Generate sparklines with vanilla PHP

Sparkline.php

<?php

class Sparkline
{
    public $values = [];

    public $width = '4em';

    public $height = '1em';

    public $stroke_width = 1;

    public $stroke_colour = '#000000';

    public $fill_colour = '#000000';

    public $fill_opacity = 0.05;

    public function __construct($values = [])
    {
        $this->values = $values;
    }

    public static function from_values($values = [])
    {
        return (new static)->set_values($values);
    }

    public function set_values($values)
    {
        $this->values = $values;

        return $this;
    }

    public function set_width($width)
    {
        $this->width = $width;

        return $this;
    }

    public function set_height($height)
    {
        $this->height = $height;

        return $this;
    }

    public function set_colour($colour)
    {
        $this->stroke_colour = $colour;
        $this->fill_colour = $colour;

        return $this;
    }

    public function set_stroke_width($stroke_width)
    {
        $this->stroke_width = $stroke_width;

        return $this;
    }

    public function set_stroke_colour($stroke_colour)
    {
        $this->stroke_colour = $stroke_colour;

        return $this;
    }

    public function set_fill_colour($fill_colour)
    {
        $this->fill_colour = $fill_colour;

        return $this;
    }

    public function set_fill_opacity($fill_opacity)
    {
        $this->fill_opacity = $fill_opacity;

        return $this;
    }

    public function render()
    {
        [$min, $max, $count] = [min($this->values), max($this->values), count($this->values)];
        [$view_box_width, $view_box_height] = [$count - 1, $max];

        $i = 0;
        $points = [];
        foreach ($this->values as $value) {
            [$x, $y] = [$i, $max - $value];

            if ($i === 0) {
                $points[] = "M {$x} {$y}";
            } else {
                $points[] = "L {$x} {$y}";
            }

            $i++;
        }

        $points = implode(' ', $points);

        return <<<SVG
            <svg width="{$this->width}" height="{$this->height}" viewBox="0 0 {$view_box_width} {$view_box_height}" preserveAspectRatio="none" role="img" xmlns="http://www.w3.org/2000/svg">
                <path d="{$points}" stroke-width="{$this->stroke_width}" stroke="{$this->stroke_colour}" fill="transparent" vector-effect="non-scaling-stroke" />
                <path d="{$points} V {$max} H 0 Z" fill="{$this->fill_colour}" fill-opacity="{$this->fill_opacity}" vector-effect="non-scaling-stroke" />
            </svg>
            SVG;
    }
}