/**

 * 居中裁剪图片

 * @param string $source [原图路径]

 * @param int $width [设置宽度]

 * @param int $height [设置高度]

 * @param string $target [目标路径]

 * @return bool [裁剪结果]

 */

function image_center_crop($source, $width, $height, $target)

{

    if (!file_exists($source)) return false;

    /* 根据类型载入图像 */

    switch (exif_imagetype($source)) {

        case IMAGETYPE_JPEG:

            $image = imagecreatefromjpeg($source);

            break;

        case IMAGETYPE_PNG:

            $image = imagecreatefrompng($source);

            break;

        case IMAGETYPE_GIF:

            $image = imagecreatefromgif($source);

            break;

    }

    if (!isset($image)) return false;

    /* 获取图像尺寸信息 */

    $target_w = $width;

    $target_h = $height;

    $source_w = imagesx($image);

    $source_h = imagesy($image);

    /* 计算裁剪宽度和高度 */

    $judge = (($source_w / $source_h) > ($target_w / $target_h));

    $resize_w = $judge ? ($source_w * $target_h) / $source_h : $target_w;

    $resize_h = !$judge ? ($source_h * $target_w) / $source_w : $target_h;

    $start_x = $judge ? ($resize_w - $target_w) / 2 : 0;

    $start_y = !$judge ? ($resize_h - $target_h) / 2 : 0;

    /* 绘制居中缩放图像 */

    $resize_img = imagecreatetruecolor($resize_w, $resize_h);

    imagecopyresampled($resize_img, $image, 0, 0, 0, 0, $resize_w, $resize_h, $source_w, $source_h);

    $target_img = imagecreatetruecolor($target_w, $target_h);

    imagecopy($target_img, $resize_img, 0, 0, $start_x, $start_y, $resize_w, $resize_h);

    /* 将图片保存至文件 */

    if (!file_exists(dirname($target))) mkdir(dirname($target), 0777, true);

    switch (exif_imagetype($source)) {

        case IMAGETYPE_JPEG:

            imagejpeg($target_img, $target);

            break;

        case IMAGETYPE_PNG:

            imagepng($target_img, $target);

            break;

        case IMAGETYPE_GIF:

            imagegif($target_img, $target);

            break;

    }

    return boolval(file_exists($target));

}

// 原始图片的路径

$source = '../source/img/middle.jpg';

$width = 480; // 裁剪后的宽度

$height = 480;// 裁剪后的高度

// 裁剪后的图片存放目录

$target = '../source/temp/resize.jpg';

// 裁剪后保存到目标文件夹

if (image_center_crop($source, $width, $height, $target)) {

    echo "<img src='$target'>";

}