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Javascript 绘制 sin 曲线过程附图_javascript技巧

WBOY
WBOYOriginal
2016-05-16 16:39:091468browse

Javascript 绘制 sin 曲线代码如下:

<!DOCTYPE html> 
<html> 
<head> 
<style type="text/css"> 
#MyCanvas { 
background-color: cornflowerblue; 
} 
</style> 
<script type="text/javascript"> 
function draw(){ 
var my_canvas = document.getElementById( "MyCanvas" ); 
var content = my_canvas.getContext( "2d" ); 
content.beginPath(); 
content.moveTo( 10, 100 ); 
for( var i = 1; i < 200; i += 0.1 ){ 
var x = i * 10; 
var y = Math.sin( i ) * 10 + 100; 
content.lineTo( x, y ); 
} 
content.stroke(); 
content.closePath(); 

} 
</script> 
</head> 
<body onload="draw()"> 
<canvas id = "MyCanvas" width="400" height="400"></canvas> 
</body> 
</html>

动态效果:

<!DOCTYPE html> 
<html> 
<head> 
<style type="text/css"> 
#MyCanvas { 
background-color: cornflowerblue; 
} 
</style> 
<script type="text/javascript"> 
var i = 1; 
var x = 1; 
var y = 100; 
function moveSin(){ 
var my_canvas = document.getElementById( "MyCanvas" ); 
var content = my_canvas.getContext( "2d" ); 
content.beginPath(); 
content.moveTo( x, y ); 
i += 0.1; 
x = i * 10; 
y = Math.sin( i ) * 10 + 100; 
content.lineTo( x, y ); 
content.stroke(); 
content.closePath(); 
} 
setInterval( moveSin, 10 ); 
</script> 
</head> 
<body onload="moveSin()"> 
<canvas id = "MyCanvas" width="400" height="400"></canvas> 
</body> 
</html>
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