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diff --git a/doc/ncurses-intro.doc b/doc/ncurses-intro.doc index 4e752ed0fc54..a20ee1a1d271 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 @@ -129,7 +131,7 @@ 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 vi editor; these used the termcap @@ -163,7 +165,7 @@ A Brief History of Curses releases, curses evolved to use more facilities and offer more capabilities, going far beyond BSD curses in power and flexibility. -Scope of This Document + 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 @@ -206,7 +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: @@ -227,11 +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: @@ -245,7 +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 @@ -273,7 +275,7 @@ An Overview of Curses 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, @@ -313,7 +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. @@ -340,7 +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 @@ -409,7 +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 @@ -435,7 +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 @@ -464,7 +466,7 @@ 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 @@ -488,7 +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 @@ -500,7 +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 @@ -531,7 +533,7 @@ static void finish(int sig) 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. @@ -603,7 +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() @@ -611,12 +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(). @@ -660,7 +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 @@ -689,7 +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, @@ -719,7 +721,7 @@ Function Descriptions array ttytype[]. Subsequent calls to setupterm() will overwrite 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! @@ -747,13 +749,13 @@ 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 is probably better design to use @@ -787,7 +789,7 @@ 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" @@ -812,7 +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, @@ -835,7 +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 @@ -847,7 +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. @@ -861,14 +863,14 @@ Hints, Tips, and Tricks 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 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 @@ -888,14 +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 @@ -947,7 +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 @@ -962,7 +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 @@ -976,7 +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 @@ -993,7 +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 @@ -1004,7 +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 @@ -1047,7 +1049,7 @@ Overview of Panels 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 should not mix wnoutrefresh() or wrefresh() operations with panels code; this will work only if the argument window is either in the top @@ -1065,7 +1067,7 @@ 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 is possible to remove a panel from the deck temporarily; use hide_panel for this. Use show_panel() to render it visible again. The @@ -1076,7 +1078,7 @@ Hiding Panels or bottom_panel on a hidden panel(). Other panels operations are applicable. -Miscellaneous Other Facilities + Miscellaneous Other Facilities It is possible to navigate the deck using the functions panel_above() and panel_below. Handed a panel pointer, they return the panel above @@ -1087,7 +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 @@ -1097,7 +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 <menu.h> @@ -1107,7 +1109,7 @@ Compiling With the menu Library -lncurses. Many linkers are two-pass and will accept either order, but it is still good practice to put -lmenu first and -lncurses second. -Overview of Menus + Overview of Menus The menus created by this library consist of collections of items including a name string part and a description string part. To make @@ -1137,7 +1139,7 @@ Overview of Menus 9. Free the items using free_item(). 10. Terminate curses. -Selecting items + Selecting items Menus may be multi-valued or (the default) single-valued (see the manual page menu_opts(3x) to see how to change the default). Both @@ -1154,7 +1156,7 @@ Selecting items option so far defined for menus, but it is good practice to code as though other option bits might be on. -Menu Display + Menu Display The menu library calculates a minimum display size for your window, based on the following variables: @@ -1197,7 +1199,7 @@ Menu Display have reasonable defaults which the library allows you to change (see the menu_attribs(3x) manual page. -Menu Windows + Menu Windows Each menu has, as mentioned previously, a pair of associated windows. Both these windows are painted when the menu is posted and erased when @@ -1217,7 +1219,7 @@ Menu Windows these actually modifies the screen. To do that, call wrefresh() or some equivalent. -Processing Menu Input + Processing Menu Input The main loop of your menu-processing code should call menu_driver() repeatedly. The first argument of this routine is a menu pointer; the @@ -1261,7 +1263,7 @@ Processing Menu Input considered application-specific commands. The menu_driver() code ignores them and returns E_UNKNOWN_COMMAND. -Miscellaneous Other Features + Miscellaneous Other Features Various menu options can affect the processing and visual appearance and input processing of menus. See menu_opts(3x) for details. @@ -1280,7 +1282,7 @@ Miscellaneous Other Features Each item, and each menu, has an associated user pointer on which you can hang application data. See mitem_userptr(3x) and menu_userptr(3x). - The Forms Library +The Forms Library The form library is a curses extension that supports easy programming of on-screen forms for data entry and program control. @@ -1288,7 +1290,7 @@ Miscellaneous Other Features The form library first appeared in AT&T System V. The version documented here is the form code distributed with ncurses. -Compiling With the form Library + Compiling With the form Library Your form-using modules must import the form library declarations with #include <form.h> @@ -1298,7 +1300,7 @@ Compiling With the form Library -lncurses. Many linkers are two-pass and will accept either order, but it is still good practice to put -lform first and -lncurses second. -Overview of Forms + Overview of Forms A form is a collection of fields; each field may be either a label (explanatory text) or a data-entry location. Long forms may be @@ -1347,7 +1349,7 @@ Overview of Forms operations, the menu driver loop has to support field editing and data validation. -Creating and Freeing Fields and Forms + Creating and Freeing Fields and Forms The basic function for creating fields is new_field(): FIELD *new_field(int height, int width, /* new field size */ @@ -1423,7 +1425,7 @@ FORM *new_form(FIELD **fields); to a form, but not vice-versa; thus, you will generally free your form objects first. -Fetching and Changing Field Attributes + Fetching and Changing Field Attributes Each form field has a number of location and size attributes associated with it. There are other field attributes used to control @@ -1438,7 +1440,7 @@ Fetching and Changing Field Attributes to mean this field. Changes to it persist as defaults until your forms application terminates. - Fetching Size and Location Data + Fetching Size and Location Data You can retrieve field sizes and locations through: int field_info(FIELD *field, /* field from which to fetch */ @@ -1451,7 +1453,7 @@ int field_info(FIELD *field, /* field from which to fetch */ size and location attributes of a new field, it fetches them from an existing one. - Changing the Field Location + Changing the Field Location It is possible to move a field's location on the screen: int move_field(FIELD *field, /* field to alter */ @@ -1459,7 +1461,7 @@ int move_field(FIELD *field, /* field to alter */ You can, of course. query the current location through field_info(). - The Justification Attribute + The Justification Attribute One-line fields may be unjustified, justified right, justified left, or centered. Here is how you manipulate this attribute: @@ -1472,7 +1474,7 @@ int field_just(FIELD *field); /* fetch mode of field */ preprocessor macros NO_JUSTIFICATION, JUSTIFY_RIGHT, JUSTIFY_LEFT, or JUSTIFY_CENTER. - Field Display Attributes + Field Display Attributes For each field, you can set a foreground attribute for entered characters, a background attribute for the entire field, and a pad @@ -1507,7 +1509,7 @@ chtype new_page(FIELD *field); /* field to query */ etc). The page bit of a field controls whether it is displayed at the start of a new form screen. - Field Option Bits + Field Option Bits There is also a large collection of field option bits you can set to control various aspects of forms processing. You can manipulate them @@ -1593,7 +1595,7 @@ int field_opts(FIELD *field); /* field to query */ The option values are bit-masks and can be composed with logical-or in the obvious way. -Field Status + Field Status Every field has a status flag, which is set to FALSE when the field is created and TRUE when the value in field buffer 0 changes. This flag @@ -1616,7 +1618,7 @@ int field_status(FIELD *field); /* fetch mode of field */ initialization or termination hooks, or (3) just after a REQ_VALIDATION request has been processed by the forms driver. -Field User Pointer + Field User Pointer Each field structure contains one character pointer slot that is not used by the forms library. It is intended to be used by applications @@ -1634,7 +1636,7 @@ char *field_userptr(FIELD *field); /* fetch mode of field */ field is created, the default-field user pointer is copied to initialize the new field's user pointer. -Variable-Sized Fields + Variable-Sized Fields Normally, a field is fixed at the size specified for it at creation time. If, however, you turn off its O_STATIC bit, it becomes dynamic @@ -1673,7 +1675,7 @@ int set_max_field(FIELD *field, /* field to alter (may not be NULL) */ the field; use dynamic_field_info() to get the actual dynamic size. -Field Validation + Field Validation By default, a field will accept any data that will fit in its input buffer. However, it is possible to attach a validation type to a @@ -1703,7 +1705,7 @@ FIELDTYPE *field_type(FIELD *field); /* field to query */ Here are the pre-defined validation types: - TYPE_ALPHA + TYPE_ALPHA This field type accepts alphabetic data; no blanks, no digits, no special characters (this is checked at character-entry time). It is @@ -1717,7 +1719,7 @@ int set_field_type(FIELD *field, /* field to alter */ width, the validation check will always fail. A minimum width of zero makes field completion optional. - TYPE_ALNUM + TYPE_ALNUM This field type accepts alphabetic data and digits; no blanks, no special characters (this is checked at character-entry time). It is @@ -1731,7 +1733,7 @@ int set_field_type(FIELD *field, /* field to alter */ greater than the field width, the validation check will always fail. A minimum width of zero makes field completion optional. - TYPE_ENUM + TYPE_ENUM This type allows you to restrict a field's values to be among a specified set of string values (for example, the two-letter postal @@ -1760,7 +1762,7 @@ int set_field_type(FIELD *field, /* field to alter */ The REQ_NEXT_CHOICE and REQ_PREV_CHOICE input requests can be particularly useful with these fields. - TYPE_INTEGER + TYPE_INTEGER This field type accepts an integer. It is set up as follows: int set_field_type(FIELD *field, /* field to alter */ @@ -1778,7 +1780,7 @@ int set_field_type(FIELD *field, /* field to alter */ A TYPE_INTEGER value buffer can conveniently be interpreted with the C library function atoi(3). - TYPE_NUMERIC + TYPE_NUMERIC This field type accepts a decimal number. It is set up as follows: int set_field_type(FIELD *field, /* field to alter */ @@ -1798,7 +1800,7 @@ int set_field_type(FIELD *field, /* field to alter */ A TYPE_NUMERIC value buffer can conveniently be interpreted with the C library function atof(3). - TYPE_REGEXP + TYPE_REGEXP This field type accepts data matching a regular expression. It is set up as follows: @@ -1809,7 +1811,7 @@ int set_field_type(FIELD *field, /* field to alter */ The syntax for regular expressions is that of regcomp(3). The check for regular-expression match is performed on exit. -Direct Field Buffer Manipulation + Direct Field Buffer Manipulation The chief attribute of a field is its buffer contents. When a form has been completed, your application usually needs to know the state of @@ -1840,7 +1842,7 @@ int set_field_buffer(FIELD *field, /* field to alter */ or form's initialization or termination hooks, or (3) just after a REQ_VALIDATION request has been processed by the forms driver. -Attributes of Forms + Attributes of Forms As with field attributes, form attributes inherit a default from a system default form structure. These defaults can be queried or set by @@ -1868,7 +1870,7 @@ int field_count(FORM *form); /* count connect fields */ connected to a given from. It returns -1 if the form-pointer argument is NULL. -Control of Form Display + Control of Form Display In the overview section, you saw that to display a form you normally start by defining its size (and fields), posting it, and refreshing @@ -1938,7 +1940,7 @@ int pos_form_cursor(FORM *) /* form to be queried */ before handing control back to the forms driver in order to re-synchronize it. -Input Processing in the Forms Driver + Input Processing in the Forms Driver The function form_driver() handles virtualized input requests for form navigation, editing, and validation requests, just as menu_driver does @@ -1955,7 +1957,7 @@ int form_driver(FORM *form, /* form to pass input to */ field-termination functions) with which your application code can check that the input taken by the driver matched what was expected. - Page Navigation Requests + Page Navigation Requests These requests cause page-level moves through the form, triggering display of a new form screen. @@ -1976,7 +1978,7 @@ int form_driver(FORM *form, /* form to pass input to */ the last page goes to the first, and REQ_PREV_PAGE from the first page goes to the last. - Inter-Field Navigation Requests + Inter-Field Navigation Requests These requests handle navigation between fields on the same page. @@ -2039,7 +2041,7 @@ int form_driver(FORM *form, /* form to pass input to */ only if A, B, and C all share the same first line; otherwise it will skip over B to C. - Intra-Field Navigation Requests + Intra-Field Navigation Requests These requests drive movement of the edit cursor within the currently selected field. @@ -2090,7 +2092,7 @@ int form_driver(FORM *form, /* form to pass input to */ whitespace. The commands to move to beginning and end of line or field look for the first or last non-pad character in their ranges. - Scrolling Requests + Scrolling Requests Fields that are dynamic and have grown and fields explicitly created with offscreen rows are scrollable. One-line fields scroll @@ -2138,7 +2140,7 @@ int form_driver(FORM *form, /* form to pass input to */ For scrolling purposes, a page of a field is the height of its visible part. - Editing Requests + Editing Requests When you pass the forms driver an ASCII character, it is treated as a request to add the character to the field's data buffer. Whether this @@ -2223,7 +2225,7 @@ int form_driver(FORM *form, /* form to pass input to */ See Form Options for discussion of how to set and clear the overload options. - Order Requests + Order Requests If the type of your field is ordered, and has associated functions for getting the next and previous values of the type from a given value, @@ -2240,14 +2242,14 @@ int form_driver(FORM *form, /* form to pass input to */ Custom Validation Types), you can associate our own ordering functions. - Application Commands + Application Commands Form requests are represented as integers above the curses value greater than KEY_MAX and less than or equal to the constant MAX_COMMAND. If your input-virtualization routine returns a value above MAX_COMMAND, the forms driver will ignore it. -Field Change Hooks + Field Change Hooks It is possible to set function hooks to be executed whenever the current field or form changes. Here are the functions that support @@ -2309,7 +2311,7 @@ HOOK field_term(FORM *form); /* form to query */ You can disable any of these hooks by (re)setting them to NULL, the default value. -Field Change Commands + Field Change Commands Normally, navigation through the form will be driven by the user's input requests. But sometimes it is useful to be able to move the @@ -2340,7 +2342,7 @@ int form_page(FORM *form); /* return form's current page */ The initial page of a newly-created form is 0. The function set_form_fields() resets this. -Form Options + Form Options Like fields, forms may have control option bits. They can be changed or queried with these functions: @@ -2371,7 +2373,7 @@ int form_opts(FORM *form); /* form to query */ The option values are bit-masks and can be composed with logical-or in the obvious way. -Custom Validation Types + Custom Validation Types The form library gives you the capability to define custom validation types of your own. Further, the optional additional arguments of @@ -2380,7 +2382,7 @@ Custom Validation Types with the handling of the additional arguments within custom validation functions. - Union Types + Union Types The simplest way to create a custom data type is to compose it from two preexisting ones: @@ -2397,7 +2399,7 @@ FIELD *link_fieldtype(FIELDTYPE *type1, first type, then for the second, to figure what type the buffer contents should be treated as. - New Field Types + New Field Types To create a field type from scratch, you need to specify one or both of the following things: @@ -2430,7 +2432,7 @@ int free_fieldtype(FIELDTYPE *ftype); /* type to free */ argument. It too should return TRUE if the character is valid, FALSE otherwise. - Validation Function Arguments + Validation Function Arguments Your field- and character- validation functions will be passed a second argument as well. This second argument is the address of a @@ -2479,7 +2481,7 @@ int set_fieldtype_arg(FIELDTYPE *type, /* type to alter */ functions should never see a NULL file pointer and need not check specially for it. - Order Functions For Custom Types + Order Functions For Custom Types Some custom field types are simply ordered in the same well-defined way that TYPE_ENUM is. For such types, it is possible to define @@ -2499,7 +2501,7 @@ int set_fieldtype_arg(FIELDTYPE *type, /* type to alter */ success (a legal next or previous value was set) or FALSE to indicate failure. - Avoiding Problems + Avoiding Problems The interface for defining custom types is complicated and tricky. Rather than attempting to create a custom type entirely from scratch, |