php实现按指定大小等比缩放生成上传图片缩略图的方法

代码如下:

/**
* *
*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;
}

希望本文所述对大家的PHP程序设计有所帮助。