progress.js
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'use strict';
/**
* Expose `Progress`.
*/
module.exports = Progress;
/**
* Initialize a new `Progress` indicator.
*/
function Progress () {
this.percent = 0;
this.size(0);
this.fontSize(11);
this.font('helvetica, arial, sans-serif');
}
/**
* Set progress size to `size`.
*
* @api public
* @param {number} size
* @return {Progress} Progress instance.
*/
Progress.prototype.size = function (size) {
this._size = size;
return this;
};
/**
* Set text to `text`.
*
* @api public
* @param {string} text
* @return {Progress} Progress instance.
*/
Progress.prototype.text = function (text) {
this._text = text;
return this;
};
/**
* Set font size to `size`.
*
* @api public
* @param {number} size
* @return {Progress} Progress instance.
*/
Progress.prototype.fontSize = function (size) {
this._fontSize = size;
return this;
};
/**
* Set font to `family`.
*
* @param {string} family
* @return {Progress} Progress instance.
*/
Progress.prototype.font = function (family) {
this._font = family;
return this;
};
/**
* Update percentage to `n`.
*
* @param {number} n
* @return {Progress} Progress instance.
*/
Progress.prototype.update = function (n) {
this.percent = n;
return this;
};
/**
* Draw on `ctx`.
*
* @param {CanvasRenderingContext2d} ctx
* @return {Progress} Progress instance.
*/
Progress.prototype.draw = function (ctx) {
try {
var percent = Math.min(this.percent, 100);
var size = this._size;
var half = size / 2;
var x = half;
var y = half;
var rad = half - 1;
var fontSize = this._fontSize;
ctx.font = fontSize + 'px ' + this._font;
var angle = Math.PI * 2 * (percent / 100);
ctx.clearRect(0, 0, size, size);
// outer circle
ctx.strokeStyle = '#9f9f9f';
ctx.beginPath();
ctx.arc(x, y, rad, 0, angle, false);
ctx.stroke();
// inner circle
ctx.strokeStyle = '#eee';
ctx.beginPath();
ctx.arc(x, y, rad - 1, 0, angle, true);
ctx.stroke();
// text
var text = this._text || (percent | 0) + '%';
var w = ctx.measureText(text).width;
ctx.fillText(text, x - w / 2 + 1, y + fontSize / 2 - 1);
} catch (err) {
// don't fail if we can't render progress
}
return this;
};