使用Html5中的cavas画一面国旗

 var canvas = document.getElementById("canvas");//创建一个cavas画板 var context = canvas.getContext('2d');//设置画板属性 var width=canvas.width; var height=width*2/3; context.fillStyle="red"; context.fillRect(0,0,width,height); var maxR = 0.15, minR = 0.05; var maxX = 0.55, maxY = 0.35;//大五星的位置 var minX = [0.80, 0.90, 0.90, 0.80,0.65,0.50,0.40];//各个小五角星的x坐标 var minY = [0.20, 0.30, 0.45, 0.55,0.60,0.60,0.50];//各个小五角星的y坐标 var ox = height * maxX, oy = height * maxY;

 create5star(context,ox,oy,height * maxR,"#ff0",0);//绘制大五角星 for (var idx = 0; idx <7; idx++) { var  sx = minX[idx] * height, sy = minY[idx] * height; var  theta = Math.atan((oy - sy)/(ox - sx)); create5star(context,sx, sy, height * minR, "#ff0",-Math.PI/2+theta);    // 画小五角星 } //绘制五角星 function create5star(context,sx,sy,radius,color,rotato){ context.save(); context.fillStyle=color; context.translate(sx,sy);//移动坐标原点 context.rotate(Math.PI+rotato);//旋转 context.beginPath();//创建路径 var x = Math.sin(0); var y= Math.cos(0); var dig = Math.PI/5 *4; for(var i = 0;i<5;i++){//画五角星的五条边 var x = Math.sin(i*dig); var y = Math.cos(i*dig); context.lineTo(x*radius,y*radius); } context.closePath(); context.stroke(); context.fill(); context.restore(); }