PHP DevLovers: HTML5 Canvas Circles

Friday, December 27, 2013

Animate a Fill Circle using Canvas & JavaScript

The HTML5 <canvas> element is used to draw graphics, on the fly, via scripting (usually JavaScript).
The <canvas> element is only a container for graphics. You must use a script to actually draw the graphics.
Canvas has several methods for drawing paths, boxes, circles, text, and adding images.
However, the <canvas> element has no drawing abilities of its own (it is only a container for graphics) - you must use a script to actually draw the graphics.
The getContext() method returns an object that provides methods and properties for drawing on the canvas.

HTML CODE:

The markup looks like this:

<div id="container">

  <h1>html5 Canvas - Animate a Fill Circle using Canvas - by <a href="http://cathodesoft.com/">CathodeSoft</a></h1>

  <canvas id="Circle" width="578" height="200"></canvas>

</div>

JavaScript Code :

// Script by http://phpdevlovers.blogspot.in

// requestAnimationFrame Sping

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 = 10;

function draw() {

context.save();

context.beginPath();

context.arc(centerX, centerY, radius, 0, 2 * Math.PI, false);

context.clip(); // Make a clipping region out of this path

// instead of filling the arc, we fill a variable-sized rectangle

// that is clipped to the arc

context.fillStyle = '#13a8a4';

// We want the rectangle to get progressively taller starting from the bottom

// There are two ways to do this:

// 1. Change the Y value and height every time

// 2. Using a negative height

// I'm lazy, so we're going with 2

context.fillRect(centerX - radius, centerY + radius, radius * 2, -amount);

context.restore(); // reset clipping region

context.beginPath();

context.arc(centerX, centerY, radius, 0, 2 * Math.PI, false);

context.lineWidth = 10;

context.strokeStyle = '#000000';

context.stroke();

// Every time, raise amount by some value:

amount += amountToIncrease;

if (amount > full) amount = 0; // restart

}

draw();

// Every second we'll fill more;

setInterval(draw, 1000);

</script>

DEMO url

HTML5 Canvas Circle - Drawing circles with Animation & Number

HTML Code:
<div class="circleStatsItem"> <span class="num-value">20</span> <span class="percent">%</span>
<canvas id="myCanvas1" width="78" height="78"></canvas>
</div>
<div class="circleStatsItem"> <span class="num-value">35</span> <span class="percent">%</span>
<canvas id="myCanvas2" width="78" height="78"></canvas>
</div>
<div class="circleStatsItem"> <span class="num-value">55</span> <span class="percent">%</span>
<canvas id="myCanvas3" width="78" height="78"></canvas>
</div>
<div class="circleStatsItem"> <span class="num-value">85</span> <span class="percent">%</span>
<canvas id="myCanvas4" width="78" height="78"></canvas>
</div>

CSS Styles:

JAVASCRIPT code :

// requestAnimationFrame Sping

(function() {

var requestAnimationFrame = window.requestAnimationFrame || window.mozRequestAnimationFrame ||

window.webkitRequestAnimationFrame || window.msRequestAnimationFrame;

window.requestAnimationFrame = requestAnimationFrame;

})();

function animate(elementId, endPercent, color) {

var canvas = document.getElementById(elementId);

var context = canvas.getContext('2d');

var x = canvas.width / 2;

var y = canvas.height / 2;

var radius = 35;

var curPerc = 0;

var counterClockwise = false;

var circ = Math.PI * 2;

var quart = Math.PI / 2;

context.lineWidth = 6;

context.strokeStyle = color;

context.shadowOffsetX = 0;

context.shadowOffsetY = 0;

function render(current) {

context.clearRect(0, 0, canvas.width, canvas.height);

context.beginPath();

context.arc(x, y, radius, -(quart), ((circ) * current) - quart, false);

context.stroke();

curPerc++;

if (curPerc < endPercent) {

requestAnimationFrame(function () {

render(curPerc / 100);

});

}

render();

}

animate('myCanvas1', 20, '#fb7e12');

animate('myCanvas2', 35, '#54a7dd');

animate('myCanvas3', 55, '#806ce5');

animate('myCanvas4', 85, '#5fc53b');

</script>

DEMO Link