PHP下使用强大的imagick轻巧生成组合缩略图

PHP下使用强大的imagick轻松生成组合缩略图

<code class="language-meta">project: blogtarget: use-imagick-to-composite-images-thumbnail.mddate: 2016-02-19status: publishtags:    - php    - imagick    - thumbnailcategories:    - php</code>

这里说的imagick 是 ImageMagick 在PHP下的扩展。使用pecl安装起来那叫一个轻松简单 —— 一条命令就搞定：

<code class="language-sh">sudo pecl install imagick</code>

（扩展装好后还是要在php.ini中加上extension=imagick.so，然后记得重启apache或php-fpm服务。）

最近有个需求是要把多张图片组合起来生成缩略图，刚好用用这个强大的imagick扩展。
这个需求是要这样生成缩略图：

1. 如果有1张图片，就直接生成这张图片的缩略图；
2. 如果有2张图片，则一张在左边一张在右边，各一半；
3. 如果有3张图片，则两张左边平均分配，一张独占右边；
4. 如果有4张图片，则像田字格一样平均分配空间；
5. 更多张图片，则只取前4张，按田字格方式生成缩略图。

这规则还真不少，不过还不算太过复杂，很快搞出来了：

<code class="language-php">namespace \clarence\thumbnail;class Thumbnail extends \Imagick{    /**     * @param array $images     * @param int $width     * @param int $height     * @return static     * @throws ThumbnailException     */    public static function createFromImages($images, $width, $height){        if (empty($images)){            throw new ThumbnailException("No images!");        }        $thumbnail = new static();        $thumbnail->newImage($width, $height, 'white', 'jpg');        $thumbnail->compositeImages($images);        return $thumbnail;    }    public function compositeImages($images){        $imagesKeys = array_keys($images);        $compositeConfig = $this->calcCompositeImagesPosAndSize($images);        foreach ($compositeConfig as $index => $cfg){            $imgKey = $imagesKeys[$index];            $img = new \Imagick($images[$imgKey]);            $img = $this->makeCompositeThumbnail($img, $cfg);            $this->compositeImage($img, self::COMPOSITE_OVER, $cfg['to']['x'], $cfg['to']['y']);        }    }    protected function makeCompositeThumbnail(\Imagick $img, $cfg){        $img->cropThumbnailImage($cfg['size']['width'], $cfg['size']['height']);        return $img;    }    protected function calcCompositeImagesPosAndSize($images){        $width = $this->getImageWidth();        $height = $this->getImageHeight();        switch(count($images)){            case 0:                throw new ThumbnailException("No images!");            case 1:                // | 0 |                return [                    0 => [                        'to' => [ 'x' => 0, 'y' => 0 ],                        'size' => [                            'width' => $width,                            'height' => $height,                        ]                    ]                ];            case 2:                // | 0 | 1 |                return [                    0 => [                        'to' => [ 'x' => 0, 'y' => 0 ],                        'size' => [                            'width' => $width / 2,                            'height' => $height,                        ]                    ],                    1 => [                        'to' => [ 'x' => $width / 2, 'y' => 0],                        'size' => [                            'width' => $width / 2,                            'height' => $height,                        ]                    ]                ];            case 3:                // | 0 | 1 |                // | 2 |   |                return [                    0 => [                        'to' => [ 'x' => 0, 'y' => 0 ],                        'size' => [                            'width' => $width / 2,                            'height' => $height / 2,                        ]                    ],                    1 => [                        'to' => [ 'x' => $width / 2, 'y' => 0],                        'size' => [                            'width' => $width / 2,                            'height' => $height,                        ]                    ],                    2 => [                        'to' => [ 'x' => 0, 'y' => $height / 2 ],                        'size' => [                            'width' => $width / 2,                            'height' => $height / 2,                        ]                    ],                ];            default:                // >= 4:                // | 0 | 1 |                // | 2 | 3 |                return [                    0 => [                        'to' => [ 'x' => 0, 'y' => 0 ],                        'size' => [                            'width' => $width / 2,                            'height' => $height / 2,                        ]                    ],                    1 => [                        'to' => [ 'x' => $width / 2, 'y' => 0],                        'size' => [                            'width' => $width / 2,                            'height' => $height / 2,                        ]                    ],                    2 => [                        'to' => [ 'x' => 0, 'y' => $height / 2 ],                        'size' => [                            'width' => $width / 2,                            'height' => $height / 2,                        ]                    ],                    3 => [                        'to' => [ 'x' => $width / 2, 'y' => $height / 2],                        'size' => [                            'width' => $width / 2,                            'height' => $height / 2,                        ]                    ],                ];        }    }}</code>

用个试试：

<code class="language-php">$thumbnail = \clarence\thumbnail\Thumbnail::createFromImages($srcImages, 240, 320);$thumbnail->writeImage($outputDir."/example.jpg");</code>

效果立马出来了：

赞一个~

（详细代码见 http://github.com/clarence-pan/thumbnail)