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vty/src/Graphics/Vty/Terminal.hs
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1-- | Generic Terminal interface.
2--
3-- Defines the common interface supported by all terminals.
4--
5-- See also:
6--
7-- 1. Graphics.Vty.Terminal: This instantiates an abtract interface to the terminal interface based
8-- on the TERM and COLORTERM environment variables.
9--
10-- 2. Graphics.Vty.Terminal.Generic: Defines the generic interface all terminals need to implement.
11--
12-- 3. Graphics.Vty.Terminal.TerminfoBased: Defines a terminal instance that uses terminfo for all
13-- control strings. No attempt is made to change the character set to UTF-8 for these terminals.
14-- I don't know a way to reliably determine if that is required or how to do so.
15--
16-- 4. Graphics.Vty.Terminal.XTermColor: This module contains an interface suitable for xterm-like
17-- terminals. These are the terminals where TERM == xterm. This does use terminfo for as many
18-- control codes as possible.
19--
20-- Copyright 2009-2010 Corey O'Connor
21{-# LANGUAGE ScopedTypeVariables #-}
22module Graphics.Vty.Terminal ( module Graphics.Vty.Terminal
23 , Terminal(..)
24 , TerminalHandle(..)
25 , DisplayHandle(..)
26 , output_picture
27 , display_context
28 )
29 where
32import Graphics.Vty.DisplayRegion
33import Graphics.Vty.Terminal.Generic
34import Graphics.Vty.Terminal.MacOSX as MacOSX
35import Graphics.Vty.Terminal.XTermColor as XTermColor
36import Graphics.Vty.Terminal.TerminfoBased as TerminfoBased
38import Control.Applicative
39import Control.Exception ( SomeException, try )
40import Control.Monad
41import Control.Monad.Trans
43import Data.List ( isPrefixOf )
45import System.Environment
47-- | Returns a TerminalHandle (an abstract Terminal instance) for the current terminal.
48--
49-- The specific Terminal implementation used is hidden from the API user. All terminal
50-- implementations are assumed to perform more, or less, the same. Currently all implementations use
51-- terminfo for at least some terminal specific information. This is why platforms without terminfo
52-- are not supported. However, as mentioned before, any specifics about it being based on terminfo
53-- are hidden from the API user. If a terminal implementation is developed for a terminal for a
54-- platform without terminfo support then Vty should work as expected on that terminal.
55--
56-- Selection of a terminal is done as follows:
57--
58-- * If TERM == xterm
59-- then the terminal might be one of the Mac OS X .app terminals. Check if that might be
60-- the case and use MacOSX if so.
61-- otherwise use XTermColor.
62--
63-- * for any other TERM value TerminfoBased is used.
64--
65--
66-- The terminal has to be determined dynamically at runtime. To satisfy this requirement all
67-- terminals instances are lifted into an abstract terminal handle via existential qualification.
68-- This implies that the only equations that can used are those in the terminal class.
69--
70-- To differentiate between Mac OS X terminals this uses the TERM_PROGRAM environment variable.
71-- However, an xterm started by Terminal or iTerm *also* has TERM_PROGRAM defined since the
72-- environment variable is not reset/cleared by xterm. However a Terminal.app or iTerm.app started
73-- from an xterm under X11 on mac os x will likely be done via open. Since this does not propogate
74-- environment variables (I think?) this assumes that XTERM_VERSION will never be set for a true
75-- Terminal.app or iTerm.app session.
76--
77--
78-- The file descriptor used for output will a duplicate of the current stdout file descriptor.
79--
80-- todo: add an implementation for windows that does not depend on terminfo. Should be installable
81-- with only what is provided in the haskell platform.
82--
83-- todo: The Terminal interface does not provide any input support.
84terminal_handle :: ( Applicative m, MonadIO m ) => m TerminalHandle
85terminal_handle = do
86 term_type <- liftIO $ getEnv "TERM"
87 t <- if "xterm" `isPrefixOf` term_type
88 then do
89 maybe_terminal_app <- get_env "TERM_PROGRAM"
90 case maybe_terminal_app of
91 Nothing
92 -> XTermColor.terminal_instance term_type >>= new_terminal_handle
93 Just v | v == "Apple_Terminal" || v == "iTerm.app"
94 -> do
95 maybe_xterm <- get_env "XTERM_VERSION"
96 case maybe_xterm of
97 Nothing -> MacOSX.terminal_instance v >>= new_terminal_handle
98 Just _ -> XTermColor.terminal_instance term_type >>= new_terminal_handle
99 -- Assume any other terminal that sets TERM_PROGRAM to not be an OS X terminal.app
100 -- like terminal?
101 _ -> XTermColor.terminal_instance term_type >>= new_terminal_handle
102 -- Not an xterm-like terminal. try for generic terminfo.
103 else TerminfoBased.terminal_instance term_type >>= new_terminal_handle
104 return t
105 where
106 get_env var = do
107 mv <- liftIO $ try $ getEnv var
108 case mv of
109 Left (_e :: SomeException) -> return $ Nothing
110 Right v -> return $ Just v
112-- | Sets the cursor position to the given output column and row.
113--
114-- This is not necessarially the same as the character position with the same coordinates.
115-- Characters can be a variable number of columns in width.
116--
117-- Currently, the only way to set the cursor position to a given character coordinate is to specify
118-- the coordinate in the Picture instance provided to output_picture or refresh.
119set_cursor_pos :: MonadIO m => TerminalHandle -> Int -> Int -> m ()
120set_cursor_pos t x y = do
121 bounds <- display_bounds t
122 when (x >= 0 && x < region_width bounds && y >= 0 && y < region_height bounds) $ do
123 d <- display_context t bounds
124 liftIO $ marshall_to_terminal t (move_cursor_required_bytes d x y) (serialize_move_cursor d x y)
126-- | Hides the cursor
127hide_cursor :: MonadIO m => TerminalHandle -> m ()
128hide_cursor t = do
129 bounds <- display_bounds t
130 d <- display_context t bounds
131 liftIO $ marshall_to_terminal t (hide_cursor_required_bytes d) (serialize_hide_cursor d)
133-- | Shows the cursor
134show_cursor :: MonadIO m => TerminalHandle -> m ()
135show_cursor t = do
136 bounds <- display_bounds t
137 d <- display_context t bounds
138 liftIO $ marshall_to_terminal t (show_cursor_required_bytes d) (serialize_show_cursor d)