discourse/app/assets/javascripts/external/favcount.js

85 lines
2.1 KiB
JavaScript

/*
* favcount.js v1.0.1
* http://chrishunt.co/favcount
* Dynamically updates the favicon with a number.
*
* Copyright 2013, Chris Hunt
* Released under the MIT license
*/
(function(){
function Favcount(icon) {
this.icon = icon;
this.canvas = document.createElement('canvas');
}
Favcount.prototype.set = function(count) {
var self = this,
img = document.createElement('img');
if (self.canvas.getContext) {
img.onload = function() {
drawCanvas(self.canvas, img, normalize(count));
};
img.src = this.icon;
}
}
function normalize(count) {
count = Math.round(count);
if (isNaN(count) || count < 1) {
return '';
} else if (count < 10) {
return ' ' + count;
} else if (count > 99) {
return '99';
} else {
return count;
}
}
function drawCanvas(canvas, img, count) {
var head = document.getElementsByTagName('head')[0],
favicon = document.createElement('link'),
multiplier, fontSize, context, xOffset, yOffset;
favicon.rel = 'icon';
// Scale the canvas based on favicon size
multiplier = img.width / 16;
fontSize = multiplier * 11;
xOffset = multiplier;
yOffset = multiplier * 11;
canvas.height = canvas.width = img.width;
context = canvas.getContext('2d');
context.drawImage(img, 0, 0);
context.font = 'bold ' + fontSize + 'px "helvetica", sans-serif';
// Draw background for contrast
context.fillStyle = '#FFF';
context.fillText(count, xOffset, yOffset);
context.fillText(count, xOffset + 2, yOffset);
context.fillText(count, xOffset, yOffset + 2);
context.fillText(count, xOffset + 2, yOffset + 2);
// Draw count in foreground
context.fillStyle = '#000';
context.fillText(count, xOffset + 1, yOffset + 1);
// Replace the favicon
favicon.href = canvas.toDataURL('image/png');
head.removeChild(document.querySelector('link[rel=icon]'));
head.appendChild(favicon);
}
this.Favcount = Favcount;
}).call(this);
(function(){
Favcount.VERSION = '1.0.1';
}).call(this);