1.基礎(chǔ)知識(shí)

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canvas元素繪制圖像的時(shí)候有兩種方法,分別是
context.fill()//填充
context.stroke()//繪制邊框style:在進(jìn)行圖形繪制前,要設(shè)置好繪圖的樣式
context.fillStyle//填充的樣式
context.strokeStyle//邊框樣式
context.lineWidth//圖形邊框?qū)挾?/pre>context.arc(centerx圓心橫左邊,centery圓心縱坐標(biāo),radius半徑,startingAngle起始弧度值,endingAngle結(jié)束弧度值,anticlockwise='false'順時(shí)針默認(rèn)false)
2.繪制非填充線段
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title></title>
<link rel="stylesheet" >
<link rel="stylesheet" href="styles/lianxi.css">
<script src="/upload/otherpica42/77539.png');</script><![endif]-->
<style type="text/css">
.canvas{border: 1px solid #000;display: block;margin: 0 auto;margin-top: 50px;}
</style>
<script>
window.onload=function(){
function draw(){
var canvas = document.getElementById('canvas');
if (canvas.getContext){
var ctx = canvas.getContext('2d');
canvas.width=300;
canvas.height=300;
ctx.beginPath(); //一個(gè)繪畫(huà)開(kāi)始
ctx.moveTo(50,50);//線段起點(diǎn)
ctx.lineTo(100,100);//終點(diǎn)1
ctx.lineTo(50,100);//終點(diǎn)2
ctx.lineTo(50,50);//終點(diǎn)3
ctx.lineWidth=5;//邊框?qū)挾? ctx.strokeStyle="red"; //邊框樣式
ctx.closePath(); //一個(gè)繪畫(huà)結(jié)束
ctx.stroke();//繪制線段
}else{
alert('當(dāng)前瀏覽器不支持,請(qǐng)更換瀏覽器');
}
}
draw();
}
</script>
<style tyrp="text/css">
canvas{ border: 1px solid black;margin: 0 auto;display: block;}
</style>
</head>
<body>
<canvas id="canvas">當(dāng)前瀏覽器不支持,請(qǐng)更換瀏覽器</canvas>
</body>
</html>
3.繪制填充圖形
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title></title>
<link rel="stylesheet" >
<link rel="stylesheet" href="styles/lianxi.css">
<script src="/upload/otherpica42/77539.png');</script><![endif]-->
<style type="text/css">
.canvas{border: 1px solid #000;display: block;margin: 0 auto;margin-top: 50px;}
</style>
<script>
window.onload=function(){
function draw(){
var canvas = document.getElementById('canvas');
if (canvas.getContext){
var ctx = canvas.getContext('2d');
canvas.width=300;
canvas.height=300;
ctx.beginPath(); //一個(gè)繪畫(huà)開(kāi)始
ctx.moveTo(50,50);//線段起點(diǎn)
ctx.lineTo(100,100);//終點(diǎn)1
ctx.lineTo(50,100);//終點(diǎn)2
ctx.lineTo(50,50);//終點(diǎn)3
ctx.fillStyle='red';
ctx.fill();
//邊框添加
ctx.lineWidth=5;//邊框?qū)挾? ctx.strokeStyle="blue"; //邊框樣式
ctx.closePath(); //一個(gè)繪畫(huà)結(jié)束
ctx.stroke();//繪制線段
}else{
alert('當(dāng)前瀏覽器不支持,請(qǐng)更換瀏覽器');
}
}
draw();
}
</script>
<style tyrp="text/css">
canvas{ border: 1px solid black;margin: 0 auto;display: block;}
</style>
</head>
<body>
<canvas id="canvas">當(dāng)前瀏覽器不支持,請(qǐng)更換瀏覽器</canvas>
</body>
</html>
4.繪制圓弧
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title></title>
<link rel="stylesheet" >
<link rel="stylesheet" href="styles/lianxi.css">
<script src="/upload/otherpica42/77539.png');</script><![endif]-->
<style type="text/css">
canvas{border: 1px solid #000;display: block;margin: 0 auto;margin-top: 50px;}
</style>
<script>
window.onload=function(){
function draw(){
var canvas = document.getElementById('canvas');
if (canvas.getContext){
var ctx = canvas.getContext('2d');
canvas.width=800;
canvas.height=800;
ctx.beginPath(); //開(kāi)始一個(gè)新的繪畫(huà)
ctx.lineWidth=5;//邊框?qū)挾? ctx.strokeStyle="red"; //邊框樣式
ctx.arc(100, 100, 30, 0, 1.5*Math.PI);
ctx.closePath(); //一個(gè)繪畫(huà)結(jié)束,如果繪畫(huà)不是封閉的,就封閉起來(lái)
ctx.stroke();//繪制線段
ctx.beginPath(); //開(kāi)始一個(gè)新的繪畫(huà)
ctx.lineWidth=5;//邊框?qū)挾? ctx.strokeStyle="red"; //邊框樣式
ctx.arc(200, 100, 30, 0, 2*Math.PI);
ctx.closePath(); //一個(gè)繪畫(huà)結(jié)束,如果繪畫(huà)不是封閉的,就封閉起來(lái)
ctx.stroke();//繪制線段
ctx.beginPath(); //開(kāi)始一個(gè)新的繪畫(huà)
ctx.lineWidth=5;//邊框?qū)挾? ctx.strokeStyle="red"; //邊框樣式
ctx.arc(300, 100, 30, 0, 0.5*Math.PI);
ctx.closePath(); //一個(gè)繪畫(huà)結(jié)束,如果繪畫(huà)不是封閉的,就封閉起來(lái)
ctx.stroke();//繪制線段
ctx.beginPath(); //開(kāi)始一個(gè)新的繪畫(huà)
ctx.lineWidth=5;//邊框?qū)挾? ctx.strokeStyle="red"; //一個(gè)繪畫(huà)結(jié)束,如果繪畫(huà)不是封閉的,就封閉起來(lái)
ctx.arc(400, 100, 30, 0, 0.5*Math.PI,true);//注意:0*PI,0.5*PI,1*PI,1。5*PI,2*PI所占據(jù)的位置是固定的
ctx.closePath(); //一個(gè)繪畫(huà)結(jié)束
ctx.stroke();//繪制線段
ctx.beginPath(); //開(kāi)始一個(gè)新的繪畫(huà)
ctx.fillStyle="red"; //邊框樣式
ctx.arc(500, 100, 30, 0, 1.5*Math.PI);
ctx.closePath(); //一個(gè)繪畫(huà)結(jié)束,如果繪畫(huà)不是封閉的,就封閉起來(lái)
ctx.fill();//繪制填充
ctx.beginPath(); //開(kāi)始一個(gè)新的繪畫(huà)
ctx.lineWidth=5;//邊框?qū)挾? ctx.strokeStyle="red"; //邊框樣式
ctx.arc(600, 100, 30, 0, 1.5*Math.PI);
ctx.stroke();//繪制線段
}else{
alert('當(dāng)前瀏覽器不支持,請(qǐng)更換瀏覽器');
}
}
draw();
}
</script>
</head>
<body>
<canvas id="canvas">當(dāng)前瀏覽器不支持,請(qǐng)更換瀏覽器</canvas>
</body>
</html>
5.繪制矩形
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title></title>
<link rel="stylesheet" >
<link rel="stylesheet" href="styles/lianxi.css">
<script src="/upload/otherpica42/77539.png');</script><![endif]-->
<style type="text/css">
canvas{border: 1px solid #000;display: block;margin: 0 auto;margin-top: 50px;}
</style>
<script>
window.onload=function(){
function draw(){
var canvas = document.getElementById('canvas');
if (canvas.getContext){
var ctx = canvas.getContext('2d');
canvas.width=500;
canvas.height=500;
ctx.fillRect(25,25,100,100);//繪制一個(gè)填充的矩形
ctx.clearRect(45,45,60,60);//清除指定矩形區(qū)域,讓清除部分完全透明
ctx.strokeRect(50,50,50,50); //繪制一個(gè)矩形的邊框
}else{
alert('當(dāng)前瀏覽器不支持,請(qǐng)更換瀏覽器');
}
}
draw();
}
</script>
</head>
<body>
<canvas id="canvas">當(dāng)前瀏覽器不支持,請(qǐng)更換瀏覽器</canvas>
</body>
</html>
6.繪制文本
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title></title>
<link rel="stylesheet" >
<link rel="stylesheet" href="styles/lianxi.css">
<script src="/upload/otherpica42/77539.png');</script><![endif]-->
<style type="text/css">
canvas{border: 1px solid #000;display: block;margin: 0 auto;margin-top: 50px;}
</style>
<script>
window.onload=function(){
function draw(){
var canvas = document.getElementById('canvas');
if (canvas.getContext){
var ctx = canvas.getContext('2d');
canvas.width=500;
canvas.height=500;
ctx.font = "48px serif";
ctx.fillText("Hello world", 10, 50);
}else{
alert('當(dāng)前瀏覽器不支持,請(qǐng)更換瀏覽器');
}
}
draw();
}
</script>
</head>
<body>
<canvas id="canvas">當(dāng)前瀏覽器不支持,請(qǐng)更換瀏覽器</canvas>
</body>
</html>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title></title>
<link rel="stylesheet" >
<link rel="stylesheet" href="styles/lianxi.css">
<script src="/upload/otherpica42/77539.png');</script><![endif]-->
<style type="text/css">
canvas{border: 1px solid #000;display: block;margin: 0 auto;margin-top: 50px;}
</style>
<script>
window.onload=function(){
function draw(){
var canvas = document.getElementById('canvas');
if (canvas.getContext){
var ctx = canvas.getContext('2d');
canvas.width=500;
canvas.height=500;
ctx.font = "48px serif";
ctx.strokeText("Hello world", 10, 50);
}else{
alert('當(dāng)前瀏覽器不支持,請(qǐng)更換瀏覽器');
}
}
draw();
}
</script>
</head>
<body>
<canvas id="canvas">當(dāng)前瀏覽器不支持,請(qǐng)更換瀏覽器</canvas>
</body>
</html>
7.圖片操作
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title></title>
<link rel="stylesheet" >
<link rel="stylesheet" href="styles/lianxi.css">
<script src="/upload/otherpica42/77539.png');</script><![endif]-->
<style type="text/css">
canvas{border: 1px solid #000;display: block;margin: 0 auto;margin-top: 50px;}
</style>
<script>
window.onload=function(){
function draw(){
var canvas = document.getElementById('canvas');
if (canvas.getContext){
var ctx = canvas.getContext('2d');
canvas.width=500;
canvas.height=500;
var img=new Image();
img.src='/upload/otherpica42/77540.jpg'
img.onload=function(){
ctx.drawImage(img,0,0);
ctx.beginPath();
ctx.moveTo(30,96);
ctx.lineTo(70,66);
ctx.lineTo(103,76);
ctx.lineTo(170,15);
ctx.stroke();
}
}else{
alert('當(dāng)前瀏覽器不支持,請(qǐng)更換瀏覽器');
}
}
draw();
}
</script>
</head>
<body>
<canvas id="canvas">當(dāng)前瀏覽器不支持,請(qǐng)更換瀏覽器</canvas>
</body>
</html>
以上就是本文的全部?jī)?nèi)容,希望本文的內(nèi)容對(duì)大家的學(xué)習(xí)或者工作能帶來(lái)一定的幫助,同時(shí)也希望多多支持創(chuàng)新互聯(lián)!
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