$start_y 起始位置Y(当选定方位模式裁剪时，此参数不起作用)

* @return 裁剪图片存储路径

*/

function thumb($src_file, $new_width, $new_height, $type = 1, $pos = 5, $start_x = 0, $start_y = 0) {

$pathinfo = pathinfo($src_file);

$dst_file = $pathinfo['dirname'] . '/' . $pathinfo['filename'] .'_'. $new_width . 'x' . $new_height . '.' . $pathinfo['extension'];

if (!file_exists($dst_file)) {

if ($new_width < 1 || $new_height < 1) {

echo "params width or height error !";

exit();

}

if (!file_exists($src_file)) {

echo $src_file . " is not exists !";

exit();

}

// 图像类型

$img_type = exif_imagetype($src_file);

$support_type = array(IMAGETYPE_JPEG, IMAGETYPE_PNG, IMAGETYPE_GIF);

if (!in_array($img_type, $support_type, true)) {

echo "只支持jpg、png、gif格式图片裁剪";

exit();

}

/* 载入图像 */

switch ($img_type) {

case IMAGETYPE_JPEG :

$src_img = imagecreatefromjpeg($src_file);

break;

case IMAGETYPE_PNG :

$src_img = imagecreatefrompng($src_file);

break;

case IMAGETYPE_GIF :

$src_img = imagecreatefromgif($src_file);

break;

default:

echo "载入图像错误!";

exit();

}

/* 获取源图片的宽度和高度 */

$src_width = imagesx($src_img);

$src_height = imagesy($src_img);

/* 计算剪切图片的宽度和高度 */

$mid_width = ($src_width < $new_width) ? $src_width : $new_width;

$mid_height = ($src_height < $new_height) ? $src_height : $new_height;

/* 初始化源图片剪切裁剪的起始位置坐标 */

switch ($pos * $type) {

case 1://1为顶端居左

$start_x = 0;

$start_y = 0;

break;

case 2://2为顶端居中

$start_x = ($src_width - $mid_width) / 2;

$start_y = 0;

break;

case 3://3为顶端居右

$start_x = $src_width - $mid_width;

$start_y = 0;

break;

case 4://4为中部居左

$start_x = 0;

$start_y = ($src_height - $mid_height) / 2;

break;

case 5://5为中部居中

$start_x = ($src_width - $mid_width) / 2;

$start_y = ($src_height - $mid_height) / 2;

break;

case 6://6为中部居右

$start_x = $src_width - $mid_width;

$start_y = ($src_height - $mid_height) / 2;

break;

case 7://7为底端居左

$start_x = 0;

$start_y = $src_height - $mid_height;

break;

case 8://8为底端居中

$start_x = ($src_width - $mid_width) / 2;

$start_y = $src_height - $mid_height;

break;

case 9://9为底端居右

$start_x = $src_width - $mid_width;

$start_y = $src_height - $mid_height;

break;

default://随机

break;

}

// 为剪切图像创建背景画板

$mid_img = imagecreatetruecolor($mid_width, $mid_height);

//拷贝剪切的图像数据到画板，生成剪切图像

imagecopy($mid_img, $src_img, 0, 0, $start_x, $start_y, $mid_width, $mid_height);

// 为裁剪图像创建背景画板

$new_img = imagecreatetruecolor($new_width, $new_height);

//拷贝剪切图像到背景画板，并按比例裁剪

imagecopyresampled($new_img, $mid_img, 0, 0, 0, 0, $new_width, $new_height, $mid_width, $mid_height);

/* 按格式保存为图片 */

switch ($img_type) {

case IMAGETYPE_JPEG :

imagejpeg($new_img, $dst_file, 100);

break;

case IMAGETYPE_PNG :

imagepng($new_img, $dst_file, 9);

break;

case IMAGETYPE_GIF :

imagegif($new_img, $dst_file, 100);

break;

default:

break;

}

}

return ltrim($dst_file, '.');

}