From d4bf0637884b0aa1294744e6beccc510d73c32be Mon Sep 17 00:00:00 2001 From: Goffi Date: Tue, 1 Oct 2019 22:49:10 +0200 Subject: [PATCH] tools (common): helping method to calculate luminance: - a new `utils` module has been added for backend and frontends generic utilities - per_luminance method calculate the perceived luminance of a colour (is it dark or light?). This is useful to automatically select the suitable colour in a theme. --- sat/tools/common/utils.py | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) create mode 100644 sat/tools/common/utils.py diff --git a/sat/tools/common/utils.py b/sat/tools/common/utils.py new file mode 100644 index 00000000..d637d125 --- /dev/null +++ b/sat/tools/common/utils.py @@ -0,0 +1,32 @@ +#!/usr/bin/env python3 + +# SàT: a XMPP client +# Copyright (C) 2009-2019 Jérôme Poisson (goffi@goffi.org) + +# This program is free software: you can redistribute it and/or modify +# it under the terms of the GNU Affero General Public License as published by +# the Free Software Foundation, either version 3 of the License, or +# (at your option) any later version. + +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU Affero General Public License for more details. + +# You should have received a copy of the GNU Affero General Public License +# along with this program. If not, see . + +"""Misc utils for both backend and frontends""" + + +def per_luminance(red, green, blue): + """Caculate the perceived luminance of a RGB color + + @param red(int): 0-1 normalized value of red + @param green(int): 0-1 normalized value of green + @param blue(int): 0-1 normalized value of blue + @return (float): 0-1 value of luminance (<0.5 is dark, else it's light) + """ + # cf. https://stackoverflow.com/a/1855903, thanks Gacek + + return 0.299 * red + 0.587 * green + 0.114 * blue