hamed fallahi
hamed fallahi

Reputation: 67

Animate a Fill Circle like pie chart using Canvas

Basically I want to be able to Fill a Circle using canvas, but it animate like pie chart and mask to show new image in circle. My canvas knowledge isn't amazing, Here is an image to display what i want. enter image description here an anyone shed some light on how to do it? Here is a fiddle of what I've managed

    var canvas = document.getElementById('Circle');
      var context = canvas.getContext('2d');
      var centerX = canvas.width / 2;
      var centerY = canvas.height / 2;
      var radius = 80;
            var full = radius*2;
            var amount = 0;
            var amountToIncrease = 0.1;
      function draw() {
      context.beginPath();
      context.arc(centerX, centerY, radius, 0, amount * Math.PI, false);
      context.fillStyle = '#13a8a4';
      context.fill();
      context.lineWidth = 10;
      context.strokeStyle = '#000000';
      context.stroke();
    amount += amountToIncrease;
    if (amount > full) amount = 0; // restart
}
draw();
// Every second we'll fill more;
setInterval(draw, 100);

Upvotes: 1

Views: 2904

Answers (1)

markE
markE

Reputation: 105035

This is one way:

  1. Draw your gray background.
  2. Fill your percent-arc with a starting angle at -Math.PI*2 (=="12 on a clock") and an ending angle of -Math.PI*2 + Math.PI*2*percent (==a full circle of 2PI times your desired percent).
  3. Draw your logo.

To animate, just use a requestAnimationFrame loop that incrementally draws the percent-arc starting at 0 percent and ending at your target percent.

enter image description here

Example code and a Demo:

var canvas=document.getElementById("canvas");
var ctx=canvas.getContext("2d");
var cw=canvas.width;
var ch=canvas.height;

var nextTime=0;
var duration=1000;
var endingPct=75;
var pct=0;
var increment=duration/pct;
requestAnimationFrame(animate);

function animate(time){
    draw(pct);
    pct++;
    if(pct<=endingPct){requestAnimationFrame(animate);}
}

function draw(pct){
    var endRadians=-Math.PI/2+Math.PI*2*pct/100;
    ctx.fillStyle='lightgray';
    ctx.fillRect(0,0,cw,ch);
    ctx.beginPath();
    ctx.arc(150,125,100,-Math.PI/2,endRadians);
    ctx.lineTo(150,125);
    ctx.fillStyle='white';
    ctx.fill();
    ctx.beginPath();
    ctx.moveTo(150,100);
    ctx.lineTo(175,150);
    ctx.quadraticCurveTo(150,125,125,150);
    ctx.closePath();
    ctx.strokeStyle='#13a8a4';
    ctx.lineJoin='bevel';
    ctx.lineWidth=10;
    ctx.stroke();
    ctx.fillStyle='black';
    ctx.textAlign='center';
    ctx.textBaseline='middle'
    ctx.font='18px arial';
    ctx.fillText('ADUR',150,175);
}
body{ background-color: ivory; }
#canvas{border:1px solid red; margin:0 auto; }
<canvas id="canvas" width=300 height=300></canvas>

[Update: We needed an image clipped inside the animated wedge]

enter image description here

var canvas=document.getElementById("canvas");
var ctx=canvas.getContext("2d");
var cw=canvas.width;
var ch=canvas.height;

var nextTime=0;
var duration=1000;
var endingPct=75;
var pct=0;
var increment=duration/pct;
var cx=cw/2;
var cy=ch/2;

var img=new Image();
img.onload=start;
img.src="https://dl.dropboxusercontent.com/u/139992952/multple/mm.jpg";
function start(){
    requestAnimationFrame(animate);
}

function animate(time){
    draw(pct);
    pct++;
    if(pct<=endingPct){requestAnimationFrame(animate);}
}

function draw(pct){
    //
    var endRadians=-Math.PI/2+Math.PI*2*pct/100;
    //
    ctx.fillStyle='lightgray';
    ctx.fillRect(0,0,cw,ch);
    //
    ctx.beginPath();
    ctx.arc(cx,cy,100,-Math.PI/2,endRadians);
    ctx.lineTo(cx,cy);
    ctx.save();
    ctx.clip();
    ctx.drawImage(img,cx-img.width/2,cx-img.height/2);
    ctx.restore();
}
body{ background-color: ivory; }
#canvas{border:1px solid red; margin:0 auto; }
<canvas id="canvas" width=300 height=300></canvas>

Upvotes: 4

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