<?
/*
$imgPath 源图片路径
$maxWidth 缩小后最大宽度
$maxHeight 缩小后最大高度
$destPath 目标路径，留空则直接输出
*/
function resizeImg($imgPath, $maxWidth, $maxHeight, $destPath = '') {
	$img = imagecreatefromjpeg($imgPath); 
	$w = $w_o = imagesx($img);
	$h = $h_o = imagesy($img);

	if($w > $maxWidth) {
		$h = intval($h*$maxWidth/$w);
		$w = $maxWidth;
	}
	if($h > $maxHeight) {
		$w = intval($w*$maxHeight/$h);
		$h = $maxHeight;
	}
	//echo $w.",".$h;exit;
	$img2 = imagecreatetruecolor($w, $h); 
	imagecopyresampled($img2, $img, 0, 0, 0, 0, $w, $h, $w_o, $h_o); 
	if($destPath) {
		imagejpeg($img2, $destPath, 80); 
	} else {
		header("Content-Type:image/jpeg"); 
		imagejpeg($img2, '', 80); 
	}

	imagedestroy($img2);
	imagedestroy($img); 
}

//resizeImg("1.jpg", 300, 300);