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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63 lines
1.7 KiB
63 lines
1.7 KiB
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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