PbootCms缩略图裁剪优化居中裁剪（直接上干货）

// 剪切图片
function cut_img($src_image, $out_image = null, int $new_width = null, int $new_height = null, $img_quality = 90)
{
    // 输出地址
    if (! $out_image)
        $out_image = $src_image;
    
    // 读取配置文件设置
    if (! $new_width && ! $new_height)
        return;
    
    // 获取图片属性
    list ($width, $height, $type, $attr) = getimagesize($src_image);
    switch ($type) {
        case 1:
            $img = imagecreatefromgif($src_image);
            break;
        case 2:
            $img = imagecreatefromjpeg($src_image);
            break;
        case 3:
            $img = imagecreatefrompng($src_image);
            break;
    }
    
    // 不限定是等比例缩放
    if (! $new_width) {
        $new_width = floor($width * ($new_height / $height));
    }
    if (! $new_height) {
        $new_height = floor($height * ($new_width / $width));
    }
    // 创建画布
    $new_img = imagecreatetruecolor($new_width, $new_height);
    
    // 创建透明画布,避免黑色
    if ($type == 1 || $type == 3) {
        $color = imagecolorallocate($new_img, 255, 255, 255);
        imagefill($new_img, 0, 0, $color);
        imagecolortransparent($new_img, $color);
    }


    // 先缩放
    $scale = max($new_width / $width, $new_height / $height);
    $scale_width = floor($scale * $width);
    $scale_height = floor($scale * $height);
    $scale_img = imagecreatetruecolor($scale_width, $scale_height); // 创建画布
    if(function_exists("ImageCopyResampled")) {
       imagecopyresampled($scale_img, $img, 0, 0, 0, 0, $scale_width, $scale_height, $width, $height);
    } else {
       imagecopyresized($scale_img, $img, 0, 0, 0, 0, $scale_width, $scale_height, $width, $height);
    }
    //再裁剪
    $start_x = ($scale_width - $new_width) / 2;
    $start_y = ($scale_height - $new_height) / 2;

    //拷贝剪切的图像数据到画板，生成剪切图像
    imagecopy($new_img, $scale_img, 0, 0, $start_x, $start_y, $scale_width, $scale_height);

    check_dir(dirname($out_image), true); // 检查输出目录
    
    switch ($type) {
        case 1:
            imagegif($new_img, $out_image, $img_quality);
            break;
        case 2:
            imagejpeg($new_img, $out_image, $img_quality);
            break;
        case 3:
            imagepng($new_img, $out_image, $img_quality / 10); // $quality参数取值范围0-99 在php 5.1.2之后变更为0-9
            break;
        default:
            imagejpeg($new_img, $out_image, $img_quality);
    }
    imagedestroy($new_img);
    imagedestroy($img);
    return true;
}

{pboot:list scode=*}
<a href= "[list:link]"><img src="[list:ico width=600 height=400]" /></a>
{/pboot:list}