JavaScript 繪制餅圖的示例

var canvas = document.getElementById("mycanvas");
var w = window.innerWidth;
var h = window.innerHeight;
canvas.height = 1000;
canvas.width = 1400;
var ctx = canvas.getContext('2d');

var poppable = true;

var slices = [];

function shadeColor(color, percent) {
 var f = parseInt(color.slice(1), 16),
  t = percent < 0 ? 0 : 255,
  p = percent < 0 ? percent * -1 : percent,
  R = f >> 16,
  G = f >> 8 & 0x00FF,
  B = f & 0x0000FF;
 return "#" + (0x1000000 + (Math.round((t - R) * p) + R) * 0x10000 + (Math.round((t - G) * p) + G) * 0x100 + (Math.round((t - B) * p) + B)).toString(16).slice(1);
}

function pieSlice(oX, oY, r, pos, len, col,data) {
 this.data = data
 this.originX = oX;
 this.originY = oY;
 this.radius = r;
 this.startingRadian = pos;
 this.length = len;
 this.color = col;
 this.highlightedColor = shadeColor(this.color, .6);
 this.highlighted = false;
 this.popped = false;
 this.animationFrame = 0;

 function setColor(c) {
  this.color = c;
 }
}

pieSlice.prototype.displayData = function(){
 ctx.fillStyle= this.color;
 ctx.fillRect(this.originX - this.radius - 40, this.originY-this.radius-35, 25,25);
 ctx.fillStyle= "white";
 ctx.font = "15px Arial";
 ctx.fillText(this.data, this.originX - this.radius - 10, this.originY - this.radius - 18);
}

pieSlice.prototype.render = function() {
 if (!this.highlighted) {
  ctx.fillStyle = this.color;
  ctx.strokeStyle = this.color;
 } else {
  if(!this.popped && poppable){
   this.displayData();
  }
  // ctx.fillStyle = this.color;
  ctx.fillStyle = this.highlightedColor;
  ctx.strokeStyle = this.color;
 }
 ctx.beginPath();
 var xOffset = Math.cos(this.length / 2 + this.startingRadian) * this.animationFrame;
 var yOffset = Math.sin(this.length / 2 + this.startingRadian) * this.animationFrame;
 ctx.moveTo(this.originX + xOffset, this.originY + yOffset);
 var x = this.originX + xOffset + this.radius * Math.cos(this.startingRadian);
 var y = this.originY + yOffset + this.radius * Math.sin(this.startingRadian);
 ctx.lineTo(x, y);
 ctx.arc(this.originX + xOffset, this.originY + yOffset, this.radius, this.startingRadian, this.startingRadian + this.length);
 if (this.popped) {
  var fill = ctx.fillStyle;
  this.displayData();
  ctx.fillStyle = fill;
  if (this.animationFrame < 30) {
   this.animationFrame += 2;
  }
 } else {
  if (this.animationFrame > 0) {
   this.animationFrame -= 2;
  }
 }
 ctx.closePath();
 //ctx.stroke();
 //if (this.highlighted) {
 ctx.fill();
 // }
}

pieSlice.prototype.update = function() {

}

function pieChart(s) {
 this.slices = s;
}
pieChart.prototype.render = function() {
 this.slices.forEach(function(p) {
  p.render();
 });
};

pieChart.prototype.update = function() {
  this.slices.forEach(function(p) {
   p.update();
  });

 }
 //PIE ONE
var pie = new pieSlice(700, 170, 125, 0, Math.PI / 4, "#FFD1DC", 12);
var slice2 = new pieSlice(700, 170, 125, Math.PI / 4, Math.PI / 4, "#08E8DE");
var slice3 = new pieSlice(700, 170, 125, Math.PI / 2, Math.PI / 4, "#6699CC");
var slice4 = new pieSlice(700, 170, 125, 3 * Math.PI / 4, Math.PI, "#ADD8E6");
var slice5 = new pieSlice(700, 170, 125, 7 * Math.PI / 4, Math.PI / 4, "#B19CD9");
var slices1 = [pie, slice2, slice3, slice4, slice5];

var pink = new pieSlice(220, 170, 125, 0, Math.PI / 3, "#FF4B4B");
var orange = new pieSlice(220, 170, 125, Math.PI / 3, Math.PI / 3, "#FF931B");
var yellow = new pieSlice(220, 170, 125, 2 * Math.PI / 3, Math.PI / 3, "#FFE21B");
var green = new pieSlice(220, 170, 125, 3 * Math.PI / 3, Math.PI / 3, "#90E64E");
var blue = new pieSlice(220, 170, 125, 4 * Math.PI / 3, Math.PI / 3, "#6097D9");
var purple = new pieSlice(220, 170, 125, 5 * Math.PI / 3, Math.PI / 3, "#8365DD");

var redd = new pieSlice(1180, 170, 125, 0, 2 * Math.PI / 3, "#B3989B");
var orangee = new pieSlice(1180, 170, 125, 2 * Math.PI / 3, 1 * Math.PI / 8, "#C1AEE0");
var bluee = new pieSlice(1180, 170, 125, 19 * Math.PI / 24, 4 * Math.PI / 24, "#928CE9");
var greenn = new pieSlice(1180, 170, 125, 23 * Math.PI/24, 3* Math.PI/8, "#676675");
var purplee = new pieSlice(1180, 170, 125, 4 * Math.PI/3, 3* Math.PI/8, "#947D59");
var ceci = new pieSlice(1180, 170, 125, 41 * Math.PI/24, 7*Math.PI/24, "#D994E0");

var slices3 = [redd, orangee, bluee, greenn, purplee, ceci];

var slices2 = [pink, orange, yellow, green, blue, purple];
var pie1 = new pieChart(slices1);
var pie2 = new pieChart(slices2);
var pie3 = new pieChart(slices3);
var update = function() {
 pie1.update();
}
var render = function() {
 ctx.clearRect(0, 0, canvas.width, canvas.height);
 pie1.render();
 pie2.render();
 pie3.render();
}

var step = function() {
 update();
 render();
 animate(step);
}

var animate = window.requestAnimationFrame ||
 window.webkitRequestAnimationFrame ||
 window.mozRequestAnimationFrame ||
 function(callback) {
  window.setTimeout(callback, 1000 / 60);
 };

slices.push.apply(slices, slices1);
slices.push.apply(slices, slices2);
slices.push.apply(slices, slices3);

canvas.addEventListener("mousemove", function(e) {
 var x = e.clientX;
 var y = e.clientY;
 slices.forEach(function(slice) {
  ctx.beginPath();
  var xOffset = Math.cos(slice.length / 2 + slice.startingRadian) * slice.animationFrame;
  var yOffset = Math.sin(slice.length / 2 + slice.startingRadian) * slice.animationFrame;
  ctx.moveTo(slice.originX + xOffset, slice.originY + yOffset);
  var xx = slice.originX + xOffset + slice.radius * Math.cos(slice.startingRadian);
  var yy = slice.originY + yOffset + slice.radius * Math.sin(slice.startingRadian);
  ctx.lineTo(xx, yy);
  ctx.arc(slice.originX + xOffset, slice.originY + yOffset, slice.radius, slice.startingRadian, slice.startingRadian + slice.length);
  if (ctx.isPointInPath(x, y)) {
   slice.highlighted = true;
   slice.displayData();
  } else {
   slice.highlighted = false;
  }
  ctx.closePath();

 });
});

canvas.addEventListener("click", function(e) {
 var x = e.clientX;
 var y = e.clientY;
 slices.forEach(function(slice) {
  ctx.beginPath();
  var xOffset = Math.cos(slice.length / 2 + slice.startingRadian) * slice.animationFrame;
  var yOffset = Math.sin(slice.length / 2 + slice.startingRadian) * slice.animationFrame;
  ctx.moveTo(slice.originX + xOffset, slice.originY + yOffset);
  var xx = slice.originX + xOffset + slice.radius * Math.cos(slice.startingRadian);
  var yy = slice.originY + yOffset + slice.radius * Math.sin(slice.startingRadian);
  ctx.lineTo(xx, yy);
  ctx.arc(slice.originX + xOffset, slice.originY + yOffset, slice.radius, slice.startingRadian, slice.startingRadian + slice.length);
  if (ctx.isPointInPath(x, y)) {
   if (slice.popped) {
    slice.popped = false;
    poppable = true;
   } else {
    if(poppable){
      slice.popped = true;
     poppable = false;
    }
   }
   slice.highlighted = false;
  }
  ctx.closePath();

 });
});

//start the loop
animate(step);

<canvas id="mycanvas"></canvas>