CODEWITHSUNDEEP
phppngtransparency
King Julien
King Julien

Reputation: 11298

Fix png transparency problem

I use this class to upload images on my server. The problem is that when I upload transparent png images, the transparent parts get black. Is there a way to keep transparency in png images?

class SimpleImage {

   var $image;
   var $image_type;

   function load($filename) {
      $image_info = getimagesize($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=100, $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);
   }
   function resizeToHeight($height) {
      $ratio = $height / $this->getHeight();
      $width = $this->getWidth() * $ratio;
      $this->resize($width,$height);
   }
   function resizeToWidth($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;   
   }      
}

Upvotes: 0

Views: 3758

Answers (4)

Camilo Cifuentes
Camilo Cifuentes

Reputation: 23

Solution can be found here: PNG Transparency Resize with SimpleImage.php Class

it modifies a bit the class in order to allow transparencies in case of PNG and GIF images.

Upvotes: 0

Darwin Luague
Darwin Luague

Reputation: 173

I used this one to ramain the transparency of a png or gif images.

imagecolortransparent($this->imageResized, imagecolorallocatealpha($this->imageResized, 0, 0, 0, 127));
imagealphablending($this->imageResized, false);
imagesavealpha($this->imageResized, true);

Upvotes: 1

Scott Harwell
Scott Harwell

Reputation: 7465

I don't beleive that this class can handle transparent PNGs. The PHP documentation on imagecopyresampled explains this.

You'll probably need to extend the class to use imagecolorallocatealpha.

Read for reference: http://php.net/manual/en/function.imagecreatetruecolor.php

Upvotes: 1

cabron
cabron

Reputation: 91

You may need to use imagealphablending($this->image, false); imagesavealpha($this->image, true); before imagepng

Upvotes: 0

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