{-# LANGUAGE Safe #-} {-| == Introduction Through this module, this library provides platform-independent support for control character sequences following the \'ANSI\' standards (see further below) for terminal software that supports those sequences, running on a Unix-like operating system or on Windows (see further below). The sequences of control characters (also referred to as \'escape\' sequences or codes) provide a rich range of functionality for terminal control, which includes: * Colored text output, with control over both foreground and background colors * Clearing parts of a line or the screen * Hiding or showing the cursor * Moving the cursor around * Reporting the position of the cursor * Scrolling the screen up or down * Switching between the Alternate and Normal Screen Buffers * Clickable hyperlinks to URIs * Changing the title of the terminal A terminal that supports control character sequences acts on them when they are flushed from the output buffer (with a newline character @\"\\n\"@ or, for the standard output channel, @hFlush stdout@). == \'ANSI\' standards The \'ANSI\' standards refer to (1) standard ECMA-48 \`Control Functions for Coded Character Sets\' (5th edition, 1991); (2) extensions in ITU-T Recommendation (previously CCITT Recommendation) T.416 (03/93) \'Information Technology – Open Document Architecture (ODA) and Interchange Format: Character Content Architectures\` (also published as ISO/IEC International Standard 8613-6); and (3) further extensions used by \'XTerm\', a terminal emulator for the X Window System. The escape codes are described in a [Wikipedia article](http://en.wikipedia.org/wiki/ANSI_escape_code) and those codes supported on current versions of Windows are descibed in [Microsoft's documentation](https://docs.microsoft.com/en-us/windows/console/console-virtual-terminal-sequences). The whole of the \'ANSI\' standards are not supported by this library but most (if not all) of the parts that are popular and well-supported by terminal software are supported (see further below). == Cursor positions The functions moving the cursor to an absolute position are 0-based (the top-left corner is considered to be at row 0 column 0) (see 'setCursorPosition') and so is 'getCursorPosition'. The \'ANSI\' standards themselves are 1-based (that is, the top-left corner is considered to be at row 1 column 1) and some functions reporting the position of the cursor are too (see 'reportCursorPosition'). == Windows and control character sequences The native terminal software on Windows has developed over time. Before Windows 10 version 1511 (known as the \'November [2015] Update\' or \'Threshold 2\') that software did not support control character sequences. From 2018, Microsoft introduced the Windows Pseudo Console (\'ConPTY\') API and then Windows Terminal, with the objective of replacing most of the Windows Console API with the use of control character sequences and retiring the historical user-interface role of Windows Console Host (\'ConHost\'). Terminal software other than the native software exists for Windows. One example is the \'mintty\' terminal emulator for \'Cygwin\', \'MSYS\' or \'MSYS2\', and dervied projects, and for \'WSL\' (Windows Subsystem for Linux). GHC's management of input and output (IO) on Windows has also developed over time. If they are supported by the terminal software, some control character sequences cause data to be emitted into the console input stream. For GHC's historical and default IO manager, the function 'hGetBufNonBlocking' in module "System.IO" does not work on Windows. This has been attributed to the lack of non-blocking primatives in the operating system (see [GHC bug report #806](https://ghc.haskell.org/trac/ghc/ticket/806). GHC's native IO manager on Windows (\'WinIO\'), introduced as a preview in [GHC 9.0.1](https://downloads.haskell.org/ghc/9.0.1/docs/html/users_guide/9.0.1-notes.html#highlights), has not yet provided a solution. On Windows, this library uses emulation based on the Windows Console API to try to read data emitted into the console input stream. Functions that use that emulation are not supported on consoles, such as mintty, that are not based on that API. == Function variants provided Every function exported by this module comes in three variants, namely: * A variant that has an @IO ()@ type and doesn't take a @Handle@ (for example, @clearScreen :: IO ()@). This variant just outputs the \`ANSI\` command directly to the standard output channel ('stdout') and any terminal corresponding to it. Commands issued like this should work as you expect on both Unix-like operating systems and Windows (unless exceptions on Windows are stated). * An \'@h@...\' variant that has an @IO ()@ type but takes a @Handle@ (for example, @hClearScreen :: Handle -> IO ()@). This variant outputs the \`ANSI\` command to the supplied handle and any terminal corresponding to it. Commands issued like this should also work as you expect on both Unix-like operating systems and Windows (unless exceptions on Windows are stated). * A \'...@Code@\' variant that has a @String@ type (for example, @clearScreenCode :: String@). This variant outputs the sequence of control characters as a 'String', which can be added to any other bit of text before being output. If a high degree of backwards compatability is rewuired, the use of these codes is discouraged because they will not work on legacy versions of Windows where the terminal in use is not ANSI-enabled (see further above). On Windows, where emulation has been necessary, these variants will always output the empty string. That is done so that it is possible to use them portably; for example, coloring console output on the understanding that you will see colors only if you are running on a Unix-like operating system or a version of Windows where emulation has not been necessary. If the control characters are always required, see module "System.Console.ANSI.Codes". == Examples of use A simple example is below: > module Main where > > import System.Console.ANSI > > -- Set colors and write some text in those colors. > main :: IO () > main = do > setSGR [SetColor Foreground Vivid Red] > setSGR [SetColor Background Vivid Blue] > putStrLn "Red-On-Blue" > setSGR [Reset] -- Reset to default colour scheme > putStrLn "Default colors." Another example is below: > module Main where > > import System.IO (hFlush, stdout) > import System.Console.ANSI > > main :: IO () > main = do > setSGR [SetColor Foreground Dull Blue] > putStr "Enter your name: " > setSGR [SetColor Foreground Dull Yellow] > hFlush stdout -- flush the output buffer before getLine > name <- getLine > setSGR [SetColor Foreground Dull Blue] > putStrLn $ "Hello, " ++ name ++ "!" > setSGR [Reset] -- reset to default colour scheme For many more examples, see the project's extensive file. -} module System.Console.ANSI ( -- * Basic data types module System.Console.ANSI.Types -- * Cursor movement by character , cursorUp , cursorDown , cursorForward , cursorBackward -- ** \'h...\' variants , hCursorUp , hCursorDown , hCursorForward , hCursorBackward -- ** \'...Code\' variants , cursorUpCode , cursorDownCode , cursorForwardCode , cursorBackwardCode -- * Cursor movement by line -- | The difference between movements \"by character\" and \"by line\" is -- that @*Line@ functions additionally move the cursor to the start of the -- line, while functions like @cursorUp@ and @cursorDown@ keep the column -- the same. , cursorUpLine , cursorDownLine -- ** \'h...\' variants , hCursorUpLine , hCursorDownLine -- ** \'...Code\' variants , cursorUpLineCode , cursorDownLineCode -- * Directly changing cursor position , setCursorColumn , setCursorPosition -- ** \'h...\' variants , hSetCursorColumn , hSetCursorPosition -- ** \'...Code\' variants , setCursorColumnCode , setCursorPositionCode -- * Saving, restoring and reporting cursor position -- | These code sequences are not part of ECMA-48 standard; they are popular, -- but non-portable extensions. E. g., Terminal.app on MacOS -- . -- A more portable way would be to query @terminfo@ database -- for @rc@ and @sc@ capabilities. -- -- Cursor positions -- . -- , saveCursor , restoreCursor , reportCursorPosition -- ** \'h...\' variants , hSaveCursor , hRestoreCursor , hReportCursorPosition -- ** \'...Code\' variants , saveCursorCode , restoreCursorCode , reportCursorPositionCode -- * Clearing parts of the screen -- | Note that these functions only clear parts of the screen. They do not -- move the cursor. Some functions are based on the whole screen and others -- are based on the line in which the cursor is located. , clearFromCursorToScreenEnd , clearFromCursorToScreenBeginning , clearScreen , clearFromCursorToLineEnd , clearFromCursorToLineBeginning , clearLine -- ** \'h...\' variants , hClearFromCursorToScreenEnd , hClearFromCursorToScreenBeginning , hClearScreen , hClearFromCursorToLineEnd , hClearFromCursorToLineBeginning , hClearLine -- ** \'...Code\' variants , clearFromCursorToScreenEndCode , clearFromCursorToScreenBeginningCode , clearScreenCode , clearFromCursorToLineEndCode , clearFromCursorToLineBeginningCode , clearLineCode -- * Scrolling the screen , scrollPageUp , scrollPageDown -- ** \'h...\' variants , hScrollPageUp , hScrollPageDown -- ** \'...Code\' variants , scrollPageUpCode , scrollPageDownCode -- * Using screen buffers -- | These code sequences are not part of ECMA-48 standard; they are popular, -- but non-portable extensions, corresponding to @smcup@ and @rmcup@ capabilities -- in @terminfo@ database. -- On Windows, if emulation is required, switching between alternate and -- normal screen buffers is not emulated. , useAlternateScreenBuffer , useNormalScreenBuffer -- ** \'h...\' variants , hUseAlternateScreenBuffer , hUseNormalScreenBuffer -- ** \'...Code\' variants , useAlternateScreenBufferCode , useNormalScreenBufferCode -- * Reporting the background or foreground colors , reportLayerColor , hReportLayerColor , reportLayerColorCode -- * Select Graphic Rendition mode: colors and other whizzy stuff , setSGR , hSetSGR , setSGRCode -- * Cursor visibilty changes -- | Strictly speaking, these code sequences are not part of ECMA-48 standard; -- they are popular, but non-portable extensions. However, in practice they seem -- to work pretty much everywhere. , hideCursor , showCursor -- ** \'h...\' variants , hHideCursor , hShowCursor -- ** \'...Code\' variants , hideCursorCode , showCursorCode -- * Hyperlinks -- | These code sequences are not part of ECMA-48 standard and not even an -- @xterm@ extension. Nevertheless -- -- support them. On Windows, if emulation is required, -- hyperlinks are not emulated. , hyperlink , hyperlinkWithId , hyperlinkWithParams -- ** \'h...\' variants , hHyperlink , hHyperlinkWithId , hHyperlinkWithParams -- ** \'...Code\' variants , hyperlinkCode , hyperlinkWithIdCode , hyperlinkWithParamsCode -- * Changing the title , setTitle , hSetTitle , setTitleCode -- * Checking if handle supports ANSI (not portable: GHC only) , hSupportsANSI , hSupportsANSIColor -- * Getting the cursor position , getCursorPosition , hGetCursorPosition , getReportedCursorPosition , cursorPosition -- * Getting the terminal size , getTerminalSize , hGetTerminalSize -- * Getting the background or foreground colors , getLayerColor , hGetLayerColor , getReportedLayerColor , layerColor -- * Deprecated , hSupportsANSIWithoutEmulation ) where import Control.Exception.Base ( bracket ) import Control.Monad ( when, void ) import Data.Char ( digitToInt, isDigit, isHexDigit ) import Data.Colour.SRGB ( RGB (..) ) import Data.Word ( Word16 ) import System.Environment ( getEnvironment ) import System.IO ( BufferMode (..), Handle, hFlush, hGetBuffering, hGetEcho, hPutStr , hReady, hSetBuffering, hSetEcho, stdin, stdout ) import Text.ParserCombinators.ReadP ( ReadP, (<++), char, many1, readP_to_S, satisfy, string ) import System.Console.ANSI.Codes import qualified System.Console.ANSI.Internal as Internal import System.Console.ANSI.Types hCursorUp, hCursorDown, hCursorForward, hCursorBackward :: Handle -> Int -- Number of lines or characters to move -> IO () hCursorUp h n = hPutStr h $ cursorUpCode n hCursorDown h n = hPutStr h $ cursorDownCode n hCursorForward h n = hPutStr h $ cursorForwardCode n hCursorBackward h n = hPutStr h $ cursorBackwardCode n cursorUp, cursorDown, cursorForward, cursorBackward :: Int -- ^ Number of lines or characters to move -> IO () cursorUp = hCursorUp stdout cursorDown = hCursorDown stdout cursorForward = hCursorForward stdout cursorBackward = hCursorBackward stdout hCursorDownLine, hCursorUpLine :: Handle -> Int -- Number of lines to move -> IO () hCursorDownLine h n = hPutStr h $ cursorDownLineCode n hCursorUpLine h n = hPutStr h $ cursorUpLineCode n cursorDownLine, cursorUpLine :: Int -- ^ Number of lines to move -> IO () cursorDownLine = hCursorDownLine stdout cursorUpLine = hCursorUpLine stdout hSetCursorColumn :: Handle -> Int -- 0-based column to move to -> IO () hSetCursorColumn h n = hPutStr h $ setCursorColumnCode n -- | Move the cursor to the specified column. The column numbering is 0-based -- (that is, the left-most column is numbered 0). setCursorColumn :: Int -- ^ 0-based column to move to -> IO () setCursorColumn = hSetCursorColumn stdout hSetCursorPosition :: Handle -> Int -- 0-based row to move to -> Int -- 0-based column to move to -> IO () hSetCursorPosition h n m = hPutStr h $ setCursorPositionCode n m -- | Move the cursor to the specified position (row and column). The position is -- 0-based (that is, the top-left corner is at row 0 column 0). setCursorPosition :: Int -- ^ 0-based row to move to -> Int -- ^ 0-based column to move to -> IO () setCursorPosition = hSetCursorPosition stdout hSaveCursor, hRestoreCursor, hReportCursorPosition :: Handle -> IO () hSaveCursor h = hPutStr h saveCursorCode hRestoreCursor h = hPutStr h restoreCursorCode hReportCursorPosition h = hPutStr h reportCursorPositionCode -- | Save the cursor position in memory. The only way to access the saved value -- is with the 'restoreCursor' command. -- -- @since 0.7.1 saveCursor :: IO () saveCursor = hSaveCursor stdout -- | Restore the cursor position from memory. There will be no value saved in -- memory until the first use of the 'saveCursor' command. -- -- @since 0.7.1 restoreCursor :: IO () restoreCursor = hRestoreCursor stdout -- | Looking for a way to get the cursors position? See -- 'getCursorPosition'. -- -- Emit the cursor position into the console input stream, immediately after -- being recognised on the output stream, as: -- @ESC [ \ ; \ R@ -- -- Note that the information that is emitted is 1-based (the top-left corner is -- at row 1 column 1) but 'setCursorColumn' and 'setCursorPosition' are -- 0-based. -- -- In isolation of 'getReportedCursorPosition' or 'getCursorPosition', this -- function may be of limited use on Windows operating systems because of -- difficulties in obtaining the data emitted into the console input stream. -- -- @since 0.7.1 reportCursorPosition :: IO () reportCursorPosition = hReportCursorPosition stdout hHideCursor, hShowCursor :: Handle -> IO () hHideCursor h = hPutStr h hideCursorCode hShowCursor h = hPutStr h showCursorCode hideCursor, showCursor :: IO () hideCursor = hHideCursor stdout showCursor = hShowCursor stdout hUseAlternateScreenBuffer :: Handle -> IO () hUseAlternateScreenBuffer h = hPutStr h useAlternateScreenBufferCode hUseNormalScreenBuffer :: Handle -> IO () hUseNormalScreenBuffer h = hPutStr h useNormalScreenBufferCode -- | Use the Alternate Screen Buffer. If currently using the Normal Screen -- Buffer, it will save the cursor position and switch to the Alternate Screen -- Buffer. It will always clear the Alternate Screen Buffer. The Alternate -- Screen Buffer has no scroll back facility. -- -- It is an application's responsibility to ensure that it switches back to the -- Normal Screen Buffer if an exception is raised while the Alternate Screen -- Buffer is being used. For example, by using 'Control.Exception.bracket_': -- -- > bracket_ useAlternateScreenBuffer useNormalScreenBuffer action -- -- @since 0.11.4 useAlternateScreenBuffer :: IO () useAlternateScreenBuffer = hUseAlternateScreenBuffer stdout -- | Use the Normal Screen Buffer. If currently using the Alternate Screen -- Buffer, it will clear the Alternate Screen Buffer, and switch to the Normal -- Screen Buffer. It will always restore the saved cursor position. -- -- @since 0.11.4 useNormalScreenBuffer :: IO () useNormalScreenBuffer = hUseNormalScreenBuffer stdout -- Introduce a hyperlink with (key, value) parameters. Some terminals support -- an @id@ parameter key, so that hyperlinks with the same @id@ value are -- treated as connected. -- -- @since 0.11.3 hHyperlinkWithParams:: Handle -> [(String, String)] -- Parameters -> String -- URI -> String -- Link text -> IO () hHyperlinkWithParams h params uri link = hPutStr h $ hyperlinkWithParamsCode params uri link -- | Introduce a hyperlink with (key, value) parameters. Some terminals support -- an @id@ parameter key, so that hyperlinks with the same @id@ value are -- treated as connected. -- -- @since 0.11.3 hyperlinkWithParams :: [(String, String)] -- ^ Parameters -> String -- ^ URI -> String -- ^ Link text -> IO () hyperlinkWithParams = hHyperlinkWithParams stdout -- Introduce a hyperlink. -- -- @since 0.11.3 hHyperlink :: Handle -> String -- URI -> String -- Link text -> IO () hHyperlink h = hHyperlinkWithParams h [] -- | Introduce a hyperlink. -- -- @since 0.11.3 hyperlink :: String -- ^ URI -> String -- ^ Link text -> IO () hyperlink = hHyperlink stdout -- Introduce a hyperlink with an identifier for the link. Some terminals -- support an identifier, so that hyperlinks with the same identifier are -- treated as connected. -- -- @since 0.11.3 hHyperlinkWithId :: Handle -> String -- Identifier for the link -> String -- URI -> String -- Link text -> IO () hHyperlinkWithId h linkId = hHyperlinkWithParams h [("id", linkId)] -- | Introduce a hyperlink with an identifier for the link. Some terminals -- support an identifier, so that hyperlinks with the same identifier are -- treated as connected. -- -- @since 0.11.3 hyperlinkWithId :: String -- ^ Identifier for the link -> String -- ^ URI -> String -- ^ Link text -> IO () hyperlinkWithId = hHyperlinkWithId stdout -- Set the terminal window title and icon name (that is, the text for the -- window in the Start bar, or similar). hSetTitle :: Handle -> String -- New window title and icon name -> IO () hSetTitle h title = hPutStr h $ setTitleCode title -- | Set the terminal window title and icon name (that is, the text for the -- window in the Start bar, or similar). setTitle :: String -- ^ New window title and icon name -> IO () setTitle = hSetTitle stdout -- | Use heuristics to determine whether the functions defined in this -- package will work with a given handle. -- -- If the handle is not writable (that is, it cannot manage output - see -- 'hIsWritable'), then @pure False@ is returned. -- -- For Unix-like operating systems, the current implementation checks -- that: (1) the handle is a terminal; and (2) a @TERM@ -- environment variable is not set to @dumb@ (which is what the GNU Emacs text -- editor sets for its integrated terminal). -- -- For Windows, the current implementation performs the same checks as for -- Unix-like operating systems and, as an alternative, checks whether the -- handle is connected to a \'mintty\' terminal. (That is because the function -- 'hIsTerminalDevice' is used to check if the handle is a -- terminal. However, where a non-native Windows terminal (such as \'mintty\') -- is implemented using redirection, that function will not identify a -- handle to the terminal as a terminal.) -- -- @since 0.6.2 hSupportsANSI :: Handle -> IO Bool hSupportsANSI = Internal.hSupportsANSI -- | Some terminals (e.g. Emacs) are not fully ANSI compliant but can support -- ANSI colors. This can be used in such cases, if colors are all that is -- needed. -- -- @since 0.9 hSupportsANSIColor :: Handle -> IO Bool hSupportsANSIColor h = (||) <$> hSupportsANSI h <*> isEmacsTerm where isEmacsTerm = (\env -> insideEmacs env && isDumb env) <$> getEnvironment insideEmacs = any (\(k, _) -> k == "INSIDE_EMACS") isDumb env = Just "dumb" == lookup "TERM" env -- | Use heuristics to determine whether a given handle will support \'ANSI\' -- control characters in output. The function is consistent with -- 'hSupportsANSI'. -- -- This function is deprecated as, from version 1.0, the package no longer -- supports legacy versions of Windows that required emulation. -- -- @since 0.8.1 {-# DEPRECATED hSupportsANSIWithoutEmulation "See Haddock documentation and hSupportsANSI." #-} hSupportsANSIWithoutEmulation :: Handle -> IO (Maybe Bool) hSupportsANSIWithoutEmulation h = Just <$> hSupportsANSI h -- | Parses the characters emitted by 'reportCursorPosition' into the console -- input stream. Returns the cursor row and column as a tuple. -- -- For example, if the characters emitted by 'reportCursorPosition' are in -- 'String' @input@ then the parser could be applied like this: -- -- > let result = readP_to_S cursorPosition input -- > case result of -- > [] -> putStrLn $ "Error: could not parse " ++ show input -- > [((row, column), _)] -> putStrLn $ "The cursor was at row " ++ show row -- > ++ " and column" ++ show column ++ "." -- > (_:_) -> putStrLn $ "Error: parse not unique" -- -- @since 0.7.1 cursorPosition :: ReadP (Int, Int) cursorPosition = do void $ char '\ESC' void $ char '[' row <- decimal -- A non-negative whole decimal number void $ char ';' col <- decimal -- A non-negative whole decimal number void $ char 'R' pure (read row, read col) where digit = satisfy isDigit decimal = many1 digit -- | Attempts to get the reported cursor position data from the console input -- stream. The function is intended to be called immediately after -- 'reportCursorPosition' (or related functions) have caused characters to be -- emitted into the stream. -- -- For example, on a Unix-like operating system: -- -- > -- set no buffering (if 'no buffering' is not already set, the contents of -- > -- the buffer will be discarded, so this needs to be done before the cursor -- > -- positon is emitted) -- > hSetBuffering stdin NoBuffering -- > -- ensure that echoing is off -- > input <- bracket (hGetEcho stdin) (hSetEcho stdin) $ \_ -> do -- > hSetEcho stdin False -- > reportCursorPosition -- > hFlush stdout -- ensure the report cursor position code is sent to the -- > -- operating system -- > getReportedCursorPosition -- -- On Windows operating systems, the function is not supported on consoles, such -- as mintty, that are not based on the Windows' Console API. (Command Prompt -- and PowerShell are based on the Console API.) -- -- @since 0.7.1 getReportedCursorPosition :: IO String getReportedCursorPosition = Internal.getReportedCursorPosition -- | Attempts to get the reported cursor position, combining the functions -- 'reportCursorPosition', 'getReportedCursorPosition' and 'cursorPosition'. Any -- position @(row, column)@ is translated to be 0-based (that is, the top-left -- corner is at @(0, 0)@), consistent with `setCursorColumn` and -- `setCursorPosition`. (Note that the information emitted into the console -- input stream by 'reportCursorPosition' is 1-based.) Returns 'Nothing' if any -- data emitted by 'reportCursorPosition', obtained by -- 'getReportedCursorPosition', cannot be parsed by 'cursorPosition'. Uses -- 'stdout'. If 'stdout' will be redirected, see 'hGetCursorPosition' for a more -- general function. -- -- On Windows operating systems, the function is not supported on consoles, such -- as mintty, that are not based on the Windows' Console API. (Command Prompt -- and PowerShell are based on the Console API.) -- -- @since 0.10.3 getCursorPosition :: IO (Maybe (Int, Int)) getCursorPosition = hGetCursorPosition stdout -- | Attempts to get the reported cursor position, combining the functions -- 'hReportCursorPosition' (with the specified handle), -- 'getReportedCursorPosition' and 'cursorPosition'. Any position -- @(row, column)@ is translated to be 0-based (that is, the top-left corner is -- at @(0, 0)@), consistent with 'hSetCursorColumn' and 'hSetCursorPosition'. -- (Note that the information emitted into the console input stream by -- 'hReportCursorPosition' is 1-based.) Returns 'Nothing' if any data emitted by -- 'hReportCursorPosition', obtained by 'getReportedCursorPosition', cannot be -- parsed by 'cursorPosition'. -- -- On Windows operating systems, the function is not supported on consoles, such -- as mintty, that are not based on the Windows' Console API. (Command Prompt -- and PowerShell are based on the Console API.) -- -- @since 0.10.1 hGetCursorPosition :: Handle -> IO (Maybe (Int, Int)) hGetCursorPosition h = fmap to0base <$> getCursorPosition' where to0base (row, col) = (row - 1, col - 1) getCursorPosition' = do input <- bracket (hGetBuffering stdin) (hSetBuffering stdin) $ \_ -> do -- set no buffering (if 'no buffering' is not already set, the contents of -- the buffer will be discarded, so this needs to be done before the -- cursor positon is emitted) hSetBuffering stdin NoBuffering -- ensure that echoing is off bracket (hGetEcho stdin) (hSetEcho stdin) $ \_ -> do hSetEcho stdin False clearStdin hReportCursorPosition h hFlush h -- ensure the report cursor position code is sent to the -- operating system getReportedCursorPosition case readP_to_S cursorPosition input of [] -> pure Nothing [((row, col),_)] -> pure $ Just (row, col) (_:_) -> pure Nothing clearStdin = do isReady <- hReady stdin when isReady $ do _ <-getChar clearStdin -- | Looking for a way to get layer colors? See 'getLayerColor'. -- -- Emit the layerColor into the console input stream, immediately after -- being recognised on the output stream, as: -- @ESC ] \ ; rgb: \ ; \ ; \ \@ -- where @\@ is @10@ for 'Foreground' and @11@ for 'Background'; @\@, -- @\@ and @\@ are the color channel values in hexadecimal (4, 8, -- 12 and 16 bit values are possible, although 16 bit values are most common); -- and @\@ is the STRING TERMINATOR (ST). ST depends on the terminal -- software and may be the @BEL@ character or @ESC \\@ characters. -- -- This function may be of limited, or no, use on Windows operating systems -- because (1) the function is not supported on native terminals and is -- emulated, but the emulation does not work on Windows Terminal and (2) of -- difficulties in obtaining the data emitted into the console input stream. -- -- @since 0.11.4 reportLayerColor :: ConsoleLayer -> IO () reportLayerColor = hReportLayerColor stdout -- @since 0.11.4 hReportLayerColor :: Handle -> ConsoleLayer -> IO () hReportLayerColor h layer = hPutStr h $ reportLayerColorCode layer -- | Attempts to get the reported layer color data from the console input -- stream. The function is intended to be called immediately after -- 'reportLayerColor' (or related functions) have caused characters to be -- emitted into the stream. -- -- For example, on a Unix-like operating system: -- -- > -- set no buffering (if 'no buffering' is not already set, the contents of -- > -- the buffer will be discarded, so this needs to be done before the cursor -- > -- positon is emitted) -- > hSetBuffering stdin NoBuffering -- > -- ensure that echoing is off -- > input <- bracket (hGetEcho stdin) (hSetEcho stdin) $ \_ -> do -- > hSetEcho stdin False -- > reportLayerColor Foreground -- > hFlush stdout -- ensure the report cursor position code is sent to the -- > -- operating system -- > getReportedLayerColor Foreground -- -- On Windows operating systems, the function is not supported on consoles, such -- as mintty, that are not based on the Windows' Console API. (Command Prompt -- and PowerShell are based on the Console API.) -- -- @since 0.11.4 getReportedLayerColor :: ConsoleLayer -> IO String getReportedLayerColor = Internal.getReportedLayerColor -- | Attempts to get the reported layer color, combining the functions -- 'reportLayerColor', 'getReportedLayerColor' and 'layerColor'. Any RGB color -- is scaled to be 16 bits per channel, the most common format reported by -- terminal software. Returns 'Nothing' if any data emitted by -- 'reportLayerColor', obtained by 'getReportedLayerColor', cannot be parsed by -- 'layerColor'. Uses 'stdout'. If 'stdout' will be redirected, see -- 'hGetLayerColor' for a more general function. -- -- On Windows operating systems, the function is not supported on consoles, such -- as mintty, that are not based on the Windows' Console API. (Command Prompt -- and PowerShell are based on the Console API.) This function also relies on -- emulation that does not work on Windows Terminal. -- -- @since 0.11.4 getLayerColor :: ConsoleLayer -> IO (Maybe(RGB Word16)) getLayerColor = hGetLayerColor stdout -- | Attempts to get the reported layer color, combining the functions -- 'hReportLayerColor', 'getReportedLayerColor' and 'layerColor'. Any RGB color -- is scaled to be 16 bits per channel, the most common format reported by -- terminal software. Returns 'Nothing' if any data emitted by -- 'hReportLayerColor', obtained by 'getReportedLayerColor', cannot be parsed by -- 'layerColor'. -- -- On Windows operating systems, the function is not supported on consoles, such -- as mintty, that are not based on the Windows' Console API. (Command Prompt -- and PowerShell are based on the Console API.) This function also relies on -- emulation that does not work on Windows Terminal. -- -- @since 0.11.4 hGetLayerColor :: Handle -> ConsoleLayer -> IO (Maybe (RGB Word16)) hGetLayerColor h layer = do input <- bracket (hGetBuffering stdin) (hSetBuffering stdin) $ \_ -> do -- set no buffering (if 'no buffering' is not already set, the contents of -- the buffer will be discarded, so this needs to be done before the -- cursor positon is emitted) hSetBuffering stdin NoBuffering -- ensure that echoing is off bracket (hGetEcho stdin) (hSetEcho stdin) $ \_ -> do hSetEcho stdin False clearStdin hReportLayerColor h layer hFlush h -- ensure the report cursor position code is sent to the -- operating system getReportedLayerColor layer case readP_to_S (layerColor layer) input of [] -> pure Nothing [(col, _)] -> pure $ Just col (_:_) -> pure Nothing where clearStdin = do isReady <- hReady stdin when isReady $ do _ <-getChar clearStdin -- | Parses the characters emitted by 'reportLayerColor' into the console input -- stream. -- -- For example, if the characters emitted by 'reportLayerColor' are in 'String' -- @input@ then the parser could be applied like this: -- -- > let result = readP_to_S (layerColor layer) input -- > case result of -- > [] -> putStrLn $ "Error: could not parse " ++ show input -- > [(col, _)] -> putStrLn $ "The color was " ++ show col ++ "." -- > (_:_) -> putStrLn $ "Error: parse not unique" -- -- @since 0.11.4 layerColor :: ConsoleLayer -> ReadP (RGB Word16) layerColor layer = do void $ string "\ESC]" void $ string $ case layer of Foreground -> "10" Background -> "11" void $ string ";rgb:" redHex <- hexadecimal -- A non-negative whole hexadecimal number void $ char '/' greenHex <- hexadecimal -- A non-negative whole hexadecimal number void $ char '/' blueHex <- hexadecimal -- A non-negative whole hexadecimal number void $ string "\BEL" <++ string "\ESC\\" let lenRed = length redHex lenGreen = length greenHex lenBlue = length blueHex if lenRed == lenGreen && lenGreen == lenBlue then if lenRed == 0 || lenRed > 4 then fail "Color format not recognised" else let m = 16 ^ (4 - lenRed) r = fromIntegral $ m * hexToInt redHex g = fromIntegral $ m * hexToInt greenHex b = fromIntegral $ m * hexToInt blueHex in pure $ RGB r g b else fail "Color format not recognised" where hexDigit = satisfy isHexDigit hexadecimal = many1 hexDigit hexToInt hex = foldl (\d a -> d * 16 + a) 0 (map digitToInt hex) -- | Attempts to get the current terminal size (height in rows, width in -- columns). -- -- There is no \'ANSI\' control character sequence that reports the terminal -- size. So, it attempts to set the cursor position beyond the bottom right -- corner of the terminal and then use 'getCursorPosition' to query the console -- input stream. It works only on terminals that support each step and if data -- can be emitted to 'stdin'. (Use 'System.IO.hIsTerminalDevice' to test if -- 'stdin' is connected to a terminal.) Uses 'stdout'. If 'stdout' will be -- redirected, see 'System.IO.hGetTerminalSize' for a more general function. -- -- On Windows operating systems, the function is not supported on consoles, such -- as mintty, that are not based on Windows' Console API. (Command Prompt and -- PowerShell are based on the Console API.) -- -- For a different approach, one that does not use control character sequences -- and works when 'stdin' is redirected, see the -- package. -- -- @since 0.9 getTerminalSize :: IO (Maybe (Int, Int)) getTerminalSize = hGetTerminalSize stdout -- | Attempts to get the current terminal size (height in rows, width in -- columns), by writing control character sequences to the specified handle -- (which will typically be 'stdout' or 'stderr'). -- -- There is no \'ANSI\' control character sequence that reports the terminal -- size. So, it attempts to set the cursor position beyond the bottom right -- corner of the terminal and then use 'hGetCursorPosition' to query the console -- input stream. It works only on terminals that support each step and if data -- can be emitted to 'stdin'. (Use 'System.IO.hIsTerminalDevice' to test if -- 'stdin' is connected to a terminal.) -- -- On Windows operating systems, the function is not supported on consoles, such -- as mintty, that are not based on the Windows' Console API. (Command Prompt -- and PowerShell are based on the Console API.) -- -- For a different approach, one that does not use control character sequences -- and works when 'stdin' is redirected, see the -- package. -- -- @since 0.10.1 hGetTerminalSize :: Handle -> IO (Maybe (Int, Int)) hGetTerminalSize h = do hSaveCursor h hSetCursorPosition h 9999 9999 -- Attempt to set the cursor position beyond -- the bottom right corner of the terminal. mPos <- hGetCursorPosition h hRestoreCursor h hFlush h -- ensure the restore cursor position code is sent to the -- operating system pure $ fmap (\(r, c) -> (r + 1, c + 1)) mPos -- Set the Select Graphic Rendition mode hSetSGR :: Handle -> [SGR] -- Commands: these will typically be applied on top of the -- current console SGR mode. An empty list of commands is -- equivalent to the list @[Reset]@. Commands are applied left to -- right. -> IO () hSetSGR h sgrs = hPutStr h $ setSGRCode sgrs -- | Set the Select Graphic Rendition mode setSGR :: [SGR] -- ^ Commands: these will typically be applied on top of the -- current console SGR mode. An empty list of commands is -- equivalent to the list @[Reset]@. Commands are applied left to -- right. -> IO () setSGR = hSetSGR stdout hClearFromCursorToScreenEnd, hClearFromCursorToScreenBeginning, hClearScreen :: Handle -> IO () hClearFromCursorToScreenEnd h = hPutStr h clearFromCursorToScreenEndCode hClearFromCursorToScreenBeginning h = hPutStr h clearFromCursorToScreenBeginningCode hClearScreen h = hPutStr h clearScreenCode clearFromCursorToScreenEnd, clearFromCursorToScreenBeginning, clearScreen :: IO () clearFromCursorToScreenEnd = hClearFromCursorToScreenEnd stdout clearFromCursorToScreenBeginning = hClearFromCursorToScreenBeginning stdout clearScreen = hClearScreen stdout hClearFromCursorToLineEnd, hClearFromCursorToLineBeginning, hClearLine :: Handle -> IO () hClearFromCursorToLineEnd h = hPutStr h clearFromCursorToLineEndCode hClearFromCursorToLineBeginning h = hPutStr h clearFromCursorToLineBeginningCode hClearLine h = hPutStr h clearLineCode clearFromCursorToLineEnd, clearFromCursorToLineBeginning, clearLine :: IO () clearFromCursorToLineEnd = hClearFromCursorToLineEnd stdout clearFromCursorToLineBeginning = hClearFromCursorToLineBeginning stdout clearLine = hClearLine stdout hScrollPageUp, hScrollPageDown :: Handle -> Int -- Number of lines to scroll by -> IO () hScrollPageUp h n = hPutStr h $ scrollPageUpCode n hScrollPageDown h n = hPutStr h $ scrollPageDownCode n scrollPageUp, scrollPageDown :: Int -- ^ Number of lines to scroll by -> IO () scrollPageUp = hScrollPageUp stdout scrollPageDown = hScrollPageDown stdout