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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76 lines
2.3 KiB
76 lines
2.3 KiB
9 years ago
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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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