PHP 缩放图片(2)

                exit(); 
            } 
            $im = imagecreatefromgif($srcFile); 
            break; 
             
        case 2: 
            if(!function_exists("imagecreatefromjpeg")) 
            { 
                echo "the GD can't support .jpeg, please use other picture! <a href='javascript:history.back();'>back</a>"; 
                exit(); 
            } 
            $im = imagecreatefromjpeg($srcFile); 
            break; 
               
        case 3: 
            $im = imagecreatefrompng($srcFile);     
            break; 
        } 
         
        //计算缩略图的宽高  
        $srcW = imagesx($im); 
        $srcH = imagesy($im); 
        $toWH = $toW / $toH; 
        $srcWH = $srcW / $srcH; 
        if ($toWH <= $srcWH)  
        { 
            $ftoW = $toW; 
            $ftoH = (int)($ftoW * ($srcH / $srcW)); 
        } 
        else  
        { 
            $ftoH = $toH; 
            $ftoW = (int)($ftoH * ($srcW / $srcH)); 
        }