core-bundle/src/Resources/contao/library/Contao/Image.php
public static function getPath($src)
	{
		if ($src == '')
		{
			return '';
		}

		$src = rawurldecode($src);

		if (strpos($src, '/') !== false)
		{
			return $src;
		}

		$rootDir = System::getContainer()->getParameter('kernel.project_dir');

		if (strncmp($src, 'icon', 4) === 0)
		{
			if (pathinfo($src, PATHINFO_EXTENSION) == 'svg')
			{
				return 'assets/contao/images/' . $src;
			}

			$filename = pathinfo($src, PATHINFO_FILENAME);

			// Prefer SVG icons
			if (file_exists($rootDir . '/assets/contao/images/' . $filename . '.svg'))
			{
				return 'assets/contao/images/' . $filename . '.svg';
			}

			return 'assets/contao/images/' . $src;
		}
		else
		{
			$theme = Backend::getTheme();

			if (pathinfo($src, PATHINFO_EXTENSION) == 'svg')
			{
				return 'system/themes/' . $theme . '/icons/' . $src;
			}

			$filename = pathinfo($src, PATHINFO_FILENAME);

			// Prefer SVG icons
			if (file_exists($rootDir . '/system/themes/' . $theme . '/icons/' . $filename . '.svg'))
			{
				return 'system/themes/' . $theme . '/icons/' . $filename . '.svg';
			}

			return 'system/themes/' . $theme . '/images/' . $src;
		}
	}
public static function getPath($src)
	{
		if ($src == '')
		{
			return '';
		}

		$src = rawurldecode($src);

		if (strpos($src, '/') !== false)
		{
			return $src;
		}

		$rootDir = System::getContainer()->getParameter('kernel.project_dir');

		if (strncmp($src, 'icon', 4) === 0)
		{
			if (pathinfo($src, PATHINFO_EXTENSION) == 'svg')
			{
				return 'assets/contao/images/' . $src;
			}

			$filename = pathinfo($src, PATHINFO_FILENAME);

			// Prefer SVG icons
			if (file_exists($rootDir . '/assets/contao/images/' . $filename . '.svg'))
			{
				return 'assets/contao/images/' . $filename . '.svg';
			}

			return 'assets/contao/images/' . $src;
		}
		else
		{
			$theme = Backend::getTheme();

			if (pathinfo($src, PATHINFO_EXTENSION) == 'svg')
			{
				return 'system/themes/' . $theme . '/icons/' . $src;
			}

			$filename = pathinfo($src, PATHINFO_FILENAME);

			// Prefer SVG icons
			if (file_exists($rootDir . '/system/themes/' . $theme . '/icons/' . $filename . '.svg'))
			{
				return 'system/themes/' . $theme . '/icons/' . $filename . '.svg';
			}

			return 'system/themes/' . $theme . '/images/' . $src;
		}
	}
Get the relative path to an image

@param string $src The image name or path

@return string The relative path