按比例生成缩略图代码-生成图片

php教程
 
class My_Lib_simpleimage {
 var $image;
 var $image_type;
 function load($filename) { 
    //$filename 文件的临时文件名 $_FILES['name']['tmp_name']
  $image_info = getimagesize($filename);
  $this->image_type = $image_info[2];
  if( $this->image_type == IMAGETYPE_JPEG ) {
  $this->image = imagecreatefromjpeg($filename);
  } elseif( $this->image_type == IMAGETYPE_GIF ) {
  $this->image = imagecreatefromgif($filename);
  } elseif( $this->image_type == IMAGETYPE_PNG ) {
  $this->image = imagecreatefrompng($filename);
  }
 }
 
 function save($filename, $image_type=IMAGETYPE_JPEG, $compression=75, $permissions=null) {
  if( $image_type == IMAGETYPE_JPEG ) {
  imagejpeg($this->image,$filename,$compression);
  } elseif( $image_type == IMAGETYPE_GIF ) {
  imagegif($this->image,$filename);
  } elseif( $image_type == IMAGETYPE_PNG ) {
  imagepng($this->image,$filename);
  }
  if( $permissions != null) {
  chmod($filename,$permissions);
  }
 }
 function output($image_type=IMAGETYPE_JPEG) {
  if( $image_type == IMAGETYPE_JPEG ) {
  imagejpeg($this->image);
  } elseif( $image_type == IMAGETYPE_GIF ) {
  imagegif($this->image);
  } elseif( $image_type == IMAGETYPE_PNG ) {
  imagepng($this->image);
  }
 }
 function getWidth() {
  return imagesx($this->image);
 }
 function getHeight() {
  return imagesy($this->image);
 }
 
 #设置缩略图片高度
 function resizeToHeight($height) {
  $ratio = $height / $this->getHeight();
  $width = $this->getWidth() * $ratio;
  $this->resize($width,$height);
 }
 #设置缩略图片宽度
 function resizeToWidth($width) {
  $ratio = $width / $this->getWidth();
  $height = $this->getheight() * $ratio;
  $this->resize($width,$height);
 }
 function scale($scale) {
  $width = $this->getWidth() * $scale/100;
  $height = $this->getheight() * $scale/100;
  $this->resize($width,$height);
 }
 function resize($width,$height) {
  $new_image = imagecreatetruecolor($width, $height);
  imagecopyresampled($new_image, $this->image, 0, 0, 0, 0, $width, $height, $this->getWidth(), $this->getHeight());
  $this->image = $new_image;
 }
}
?>