Fully end to end encrypted anonymous chat program. Server only stores public key lookup for users and the encrypted messages. No credentials are transfered to the server, but kept in local browser storage. This allows 100% safe chatting.
https://safechat.ch
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75 lines
2.3 KiB
75 lines
2.3 KiB
var utils = require('../utils') |
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, nodes = require('../nodes') |
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, blend = require('./blend') |
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, luminosity = require('./luminosity'); |
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/** |
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* Returns the contrast ratio object between `top` and `bottom` colors, |
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* based on http://leaverou.github.io/contrast-ratio/ |
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* and https://github.com/LeaVerou/contrast-ratio/blob/gh-pages/color.js#L108 |
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* |
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* Examples: |
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* |
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* contrast(#000, #fff).ratio |
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* => 21 |
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* |
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* contrast(#000, rgba(#FFF, 0.5)) |
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* => { "ratio": "13.15;", "error": "7.85", "min": "5.3", "max": "21" } |
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* |
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* @param {RGBA|HSLA} top |
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* @param {RGBA|HSLA} [bottom=#fff] |
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* @return {Object} |
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* @api public |
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*/ |
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module.exports = function contrast(top, bottom){ |
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if ('rgba' != top.nodeName && 'hsla' != top.nodeName) { |
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return new nodes.Literal('contrast(' + (top.isNull ? '' : top.toString()) + ')'); |
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} |
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var result = new nodes.Object(); |
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top = top.rgba; |
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bottom = bottom || new nodes.RGBA(255, 255, 255, 1); |
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utils.assertColor(bottom); |
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bottom = bottom.rgba; |
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function contrast(top, bottom) { |
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if (1 > top.a) { |
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top = blend(top, bottom); |
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} |
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var l1 = luminosity(bottom).val + 0.05 |
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, l2 = luminosity(top).val + 0.05 |
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, ratio = l1 / l2; |
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if (l2 > l1) { |
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ratio = 1 / ratio; |
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} |
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return Math.round(ratio * 10) / 10; |
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} |
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if (1 <= bottom.a) { |
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var resultRatio = new nodes.Unit(contrast(top, bottom)); |
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result.set('ratio', resultRatio); |
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result.set('error', new nodes.Unit(0)); |
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result.set('min', resultRatio); |
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result.set('max', resultRatio); |
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} else { |
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var onBlack = contrast(top, blend(bottom, new nodes.RGBA(0, 0, 0, 1))) |
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, onWhite = contrast(top, blend(bottom, new nodes.RGBA(255, 255, 255, 1))) |
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, max = Math.max(onBlack, onWhite); |
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function processChannel(topChannel, bottomChannel) { |
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return Math.min(Math.max(0, (topChannel - bottomChannel * bottom.a) / (1 - bottom.a)), 255); |
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} |
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var closest = new nodes.RGBA( |
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processChannel(top.r, bottom.r), |
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processChannel(top.g, bottom.g), |
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processChannel(top.b, bottom.b), |
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1 |
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); |
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var min = contrast(top, blend(bottom, closest)); |
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result.set('ratio', new nodes.Unit(Math.round((min + max) * 50) / 100)); |
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result.set('error', new nodes.Unit(Math.round((max - min) * 50) / 100)); |
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result.set('min', new nodes.Unit(min)); |
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result.set('max', new nodes.Unit(max)); |
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} |
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return result; |
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}
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