X-Git-Url: https://ncurses.scripts.mit.edu/?p=ncurses.git;a=blobdiff_plain;f=doc%2Fncurses-intro.doc;h=4e752ed0fc54816f5e0084db1b3fe46405aafd9b;hp=1d72f8087af6fd779552852f18d288d51a30b95a;hb=HEAD;hpb=32f9f5f12cd9159261f9db228461049e8c770404 diff --git a/doc/ncurses-intro.doc b/doc/ncurses-intro.doc index 1d72f808..a20ee1a1 100644 --- a/doc/ncurses-intro.doc +++ b/doc/ncurses-intro.doc @@ -1,9 +1,11 @@ Writing Programs with NCURSES +Writing Programs with NCURSES + by Eric S. Raymond and Zeyd M. Ben-Halim updates since release 1.9.9e by Thomas Dickey - Contents +Contents * Introduction + A Brief History of Curses @@ -96,7 +98,7 @@ o Avoiding Problems _________________________________________________________________ - Introduction +Introduction This document is an introduction to programming with curses. It is not an exhaustive reference for the curses Application Programming @@ -129,31 +131,47 @@ will typically be a great deal simpler and less expensive than one using an X toolkit. -A Brief History of Curses + A Brief History of Curses Historically, the first ancestor of curses was the routines written to - provide screen-handling for the game rogue; these used the - already-existing termcap database facility for describing terminal + provide screen-handling for the vi editor; these used the termcap + database facility (both released in 3BSD) for describing terminal capabilities. These routines were abstracted into a documented library - and first released with the early BSD UNIX versions. - - System III UNIX from Bell Labs featured a rewritten and much-improved - curses library. It introduced the terminfo format. Terminfo is based - on Berkeley's termcap database, but contains a number of improvements - and extensions. Parameterized capabilities strings were introduced, - making it possible to describe multiple video attributes, and colors - and to handle far more unusual terminals than possible with termcap. - In the later AT&T System V releases, curses evolved to use more - facilities and offer more capabilities, going far beyond BSD curses in - power and flexibility. - -Scope of This Document + and first released with the early BSD UNIX versions. All of this work + was done by students at the University of California (Berkeley + campus). The curses library was first published in 4.0BSD, a year + after 3BSD (i.e., late 1980). + + After graduation, one of those students went to work at AT&T Bell + Labs, and made an improved termcap library called terminfo (i.e., + "libterm"), and adapted the curses library to use this. That was + subsequently released in System V Release 2 (early 1984). Thereafter, + other developers added to the curses and terminfo libraries. For + instance, a student at Cornell University wrote an improved terminfo + library as well as a tool (tic) to compile the terminal descriptions. + As a general rule, AT&T did not identify the developers in the + source-code or documentation; the tic and infocmp programs are the + exceptions. + + System V Release 3 (System III UNIX) from Bell Labs featured a + rewritten and much-improved curses library, along with the tic program + (late 1986). + + To recap, terminfo is based on Berkeley's termcap database, but + contains a number of improvements and extensions. Parameterized + capabilities strings were introduced, making it possible to describe + multiple video attributes, and colors and to handle far more unusual + terminals than possible with termcap. In the later AT&T System V + releases, curses evolved to use more facilities and offer more + capabilities, going far beyond BSD curses in power and flexibility. + + Scope of This Document This document describes ncurses, a free implementation of the System V curses API with some clearly marked extensions. It includes the following System V curses features: * Support for multiple screen highlights (BSD curses could only - handle one `standout' highlight, usually reverse-video). + handle one "standout" highlight, usually reverse-video). * Support for line- and box-drawing using forms characters. * Recognition of function keys on input. * Color support. @@ -164,7 +182,7 @@ Scope of This Document character features of terminals so equipped, and determines how to optimally use these features with no help from the programmer. It allows arbitrary combinations of video attributes to be displayed, - even on terminals that leave ``magic cookies'' on the screen to mark + even on terminals that leave "magic cookies" on the screen to mark changes in attributes. The ncurses package can also capture and use event reports from a @@ -190,7 +208,7 @@ Scope of This Document extension libraries, also cloned from System V, which support easy construction and sequences of menus and fill-in forms. -Terminology + Terminology In this document, the following terminology is used with reasonable consistency: @@ -211,11 +229,11 @@ Terminology The package's idea of what the terminal display currently looks like, i.e., what the user sees now. This is a special screen. - The Curses Library +The Curses Library -An Overview of Curses + An Overview of Curses - Compiling Programs using Curses + Compiling Programs using Curses In order to use the library, it is necessary to have certain types and variables defined. Therefore, the programmer must have a line: @@ -229,7 +247,7 @@ An Overview of Curses your LDFLAGS or on the command line. There is no need for any other libraries. - Updating the Screen + Updating the Screen In order to update the screen optimally, it is necessary for the routines to know what the screen currently looks like and what the @@ -242,8 +260,8 @@ An Overview of Curses standard screen) is provided by default to make changes on. A window is a purely internal representation. It is used to build and - store a potential image of a portion of the terminal. It doesn't bear - any necessary relation to what is really on the terminal screen; it's + store a potential image of a portion of the terminal. It does not bear + any necessary relation to what is really on the terminal screen; it is more like a scratchpad or write buffer. To make the section of physical screen corresponding to a window @@ -253,11 +271,11 @@ An Overview of Curses A given physical screen section may be within the scope of any number of overlapping windows. Also, changes can be made to windows in any order, without regard to motion efficiency. Then, at will, the - programmer can effectively say ``make it look like this,'' and let the + programmer can effectively say "make it look like this," and let the package implementation determine the most efficient way to repaint the screen. - Standard Windows and Function Naming Conventions + Standard Windows and Function Naming Conventions As hinted above, the routines can use several windows, but two are automatically given: curscr, which knows what the terminal looks like, @@ -269,8 +287,8 @@ An Overview of Curses Many functions are defined to use stdscr as a default screen. For example, to add a character to stdscr, one calls addch() with the desired character as argument. To write to a different window. use the - routine waddch() (for `w'indow-specific addch()) is provided. This - convention of prepending function names with a `w' when they are to be + routine waddch() (for window-specific addch()) is provided. This + convention of prepending function names with a "w" when they are to be applied to specific windows is consistent. The only routines which do not follow it are those for which a window must always be specified. @@ -278,7 +296,7 @@ An Overview of Curses another, the routines move() and wmove() are provided. However, it is often desirable to first move and then perform some I/O operation. In order to avoid clumsiness, most I/O routines can be preceded by the - prefix 'mv' and the desired (y, x) coordinates prepended to the + prefix "mv" and the desired (y, x) coordinates prepended to the arguments to the function. For example, the calls move(y, x); addch(ch); @@ -297,7 +315,7 @@ An Overview of Curses (y, x) coordinates. If a function requires a window pointer, it is always the first parameter passed. - Variables + Variables The curses library sets some variables describing the terminal capabilities. @@ -310,13 +328,13 @@ An Overview of Curses general usefulness: bool - boolean type, actually a `char' (e.g., bool doneit;) + boolean type, actually a "char" (e.g., bool doneit;) TRUE - boolean `true' flag (1). + boolean "true" flag (1). FALSE - boolean `false' flag (0). + boolean "false" flag (0). ERR error flag returned by routines on a failure (-1). @@ -324,7 +342,7 @@ An Overview of Curses OK error flag returned by routines when things go right. -Using the Library + Using the Library Now we describe how to actually use the screen package. In it, we assume all updating, reading, etc. is applied to stdscr. These @@ -381,7 +399,7 @@ main(int argc, char *argv[]) /* process the command keystroke */ } - finish(0); /* we're done */ + finish(0); /* we are done */ } static void finish(int sig) @@ -393,7 +411,7 @@ static void finish(int sig) exit(0); } - Starting up + Starting up In order to use the screen package, the routines must know about terminal characteristics, and the space for curscr and stdscr must be @@ -411,7 +429,7 @@ static void finish(int sig) Once the screen windows have been allocated, you can set them up for your program. If you want to, say, allow a screen to scroll, use scrollok(). If you want the cursor to be left in place after the last - change, use leaveok(). If this isn't done, refresh() will move the + change, use leaveok(). If this is not done, refresh() will move the cursor to the window's current (y, x) coordinates after updating it. You can create new windows of your own using the functions newwin(), @@ -419,7 +437,7 @@ static void finish(int sig) of old windows. All the options described above can be applied to any window. - Output + Output Now that we have set things up, we will want to actually update the terminal. The basic functions used to change what will go on a window @@ -448,14 +466,14 @@ static void finish(int sig) implementing a command which would redraw the screen in case it get messed up. - Input + Input The complementary function to addch() is getch() which, if echo is set, will call addch() to echo the character. Since the screen package needs to know what is on the terminal at all times, if characters are to be echoed, the tty must be in raw or cbreak mode. Since initially - the terminal has echoing enabled and is in ordinary ``cooked'' mode, - one or the other has to changed before calling getch(); otherwise, the + the terminal has echoing enabled and is in ordinary "cooked" mode, one + or the other has to changed before calling getch(); otherwise, the program's output will be unpredictable. When you need to accept line-oriented input in a window, the functions @@ -472,7 +490,7 @@ static void finish(int sig) curses.h The mapping from sequences to #define values is determined by key_ capabilities in the terminal's terminfo entry. - Using Forms Characters + Using Forms Characters The addch() function (and some others, including box() and border()) can accept some pseudo-character arguments which are specially defined @@ -484,7 +502,7 @@ static void finish(int sig) the terminal does not have such characters, curses.h will map them to a recognizable (though ugly) set of ASCII defaults. - Character Attributes and Color + Character Attributes and Color The ncurses package supports screen highlights including standout, reverse-video, underline, and blink. It also supports color, which is @@ -499,7 +517,7 @@ static void finish(int sig) of the highlights you want into the character argument of an addch() call, or any other output call that takes a chtype argument. - The other is to set the current-highlight value. This is logical-or'ed + The other is to set the current-highlight value. This is logical-ORed with any highlight you specify the first way. You do this with the functions attron(), attroff(), and attrset(); see the manual pages for details. Color is a special kind of highlight. The package actually @@ -510,12 +528,12 @@ static void finish(int sig) range of eight non-conflicting values could have been used as the first arguments of the init_pair() values. - Once you've done an init_pair() that creates color-pair N, you can use - COLOR_PAIR(N) as a highlight that invokes that particular color + Once you have done an init_pair() that creates color-pair N, you can + use COLOR_PAIR(N) as a highlight that invokes that particular color combination. Note that COLOR_PAIR(N), for constant N, is itself a compile-time constant and can be used in initializers. - Mouse Interfacing + Mouse Interfacing The ncurses library also provides a mouse interface. @@ -550,11 +568,11 @@ static void finish(int sig) otherwise another mouse event might come in and make the first one inaccessible). - Each call to getmouse() fills a structure (the address of which you'll - pass it) with mouse event data. The event data includes zero-origin, - screen-relative character-cell coordinates of the mouse pointer. It - also includes an event mask. Bits in this mask will be set, - corresponding to the event type being reported. + Each call to getmouse() fills a structure (the address of which you + will pass it) with mouse event data. The event data includes + zero-origin, screen-relative character-cell coordinates of the mouse + pointer. It also includes an event mask. Bits in this mask will be + set, corresponding to the event type being reported. The mouse structure contains two additional fields which may be significant in the future as ncurses interfaces to new kinds of @@ -567,7 +585,7 @@ static void finish(int sig) The class of visible events may be changed at any time via mousemask(). Events that can be reported include presses, releases, single-, double- and triple-clicks (you can set the maximum - button-down time for clicks). If you don't make clicks visible, they + button-down time for clicks). If you do not make clicks visible, they will be reported as press-release pairs. In some environments, the event mask may include bits reporting the state of shift, alt, and ctrl keys on the keyboard during the event. @@ -587,7 +605,7 @@ static void finish(int sig) See the manual page curs_mouse(3X) for full details of the mouse-interface functions. - Finishing Up + Finishing Up In order to clean up after the ncurses routines, the routine endwin() is provided. It restores tty modes to what they were when initscr() @@ -595,12 +613,12 @@ static void finish(int sig) Thus, anytime after the call to initscr, endwin() should be called before exiting. -Function Descriptions + Function Descriptions We describe the detailed behavior of some important curses functions here, as a supplement to the manual page descriptions. - Initialization and Wrapup + Initialization and Wrapup initscr() The first function called should almost always be initscr(). @@ -644,7 +662,7 @@ Function Descriptions The inverse of newterm(); deallocates the data structures associated with a given SCREEN reference. - Causing Output to the Terminal + Causing Output to the Terminal refresh() and wrefresh(win) These functions must be called to actually get any output on @@ -673,7 +691,7 @@ Function Descriptions with fewer total characters transmitted (this also avoids a visually annoying flicker at each update). - Low-Level Capability Access + Low-Level Capability Access setupterm(term, filenum, errret) This routine is called to initialize a terminal's description, @@ -701,16 +719,16 @@ Function Descriptions more terminals at once. Setupterm() also stores the names section of the terminal description in the global character array ttytype[]. Subsequent calls to setupterm() will overwrite - this array, so you'll have to save it yourself if need be. + this array, so you will have to save it yourself if need be. - Debugging + Debugging NOTE: These functions are not part of the standard curses API! trace() This function can be used to explicitly set a trace level. If the trace level is nonzero, execution of your program will - generate a file called `trace' in the current working directory + generate a file called "trace" in the current working directory containing a report on the library's actions. Higher trace levels enable more detailed (and verbose) reporting -- see comments attached to TRACE_ defines in the curses.h file for @@ -731,16 +749,16 @@ Function Descriptions single-line pseudo-operations. These pseudo-ops can be distinguished by the fact that they are named in capital letters. -Hints, Tips, and Tricks + Hints, Tips, and Tricks The ncurses manual pages are a complete reference for this library. In the remainder of this document, we discuss various useful methods that may not be obvious from the manual page descriptions. - Some Notes of Caution + Some Notes of Caution If you find yourself thinking you need to use noraw() or nocbreak(), - think again and move carefully. It's probably better design to use + think again and move carefully. It is probably better design to use getstr() or one of its relatives to simulate cooked mode. The noraw() and nocbreak() functions try to restore cooked mode, but they may end up clobbering some control bits set before you started your @@ -748,7 +766,7 @@ Hints, Tips, and Tricks likely to hurt your application's usability with other curses libraries. - Bear in mind that refresh() is a synonym for wrefresh(stdscr). Don't + Bear in mind that refresh() is a synonym for wrefresh(stdscr). Do not try to mix use of stdscr with use of windows declared by newwin(); a refresh() call will blow them off the screen. The right way to handle this is to use subwin(), or not touch stdscr at all and tile your @@ -771,10 +789,10 @@ Hints, Tips, and Tricks in an environment with window resizes, in which case several screens could be open with different sizes. - Temporarily Leaving NCURSES Mode + Temporarily Leaving NCURSES Mode Sometimes you will want to write a program that spends most of its - time in screen mode, but occasionally returns to ordinary `cooked' + time in screen mode, but occasionally returns to ordinary "cooked" mode. A common reason for this is to support shell-out. This behavior is simple to arrange in ncurses. @@ -796,7 +814,7 @@ Hints, Tips, and Tricks addstr("returned.\n"); /* prepare return message */ refresh(); /* restore save modes, repaint screen */ - Using NCURSES under XTERM + Using NCURSES under XTERM A resize operation in X sends SIGWINCH to the application running under xterm. The easiest way to handle SIGWINCH is to do an endwin, @@ -819,7 +837,7 @@ Hints, Tips, and Tricks it cannot know how you want the screen re-painted. You will usually have to write special-purpose code to handle KEY_RESIZE yourself. - Handling Multiple Terminal Screens + Handling Multiple Terminal Screens The initscr() function actually calls a function named newterm() to do most of its work. If you are writing a program that opens multiple @@ -831,7 +849,7 @@ Hints, Tips, and Tricks with the set_term call. Note that you will also have to call def_shell_mode and def_prog_mode on each tty yourself. - Testing for Terminal Capabilities + Testing for Terminal Capabilities Sometimes you may want to write programs that test for the presence of various capabilities before deciding whether to go into ncurses mode. @@ -839,20 +857,20 @@ Hints, Tips, and Tricks tigetflag(), tigetnum(), and tigetstr() to do your testing. A particularly useful case of this often comes up when you want to - test whether a given terminal type should be treated as `smart' - (cursor-addressable) or `stupid'. The right way to test this is to see + test whether a given terminal type should be treated as "smart" + (cursor-addressable) or "stupid". The right way to test this is to see if the return value of tigetstr("cup") is non-NULL. Alternatively, you can include the term.h file and test the value of the macro cursor_address. - Tuning for Speed + Tuning for Speed Use the addchstr() family of functions for fast screen-painting of - text when you know the text doesn't contain any control characters. - Try to make attribute changes infrequent on your screens. Don't use + text when you know the text does not contain any control characters. + Try to make attribute changes infrequent on your screens. Do not use the immedok() option! - Special Features of NCURSES + Special Features of NCURSES The wresize() function allows you to resize a window in place. The associated resizeterm() function simplifies the construction of @@ -872,14 +890,14 @@ Hints, Tips, and Tricks 8. While most terminals which provide color allow only 8 colors, about a quarter (including XFree86 xterm) support 16 colors. -Compatibility with Older Versions + Compatibility with Older Versions Despite our best efforts, there are some differences between ncurses and the (undocumented!) behavior of older curses implementations. These arise from ambiguities or omissions in the documentation of the API. - Refresh of Overlapping Windows + Refresh of Overlapping Windows If you define two windows A and B that overlap, and then alternately scribble on and refresh them, the changes made to the overlapping @@ -913,7 +931,7 @@ Compatibility with Older Versions they do change copy or entire copy. We know that System V release 3 curses has logic in it that looks like an attempt to do change copy, but the surrounding logic and data representations are sufficiently - complex, and our knowledge sufficiently indirect, that it's hard to + complex, and our knowledge sufficiently indirect, that it is hard to know whether this is reliable. It is not clear what the SVr4 documentation and XSI standard intend. The XSI Curses standard barely mentions wnoutrefresh(); the SVr4 documents seem to be describing @@ -931,7 +949,7 @@ Compatibility with Older Versions you have defined. Then you can do one doupdate() and there will be a single burst of physical I/O that will do all your updates. - Background Erase + Background Erase If you have been using a very old versions of ncurses (1.8.7 or older) you may be surprised by the behavior of the erase functions. In older @@ -946,7 +964,7 @@ Compatibility with Older Versions This change in behavior conforms ncurses to System V Release 4 and the XSI Curses standard. -XSI Curses Conformance + XSI Curses Conformance The ncurses library is intended to be base-level conformant with the XSI Curses standard from X/Open. Many extended-level features (in @@ -960,7 +978,7 @@ XSI Curses Conformance have a corresponding function which may be linked (and will be prototype-checked) if the macro definition is disabled with #undef. - The Panels Library +The Panels Library The ncurses library by itself provides good support for screen displays in which the windows are tiled (non-overlapping). In the more @@ -977,7 +995,7 @@ XSI Curses Conformance The panel library first appeared in AT&T System V. The version documented here is the panel code distributed with ncurses. -Compiling With the Panels Library + Compiling With the Panels Library Your panels-using modules must import the panels library declarations with @@ -988,7 +1006,7 @@ Compiling With the Panels Library -lncurses. Many linkers are two-pass and will accept either order, but it is still good practice to put -lpanel first and -lncurses second. -Overview of Panels + Overview of Panels A panel object is a window that is implicitly treated as part of a deck including all other panel objects. The deck has an implicit @@ -997,8 +1015,8 @@ Overview of Panels in the proper order to resolve overlaps. The standard window, stdscr, is considered below all panels. - Details on the panels functions are available in the man pages. We'll - just hit the highlights here. + Details on the panels functions are available in the man pages. We + will just hit the highlights here. You create a panel from a window by calling new_panel() on a window pointer. It then becomes the top of the deck. The panel's window is @@ -1009,11 +1027,11 @@ Overview of Panels This will not deallocate the associated window; you have to do that yourself. You can replace a panel's window with a different window by calling replace_window. The new window may be of different size; the - panel code will re-compute all overlaps. This operation doesn't change - the panel's position in the deck. + panel code will re-compute all overlaps. This operation does not + change the panel's position in the deck. To move a panel's window, use move_panel(). The mvwin() function on - the panel's window isn't sufficient because it doesn't update the + the panel's window is not sufficient because it does not update the panels library's representation of where the windows are. This operation leaves the panel's depth, contents, and size unchanged. @@ -1028,12 +1046,12 @@ Overview of Panels Typically, you will want to call update_panels() and doupdate() just before accepting command input, once in each cycle of interaction with the user. If you call update_panels() after each and every panel - write, you'll generate a lot of unnecessary refresh activity and + write, you will generate a lot of unnecessary refresh activity and screen flicker. -Panels, Input, and the Standard Screen + Panels, Input, and the Standard Screen - You shouldn't mix wnoutrefresh() or wrefresh() operations with panels + You should not mix wnoutrefresh() or wrefresh() operations with panels code; this will work only if the argument window is either in the top panel or unobscured by any other panels. @@ -1049,9 +1067,9 @@ Panels, Input, and the Standard Screen There is presently no way to display changes to one obscured panel without repainting all panels. -Hiding Panels + Hiding Panels - It's possible to remove a panel from the deck temporarily; use + It is possible to remove a panel from the deck temporarily; use hide_panel for this. Use show_panel() to render it visible again. The predicate function panel_hidden tests whether or not a panel is hidden. @@ -1060,9 +1078,9 @@ Hiding Panels or bottom_panel on a hidden panel(). Other panels operations are applicable. -Miscellaneous Other Facilities + Miscellaneous Other Facilities - It's possible to navigate the deck using the functions panel_above() + It is possible to navigate the deck using the functions panel_above() and panel_below. Handed a panel pointer, they return the panel above or below that panel. Handed NULL, they return the bottom-most or top-most panel. @@ -1071,7 +1089,7 @@ Miscellaneous Other Facilities code, to which you can attach application data. See the man page documentation of set_panel_userptr() and panel_userptr for details. - The Menu Library +The Menu Library A menu is a screen display that assists the user to choose some subset of a given set of items. The menu library is a curses extension that @@ -1081,7 +1099,7 @@ Miscellaneous Other Facilities The menu library first appeared in AT&T System V. The version documented here is the menu code distributed with ncurses. -Compiling With the menu Library + Compiling With the menu Library Your menu-using modules must import the menu library declarations with #include