我们经常会遇到对图像进行裁剪动作，下面这段代码就是裁剪的源码

处理方法是:

1.当原图的宽或高任一比规定的尺寸小,只进行等比缩略处理,

2.当原图的宽与高都比规定尺寸大,先进行等比缩略处理,然后算出居中位置进行裁剪

/*
 *        $o_photo 原图路径
 *        $d_photo 处理后图片路径
 *        $width   定义宽
 *        $height  定义高
 *        调用方法  cutphoto("test.jpg","temp.jpg",256,146);
 */
function cutphoto($o_photo, $d_photo, $width, $height) {
    $temp_img = imagecreatefromjpeg($o_photo);
    $o_width = imagesx($temp_img);                                //取得原图宽
    $o_height = imagesy($temp_img);                                //取得原图高
//判断处理方法
    if ($width > $o_width || $height > $o_height) {        //原图宽或高比规定的尺寸小,进行压缩
        $newwidth = $o_width;
        $newheight = $o_height;
        if ($o_width > $width) {
            $newwidth = $width;
            $newheight = $o_height * $width / $o_width;
        }
        if ($newheight > $height) {
            $newwidth = $newwidth * $height / $newheight;
            $newheight = $height;
        }
        //缩略图片
        $new_img = imagecreatetruecolor($newwidth, $newheight);
        imagecopyresampled($new_img, $temp_img, 0, 0, 0, 0, $newwidth, $newheight, $o_width, $o_height);
        imagejpeg($new_img, $d_photo);
        imagedestroy($new_img);
    } else {                                                                                //原图宽与高都比规定尺寸大,进行压缩后裁剪
        if ($o_height * $width / $o_width > $height) {        //先确定width与规定相同,如果height比规定大,则ok
            $newwidth = $width;
            $newheight = $o_height * $width / $o_width;
            $x = 0;
            $y = ($newheight - $height) / 2;
        } else {                                                                        //否则确定height与规定相同,width自适应
            $newwidth = $o_width * $height / $o_height;
            $newheight = $height;
            $x = ($newwidth - $width) / 2;
            $y = 0;
        }
        //缩略图片
        $new_img = imagecreatetruecolor($newwidth, $newheight);
        imagecopyresampled($new_img, $temp_img, 0, 0, 0, 0, $newwidth, $newheight, $o_width, $o_height);
        imagejpeg($new_img, $d_photo);
        imagedestroy($new_img);
        $temp_img = imagecreatefromjpeg($d_photo);
        $o_width = imagesx($temp_img);                                //取得缩略图宽
        $o_height = imagesy($temp_img);                                //取得缩略图高
        //裁剪图片
        $new_imgx = imagecreatetruecolor($width, $height);
        imagecopyresampled($new_imgx, $temp_img, 0, 0, $x, $y, $width, $height, $width, $height);
        imagejpeg($new_imgx, $d_photo);
        imagedestroy($new_imgx);
    }
}
cutphoto("http://tp3.sinaimg.cn/1700691210/180/1280120708/1", "temp1.jpg", 100, 100);
cutphoto("http://hhcf.tk/img/avatar_big/1318072877.jpg", "temp2.jpg", 100, 100);