PHP generates image thumbnails and displays them in the browser, flexible and practical

Because I personally need to upload pictures to the website album and display them in the form of thumbnails, Baidu searched a lot of source codes and tried and failed. I wrote a function myself and it has run successfully. The way to display thumbnails in the browser is to point the src address of the image to a PHP file and call this function to display it.

/**
 *  _thumb()生成缩略图的函数
 */

function _thumb($_filename,$_max_size){  //(图片源地址，最大宽or高)
	//获取文件后缀
	$_n = explode('.', $_filename);
	//生成png表头文件
	header('Content-type:image/png');
	//获取文件的长和高
	list($_width,$_height) = getimagesize($_filename);
	//生成微缩的长和高
	$_percent = $_max_size / (($_width > $_height) ? $_width:$_height);
	$_new_width = $_width * $_percent;
	$_new_height = $_height * $_percent;
	//创建一个微缩画布
	$_new_image = imagecreatetruecolor($_new_width, $_new_height);
	//按照已有的图片创建一个画布
	switch ($_n[1]) {
		case 'jpg':
			$_image = imagecreatefromjpeg($_filename);
			break;
		case 'png':
			$_image = imagecreatefrompng($_filename);
			break;
		case 'gif':
			$_image = imagecreatefromgif($_filename);
			break;
	}
	//将原图采集后重新复制到图上，就缩略了
	imagecopyresampled($_new_image, $_image, 0,0,0,0, $_new_width, $_new_height, $_width, $_height);
	imagepng($_new_image);
	imagedestroy($_new_image);
	imagedestroy($_image);
}

The above introduces how to generate image thumbnails with PHP and display them in the browser. It is flexible and practical, including various aspects. I hope it will be helpful to friends who are interested in PHP tutorials.