How can I generate a PNG file without alpha channel?

[Huseriato]

This is the code I used:

      $sepaQr = new SepaQr();
      $sepaQr->setName('Recipients Name');
      $sepaQr->setIban('DE12345678901234567890');
      $sepaQr->setBic('SOMEBICNUM');
      $sepaQr->setAmount(100.00);
      $sepaQr->setRemittanceText('R-123456789-0');
      $sepaQr->setSize(600);
      $sepaQr->setBackgroundColor(array('r' => 255, 'g' => 255, 'b' => 255, 'a' => 0));

      $filename = tempnam(sys_get_temp_dir(), 'qrcode');

      try
      {
        $sepaQr->writeFile($filename);
        // Using the image with FPDF 1.52 here does not work (there is a big dependency in our software here)
      }
      finally
      {
        unlink($filename);
      }

What I found in Writers/PngWriter.php inside function createInterpolatedImage is imagesavealpha($image, true);, which is always set. If I remove the line, all is fine. I tried this:

        if($qrCode->getBackgroundColor()['a'] > 0)
          imagesavealpha($image, true);

So the alpha channel is only activated, if the background is opaque. But I don't know, if this should be the way to do this.

[endroid]

Hi @Huseriato what exactly is the issue when alpha channel information is saved, besides the small increase in file size?

[Huseriato]

I want to add this QR-Code to a bill, using FPDF. I'm using an older version of this lib (update not possible), which supports no alpha channel for png. The only other supported image format is jpg, but qr-code lib can't generate jpegs.

However, if the background of the qr code is fully opaque, there is no need to save an alpha channel for the resulting png.

[endroid]

Hi @Huseriato the current master includes the fix.