canvas一周一练 -- canvas绘制中国银行标志（4）
运行效果：
<!DOCTYPE html>
<html>
<head>
</head>
<body>
<canvas id="drawing" width="600" height="400">A drawing of someing!</canvas>
<script type="text/javascript">
//绘制中国银行标志
var drawBoc = function(){
var drawing = document.getElementById('drawing');
if(drawing.getContext) {
var context = drawing.getContext('2d');
//画外环
context.fillStyle = '#f00';
context.strokeStyle = '#f00';
context.beginPath();
context.arc(200, 200, 100, 0, 2*Math.PI, false);
context.closePath();
context.stroke();
context.fill();
context.save();
context.fillStyle = '#fff';
context.beginPath();
context.arc(200, 200, 77, 0, 2*Math.PI, false);
context.closePath();
context.stroke();
context.fill();
//画外面的口（圆角矩形）
context.restore();
roundRec(context, 150, 160, 100, 80, 25, true, false);
//画里面的口
context.fillStyle = '#fff';
context.fillRect(170, 180, 60, 40);
//画上下两竖
context.fillStyle = '#f00';
context.fillRect(190, 123, 20, 37);
context.fillRect(190, 240, 20, 37);
}
};
//画圆角矩形
var roundRec = function(context, x, y, width, height, radius, fill, stroke){
if(typeof stroke == 'undefined') {
stroke = true;
}
if(typeof radius == 'undefined') {
radius = 5;
}
context.beginPath();
context.moveTo(x+radius, y);
context.lineTo(x+width-radius, y);
context.quadraticCurveTo(x+width, y, x+width, y+radius);
context.lineTo(x+width, y+height-radius);
context.quadraticCurveTo(x+width, y+height, x+width-radius, y+height);
context.lineTo(x+radius, y+height);
context.quadraticCurveTo(x, y+height, x, y+height-radius);
context.lineTo(x, y+radius);
context.quadraticCurveTo(x, y, x+radius, y);
context.closePath();
if(stroke) {
context.stroke();
}
if(fill) {
context.fill();
}
};
drawBoc();
</script>
</body>
</html>
