Add 'meshmc/' from commit 'fad6a1066616b69d7f5fef01178efdf014c59537'

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diff --git a/meshmc/libraries/rainbow/include/rainbow.h b/meshmc/libraries/rainbow/include/rainbow.h
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+/* SPDX-License-Identifier: LGPL-2.0-or-later
+ *
+ * This was part of the KDE project - see KGuiAddons
+ * Copyright (C) 2007 Matthew Woehlke <mw_triad@users.sourceforge.net>
+ * Copyright (C) 2007 Olaf Schmidt <ojschmidt@kde.org>
+ * Copyright (C) 2007 Thomas Zander <zander@kde.org>
+ * Copyright (C) 2007 Zack Rusin <zack@kde.org>
+ * Copyright (C) 2015 Petr Mrazek <peterix@gmail.com>
+ * Copyright (C) 2026 Project Tick
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public License
+ * along with this library; see the file COPYING.LIB.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#pragma once
+
+#include "rainbow_config.h"
+
+#include <QPainter>
+class QColor;
+
+/**
+ * A set of methods used to work with colors.
+ */
+namespace Rainbow
+{
+	/**
+	 * Calculate the luma of a color. Luma is weighted sum of gamma-adjusted
+	 * R'G'B' components of a color. The result is similar to qGray. The range
+	 * is from 0.0 (black) to 1.0 (white).
+	 *
+	 * Rainbow::darken(), Rainbow::lighten() and Rainbow::shade()
+	 * operate on the luma of a color.
+	 *
+	 * @see http://en.wikipedia.org/wiki/Luma_(video)
+	 */
+	RAINBOW_EXPORT qreal luma(const QColor&);
+
+	/**
+	 * Calculate hue, chroma and luma of a color in one call.
+	 * @since 5.0
+	 */
+	RAINBOW_EXPORT void getHcy(const QColor&, qreal* hue, qreal* chroma,
+							   qreal* luma, qreal* alpha = 0);
+
+	/**
+	 * Calculate the contrast ratio between two colors, according to the
+	 * W3C/WCAG2.0 algorithm, (Lmax + 0.05)/(Lmin + 0.05), where Lmax and Lmin
+	 * are the luma values of the lighter color and the darker color,
+	 * respectively.
+	 *
+	 * A contrast ration of 5:1 (result == 5.0) is the minimum for "normal"
+	 * text to be considered readable (large text can go as low as 3:1). The
+	 * ratio ranges from 1:1 (result == 1.0) to 21:1 (result == 21.0).
+	 *
+	 * @see Rainbow::luma
+	 */
+	RAINBOW_EXPORT qreal contrastRatio(const QColor&, const QColor&);
+
+	/**
+	 * Adjust the luma of a color by changing its distance from white.
+	 *
+	 * @li amount == 1.0 gives white
+	 * @li amount == 0.5 results in a color whose luma is halfway between 1.0
+	 * and that of the original color
+	 * @li amount == 0.0 gives the original color
+	 * @li amount == -1.0 gives a color that is 'twice as far from white' as
+	 * the original color, that is luma(result) == 1.0 - 2*(1.0 - luma(color))
+	 *
+	 * @param amount factor by which to adjust the luma component of the color
+	 * @param chromaInverseGain (optional) factor by which to adjust the chroma
+	 * component of the color; 1.0 means no change, 0.0 maximizes chroma
+	 * @see Rainbow::shade
+	 */
+	RAINBOW_EXPORT QColor lighten(const QColor&, qreal amount = 0.5,
+								  qreal chromaInverseGain = 1.0);
+
+	/**
+	 * Adjust the luma of a color by changing its distance from black.
+	 *
+	 * @li amount == 1.0 gives black
+	 * @li amount == 0.5 results in a color whose luma is halfway between 0.0
+	 * and that of the original color
+	 * @li amount == 0.0 gives the original color
+	 * @li amount == -1.0 gives a color that is 'twice as far from black' as
+	 * the original color, that is luma(result) == 2*luma(color)
+	 *
+	 * @param amount factor by which to adjust the luma component of the color
+	 * @param chromaGain (optional) factor by which to adjust the chroma
+	 * component of the color; 1.0 means no change, 0.0 minimizes chroma
+	 * @see Rainbow::shade
+	 */
+	RAINBOW_EXPORT QColor darken(const QColor&, qreal amount = 0.5,
+								 qreal chromaGain = 1.0);
+
+	/**
+	 * Adjust the luma and chroma components of a color. The amount is added
+	 * to the corresponding component.
+	 *
+	 * @param lumaAmount amount by which to adjust the luma component of the
+	 * color; 0.0 results in no change, -1.0 turns anything black, 1.0 turns
+	 * anything white
+	 * @param chromaAmount (optional) amount by which to adjust the chroma
+	 * component of the color; 0.0 results in no change, -1.0 minimizes chroma,
+	 * 1.0 maximizes chroma
+	 * @see Rainbow::luma
+	 */
+	RAINBOW_EXPORT QColor shade(const QColor&, qreal lumaAmount,
+								qreal chromaAmount = 0.0);
+
+	/**
+	 * Create a new color by tinting one color with another. This function is
+	 * meant for creating additional colors withings the same class (background,
+	 * foreground) from colors in a different class. Therefore when @p amount
+	 * is low, the luma of @p base is mostly preserved, while the hue and
+	 * chroma of @p color is mostly inherited.
+	 *
+	 * @param base color to be tinted
+	 * @param color color with which to tint
+	 * @param amount how strongly to tint the base; 0.0 gives @p base,
+	 * 1.0 gives @p color
+	 */
+	RAINBOW_EXPORT QColor tint(const QColor& base, const QColor& color,
+							   qreal amount = 0.3);
+
+	/**
+	 * Blend two colors into a new color by linear combination.
+	 * @code
+		QColor lighter = Rainbow::mix(myColor, Qt::white)
+	 * @endcode
+	 * @param c1 first color.
+	 * @param c2 second color.
+	 * @param bias weight to be used for the mix. @p bias <= 0 gives @p c1,
+	 * @p bias >= 1 gives @p c2. @p bias == 0.5 gives a 50% blend of @p c1
+	 * and @p c2.
+	 */
+	RAINBOW_EXPORT QColor mix(const QColor& c1, const QColor& c2,
+							  qreal bias = 0.5);
+
+	/**
+	 * Blend two colors into a new color by painting the second color over the
+	 * first using the specified composition mode.
+	 * @code
+		QColor white(Qt::white);
+		white.setAlphaF(0.5);
+		QColor lighter = Rainbow::overlayColors(myColor, white);
+	   @endcode
+	 * @param base the base color (alpha channel is ignored).
+	 * @param paint the color to be overlayed onto the base color.
+	 * @param comp the CompositionMode used to do the blending.
+	 */
+	RAINBOW_EXPORT QColor overlayColors(
+		const QColor& base, const QColor& paint,
+		QPainter::CompositionMode comp = QPainter::CompositionMode_SourceOver);
+} // namespace Rainbow