core-bundle/src/Resources/contao/library/Contao/GdImage.php
public function setResource($gdResource)
	{
		if (!\is_resource($gdResource) || get_resource_type($gdResource) !== 'gd')
		{
			throw new \InvalidArgumentException('$gdResource is not a valid GD resource');
		}

		$this->gdResource = $gdResource;

		return $this;
	}
public function setResource($gdResource)
	{
		if (!\is_resource($gdResource) || get_resource_type($gdResource) !== 'gd')
		{
			throw new \InvalidArgumentException('$gdResource is not a valid GD resource');
		}

		$this->gdResource = $gdResource;

		return $this;
	}
Set the GD resource handle

@param resource $gdResource The GD resource handle

@return static

@throws \InvalidArgumentException If $gdResource is not a GD resource