?php
	/**
  * 生成縮略圖
  * $imgSrc     圖片源路徑
  * $thumbWidth   縮略圖寬度
  * $thumbHeight  縮略圖高度
  * $thumbSrc    縮略圖路徑
  * $isCut     是否剪切圖片
  */
  function createThumbImg($imgSrc, $thumbWidth, $thumbHeight, $thumbSrc, $isCut = false) {
    //1.獲取圖片的類型
    $type = substr(strrchr($imgSrc, "."), 1);
    //2.初始化圖象
    if ($type == "jpg" || $type == "jpeg") {
			//創建一塊畫布，并從JPEG文件或URL地址載入一副圖像
      $sourceImg = imagecreatefromjpeg($imgSrc);
    }elseif ($type == "gif") {
			//創建一塊畫布，并從GIF文件或URL地址載入一副圖像
      $sourceImg = imagecreatefromgif($imgSrc);
    }elseif ($type == "png") {
			//創建一塊畫布，并從PNG文件或URL地址載入一副圖像
      $sourceImg = imagecreatefrompng($imgSrc);
    }
		elseif ($type == "wbmp") {
			//創建一塊畫布，并從WBMP文件或URL地址載入一副圖像
      $sourceImg = imagecreatefromwbmp($imgSrc);
    }
		//取得圖像寬度
    $width = imagesx($sourceImg);
		//取得圖像高度
    $height = imagesy($sourceImg);
 
    //3.生成圖象
    //縮略圖的圖象比例
    $scale = ($thumbWidth) / ($thumbHeight);
    //源圖片的圖象比例
    $ratio = ($width) / ($height);
    if (($isCut) == 1) {
			//高度優先
      if ($ratio >= $scale) {        
				//創建真彩圖像資源（imagecreatetruecolor()函數使用GDLibrary創建新的真彩色圖像）
        $newimg = imagecreatetruecolor($thumbWidth, $thumbHeight);
				//圖像處理
        imagecopyresampled($newimg, $sourceImg, 0, 0, 0, 0, $thumbWidth, $thumbHeight, (($height) * $scale), $height);
        //以JPEG格式將圖像輸出到瀏覽器或文件
				ImageJpeg($newimg, $thumbSrc);
      }
			 //寬度優先
      if ($ratio  $scale) {       
        $newimg = imagecreatetruecolor($thumbWidth, $thumbHeight);
        imagecopyresampled($newimg, $sourceImg, 0, 0, 0, 0, $thumbWidth, $thumbHeight, $width, (($width) / $scale));
        ImageJpeg($newimg, $thumbSrc);
      }
    } else {
      if ($ratio >= $scale) {
        $newimg = imagecreatetruecolor($thumbWidth, ($thumbWidth) / $ratio);
        imagecopyresampled($newimg, $sourceImg, 0, 0, 0, 0, $thumbWidth, ($thumbWidth) / $ratio, $width, $height);
        ImageJpeg($newimg, $thumbSrc);
      }
      if ($ratio  $scale) {
        $newimg = imagecreatetruecolor(($thumbHeight) * $ratio, $thumbHeight);
        imagecopyresampled($newimg, $sourceImg, 0, 0, 0, 0, ($thumbHeight) * $ratio, $thumbHeight, $width, $height);
        ImageJpeg($newimg, $thumbSrc);
      }
    }
		//銷毀圖像
    ImageDestroy($sourceImg);
  }
?>

?php
	//圖片源路徑
	$imgSrc="D:/PHP/test/demo.jpg";
	//縮略圖路徑
	$thumbSrc="D:/PHP/test/thumb.jpg";
	createThumbImg($path,100,100,$thumbSrc);
?>