HGKeeper

* Pidgin - Internet Messenger

* Copyright (C) Pidgin Developers <devel@pidgin.im>

* Pidgin is the legal property of its developers, whose names are too numerous

* to list here. Please refer to the COPYRIGHT file distributed with this

* source distribution.

* This program is free software; you can redistribute it and/or modify

* it under the terms of the GNU General Public License as published by

* the Free Software Foundation; either version 2 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 General Public License for more details.

* You should have received a copy of the GNU General Public License

* along with this library; if not, see <https://www.gnu.org/licenses/>.

#include "pidgincolor.h"

#include "pidginstylecontext.h"

/******************************************************************************

* Public API

*****************************************************************************/

void

pidgin_color_calculate_for_text(const gchar *text, GdkRGBA *color) {

GdkRGBA background;

GChecksum *checksum = NULL;

guchar digest[20];

gsize digest_len = sizeof(digest);

gdouble hue = 0, red = 0, green = 0, blue = 0;

g_return_if_fail(color != NULL);

pidgin_style_context_get_background_color(&background);

/* hash the string and get the first 2 bytes of the digest */

checksum = g_checksum_new(G_CHECKSUM_SHA1);

g_checksum_update(checksum, (const guchar *)text, -1);

g_checksum_get_digest(checksum, digest, &digest_len);

g_checksum_free(checksum);

/* Calculate the hue based on the digest. We need a value between 0 and 1

* so we divide the value by 65535 which is the maximum value for 2 bytes.

hue = (digest[0] << 8 | digest[1]) / 65535.0;

/* Get the rgb values for the hue at full saturation and value. */

gtk_hsv_to_rgb(hue, 1.0, 1.0, &red, &green, &blue);

/* Finally calculate the color summing 20% of the inverted background color

* with 80% of the color.

color->red = (0.2 * (1 - background.red)) + (0.8 * red);

color->green = (0.2 * (1 - background.green)) + (0.8 * green);

color->blue = (0.2 * (1 - background.blue)) + (0.8 * blue);

color->alpha = 1.0;

}