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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64 lines
1.7 KiB
64 lines
1.7 KiB
9 years ago
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var utils = require('../utils')
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, nodes = require('../nodes');
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/**
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* Returns the transparent version of the given `top` color,
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* as if it was blend over the given `bottom` color.
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*
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* Examples:
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*
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* transparentify(#808080)
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* => rgba(0,0,0,0.5)
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*
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* transparentify(#414141, #000)
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* => rgba(255,255,255,0.25)
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*
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* transparentify(#91974C, #F34949, 0.5)
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* => rgba(47,229,79,0.5)
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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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* @param {Unit} [alpha]
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* @return {RGBA}
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* @api public
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*/
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module.exports = function transparentify(top, bottom, alpha){
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utils.assertColor(top);
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top = top.rgba;
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// Handle default arguments
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bottom = bottom || new nodes.RGBA(255, 255, 255, 1);
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if (!alpha && bottom && !bottom.rgba) {
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alpha = bottom;
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bottom = new nodes.RGBA(255, 255, 255, 1);
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}
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utils.assertColor(bottom);
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bottom = bottom.rgba;
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var bestAlpha = ['r', 'g', 'b'].map(function(channel){
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return (top[channel] - bottom[channel]) / ((0 < (top[channel] - bottom[channel]) ? 255 : 0) - bottom[channel]);
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}).sort(function(a, b){return a < b;})[0];
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if (alpha) {
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utils.assertType(alpha, 'unit', 'alpha');
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if ('%' == alpha.type) {
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bestAlpha = alpha.val / 100;
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} else if (!alpha.type) {
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bestAlpha = alpha = alpha.val;
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}
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}
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bestAlpha = Math.max(Math.min(bestAlpha, 1), 0);
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// Calculate the resulting color
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function processChannel(channel) {
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if (0 == bestAlpha) {
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return bottom[channel]
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} else {
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return bottom[channel] + (top[channel] - bottom[channel]) / bestAlpha
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}
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}
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return new nodes.RGBA(
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processChannel('r'),
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processChannel('g'),
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processChannel('b'),
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Math.round(bestAlpha * 100) / 100
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);
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}
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