p>Q&A</p></a></li><li><a href="http://m.php.cn/login"><b class="icon5"></b><p>My</p></a></li><div class="clear"></div></ul></div></div><div class="nphpYouBox" style="display: none;"><div class="nphpYouBg"><div class="nphpYouTitle"><span onclick="$('.nphpYouBox').hide()"></span><a href="http://m.php.cn/"></a><div class="clear"></div></div><ul class="nphpYouList"><li><a href="http://m.php.cn/"><b class="icon1"></b><span>Home</span><div class="clear"></div></a></li><li><a href="http://m.php.cn/course.html"><b class="icon2"></b><span>Course</span><div class="clear"></div></a></li><li><a href="http://m.php.cn/article.html"><b class="icon3"></b><span>Article</span><div class="clear"></div></a></li><li><a href="http://m.php.cn/wenda.html"><b class="icon4"></b><span>Q&A</span><div class="clear"></div></a></li><li><a href="http://m.php.cn/dic.html"><b class="icon6"></b><span>Dictionary</span><div class="clear"></div></a></li><li><a href="http://m.php.cn/course/type/99.html"><b class="icon7"></b><span>Manual</span><div class="clear"></div></a></li><li><a href="http://m.php.cn/xiazai/"><b class="icon8"></b><span>Download</span><div class="clear"></div></a></li><li><a href="http://m.php.cn/faq/zt" title="Topic"><b class="icon12"></b><span>Topic</span><div class="clear"></div></a></li><div class="clear"></div></ul></div></div><div class="nphpDing" style="display: none;"><div class="nphpDinglogo"><a href="http://m.php.cn/"></a></div><div class="nphpNavIn1"><div class="swiper-container nphpNavSwiper1"><div class="swiper-wrapper"><div class="swiper-slide"><a href="http://m.php.cn/" >Home</a></div><div class="swiper-slide"><a href="http://m.php.cn/article.html" class="hover">Article</a></div><div class="swiper-slide"><a href="http://m.php.cn/wenda.html" >Q&A</a></div><div class="swiper-slide"><a href="http://m.php.cn/course.html" >Course</a></div><div class="swiper-slide"><a href="http://m.php.cn/faq/zt" >Topic</a></div><div class="swiper-slide"><a href="http://m.php.cn/xiazai" >Download</a></div><div class="swiper-slide"><a href="http://m.php.cn/game" >Game</a></div><div class="swiper-slide"><a href="http://m.php.cn/dic.html" >Dictionary</a></div><div class="clear"></div></div></div><div class="langadivs" ><a href="javascript:;" class="bg4 bglanguage"></a><div class="langadiv" ><a onclick="javascript:setlang('zh-cn');" class="language course-right-orders chooselan " href="javascript:;"><span>简体中文</span><span>（ZH-CN）</span></a><a onclick="javascript:;" class="language course-right-orders chooselan chooselanguage" href="javascript:;"><span>English</span><span>（EN）</span></a><a onclick="javascript:setlang('zh-tw');" class="language course-right-orders chooselan " href="javascript:;"><span>繁体中文</span><span>（ZH-TW）</span></a><a onclick="javascript:setlang('ja');" class="language course-right-orders chooselan " href="javascript:;"><span>日本語</span><span>（JA）</span></a><a onclick="javascript:setlang('ko');" class="language course-right-orders chooselan " href="javascript:;"><span>한국어</span><span>（KO）</span></a><a onclick="javascript:setlang('ms');" class="language course-right-orders chooselan " href="javascript:;"><span>Melayu</span><span>（MS）</span></a><a onclick="javascript:setlang('fr');" class="language course-right-orders chooselan " href="javascript:;"><span>Français</span><span>（FR）</span></a><a onclick="javascript:setlang('de');" class="language course-right-orders chooselan " href="javascript:;"><span>Deutsch</span><span>（DE）</span></a></div></div><script> var swiper = new Swiper('.nphpNavSwiper1', {
slidesPerView : 'auto',
observer: true,//修改swiper自己或子元素时，自动初始化swiper
observeParents: true,//修改swiper的父元素时，自动初始化swiper
});
</script></div></div><!--顶部导航 end--><script>isLogin = 0;</script><script type="text/javascript" src="/static/layui/layui.js"></script><script type="text/javascript" src="/static/js/global.js?4.9.47"></script></div><script src="https://vdse.bdstatic.com//search-video.v1.min.js"></script><link rel='stylesheet' id='_main-css' href='/static/css/viewer.min.css' type='text/css' media='all'/><script type='text/javascript' src='/static/js/viewer.min.js?1'></script><script type='text/javascript' src='/static/js/jquery-viewer.min.js'></script><script>jQuery.fn.wait = function (func, times, interval) {
var _times = times || -1, //100次
_interval = interval || 20, //20毫秒每次
_self = this,
_selector = this.selector, //选择器
_iIntervalID; //定时器id
if( this.length ){ //如果已经获取到了，就直接执行函数
func && func.call(this);
} else {
_iIntervalID = setInterval(function() {
if(!_times) { //是0就退出
clearInterval(_iIntervalID);
}
_times <= 0 || _times--; //如果是正数就 --
_self = $(_selector); //再次选择
if( _self.length ) { //判断是否取到
func && func.call(_self);
clearInterval(_iIntervalID);
}
}, _interval);
}
return this;
}
$("table.syntaxhighlighter").wait(function() {
$('table.syntaxhighlighter').append("<p class='cnblogs_code_footer'><span class='cnblogs_code_footer_icon'></span></p>");
});
$(document).on("click", ".cnblogs_code_footer",function(){
$(this).parents('table.syntaxhighlighter').css('display','inline-table');$(this).hide();
});
$('.nphpQianCont').viewer({navbar:true,title:false,toolbar:false,movable:false,viewed:function(){$('img').click(function(){$('.viewer-close').trigger('click');});}});
</script></body></html>