PNG Transparency Resize with SimpleImage.php Class

Question

I\'m using a modified version of the SimpleImage.php class: http://www.white-hat-web-design.co.uk/articles/php-image-resizing.php

The edits I found on phpfreaks (htt

Answer 1

I did the same as in this https://stackoverflow.com/a/6401135/262462 but edited this part

function save($filename, $image_type=IMAGETYPE_JPEG, $compression=75, $permissions=null) {

// do this or they'll all go to jpeg
$image_type=$this->image_type;

to this

function save($filename, $image_type="original", $compression=75, $permissions=null) {

    if ($image_type=="original")
        $image_type=$this->image_type;

Answer 2

Now have the transparency working for PNG but not gif. Here are the edits to the specific functions in case it will help someone else:

Save Function:

function save($filename, $image_type=IMAGETYPE_JPEG, $compression=75, $permissions=null) {

   // do this or they'll all go to jpeg
   $image_type=$this->image_type;

  if( $image_type == IMAGETYPE_JPEG ) {
     imagejpeg($this->image,$filename,$compression);
  } elseif( $image_type == IMAGETYPE_GIF ) {
     imagegif($this->image,$filename);  
  } elseif( $image_type == IMAGETYPE_PNG ) {
    // need this for transparent png to work          
    imagealphablending($this->image, false);
    imagesavealpha($this->image,true);
    imagepng($this->image,$filename);
  }   
  if( $permissions != null) {
     chmod($filename,$permissions);
  }

}

Resize Function

 function resize($width,$height,$forcesize='n') {

  /* optional. if file is smaller, do not resize. */
  if ($forcesize == 'n') {
      if ($width > $this->getWidth() && $height > $this->getHeight()){
          $width = $this->getWidth();
          $height = $this->getHeight();
      }
  }

  $new_image = imagecreatetruecolor($width, $height);
  /* Check if this image is PNG or GIF, then set if Transparent*/  
  if(($this->image_type == IMAGETYPE_GIF) || ($this->image_type==IMAGETYPE_PNG)){
      imagealphablending($new_image, false);
      imagesavealpha($new_image,true);
      $transparent = imagecolorallocatealpha($new_image, 255, 255, 255, 127);
      imagefilledrectangle($new_image, 0, 0, $width, $height, $transparent);
  }
  imagecopyresampled($new_image, $this->image, 0, 0, 0, 0, $width, $height, $this->getWidth(), $this->getHeight());

  $this->image = $new_image;   

}

Answer 3

The function imagecreatetruecolor() does not work with GIF's. Use the imagecreate method instead:

if($this->image_type == IMAGETYPE_GIF){
    $new_image = imagecreate( $Width, $Height ); // for gif files
} else{
    $new_image = imagecreatetruecolor($Width, $Height); // for all other files
}

Answer 4

I haven't been playing with GD for a long time myself (I prefer Imagemagick), but you could try setting alpha also to the source image before copying:

...
// ADDED CODE IS HERE ..
imagealphablending($this->image, true);
...

HTH.