用GD库生成高质量的缩略图片_PHP

<?

$FILENAME="image_name";

// 生成图片的宽度

$RESIZEWIDTH=400;

// 生成图片的高度

$RESIZEHEIGHT=400;

function ResizeImage($im,$maxwidth,$maxheight,$name){

$width = imagesx($im);

$height = imagesy($im);

if(($maxwidth && $width > $maxwidth) || ($maxheight && $height > $maxheight)){

if($maxwidth && $width > $maxwidth){

$widthratio = $maxwidth/$width;

$RESIZEWIDTH=true;

}

if($maxheight && $height > $maxheight){

$heightratio = $maxheight/$height;

$RESIZEHEIGHT=true;

}

if($RESIZEWIDTH && $RESIZEHEIGHT){

if($widthratio < $heightratio){

$ratio = $widthratio;

}else{

$ratio = $heightratio;

}

}elseif($RESIZEWIDTH){

$ratio = $widthratio;

}elseif($RESIZEHEIGHT){

$ratio = $heightratio;

}

$newwidth = $width * $ratio;

$newheight = $height * $ratio;

if(function_exists("imagecopyresampled")){

$newim = imagecreatetruecolor($newwidth, $newheight);

imagecopyresampled($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);

}else{

$newim = imagecreate($newwidth, $newheight);

imagecopyresized($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);

}

ImageJpeg ($newim,$name . ".jpg");

ImageDestroy ($newim);

}else{

ImageJpeg ($im,$name . ".jpg");

}

}

if($_FILES['image']['size']){

if($_FILES['image']['type'] == "image/pjpeg"){

$im = imagecreatefromjpeg($_FILES['ima本2文来*源gao($daima.com搞@代@#码(网搞gaodaima代码ge']['tmp_name']);

}elseif($_FILES['image']['type'] == "image/x-png"){

$im = imagecreatefrompng($_FILES['image']['tmp_name']);

}elseif($_FILES['image']['type'] == "image/gif"){

$im = imagecreatefromgif($_FILES['image']['tmp_name']);

}

if($im){

if(file_exists("$FILENAME.jpg")){

unlink("$FILENAME.jpg");

}

ResizeImage($im,$RESIZEWIDTH,$RESIZEHEIGHT,$FILENAME);

ImageDestroy ($im);

}

}

?>