Image.php

<?php

namespace Hft\Font;

/**
 * Class ImageTtfBbox
 * @package Hft\Font
 * @author  Aydin Hassan <aydin@hotmail.co.uk>
 */
class Image
{
    /**
     * @param int $size
     * @param int $angle
     * @param string $font
     * @param string $text
     *
     * @return array
     */
    public function imagettfbbox($size, $angle, $font, $text)
    {
        $dimensions         = imagettfbbox($size, $angle, $font, $text);
        $width              = abs($dimensions[4] - $dimensions[0]);
        $height             = abs($dimensions[5] - $dimensions[1]);
        $exaggeratedWidth   = $width * 2;
        $exaggeratedHeight  = $height * 2;

        $image      = imagecreatetruecolor($exaggeratedWidth, $exaggeratedHeight);

        $fontColour = imagecolorallocate($image, 0, 0, 0); //000000
        $bgColour   = imagecolorallocate($image, 204, 204, 204); //CCCCCC
        imagefilledrectangle($image, 0, 0, $exaggeratedWidth, $exaggeratedHeight, $bgColour);

        $x1 = $dimensions[0] + ($width / 2);
        $y1 = $dimensions[7] + $height;
        $x2 = $dimensions[2] + ($width / 2);
        $y2 = $dimensions[3] + $height;

        imagefilledrectangle($image, $x1, $y1, $x2, $y2, imagecolorallocate($image, 255, 255, 255));
        imagettftext($image, $size, $angle, $width / 2, $height, $fontColour, $font, $text);

        $xOffset = $this->getXOffset($image, $x1, $y1, $width, $height);

        return [
            -$xOffset,
            $dimensions[1],
            $dimensions[2] - $xOffset,
            $dimensions[3],
            $dimensions[4] - $xOffset,
            $dimensions[5],
            -$xOffset,
            $dimensions[7]
        ];
    }

    /**
     * @param resource $image
     * @param int $xStart
     * @param int $yStart
     * @param int $width
     * @param int $height
     *
     * @return int
     */
    private function getXOffset($image, $xStart, $yStart, $width, $height)
    {
        $rgbWhite   = [255, 255, 255];
        $xRight     = $xStart + $width;
        $yBottom    = $yStart + $height;

        for ($x = $xRight; $x >= $xStart; $x--) {
            for ($y = $yBottom; $y >= $yStart; $y--) {
                $pixelColour = imagecolorat($image, $x, $y);

                if ($this->indexToRgb($pixelColour) !== $rgbWhite) {
                    return ($width + $xStart) - $x;
                }
            }
        }

        return 0;
    }

    /**
     * @param int $index
     * @return array
     */
    private function indexToRgb($index)
    {
        $r = ($index >> 16) & 0xFF;
        $g = ($index >> 8) & 0xFF;
        $b = $index & 0xFF;
        return [$r, $g, $b];
    }
}