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1. chavo
   Member
   Posted 9 months ago #

   Why png images have black background? Is any fix to this?

   Same problem with gif images with transparent background.

   Thanks in advance.

2. Jackson
   Member
   Posted 9 months ago #

   It's probably a transparency/alpha channel issue.

   Try a 24 bit PNG* or an image without transparency/alpha

   *http://core.trac.wordpress.org/ticket/2805#comment:12

3. chavo
   Member
   Posted 9 months ago #

   Hi. Thanks for your reply. I used a png-24 image with transparency. I need transparency/alpha channel.

4. chavo
   Member
   Posted 9 months ago #

   Looking at the referred post and taking a look at the class-Category-Images-II.php file I think that the problem resides in how the plugin generates the thumbnail image:

   protected function save_thumb( $original_file, $thumb_file )
   	{
   		// Scale the image.
   		list( $w, $h, $format ) = getimagesize( $original_file );
   		$max_side = $this->get_max_side();
   		$xratio = $max_side / $w;
   		$yratio = $max_side / $h;
   		$ratio = min( $xratio, $yratio );
   		$targetw = (int) $w * $ratio;
   		$targeth = (int) $h * $ratio;
   
   		$src_gd = $this->image_create_from_file( $original_file );
   		assert( $src_gd );
   		$target_gd = imagecreatetruecolor( $targetw, $targeth );
   		imagecopyresampled ( $target_gd, $src_gd, 0, 0, 0, 0, $targetw, $targeth, $w, $h );
   		// create the initial copy from the original file
   		// also overwrite the filename (in case the extension isn't accurate)
   		$success = false;
   		if ( $format == IMAGETYPE_GIF ) {
   			$success = imagegif( $target_gd, $thumb_file );
   		} elseif ( $format == IMAGETYPE_JPEG ) {
   			$success = imagejpeg( $target_gd, $thumb_file, 90 );
   		} elseif ( $format == IMAGETYPE_PNG ) {
   			$success = imagepng( $target_gd, $thumb_file );
   		} else {
   			wp_die( __( 'Unknown image type. Please upload a JPEG, GIF or PNG.', 'category-images-ii' ) );
   		}
   		if ( ! $success )
   			wp_die( __( 'Image resizing failed.', 'category-images-ii' ) );
   	}

   Unfortunately, I'm not a code master to try to fix it. Any solve?

   ps: sorry for my english

5. Jackson
   Member
   Posted 9 months ago #

   My mistake, I thought you were talking about core WP image resizing.

   You should contact the plugin author about a fix, looks like he's actively working on it. This way everyone wins, and you can upgrade without worrying about breaking the change.

   The solution is outlined here:

   http://php.net/manual/en/function.imagecopyresampled.php#44134

6. chavo
   Member
   Posted 9 months ago #

   Thanks madjax! I will take a look.

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