详细介绍HTML5简易在线画图工具的实现案例(3)_H5之家

css代码：

body{ background-color: #4E4226; }#container { position: relative; height: 700px; width: 500px; margin: 10px auto; overflow: hidden; border: 4px solid #5C090A; background: #4E4226 url('images/backgroundLeaves.jpg') no-repeat top left; }#leafContainer { position: absolute; width: 100%; height: 100%; }#message{ position: absolute; top: 160px; width: 100%; height: 300px; background:transparent url('images/textBackground.png') repeat-x center; color: #5C090A; font-size: 220%; font-family: 'Georgia'; text-align: center; padding: 20px 10px; -webkit-box-sizing: border-box; -webkit-background-size: 100% 100%; z-index: 1; }em { font-weight: bold; font-style: normal; }#leafContainer > p { position: absolute; width: 100px; height: 100px; -webkit-animation-iteration-count: infinite; -webkit-animation-direction: normal; -webkit-animation-timing-function: linear; }#leafContainer > p > img { position: absolute; width: 100px; height: 100px; -webkit-animation-iteration-count: infinite; -webkit-animation-direction: alternate; -webkit-animation-timing-function: ease-in-out; -webkit-transform-origin: 50% -100%; }@-webkit-keyframes fade{ 0% { opacity: 1; } 95% { opacity: 1; } 100% { opacity: 0; }} @-webkit-keyframes drop{ 0% { -webkit-transform: translate(0px, -50px); } 100% { -webkit-transform: translate(0px, 650px); }} @-webkit-keyframes clockwiseSpin{ 0% { -webkit-transform: rotate(-50deg); } 100% { -webkit-transform: rotate(50deg); }} @-webkit-keyframes counterclockwiseSpinAndFlip { 0% { -webkit-transform: scale(-1, 1) rotate(50deg); } 100% { -webkit-transform: scale(-1, 1) rotate(-50deg); }}

js代码：

以上就是使用Html5实现树叶飘落的效果的详细内容，更多请关注php中文网其它相关文章！

实现效果

1.首先创建html代码<canvas id="canvas" width="500" height="500" style="background:#000;"></canvas>2.创建canvas环境var canvas = document.getElementById('canvas'), //获取canvas元素 context = canvas.getContext('2d'), //获取画图环境，指明为2d centerX = canvas.width/2, //Canvas中心点x轴坐标 centerY = canvas.height/2, //Canvas中心点y轴坐标 rad = Math.PI*2/100, //将360度分成100份，那么每一份就是rad度 speed = 0.1; //加载的快慢就靠它了3.绘制5像素宽的运动外圈//绘制5像素宽的运动外圈 function blueCircle(n){ context.save(); context.strokeStyle = "#fff"; //设置描边样式 context.lineWidth = 5; //设置线宽 context.beginPath(); //路径开始 context.arc(centerX, centerY, 100 , -Math.PI/2, -Math.PI/2 +n*rad, false); //用于绘制圆弧context.arc(x坐标，y坐标，半径，起始角度，终止角度，顺时针/逆时针) context.stroke(); //绘制 context.closePath(); //路径结束 context.restore(); } 4.绘制白色外圈//绘制白色外圈 function whiteCircle(){ context.save(); context.beginPath(); context.lineWidth = 2; //设置线宽 context.strokeStyle = "red"; context.arc(centerX, centerY, 100 , 0, Math.PI*2, false); context.stroke(); context.closePath(); context.restore(); }5.百分比文字绘制function text(n){ context.save(); //save和restore可以保证样式属性只运用于该段canvas元素 context.strokeStyle = "#fff"; //设置描边样式 context.font = "40px Arial"; //设置字体大小和字体 //绘制字体，并且指定位置 context.strokeText(n.toFixed(0)+"%", centerX-25, centerY+10); context.stroke(); //执行绘制 context.restore(); }6.让它运动起来//动画循环 (function drawFrame(){ window.requestAnimationFrame(drawFrame); context.clearRect(0, 0, canvas.width, canvas.height); whiteCircle(); text(speed); blueCircle(speed); if(speed > 100) speed = 0; speed += 0.1; }());完整代码<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>HTML5 Canvas 圆形进度条并显示数字百分比</title> <style> *{margin:0;padding:0;} body{text-align:center;background-color:#000;} </style> </head> <body> <canvas id="canvas" width="500" height="500" style="background:#000;"></canvas> <script> window.onload = function(){ var canvas = document.getElementById('canvas'), //获取canvas元素 context = canvas.getContext('2d'), //获取画图环境，指明为2d centerX = canvas.width/2, //Canvas中心点x轴坐标 centerY = canvas.height/2, //Canvas中心点y轴坐标 rad = Math.PI*2/100, //将360度分成100份，那么每一份就是rad度 speed = 0.1; //加载的快慢就靠它了 //绘制5像素宽的运动外圈 function blueCircle(n){ context.save(); context.strokeStyle = "#fff"; //设置描边样式 context.lineWidth = 5; //设置线宽 context.beginPath(); //路径开始 context.arc(centerX, centerY, 100 , -Math.PI/2, -Math.PI/2 +n*rad, false); //用于绘制圆弧context.arc(x坐标，y坐标，半径，起始角度，终止角度，顺时针/逆时针) context.stroke(); //绘制 context.closePath(); //路径结束 context.restore(); } //绘制白色外圈 function whiteCircle(){ context.save(); context.beginPath(); context.lineWidth = 2; //设置线宽 context.strokeStyle = "red"; context.arc(centerX, centerY, 100 , 0, Math.PI*2, false); context.stroke(); context.closePath(); context.restore(); } //百分比文字绘制 function text(n){ context.save(); //save和restore可以保证样式属性只运用于该段canvas元素 context.strokeStyle = "#fff"; //设置描边样式 context.font = "40px Arial"; //设置字体大小和字体 //绘制字体，并且指定位置 context.strokeText(n.toFixed(0)+"%", centerX-25, centerY+10); context.stroke(); //执行绘制 context.restore(); } //动画循环 (function drawFrame(){ window.requestAnimationFrame(drawFrame); context.clearRect(0, 0, canvas.width, canvas.height); whiteCircle(); text(speed); blueCircle(speed); if(speed > 100) speed = 0; speed += 0.1; }()); } </script> </body> </html>

以上就是Canvas实现圆形进度条并显示数字百分比的详细内容，更多请关注php中文网其它相关文章！