探讨下缩略图算法的实现(70行实现和3行实现)

[nozerock]

前几天在找缩略图算法的时候发现网上的算法和我想的不太一样
这个是原帖
http://www.open-open.com/lib/view/open1337330620354.html

这个是我写的
当然,某些部分是参考上面的一篇帖子的

  public function createThumbImage($SourcePath, $SavePath)
  {
    if(!is_file($SourcePath))
    {return false;}
    $FilePath = pathinfo($SourcePath);
    $FileExt = $FilePath['extension'];
    if(!$this->checkFileExt($FileExt))
    {return false;}
    $createfun = 'imagecreatefrom' . ($FileExt == 'jpg' ? 'jpeg' : strtolower($FileExt));
    
    $ImgInfo = getimagesize($SourcePath);
    $SourceW = floatval($ImgInfo[0]);
    $SourceH = floatval($ImgInfo[1]);
    $NewW = $TargetW = floatval($this->DefaultWidth);
    $NewH = $TargetH = floatval($this->DefaultHeight);
    (($SourceW / $SourceH) <= ($TargetW / $TargetH)) ? $NewH = $SourceH * ($TargetW / $SourceW) : $NewW = $SourceW * ($TargetH / $SourceH);
    $x = ($TargetW - $NewW) / 2;
    $y = ($TargetH - $NewH) / 2;
    
    $SourceImg = $createfun($SourcePath);
    $TargetImg = imagecreatetruecolor($TargetW, $TargetH);
    if(function_exists('imagecopyresampled'))
    {
      imagecopyresampled($TargetImg, $SourceImg, $x, $y, 0, 0, $NewW, $NewH, $SourceW, $SourceH);
    }
    else
    {
      imagecopyresized($TargetImg, $SourceImg, $x, $y, 0, 0, $NewW, $NewH, $SourceW, $SourceH);
    }
    return $this->saveImageByExt($TargetImg, $FileExt, $SavePath);
  }

关键实现的是这几行

    $NewW = $TargetW = floatval($this->DefaultWidth);
    $NewH = $TargetH = floatval($this->DefaultHeight);
    (($SourceW / $SourceH) <= ($TargetW / $TargetH)) ? $NewH = $SourceH * ($TargetW / $SourceW) : $NewW = $SourceW * ($TargetH / $SourceH);

我想请教下这样实现有什么弊端么?

[nozerock]

[Quote=引用 1 楼 的回复:]
其实就是等比例缩放 ，你运行下就知道。可能清晰度不如原图。
[/Quote]
其实我觉得缩略图三个字已经包含你说的意思了

[一起混吧]

其实就是等比例缩放 ，你运行下就知道。可能清晰度不如原图。