【黄啊码】一次性讲清楚thinkphp给图片添加水印

/**
     * @param $sourcePath
     * @param $logoPath
     * @param $savePath
     * 给图片加水印
     */
    function addImageWater($sourcePath,$logoPath,$savePath){

        $img_info =  getimagesize($sourcePath);

        $im = null;
        
        if($img_info[2]==3){
            $im = imagecreatefrompng($sourcePath);
        }else{
            $im = imagecreatefromjpeg($sourcePath);
        }
        $watermark = imagecreatefrompng($logoPath);
        //获取图、水印 宽高类型
        list($bgWidth, $bgHight, $bgType) = getimagesize($sourcePath);
        list($logoWidth, $logoHight, $logoType) = getimagesize($logoPath);
        //定义平铺数据
        $x_length = $bgWidth-10; //x轴总长度
        $y_length = $bgHight-10; //y轴总长度
        //创建透明画布
        $opacity=0;
        $w = imagesx($watermark);
        $h = imagesy($watermark);
        $cut = imagecreatetruecolor($w,$h);
        $background_color = imagecolortransparent($cut,  0);
        
        imagefill($cut, 0, 0,$background_color);
        //整合水印
        imagecopy($cut, $watermark, 0, 0, 0, 0, $w, $h);
        //循环平铺水印
        for ($x = 0; $x < $x_length; $x++)
        {
            for ($y = 0; $y < $y_length; $y++) {
                imagecopymerge($im, $cut, $x, $y, 0, 0, $logoWidth, $logoHight, 20);
                $y += $logoHight+120;
            }
            $x += $logoWidth+140;
        }

        if($img_info[2]==3){
            imagepng($im,$savePath);
        }else{
            imagejpeg($im,$savePath);
        }
    }