Yii 框架生成缩略图

控制器

if($model->load(Yii::$app->request->post()))
        {

//原图
            $model->img = UploadedFile::getInstance($model, 'img');
            $imgname=$model->img->name = time().$model->img->name;
    
            //$model->img->saveAs('./upload/image/' . $model->img->baseName . '.' . $model->img->extension);
            
            //设定上传目录
            $path=Yii::$app->basePath.'/web/upload/image/'.$imgname;
            //上传原图 图片
            $model->img->saveAs($path);

//获取上传原图文件的名称   
            $image=$model->img;
            $img=$image->name;
            //echo $img;die;            
            //利用扩展生成缩略图
            $im = null;
            //取图片类型
            $imagetype = strtolower($model->img->extension);
            if($imagetype == 'gif')
                $im = imagecreatefromgif($path);
            else if ($imagetype == 'jpg')
                $im = imagecreatefromjpeg($path);
            else if ($imagetype == 'png')
                $im = imagecreatefrompng($path);
           
            //按时间生成新文件名
            $newName=$model->img->baseName.'_thumb_'.'.'.$model->img->extension;
            //设定缩略图的存放目录+名字
            $thumb_path=Yii::$app->basePath.'/web/upload/image/image_thumb/'.$newName;
            //生成缩略图
            $sql=$model->resizeImage($im,800,450,$thumb_path,$model->img->extension);
    }

在model 模型层里添加 resizeImage 方法

public static function resizeImage($im, $maxwidth, $maxheight, $name,$filetype) {
        $pic_width = imagesx ( $im );
        $pic_height = imagesy ( $im );

if (($maxwidth && $pic_width > $maxwidth) || ($maxheight && $pic_height > $maxheight)) {
            if ($maxwidth && $pic_width > $maxwidth) {
                $widthratio = $maxwidth / $pic_width;
                $resizewidth_tag = true;
            }
            
            if ($maxheight && $pic_height > $maxheight) {
                $heightratio = $maxheight / $pic_height;
                $resizeheight_tag = true;
            }
            
            if ($resizewidth_tag && $resizeheight_tag) {
                if ($widthratio < $heightratio)
                    $ratio = $widthratio;
                else
                    $ratio = $heightratio;
            }
            
            if ($resizewidth_tag && ! $resizeheight_tag)
                $ratio = $widthratio;
            if ($resizeheight_tag && ! $resizewidth_tag)
                $ratio = $heightratio;
            
            $newwidth = $pic_width * $ratio;
            $newheight = $pic_height * $ratio;
            
            if (function_exists ( "imagecopyresampled" )) {
                $newim = imagecreatetruecolor ( $newwidth, $newheight );
                imagecopyresampled ( $newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $pic_width, $pic_height );
            } else {
                $newim = imagecreate ( $newwidth, $newheight );
                imagecopyresized ( $newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $pic_width, $pic_height );
            }
            
            imagejpeg ( $newim, $name );
            imagedestroy ( $newim );
        } else {
            //$name = $name . $filetype;//这句好像多余了
            imagejpeg ( $im, $name );
        }
    }

很简单,,这样就可以了