system/Images/Handlers/GDHandler.php
protected function _rotate(int $angle): bool
	{
		// Create the image handle
		$srcImg = $this->createImage();

		// Set the background color
		// This won't work with transparent PNG files so we are
		// going to have to figure out how to determine the color
		// of the alpha channel in a future release.

		$white = imagecolorallocate($srcImg, 255, 255, 255);

		// Rotate it!
		$destImg = imagerotate($srcImg, $angle, $white);

		// Kill the file handles
		imagedestroy($srcImg);

		$this->resource = $destImg;

		return true;
	}
protected function _rotate(int $angle): bool
	{
		// Create the image handle
		$srcImg = $this->createImage();

		// Set the background color
		// This won't work with transparent PNG files so we are
		// going to have to figure out how to determine the color
		// of the alpha channel in a future release.

		$white = imagecolorallocate($srcImg, 255, 255, 255);

		// Rotate it!
		$destImg = imagerotate($srcImg, $angle, $white);

		// Kill the file handles
		imagedestroy($srcImg);

		$this->resource = $destImg;

		return true;
	}
Handles the rotation of an image resource.
Doesn't save the image, but replaces the current resource.

@param integer $angle

@return boolean