pixelfed/app/Util/Media/Blurhash.php

<?php

namespace App\Util\Media;

use App\Media;
use App\Util\Blurhash\Blurhash as BlurhashEngine;

class Blurhash
{
    const DEFAULT_HASH = 'U4Rfzst8?bt7ogayj[j[~pfQ9Goe%Mj[WBay';

    public static function generate(Media $media, $path = false)
    {
        if (! in_array($media->mime, ['image/png', 'image/jpeg', 'image/jpg', 'video/mp4'])) {
            return self::DEFAULT_HASH;
        }

        if ($media->thumbnail_path == null) {
            return self::DEFAULT_HASH;
        }

        if ($path) {
            $file = $path;
        } else {
            $localFs = config('filesystems.default') === 'local';
            $file = storage_path('app/'.$media->thumbnail_path);
        }

        if (! is_file($file)) {
            return self::DEFAULT_HASH;
        }

        $image = imagecreatefromstring(file_get_contents($file));
        if (! $image) {
            return self::DEFAULT_HASH;
        }
        $width = imagesx($image);
        $height = imagesy($image);

        $pixels = [];
        for ($y = 0; $y < $height; $y++) {
            $row = [];
            for ($x = 0; $x < $width; $x++) {
                $index = imagecolorat($image, $x, $y);
                $colors = imagecolorsforindex($image, $index);

                $row[] = [$colors['red'], $colors['green'], $colors['blue']];
            }
            $pixels[] = $row;
        }

        imagedestroy($image);

        $components_x = 4;
        $components_y = 4;
        $blurhash = BlurhashEngine::encode($pixels, $components_x, $components_y);
        if (strlen($blurhash) > 191) {
            return self::DEFAULT_HASH;
        }

        return $blurhash;
    }
}