php实现按指定大小等比缩放生成上传图片缩略图的方法

/** 

 * * 

 *等比缩放 

 * @param unknown_type $srcImage   源图片路径 

 * @param unknown_type $toFile     目标图片路径 

 * @param unknown_type $maxWidth   最大宽 

 * @param unknown_type $maxHeight  最大高 

 * @param unknown_type $imgQuality 图片质量 

 * @return unknown 

 */ 

function resize($srcImage,$toFile,$maxWidth = 100,$maxHeight = 100,$imgQuality=100) 

{ 

   

    list($width, $height, $type, $attr) = getimagesize($srcImage); 

    if($width < $maxWidth  || $height < $maxHeight) return ; 

    switch ($type) { 

    case 1: $img = imagecreatefromgif($srcImage); break; 

    case 2: $img = imagecreatefromjpeg($srcImage); break; 

    case 3: $img = imagecreatefrompng($srcImage); break; 

    } 

    $scale = min($maxWidth/$width, $maxHeight/$height); //求出绽放比例 

     

    if($scale < 1) { 

    $newWidth = floor($scale*$width); 

    $newHeight = floor($scale*$height); 

    $newImg = imagecreatetruecolor($newWidth, $newHeight); 

    imagecopyresampled($newImg, $img, 0, 0, 0, 0, $newWidth, $newHeight, $width, $height); 

    $newName = ""; 

    $toFile = preg_replace("/(.gif|.jpg|.jpeg|.png)/i","",$toFile); 

 

    switch($type) { 

        case 1: if(imagegif($newImg, "$toFile$newName.gif", $imgQuality)) 

        return "$newName.gif"; break; 

        case 2: if(imagejpeg($newImg, "$toFile$newName.jpg", $imgQuality)) 

        return "$newName.jpg"; break; 

        case 3: if(imagepng($newImg, "$toFile$newName.png", $imgQuality)) 

        return "$newName.png"; break; 

        default: if(imagejpeg($newImg, "$toFile$newName.jpg", $imgQuality))

        return "$newName.jpg"; break; 

    } 

    imagedestroy($newImg); 

    } 

    imagedestroy($img); 

    return false; 

}