Nerdblog.pl - Kohana PHP - adding watermark with PNG-24 support

Kohana PHP - adding watermark with PNG-24 support

This function is based on phpion's code but with added PNG-24 alpha channel support. Took me a while to figure it out, but imagecopymerge doesn't support transparency (don't ask me) so I had to use imagecopy and turn on imageAlphaBlending (despite what people in PHP manual's comments say). Too bad it couldn't be done in application/ and I had to edit system/ files.

system/libraries/Image.php:

    public function watermark(Image $image, $left = 0, $top = 0) 
    {
        $this->actions['watermark'] = array(
            'image' => $image,
            'transparency' => (int)$transparency,
            'left' => (int)$left,
            'top' => (int)$top
        );
 
        return $this;
    }

system/libraries/drivers/Image/GD.php:

    public function watermark($properties) 
    {
        $img = $this->tmp_image;
 
        switch ($properties['image']->type) 
        {
            case IMAGETYPE_JPEG:
                $create = 'imagecreatefromjpeg';
            break;
            case IMAGETYPE_GIF:
                $create = 'imagecreatefromgif';
            break;
            case IMAGETYPE_PNG:
                $create = 'imagecreatefrompng';
            break;
        }
 
        $watermark = $create($properties['image']->file);
        imageAlphaBlending($img, true);
 
        imagecopy($img, $watermark, 
            $properties['left'], $properties['top'], 0, 0, 
            $properties['image']->width, $properties['image']->height);
 
        $this->tmp_image = $img;
 
        return $img;
    }

It's not perfect, I'll have to add some fancy stuff in the future, but for now I can get back to work.