PHP实现图片压缩的两则实例_php技巧

本文介绍了PHP实现图片压缩的两种方法，读者可以根据具体应用参考或加以改进，以适应自身应用需求！废话不多说，主要代码部分如下：

实例1：

600?600:$width)*0.9; 
  $new_height =($height>600?600:$height)*0.9; 
  switch($type){ 
    case 1: 
      $giftype=check_gifcartoon($imgsrc); 
      if($giftype){ 
        header('Content-Type:image/gif'); 
        $image_wp=imagecreatetruecolor($new_width, $new_height); 
        $image = imagecreatefromgif($imgsrc); 
        imagecopyresampled($image_wp, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height); 
        imagejpeg($image_wp, $imgdst,75); 
        imagedestroy($image_wp); 
      } 
      break; 
    case 2: 
      header('Content-Type:image/jpeg'); 
      $image_wp=imagecreatetruecolor($new_width, $new_height); 
      $image = imagecreatefromjpeg($imgsrc); 
      imagecopyresampled($image_wp, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height); 
      imagejpeg($image_wp, $imgdst,75); 
      imagedestroy($image_wp); 
      break; 
    case 3: 
      header('Content-Type:image/png'); 
      $image_wp=imagecreatetruecolor($new_width, $new_height); 
      $image = imagecreatefrompng($imgsrc); 
      imagecopyresampled($image_wp, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height); 
      imagejpeg($image_wp, $imgdst,75); 
      imagedestroy($image_wp); 
      break; 
  } 
} 
/** 
* desription 判断是否gif动画 
* @param sting $image_file图片路径 
* @return boolean t 是 f 否 
*/
function check_gifcartoon($image_file){ 
  $fp = fopen($image_file,'rb'); 
  $image_head = fread($fp,1024); 
  fclose($fp); 
  return preg_match("/".chr(0x21).chr(0xff).chr(0x0b).'NETSCAPE2.0'."/",$image_head)?false:true; 
} 
?>

实例2：

$Dw){
   $Par=$Dw/$width;
   $width=$Dw;
   $height=$height*$Par;
   IF($height>$Dh){
   $Par=$Dh/$height;
   $height=$Dh;
   $width=$width*$Par;
   }
  }ElseIF($height>$Dh){
   $Par=$Dh/$height;
   $height=$Dh;
   $width=$width*$Par;
   IF($width>$Dw){
   $Par=$Dw/$width;
   $width=$Dw;
   $height=$height*$Par;
   }
  }Else{
   $width=$width;
   $height=$height;
  }
  $nImg = ImageCreateTrueColor($width,$height);   //新建一个真彩色画布
  ImageCopyReSampled($nImg,$Img,0,0,0,0,$width,$height,$w,$h);//重采样拷贝部分图像并调整大小
  ImageJpeg ($nImg,$Image);     //以JPEG格式将图像输出到浏览器或文件
  Return True;
  //如果是执行生成缩略图操作则
  }Else{
  $w=ImagesX($Img);
  $h=ImagesY($Img);
  $width = $w;
  $height = $h;
  $nImg = ImageCreateTrueColor($Dw,$Dh);
  IF($h/$w>$Dh/$Dw){ //高比较大
   $width=$Dw;
   $height=$h*$Dw/$w;
   $IntNH=$height-$Dh;
   ImageCopyReSampled($nImg, $Img, 0, -$IntNH/1.8, 0, 0, $Dw, $height, $w, $h);
  }Else{   //宽比较大
   $height=$Dh;
   $width=$w*$Dh/$h;
   $IntNW=$width-$Dw;
   ImageCopyReSampled($nImg, $Img, -$IntNW/1.8, 0, 0, 0, $width, $Dh, $w, $h);
  }
  ImageJpeg ($nImg,$Image);
  Return True;
  }
}
?>

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