這個不完全是我自己寫的-_-！,但是好用呀

<?php
/**
 * Created by PhpStorm.
 * Note：文件介紹
 * User: Lynly
 * Date: 2018/11/19
 * Time: 14:33
 */

class Imgcompress
{
    private $src;
    private $image;
    private $imageinfo;
    private $percent = 0.5;

    /**
     * 圖片壓縮
     * @param string $src 源圖
     * @param float $percent 壓縮比例
     */
    public function __construct($src, $percent = 1)
    {
        $this->src = $src;
        $this->percent = $percent;
    }    /** 高清壓縮圖片
     * @param string $saveName 提供圖片名（可不帶擴展名，用源圖擴展名）用於保存。或不提供文件名直接顯示
     */
    public function compressImg($saveName = ‘‘)
    {
        $this->_openImage();
        if (!empty($saveName)) $this->_saveImage($saveName);  //保存
        else $this->_showImage();
    }

    /**
     * 內部：打開圖片
     */
    private function _openImage()
    {
        list($width, $height, $type, $attr) = getimagesize($this->src);
        $this->imageinfo = array(
            ‘width‘ => $width,
            ‘height‘ => $height,
            ‘type‘ => image_type_to_extension($type, false),
            ‘attr‘ => $attr
        );
        $fun = "imagecreatefrom" . $this->imageinfo[‘type‘];
        $this->image = $fun($this->src);
        $this->_thumpImage();
    }

    /**
     * 內部：操作圖片
     */
    private function _thumpImage()
    {
        $new_width = $this->imageinfo[‘width‘] * $this->percent;
        $new_height = $this->imageinfo[‘height‘] * $this->percent;
        $image_thump = imagecreatetruecolor($new_width, $new_height);
        //將原圖復制帶圖片載體上面，並且按照一定比例壓縮,極大的保持了清晰度
        imagecopyresampled($image_thump, $this->image, 0, 0, 0, 0, $new_width, $new_height, $this->imageinfo[‘width‘], $this->imageinfo[‘height‘]);
        imagedestroy($this->image);
        $this->image = $image_thump;
    }

    /**
     * 輸出圖片:保存圖片則用saveImage()
     */
    private function _showImage()
    {
        header(‘Content-Type: image/‘ . $this->imageinfo[‘type‘]);
        $funcs = "image" . $this->imageinfo[‘type‘];
        $funcs($this->image);
    }

    /**
     * 保存圖片到硬盤：
     * @param  string $dstImgName 1、可指定字符串不帶後綴的名稱，使用源圖擴展名 。2、直接指定目標圖片名帶擴展名。
     */
    private function _saveImage($dstImgName)
    {
        if (empty($dstImgName)) return false;
        $allowImgs = array(‘.jpg‘, ‘.jpeg‘, ‘.png‘, ‘.bmp‘, ‘.wbmp‘, ‘.gif‘);   //如果目標圖片名有後綴就用目標圖片擴展名 後綴，如果沒有，則用源圖的擴展名
        $dstExt = strrchr($dstImgName, ".");
        $sourseExt = strrchr($this->src, ".");
        if (!empty($dstExt)) $dstExt = strtolower($dstExt);
        if (!empty($sourseExt)) $sourseExt = strtolower($sourseExt);

        //有指定目標名擴展名
        if (!empty($dstExt) && in_array($dstExt, $allowImgs)) {
            $dstName = $dstImgName;
        } elseif (!empty($sourseExt) && in_array($sourseExt, $allowImgs)) {
            $dstName = $dstImgName . $sourseExt;
        } else {
            $dstName = $dstImgName . $this->imageinfo[‘type‘];
        }
        $funcs = "image" . $this->imageinfo[‘type‘];
        $funcs($this->image, $dstName);
    }

    /**
     * 銷毀圖片
     */
    public function __destruct()
    {
        imagedestroy($this->image);
    }}
 

PHP圖片壓縮類，高清無損直接用就ok啦