PHP实现图片旋转的方法详解

<?php
 
namespace common\traits;
 
use Yii;
use yii\helpers\FileHelper;
 

class ImageRotate
{
 
    
    public static function base64Rotate($image, $rotate = '90', $savePath = false)
    {
        if (empty($image)) {
            return false;
        }
        if (preg_match('/^(data:\s*image\/(\w+);base64,)/', $image, $result)) {
            $type = $result[2];
            //设置临时目录
            $temporaryPath = '/tmp/';
            $temporaryPath = dirname(Yii::getAlias('@common')) . '/WEB' . $temporaryPath;
            FileHelper::createDirectory($temporaryPath);
 
            //将原图保存到零食目录
            $temporaryImage = date('YmdHis') . rand(1000, 9999) . '.' . $type;
            if (file_put_contents($temporaryPath . $temporaryImage, base64_decode(str_replace($result[1], '', $image)))) {
                $newImage = self::rotateImage($temporaryPath . $temporaryImage, $rotate); //旋转图片
                //删除临时文件
                @unlink($temporaryPath . $temporaryImage);
 
                ob_start();
                if ($savePath === false) { //返回base
                    imagepng($newImage);
                    $imageString = $result[1] . base64_encode(ob_get_contents());
                    @unlink($newImage);
                } else {
                    $imageString = imagepng($newImage, $savePath);
                }
                ob_end_clean();
 
                return $imageString;
            }
        }
 
        return false;
    }
 
    
    public static function imageRotate($image, $rotate = '90', $savePath = false)
    {
        if (empty($image)) {
            return false;
        }
        //旋转图片
        $newImage = self::rotateImage($image, $rotate);
        ob_start();
        if ($savePath === false) {
            //替换原图
            $url = $image;
        } else {
            $url = $savePath;
        }
        $imageString = imagepng($newImage, $url);
        ob_end_clean();
        return $imageString;
    }
 
    
    private static function rotateImage($file, $rotate)
    {
        $imageSize = getimagesize($file);
        $imageSize = explode('/', $imageSize['mime']);
        $type = $imageSize[1];
 
        switch ($type) {
            case "png":
                $image = imagecreatefrompng($file);
                break;
            case "jpeg":
                $image = imagecreatefromjpeg($file);
                break;
            case "jpg":
                $image = imagecreatefromjpeg($file);
                break;
            case "gif":
                $image = imagecreatefromgif($file);
                break;
        }
        $rotateImage = imagerotate($image, $rotate, 0); //逆时针旋转
        //获取旋转后的宽高
        $srcWidth = imagesx($rotateImage);
        $srcHeight = imagesy($rotateImage);
        //创建新图
        $newImage = imagecreatetruecolor($srcWidth, $srcHeight);
        //分配颜色 + alpha，将颜色填充到新图上
        $alpha = imagecolorallocatealpha($newImage, 0, 0, 0, 127);
        imagefill($newImage, 0, 0, $alpha);
        //将源图拷贝到新图上，并设置在保存 PNG 图像时保存完整的 alpha 通道信息
        imagecopyresampled($newImage, $rotateImage, 0, 0, 0, 0, $srcWidth, $srcHeight, $srcWidth, $srcHeight);
        imagesavealpha($newImage, true);
 
        return $newImage;
    }
 
}

ImageRotate::base64Rotate('base64图片', '旋转角度');

ImageRotate::base64Rotate('base64图片', '旋转角度', '保存地址');

ImageRotate::imageRotate('本地图片地址', '旋转角度', '保存地址');