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ColourRangeRGB.php
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ColourRangeRGB.php
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<?php
/**
* Copyright (C) 2019-2022 Graham Breach
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* For more information, please contact <graham@goat1000.com>
*/
namespace Goat1000\SVGGraph;
/**
* Colour range for RGB values
*/
class ColourRangeRGB extends ColourRange {
private $r1, $g1, $b1;
private $rdiff, $gdiff, $bdiff;
/**
* RGB range
*/
public function __construct($r1, $g1, $b1, $r2, $g2, $b2)
{
$this->r1 = $this->clamp($r1, 0, 255);
$this->g1 = $this->clamp($g1, 0, 255);
$this->b1 = $this->clamp($b1, 0, 255);
$this->rdiff = $this->clamp($r2, 0, 255) - $this->r1;
$this->gdiff = $this->clamp($g2, 0, 255) - $this->g1;
$this->bdiff = $this->clamp($b2, 0, 255) - $this->b1;
}
/**
* Return the colour from the range
*/
#[\ReturnTypeWillChange]
public function offsetGet($offset)
{
$c = max($this->count - 1, 1);
$offset = $this->clamp($offset, 0, $c);
$r = $this->r1 + $offset * $this->rdiff / $c;
$g = $this->g1 + $offset * $this->gdiff / $c;
$b = $this->b1 + $offset * $this->bdiff / $c;
return sprintf('#%02x%02x%02x', $r, $g, $b);
}
}