HTML5的canvas实现的画曲线图效果:
本章节分享一段代码实例，此代码能够实现画曲线图和心形图等，感兴趣的朋友可以自己做一下分析。
代码实例如下:
<!DOCTYPE html><html><head><meta charset="utf-8"><meta name="author" content="http://www.51texiao.cn/" /><title>蚂蚁部落</title><style type="text/css">#apDiv1 { position:absolute; width:120px; height:300px; z-index:1; left: 840px; top: 80px;}</style></head><body><canvas id="canvas" width="900" height="600" style="border:1px solid #c3c3c3">浏览器不支持canvas</canvas><div id="apDiv1"> <form> 玫瑰曲线方程： r=a+bsin(m/n*x) 选择参数： m:<input type="number" name="m" min="2" max="29" value="29"/> n:<input type="number" name="n" min="1" max="12" value="11"/> a:<input type="number" name="a" min="0" max="5" value="1"/> b:<input type="number" name="b" min="1" max="7" value="5"/> <input type="button" value=" 画 图 " onClick="draw();"> <hr> <input type="button" value=" 画 图 2 " onClick="draw2();"> <hr> <input type="button" value=" 心形图 " onClick="draw3();"> </form></div><script type="text/javascript"> function draw(){ var ctx = document.getElementById('canvas').getContext('2d'); ctx.save(); ctx.translate(400,300); ctx.clearRect(-400,-300,800,600); ctx.strokeStyle = "#cc0000"; var a = 0, b = 1, m = 6, n = 1; m = document.forms[0].m.value; n = document.forms[0].n.value; a = document.forms[0].a.value; b = document.forms[0].b.value; drawRose(ctx,a,b,m,n); ctx.restore(); } function drawRose(ctx,a,b,m,n){ ctx.beginPath(); var e = 0, c = 120; var k = 2 * Math.PI / 360; do { var r = a/b + Math.sin( m * e / n * k); r = r * c; var x = r * Math.cos( e * k ); var y = r * Math.sin( e * k ); e += 0.1; ctx.lineTo(x,y); } while ( e <= 4320 ); ctx.stroke(); } function draw2(){ var ctx = document.getElementById('canvas').getContext('2d'); ctx.save(); ctx.translate(400,300); ctx.clearRect(-400,-300,800,600); ctx.strokeStyle = "#cc0000"; ctx.beginPath(); //ctx.moveTo(0,0); var e = 0, c = 150; var k = 2 * Math.PI / 360; do { x = 150*Math.cos( 5/2 * e*k ) + 50*Math.cos( 15/16 * 5/2 * e*k ); y = 150*Math.sin( 5/2 * e*k ) - 50*Math.sin( 15/16 * 5/2 * e*k ); e += 0.1; ctx.lineTo(x,y); } while ( e <= 3600 ); ctx.stroke(); ctx.restore();} function draw3(){ var ctx = document.getElementById('canvas').getContext('2d'); ctx.save(); ctx.translate(400,300); ctx.clearRect(-400,-300,800,600); ctx.strokeStyle = "#ff0000"; ctx.beginPath(); var x = 1, y; do { y = -80*(Math.sqrt(1-x*x) + Math.pow(x*x,1/3)); x -= 0.001; ctx.lineTo(100*x,y); } while ( x >= -1 ); do { y = 80*(Math.sqrt(1-x*x) - Math.pow(x*x,1/3)); x += 0.001; ctx.lineTo(100*x,y); } while ( x <= 1 ); ctx.closePath(); var grad = ctx.createRadialGradient(-40,-60,10,-40,-40,200); grad.addColorStop(0, "#ffcc00"); grad.addColorStop(1, "#ff0000"); ctx.fillStyle = grad; ctx.fill(); ctx.restore();} window.onload=function (){ draw();} </script></body></html>原文地址是:http://www.51texiao.cn/HTML5jiaocheng/2015/0613/4159.html
最为原始地址是:http://www.softwhy.com/forum.php?mod=viewthread&tid=13478
原标题：HTML5的canvas实现的画曲线图效果
关键词：HTML
我知道了 