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<!DOCTYPE html> 
<html lang="en"> 
<head> 
    <meta charset="UTF-8"> 
    <title>繪制餅形圖。</title> 
    <style> 
        canvas{ 
            border: 1px solid green; 
        } 
    </style> 
</head> 
<body> 
    <!-- 繪制餅形圖 --> 
    <canvas width="500" height="500" id="canvas"></canvas> 
</body> 
<script> 
    var canvas = document.getElementById(’canvas’); 
    var ctx = canvas.getContext(’2d’); 
    function toAngle(radian){ 
        return radian*180/Math.PI; 
    } 
    function toRadian(angle){ 
        return angle*Math.PI/180; 
    } 
    /*將餅狀圖畫出來*/ 
    var colors = ’green,yellow,pink,blue,red,lightgreen,lightblue’.split(’,’); 
    var text = ’HTML5,Canvas,Javascript,Css3,Ajax,框架封裝,jQuery與移動Web’.split(’,’); 
    var x0 = canvas.width/2, 
        y0 = canvas.height/2, 
        radius = 100, 
        start = -5, 
        distance = 20, 
        padding = 5, 
        step = 360/colors.length; 
    for(var i = 0 ; i < colors.length ; i ++){ 
        ctx.beginPath(); 
        ctx.fillStyle = colors[i]; 
        ctx.moveTo(x0,y0); 
        ctx.arc(x0,y0,radius,toRadian(start),toRadian(start+=step)); 
        ctx.fill(); 
        /*畫斜線*/ 
        ctx.beginPath(); 
        ctx.strokeStyle = colors[i]; 
        var x1 = x0 + (radius+distance)*Math.cos(toRadian(( start-step/2 ))), 
            y1 = y0 + (radius+distance)*Math.sin(toRadian(( start-step/2 ))); 
        ctx.moveTo(x0,y0); 
        ctx.lineTo(x1,y1); 
        ctx.stroke(); 
        /*寫文字*/ 
        ctx.beginPath(); 
        ctx.fillStyle = colors[i]; 
        var textX = x1, 
            textY = y1; 
        if(start-step/2 > 90 && start-step/2 < 270){ 
            ctx.textAlign = ’right’; 
            textX = textX - padding; 
        }else{ 
            ctx.textAlign = ’left’; 
            textX = textX + padding; 
        } 
        ctx.fillText(text[i],textX,textY-padding/2); 
        /*畫直線*/ 
        ctx.beginPath(); 
        ctx.moveTo(x1,y1); 
        //計算文字的寬度 
        var length = ctx.measureText( text[ i ] ).width 
        if(start-step/2 > 90 && start-step/2 < 270){ 
            x1 += -2*padding-length; 
        }else{ 
            x1 += 2*padding + length; 
        } 
        ctx.lineTo(x1,y1); 
        ctx.stroke(); 
        /*畫餅形圖*/ 
        /*ctx.beginPath(); 
        ctx.fillStyle = colors[i]; 
        ctx.moveTo(x0,y0); 
        ctx.arc(x0,y0,radius,toRadian(start),toRadian(start+=step)); 
        ctx.fill();*/ 
    } 
</script> 
</html>