1notcurses(3) notcurses(3)
2
6 notcurses - TUI library for modern terminal emulators
7
9 #include <notcurses/notcurses.h> or #include <notcurses/notcurses-
10 core.h>
11 -lnotcurses-core -lnotcurses or -lnotcurses-core
13
15 Notcurses builds atop the terminfo(5) abstraction layer to provide rea‐
16 sonably portable vivid character displays. It is an intellectual de‐
17 scendant of ncurses(3NCURSES), but goes beyond that library (and the
18 X/Open Curses API it implements).
19 A program wishing to use Notcurses will need to link it, ideally using
21 the output of pkg-config --libs notcurses (see pkg-config(1)). It is
22 advised to compile with the output of pkg-config --cflags notcurses.
23 If using CMake, a support file is provided, and can be accessed as
24 Notcurses (see cmake(1)). If multimedia capabilities are not needed,
25 it is possible to link against a minimal Notcurses using pkg-config
26 --libs notcurses-core.
27 notcurses_init(3) can then be used to initialize a Notcurses instance
29 for a given FILE* (usually stdout, usually attached to a terminal).
30 Construction
32 Before calling into Notcurses—and usually as one of the first calls of
33 the program—be sure to call setlocale with an appropriate UTF-8 LC_ALL
34 locale. It is usually appropriate to use setlocale(LC_ALL, ""), rely‐
35 ing on the user to properly set the LANG environment variable.
36 Notcurses will refuse to start if nl_langinfo(3) doesn't indicate UTF-8
37 or ANSI_X3.4-1968 (aka US-ASCII). Be aware that capabilities are sub‐
38 stantially reduced in ASCII.
39 notcurses_init(3) accepts a struct notcurses_options allowing fine-
41 grained control of Notcurses behavior, including signal handlers, al‐
42 ternative screens, and overriding the TERM environment variable. A
43 terminfo entry appropriate for the actual terminal must be available.
44 ncdirect_init(3) makes available a restricted subset of Notcurses func‐
46 tionality. This subset is intended to be interleaved with user-gener‐
47 ated output, and is limited to coloring and styling. Direct mode is
48 documented in notcurses_direct(3).
49 Only one context can be active in a process at a time, whether direct
51 mode (struct ncdirect) or rendered mode (struct notcurses).
52 Output
54 All output is performed on struct ncplanes (see Ncplanes below). Out‐
55 put is not visible until explicitly rendered via notcurses_render(3).
56 It is safe to output from multiple threads. Information on drawing
57 functions is available at notcurses_output(3).
58 Input
60 Notcurses supports input from keyboards (via stdin) and pointing de‐
61 vices (via a broker such as GPM, X, or Wayland). Input is delivered as
62 32-bit Unicode code points. Synthesized events such as mouse button
63 presses and arrow keys are mapped into Unicode's Supplementary Private
64 Use Area-B (https://unicode.org/charts/PDF/U100000.pdf). Information
65 on input is available at notcurses_input(3). The included tool
66 notcurses-input(1) can be used to test input decoding.
67 Ncpiles
69 A given notcurses context is made up of one or more piles. Piles pro‐
70 vide distinct rendering contexts: a thread can be rendering or mutating
71 one pile, while another thread concurrently renders or mutates another
72 pile. A pile is made up of planes, totally ordered on a z-axis. In
73 addition to the z-ordering, the planes of a pile are bound in a forest
74 (a set of directed, acyclic graphs). Those planes which are not bound
75 to some other plane constitute the root planes of a pile. A pile is
76 destroyed when all its planes are destroyed, or moved to other piles.
77 Since the standard plane (see below) always exists, and cannot be moved
78 to another pile, one pile always exists, known as the standard pile.
79 Note that rasterizing a pile will replace all content within its mar‐
81 gins.
82 Ncplanes
84 Following initialization, a single ncplane exists, the "standard plane"
85 (see notcurses_stdplane(3)). This plane cannot be destroyed nor manu‐
86 ally resized, and is always exactly as large as the screen (if run
87 without a TTY, the "screen" is assumed to be 80x24 cells). Further nc‐
88 planes can be created with ncplane_create(3). A total z-ordering al‐
89 ways exists on the set of ncplanes, and new ncplanes are placed at the
90 top of the z-buffer. Ncplanes can be larger, smaller, or the same size
91 as the physical screen, and can be placed anywhere relative to it (in‐
92 cluding entirely off-screen). Ncplanes are made up of nccells (see Nc‐
93 Cells below). Information on ncplanes is available at notcurs‐
94 es_plane(3).
95 NcCells
97 nccells make up the framebuffers backing each ncplane, one cell per co‐
98 ordinate, one extended grapheme cluster (see unicode(7)) per cell. An
99 nccell consists of a gcluster (either a directly-encoded 7-bit ASCII
100 character (see ascii(7)), or a 25-bit index into the ncplane's
101 egcpool), a set of attributes, and two channels (one for the fore‐
102 ground, and one for the background—see notcurses_channels(3)). Infor‐
103 mation on cells is available at notcurses_cell(3).
104 It is not usually necessary for users to interact directly with nc‐
106 cells. They are typically encountered when retrieving data from nc‐
107 planes or the rendered scene (see e.g. ncplane_at_yx(3)), or to
108 achieve peak performance when a particular EGC is heavily reused within
109 a plane.
110 Visuals
112 Bitmaps can be loaded from disk or memory, or even synthesized from the
113 content of existing planes. These are stored in ncvisual objects, de‐
114 scribed in notcurses_visual(3). Visuals can be rendered to arbitrarily
115 many planes using a variety of blitters, varying in their aspect ratios
116 and resolution. If the terminal supports a pixel protocol such as Six‐
117 el or Kitty, it is possible to render bitmaps at the pixel level (as
118 opposed to the cell level, using geometric glyphs). Otherwise, various
119 Unicode-based blitters are available to render bitmaps in the text par‐
120 adigm.
121 Widgets
123 A few high-level widgets are included, all built atop ncplanes:
124 • notcurses_fds(3) for dumping file descriptors/subprocesses to a plane
126 • notcurses_menu(3) for menu bars at the top or bottom of the screen
128 • notcurses_multiselector(3) for selecting one or more items from a set
130 • notcurses_plot(3) for drawing histograms and lineplots
132 • notcurses_progbar(3) for drawing progress bars
134 • notcurses_reader(3) for free-form input data
136 • notcurses_reel(3) for hierarchal display of block-based data
138 • notcurses_tabbed(3) for tabbed interfaces
140 • notcurses_selector(3) for selecting one item from a set
142 • notcurses_tree(3) for hierarchal display of line-based data
144 Threads
146 Notcurses explicitly supports use in multithreaded environments, but it
147 does not itself perform any locking.
148 • Only one pile's rendered frame can be rasterized at a time, and it is
150 not safe to concurrently render that pile. It is safe to rasterize a
151 frame while rendering some other pile.
152 • It is otherwise always safe to operate concurrently on distinct
154 piles.
155 • It is not safe to render a pile while concurrently modifying that
157 pile.
158 • It is safe to output to multiple distinct ncplanes at the same time,
160 even within the same pile.
161 • It is safe to output to ncplanes while adding or deleting some other
163 ncplane.
164 • It is not safe for multiple threads to output to the same ncplane.
166 • It is not safe to add, delete, or reorder ncplanes within a single
168 pile from multiple threads.
169 Only one thread may call notcurses_get(3) or any other input-related
171 thread at a time, but it is safe to call for input while another thread
172 renders.
173 Since multiple threads can concurrently manipulate distinct ncplanes,
175 peak performance might require dividing the screen into several planes,
176 and manipulating them from multiple threads.
177 Destruction
179 Before exiting, notcurses_stop(3) should be called. In addition to
180 freeing up resources, this is necessary to restore the terminal to a
181 state useful for the shell. By default, notcurses_init(3) installs
182 signal handlers to catch all signals which would normally terminate the
183 process. The new handlers will try to call notcurses_stop(3), and then
184 propagate the received signal to the previous action.
185
187 When using the C++ wrappers, NCPP_EXCEPTIONS_PLEASE can be defined in
188 order to turn most error returns into exceptions.
189
191 ncurses(3NCURSES), notcurses-demo(1), notcurses-input(1), notcurses_ca‐
192 pabilities(3), notcurses_cell(3), notcurses_channels(3), notcurses_di‐
193 rect(3), notcurses_fade(3), notcurses_fds(3), notcurses_init(3),
194 notcurses_input(3), notcurses_lines(3), notcurses_menu(3), notcurs‐
195 es_multiselector(3), notcurses_output(3), notcurses_palette(3),
196 notcurses_plane(3), notcurses_plot(3), notcurses_progbar(3), notcurs‐
197 es_reader(3), notcurses_reel(3), notcurses_refresh(3), notcurses_ren‐
198 der(3), notcurses_selector(3), notcurses_stats(3), notcurses_std‐
199 plane(3), notcurses_stop(3), notcurses_tabbed(3), notcurses_tree(3),
200 notcurses_visual(3), terminfo(5), ascii(7), utf-8(7), unicode(7)
201
203 nick black <nickblack@linux.com>.
204 v2.4.9 notcurses(3)