project: blog
target: use-imagick-to-composite-images-thumbnail.md
date: 2016-02-19
status: publish
tags:
- php
- imagick
- thumbnail
categories:
- php
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：
sudo pecl install imagick
（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：
- 如果有1张图片，就直接生成这张图片的缩略图；
- 如果有2张图片，则一张在左边一张在右边，各一半；
- 如果有3张图片，则两张左边平均分配，一张独占右边；
- 如果有4张图片，则像田字格一样平均分配空间；
- 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：
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,
]
],
];
}
}
}
用个试试：
$thumbnail = \clarence\thumbnail\Thumbnail::createFromImages($srcImages, 240, 320);
$thumbnail->writeImage($outputDir."/example.jpg");
效果立马出来了：
赞一个~
