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Html5 Canvas开发之鼠标绘图和方块移动

2012-11-17 01:53 357 查看

1.鼠标绘图

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<style>
body{ background:black;}
#c1{ background:white;}
span{ color:white;}
</style>
<script>

window.onload = function(){
var oC = document.getElementById('c1');

var oGC = oC.getContext('2d');

oC.onmousedown = function(ev){
var ev = ev || window.event;
oGC.moveTo(ev.clientX-oC.offsetLeft,ev.clientY-oC.offsetTop);
document.onmousemove = function(ev){
var ev = ev || window.event;
oGC.lineTo(ev.clientX-oC.offsetLeft,ev.clientY-oC.offsetTop);
oGC.stroke();
};
document.onmouseup = function(){
document.onmousemove = null;
document.onmouseup = null;
};
};

};

</script>
</head>

<body>
<canvas id="c1" width="400" height="400">
<span>不支持canvas浏览器</span>
</canvas> <!--默认：宽300 高150-->
</body>
</html>

2.方块移动

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<style>
body{ background:black;}
#c1{ background:white;}
span{ color:white;}
</style>
<script>

window.onload = function(){
var oC = document.getElementById('c1');

var oGC = oC.getContext('2d');

var num = 0;

oGC.fillRect(0,0,100,100);

setInterval(function(){

num++;

oGC.clearRect(0,0,oC.width,oC.height);

oGC.fillRect(num,num,100,100);

},30);

};

</script>
</head>

<body>
<canvas id="c1" width="400" height="400">
<span>不支持canvas浏览器</span>
</canvas> <!--默认：宽300 高150-->
</body>
</html>

3.Canvas开发注意事项 canvas画布宽高定义

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<style>
body{ background:black;}
#c1{ background:white; width:600px; height:300px;}
span{ color:white;}
</style>
<script>

window.onload = function(){
var oC = document.getElementById('c1');

var oGC = oC.getContext('2d');

var num = 0;

oGC.fillRect(0,0,100,100);

};

</script>
</head>

<body>
<canvas id="c1">
<span>不支持canvas浏览器</span>
</canvas> <!--默认：宽300 高150-->
</body>
</html>

此定义方式为按（默认大小）比例矢量放大缩小，如果要定义宽高应如下定义

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<style>
body{ background:black;}
#c1{ background:white; }
span{ color:white;}
</style>
<script>

window.onload = function(){
var oC = document.getElementById('c1');

var oGC = oC.getContext('2d');

var num = 0;

oGC.fillRect(0,0,100,100);

};

</script>
</head>

<body>
<canvas id="c1" width:600px; height:300px;>
<span>不支持canvas浏览器</span>
</canvas> <!--默认：宽300 高150-->
</body>
</html>

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