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∗@paramunknowntypetoFile 目标图片路径

* @param unknown_type maxWidth最大宽∗@paramunknowntypemaxHeight 最大高

* @param unknown_type imgQuality图片质量∗@returnunknown∗/functionresize(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;

}