PreviewImage::getSize

static function getSize(FileInfo $fileInfo, PreviewImageOptions $options = null): Rectangle
{
	$previewWidth = 0;
	$previewHeight = 0;
	if ($fileInfo->isImage())
	{
		// Sync with BitrixUIControllerFileUploader::previewAction
		$previewWidth = $options ? $options->getWidth() : 300;
		$previewHeight = $options ? $options->getHeight() : 300;
		$previewMode = $options ? $options->getMode() : Image::RESIZE_PROPORTIONAL;

		$destinationRectangle = new Rectangle($previewWidth, $previewHeight);
		$sourceRectangle = new Rectangle($fileInfo->getWidth(), $fileInfo->getHeight());
		$needResize = $sourceRectangle->resize($destinationRectangle, $previewMode);
		if ($needResize)
		{
			$previewWidth = $destinationRectangle->getWidth();
			$previewHeight = $destinationRectangle->getHeight();
		}
		else
		{
			$previewWidth = $sourceRectangle->getWidth();
			$previewHeight = $sourceRectangle->getHeight();
		}
	}

	return new Rectangle($previewWidth, $previewHeight);
}