Question

I am having a problem rotating a PNG image and keeping the quality as high as it is when it wasn’t rotated. It is also losing its transparency.

Here is the code I’m using to rotate it:

$source = imagecreatefrompng('cake-test.png');
$col = imagecolorexact($source, 255, 255, 255);
imagecolortransparent($source, $col) ;
$rotate = imagerotate($source, 10, 0);

imagepng($rotate, 'temp.png') ;

The created image looks all aliased around the edges and has no transparency. Does anyone know how to get it to work or have a function they are willing to share?

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Thanks! I had a background set on the div the image was in, now it looks fine.

Answer 1

You must allocate alpha channel with imagecolorallocatealpha and set imagesavealpha to true.
Try this:

 $source  = imagecreatefrompng('cake-test.png');
 $bgColor = imagecolorallocatealpha($source, 255, 255, 255, 127);
 $rotate  = imagerotate($source, 10, $bgColor);
 imagesavealpha($rotate, true);

 imagepng($rotate, 'temp.png') ;