project: blog
target: use-imagick-to-composite-images-thumbnail.md
date: 2016-02-19
status: publish
tags:
- php
- imagick
- thumbnail
categories:
- php
這裡說的imagick 是 ImageMagick 在PHP下的擴展。使用pecl安裝起來那叫一個輕松簡單 —— 一條命令就搞定：
sudo pecl install imagick
（擴展裝好後還是要在php.ini中加上extension=imagick.so，然後記得重啟apache或php-fpm服務。）
最近有個需求是要把多張圖片組合起來生成縮略圖，剛好用用這個強大的imagick擴展。
這個需求是要這樣生成縮略圖：
這規則還真不少，不過還不算太過復雜，很快搞出來了：
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,
]
],
];
}
}
}
用個試試：
$thumbnail = \clarence\thumbnail\Thumbnail::createFromImages($srcImages, 240, 320);
$thumbnail->writeImage($outputDir."/example.jpg");
效果立馬出來了：
贊一個~
（詳細代碼見 http://github.com/clarence-pan/thumbnail)
