README

这是 Blurhash 的纯 PHP 实现。[Blurhash](https://github.com/woltapp/blurhash)。API 是稳定的，但任意方向的哈希函数可能不稳定。

Blurhash 是由 [Dag Ågren](https://github.com/DagAgren) 为 [Wolt (woltapp/blurhash)](https://github.com/woltapp/blurhash) 编写的算法，可以将图像编码为短 (~20-30 字节) 的 ASCII 字符串。当你将字符串解码回图像时，你得到代表原始图像的颜色渐变。这在需要图像占位符的情况或甚至用于屏蔽图像内容（例如 [Mastodon](https://blog.joinmastodon.org/2019/05/improving-support-for-adult-content-on-mastodon/)）时非常有用。

安装

$ composer require kornrunner/blurhash

用法

使用 GD 进行编码

编码图像为 blurhash 需要图像像素颜色的二维数组，示例代码

<?php

require_once 'vendor/autoload.php';

use kornrunner\Blurhash\Blurhash;

$file  = 'test/data/img1.jpg';
$image = imagecreatefromstring(file_get_contents($file));
$width = imagesx($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;
}

$components_x = 4;
$components_y = 3;
$blurhash = Blurhash::encode($pixels, $components_x, $components_y);
// LEHV9uae2yk8pyo0adR*.7kCMdnj

使用 Intervention 进行编码

require_once 'vendor/autoload.php';

use kornrunner\Blurhash\Blurhash;
use Intervention\Image\Colors\Rgb\Channels\Blue;
use Intervention\Image\Colors\Rgb\Channels\Green;
use Intervention\Image\Colors\Rgb\Channels\Red;
use Intervention\Image\Colors\Rgb\Color as RgbColor;
use Intervention\Image\Colors\Rgb\Colorspace as RgbColorspace;
use Intervention\Image\Drivers\Gd\Driver;
use Intervention\Image\ImageManager;

$file  = 'test/data/img1.jpg';
$manager = new ImageManager(new Driver());
$image = $manager->read($file);
$width = $image->width();
$height = $image->height();

$pixels = [];
for ($y = 0; $y < $height; ++$y) {
    $row = [];
    for ($x = 0; $x < $width; ++$x) {
        $colors = $image->pickColor($x, $y);
        
        if (!($colors instanceof RgbColor)) {
            $colors = $colors->convertTo(new RgbColorspace());
        }

        $row[] = [
            $colors->channel(Red::class)->value(),
            $colors->channel(Green::class)->value(),
            $colors->channel(Blue::class)->value(),
        ];
    }
    $pixels[] = $row;
}

$components_x = 4;
$components_y = 3;
$blurhash = Blurhash::encode($pixels, $components_x, $components_y);
// LEHV9uae2yk8pyo0adR*.7kCMdnj

使用 JS/TS 进行解码

对于 blurhash 的解码，人们可能会选择其他实现（[JavaScript/TypeScript](https://github.com/woltapp/blurhash/tree/master/TypeScript)）。PHP 解码器返回一个像素数组，可以用来生成图像。

<?php

require_once 'vendor/autoload.php';

use kornrunner\Blurhash\Blurhash;

$blurhash = 'LEHV6nWB2yk8pyo0adR*.7kCMdnj';
$width    = 269;
$height   = 173;

$pixels = Blurhash::decode($blurhash, $width, $height);
$image  = imagecreatetruecolor($width, $height);
for ($y = 0; $y < $height; ++$y) {
    for ($x = 0; $x < $width; ++$x) {
        [$r, $g, $b] = $pixels[$y][$x];
        imagesetpixel($image, $x, $y, imagecolorallocate($image, $r, $g, $b));
    }
}
imagepng($image, 'blurhash.png');

贡献

欢迎问题、功能请求或改进！

许可协议

本项目采用 [MIT 许可协议](https://github.com/kornrunner/php-blurhash/blob/HEAD/LICENSE)。

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