BP_GOPP_Image_Editor_GS::gs_cmd_win()

	protected static function gs_cmd_win() {
		$win_path = false;

		// Try using REG QUERY to access the registry.
		// Do one test query first to see if it works.
		$cmd        = 'REG QUERY HKEY_LOCAL_MACHINE\\SOFTWARE 2>&1';
		$return_var = -1;
		$output     = array();
		exec( $cmd, $output, $return_var );
		if ( 0 === $return_var && is_array( $output ) ) {
			// Might work.
			$products = array(
				'GPL Ghostscript',
				'GNU Ghostscript',
				'AFPL Ghostscript',
				'Aladdin Ghostscript',
			);
			foreach ( $products as $product ) {
				$cmd    = sprintf( 'REG QUERY "HKEY_LOCAL_MACHINE\\SOFTWARE\\%s" /S 2>&1', $product );
				$output = array();
				exec( $cmd, $output, $return_var );
				if ( 0 === $return_var && is_array( $output ) ) {
					// Find latest version.
					$best_match  = '';
					$highest_ver = 0;
					foreach ( $output as $out ) {
						$out = trim( $out );
						if ( preg_match( '/^GS_DLL[\t ]+REG_SZ[\t ]+(.+)\\\\gs([0-9.]+)\\\\bin\\\\gsdll(64|32)\.dll$/', $out, $matches ) ) {
							$ver = (float) $matches[2];
							if ( $highest_ver < $ver ) {
								$possible_path = $matches[1] . '\\gs' . $matches[2] . '\\bin\\gswin' . $matches[3] . 'c.exe';
								if ( self::test_gs_cmd( $possible_path ) ) {
									$best_match  = $possible_path;
									$highest_ver = $ver;
								}
							}
						}
					}
					if ( $best_match ) {
						$win_path = $best_match;
						break;
					}
				}
			}
		}

		if ( ! $win_path ) {
			// Try GSC environment variable. TODO: Is this still used?
			if ( ! empty( $_SERVER['GSC'] ) && is_string( $_SERVER['GSC'] ) && self::test_gs_cmd( $_SERVER['GSC'] ) ) {
				$win_path = $_SERVER['GSC'];
			}
		}

		if ( ! $win_path ) {
			// Try default install location.
			$program_dirs = array();
			if ( ! empty( $_SERVER['ProgramW6432'] ) && is_string( $_SERVER['ProgramW6432'] ) ) {
				$program_dirs[] = stripslashes( $_SERVER['ProgramW6432'] );
			}
			if ( ! empty( $_SERVER['ProgramFiles'] ) && is_string( $_SERVER['ProgramFiles'] ) ) {
				$program_dirs[] = stripslashes( $_SERVER['ProgramFiles'] );
			}
			if ( ! empty( $_SERVER['ProgramFiles(x86)'] ) && is_string( $_SERVER['ProgramFiles(x86)'] ) ) {
				$program_dirs[] = stripslashes( $_SERVER['ProgramFiles(x86)'] );
			}
			if ( $program_dirs ) {
				$program_dirs = array_unique( $program_dirs );
			} else {
				$program_dirs[] = 'C:\\Program Files';
			}
			foreach ( $program_dirs as $program_dir ) {
				$gs_dir = glob( $program_dir . '\\gs\\gs*', GLOB_NOESCAPE );
				if ( $gs_dir ) {
					// Find latest version.
					$best_match  = '';
					$highest_ver = 0;
					foreach ( $gs_dir as $gs_entry ) {
						if ( preg_match( '/[0-9]+\.[0-9]+$/', $gs_entry, $matches ) ) {
							$ver = (float) $matches[0];
							if ( $highest_ver < $ver ) {
								if ( @ is_executable( $gs_entry . '\\bin\\gswin64c.exe' ) && self::test_gs_cmd( $gs_entry . '\\bin\\gswin64c.exe' ) ) {
									$best_match  = $gs_entry . '\\bin\\gswin64c.exe';
									$highest_ver = $ver;
								} elseif ( @ is_executable( $gs_entry . '\\bin\\gswin32c.exe' ) && self::test_gs_cmd( $gs_entry . '\\bin\\gswin32c.exe' ) ) {
									$best_match  = $gs_entry . '\\bin\\gswin32c.exe';
									$highest_ver = $ver;
								}
							}
						}
					}
					if ( $best_match ) {
						$win_path = $best_match;
						break;
					}
				}
			}
		}

		// Resort to PATH.
		if ( ! $win_path && self::test_gs_cmd( 'gswin64c.exe' ) ) {
			$win_path = 'gswin64c.exe';
		}
		if ( ! $win_path && self::test_gs_cmd( 'gswin32c.exe' ) ) {
			$win_path = 'gswin32c.exe';
		}

		return $win_path;
	}