php生成水印，包括位置和透明度(4)

                                $start_w  = ($old_w-$end_w)/2;

                                $start_h = 0;

                                $end_h   = $old_h;

                        }

                        $width = $new_w;

                    $height= $new_h;

                } elseif($cut == 2){ // left top 裁剪

                        $scale1 = round($new_w/$new_h,2);

                    $scale2 = round($old_w/$old_h,2);

                    if($scale1 > $scale2){

                            $end_h = round($old_w/$scale1,2);

                            $end_w = $old_w;

                    } else{

                            $end_w = round($old_h*$scale1,2);

                            $end_h = $old_h;

                    }

                    $start_w = 0;

                    $start_h = 0;