改变图片尺寸

<?php
	/**
	 * 图片缩放函数（可设置高度固定，宽度固定或者最大宽高，支持gif/jpg/png三种类型）
	 * @param string $source_path 源图片
	 * @param int $target_width 目标宽度
	 * @param int $target_height 目标高度
	 * @param string $fixed_orig 锁定宽高（可选参数 width、height或者空值）
	 * @return string
	 */
	function myImageResize($source_path, $target_width = 200, $target_height = 200, $fixed_orig = ''){
		$source_info = getimagesize($source_path);
		$source_width = $source_info[0];
		$source_height = $source_info[1];
		$source_mime = $source_info['mime'];
		$ratio_orig = $source_width / $source_height;
		//$fixed_orig随便填写,将强制按照填写的大小存储
		if ($fixed_orig == 'width'){
			//宽度固定
			$target_height = $target_width / $ratio_orig;
		} elseif ($fixed_orig == 'height'){
			//高度固定
			$target_width = $target_height * $ratio_orig;	
		} elseif ($fixed_orig === '') {
			//最大宽或最大高
			if ($target_width / $target_height > $ratio_orig){
				$target_width = $target_height * $ratio_orig;
			}else{
				$target_height = $target_width / $ratio_orig;
			}
		}
		switch ($source_mime){
			case 'image/gif':
				$source_image = imagecreatefromgif($source_path);
				break;
			
			case 'image/jpeg':
				$source_image = imagecreatefromjpeg($source_path);
				break;
			
			case 'image/png':
				$source_image = imagecreatefrompng($source_path);
				break;
			
			default:
				return false;
				break;
		}
		$target_image = imagecreatetruecolor($target_width, $target_height);
		imagecopyresampled($target_image, $source_image, 0, 0, 0, 0, $target_width, $target_height, $source_width, $source_height);
		$imgArr = explode('.', $source_path);
		$target_path = $imgArr[0] . '_new.' . $imgArr[1];
		imagejpeg($target_image, $target_path, 100);
		imagedestroy($target_image);
		imagedestroy($source_image);
	}
	$filename= '1.jpg';
	myImageResize($filename, 200, 200, 'free'); //宽高200
?>