identicon.js

/*
 * @author  Don Park
 * @version 0.2
 * @date    January 21th, 2007
 *
 * (The MIT License)
 *
 * Copyright (c) 2007-2012 Don Park <donpark@docuverse.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * 'Software'), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

var crypto = require('crypto');
var isBrowser = typeof window !== 'undefined' && typeof window.document !== 'undefined';
var Canvas = isBrowser ? require('./lib/canvas') : require('canvas');

var patch0 = new Array(0, 4, 24, 20);
var patch1 = new Array(0, 4, 20);
var patch2 = new Array(2, 24, 20);
var patch3 = new Array(0, 2,  20, 22);
var patch4 = new Array(2, 14, 22, 10);
var patch5 = new Array(0, 14, 24, 22);
var patch6 = new Array(2, 24, 22, 13, 11, 22, 20);
var patch7 = new Array(0, 14, 22);
var patch8 = new Array(6, 8, 18, 16);
var patch9 = new Array(4, 20, 10, 12, 2);
var patch10 = new Array(0, 2, 12, 10);
var patch11 = new Array(10, 14, 22);
var patch12 = new Array(20, 12, 24);
var patch13 = new Array(10, 2, 12);
var patch14 = new Array(0, 2, 10);

var patchTypes = new Array(patch0, patch1, patch2, patch3, patch4, patch5, patch6, patch7, patch8, patch9, patch10, patch11, patch12, patch13, patch14, patch0);
var centerPatchTypes = new Array(0, 4, 8, 15);

function render_identicon_patch (ctx, x, y, size, patch, turn, invert, foreColor, backColor) {

    patch %= patchTypes.length;
    turn %= 4;
    if (patch == 15) {
        invert = !invert;
    }

    var vertices = patchTypes[patch];
    var offset = size / 2;
    var scale = size / 4;

    ctx.save();

    // paint background
    ctx.fillStyle = invert ? foreColor : backColor;
    ctx.fillRect(x, y, size, size);

    // build patch path
    ctx.translate(x + offset, y + offset);
    ctx.rotate(turn * Math.PI / 2);
    ctx.beginPath();
    ctx.moveTo((vertices[0] % 5 * scale - offset), (Math.floor(vertices[0] / 5) * scale - offset));
    for (var i = 1; i < vertices.length; i++)
    ctx.lineTo((vertices[i] % 5 * scale - offset), (Math.floor(vertices[i] / 5) * scale - offset));
    ctx.closePath();

    // offset and rotate coordinate space by patch position (x, y) and
    // 'turn' before rendering patch shape

    // render rotated patch using fore color (back color if inverted)
    ctx.fillStyle = invert ? backColor : foreColor;
    ctx.fill();

    // restore rotation
    ctx.restore();
}

function render_identicon (ctx, code, size) {

    var patchSize = size / 3;
    var middleType = centerPatchTypes[code & 3];
    var middleInvert = ((code >> 2) & 1) != 0;
    var cornerType = (code >> 3) & 15;
    var cornerInvert = ((code >> 7) & 1) != 0;
    var cornerTurn = (code >> 8) & 3;
    var sideType = (code >> 10) & 15;
    var sideInvert = ((code >> 14) & 1) != 0;
    var sideTurn = (code >> 15) & 3;
    var blue = (code >> 16) & 31;
    var green = (code >> 21) & 31;
    var red = (code >> 27) & 31;
    var foreColor = 'rgb(' + (red << 3) + ',' + (green << 3) + ',' + (blue << 3) + ')';
    var backColor = 'rgb(255,255,255)';

    // middle patch
    render_identicon_patch(ctx, patchSize, patchSize, patchSize, middleType, 0, middleInvert, foreColor, backColor);

    // side patchs, starting from top and moving clock-wise
    render_identicon_patch(ctx, patchSize, 0, patchSize, sideType, sideTurn++, sideInvert, foreColor, backColor);
    render_identicon_patch(ctx, patchSize * 2, patchSize, patchSize, sideType, sideTurn++, sideInvert, foreColor, backColor);
    render_identicon_patch(ctx, patchSize, patchSize * 2, patchSize, sideType, sideTurn++, sideInvert, foreColor, backColor);
    render_identicon_patch(ctx, 0, patchSize, patchSize, sideType, sideTurn++, sideInvert, foreColor, backColor);

    // corner patchs, starting from top left and moving clock-wise
    render_identicon_patch(ctx, 0, 0, patchSize, cornerType, cornerTurn++, cornerInvert, foreColor, backColor);
    render_identicon_patch(ctx, patchSize * 2, 0, patchSize, cornerType, cornerTurn++, cornerInvert, foreColor, backColor);
    render_identicon_patch(ctx, patchSize * 2, patchSize * 2, patchSize, cornerType, cornerTurn++, cornerInvert, foreColor, backColor);
    render_identicon_patch(ctx, 0, patchSize * 2, patchSize, cornerType, cornerTurn++, cornerInvert, foreColor, backColor);
}

function _gen(str, size, callback) {
    var hash = crypto.createHash('sha1').update(Buffer.from(str, 'utf8')).digest('binary');
    var code = (hash.charCodeAt(0) << 24) | (hash.charCodeAt(1) << 16) |
    (hash.charCodeAt(2) << 8) | hash.charCodeAt(3);

    var canvas = isBrowser ? new Canvas(size, size) : Canvas.createCanvas(size, size);
    var ctx = canvas.getContext('2d');

    render_identicon(ctx, code, size);

    if (callback && typeof callback === 'function') {
        if (!canvas.toBuffer) {
            var imageData = ctx.getImageData(0, 0, size, size);
            callback(null, canvas.toDataURL('image/png'));
            return;
        }
        return canvas.toBuffer(function (err, buffer) {
            callback(err, buffer);
        });
    }
    else {
        if (!canvas.toBuffer) {
            return canvas.toDataURL('image/png');
        }
        return canvas.toBuffer();
    }
}

exports.generate = exports.gen = function (str, size, callback) {
    if (typeof str === 'object' && typeof size === 'function') {
        return _gen(str.id, str.size, size);
    }

    return _gen(str, size, callback);
}

exports.generateSync = exports.genSync = function (str, size) {
    if (typeof str === 'object') {
        return _gen(str.id, str.size);
    }

    return _gen(str, size);
}