Introduction

This file documents the support for various windowing systems in
NetHack.  The support is through a standard interface, separating the
main NetHack code from window-system specific code.  The implementation
supports multiple window systems in the same binary.  Even if you only
wish to support one window-port on your port, you will need to follow
the instructions in Section VII to get a compilable binary.

Contents:
	I.   Window Types and Terminology
	II.  Interface Specification
	III. Global variables
	IV.  New or respecified common, high level routines
	V.   Game startup
	VI.  Conventions
	VII. Implementation and Multi-window support

I.  Window Types and Terminology

There are 5 basic window types, used to call create_nhwindow():

	NHW_MESSAGE	(top line)
	NHW_STATUS	(bottom lines)
	NHW_MAP		(main dungeon)
	NHW_MENU	(inventory or other "corner" windows)
	NHW_TEXT	(help/text, full screen paged window)

The tty window-port also uses NHW_BASE (the base display) internally.

NHW_MENU windows can be used for either menu or text display.  Their
basic feature is that for the tty-port, if the window is small enough,
it appears in the corner of the tty display instead of overwriting
the whole screen.  The first call to add information to the window
will decide if it is going to be used to display a menu or text.
If start_menu() is called, then it will be used as a menu.  If
putstr() is called, it will be used as text.  Once decided, there
is no turning back.  For the tty-port, if the data is too large for
a single screen then the data is paged (with --more--) between pages.
Only NHW_MENU type windows can be used for menus.

NHW_TEXT windows are used to display a large amount of textual data.
This is the type of window one would use for displaying a help file,
for example.  In the tty window-port, windows of type NHW_TEXT can
page using the DEF_PAGER, if DEF_PAGER is defined.  There exists an
assumption that the font for text windows is monospaced.  The help
files are all formatted accordingly.

"window" is always of type winid.  This is currently implemented as an
integer, but doesn't necessarily have to be done that way.  There are
a few fixed window names that are known throughout the code:

	WIN_MESSAGE	(top line)
	WIN_STATUS	(bottom lines)
	WIN_MAP		(main dungeon)
	WIN_INVEN	(inventory)

Other windows are created and destroyed as needed.

"Port" in this document refers to a CPU/OS/hardware platform (UNIX, MSDOS
TOS, etc.)  "window-port" refers to the windowing platform.  This is
orthogonal (e.g.  UNIX might use either a tty window-port or an X11
window-port).


II.  Interface Specification

All functions below are void unless otherwise noted.

A.  Low-level routines:

raw_print(str)	-- Print directly to a screen, or otherwise guarantee that
		   the user sees str.  raw_print() appends a newline to str.
		   It need not recognize ASCII control characters.  This is
		   used during startup (before windowing system initialization
		   -- maybe this means only error startup messages are raw),
		   for error messages, and maybe other "msg" uses.  E.g.
		   updating status for micros (i.e, "saving").
raw_print_bold(str)
		-- Like raw_print(), but prints in bold/standout (if possible).
curs(window, x, y)
		-- Next output to window will start at (x,y), also moves
		   displayable cursor to (x,y).  For backward compatibility,
		   1 <= x < cols, 0 <= y < rows, where cols and rows are
		   the size of window.
		-- For variable sized windows, like the status window, the
		   behavior when curs() is called outside the window's limits
		   is unspecified. The mac port wraps to 0, with the status
		   window being 2 lines high and 80 columns wide.
		-- Still used by curs_on_u(), status updates, screen locating
		   (identify, teleport).
		-- NHW_MESSAGE, NHW_MENU and NHW_TEXT windows do not
		   currently support curs in the tty window-port.
putstr(window, attr, str)
		-- Print str on the window with the given attribute.  Only
		   printable ASCII characters (040-0126) must be supported.
		   Multiple putstr()s are output on separate lines.  Attributes
		   can be one of
			ATR_NONE (or 0)
			ATR_ULINE
			ATR_BOLD
			ATR_BLINK
			ATR_INVERSE
		   If a window-port does not support all of these, it may map
		   unsupported attributes to a supported one (e.g. map them
		   all to ATR_INVERSE).  putstr() may compress spaces out of
		   str, break str, or truncate str, if necessary for the
		   display.  Where putstr() breaks a line, it has to clear
		   to end-of-line.
		-- putstr should be implemented such that if two putstr()s
		   are done consecutively the user will see the first and
		   then the second.  In the tty port, pline() achieves this
		   by calling more() or displaying both on the same line.
get_nh_event()	-- Does window event processing (e.g. exposure events).
		   A noop for the tty and X window-ports.
int nhgetch()	-- Returns a single character input from the user.
		-- In the tty window-port, nhgetch() assumes that tgetch()
		   will be the routine the OS provides to read a character.
		   Returned character _must_ be non-zero.
int nh_poskey(int *x, int *y, int *mod)
		-- Returns a single character input from the user or a
		   a positioning event (perhaps from a mouse).  If the
		   return value is non-zero, a character was typed, else,
		   a position in the MAP window is returned in x, y and mod.
		   mod may be one of

			CLICK_1		/* mouse click type 1 */
			CLICK_2		/* mouse click type 2 */

		   The different click types can map to whatever the
		   hardware supports.  If no mouse is supported, this
		   routine always returns a non-zero character.

B.  High-level routines:

print_glyph(window, x, y, glyph)
		-- Print the glyph at (x,y) on the given window.  Glyphs are
		   integers at the interface, mapped to whatever the window-
		   port wants (symbol, font, color, attributes, ...there's
		   a 1-1 map between glyphs and distinct things on the map).
char yn_function(const char *ques, const char *choices, char default)
		-- Print a prompt made up of ques, choices and default.
		   Read a single character response that is contained in
		   choices or default.  If choices is NULL, all possible
		   inputs are accepted and returned.  This overrides
		   everything else.  The choices are expected to be in
		   lower case.  Entering ESC always maps to 'q', or 'n',
		   in that order, if present in choices, otherwise it maps
		   to default.  Entering any other quit character (SPACE,
		   RETURN, NEWLINE) maps to default.
		-- If the choices string contains ESC, then anything after
		   it is an acceptable response, but the ESC and whatever
		   follows is not included in the prompt.
		-- If the choices string contains a '#' then accept a count.
		   Place this value in the global "yn_number" and return '#'.
		-- This uses the top line in the tty window-port, other
		   ports might use a popup.
getlin(const char *ques, char *input)
		-- Prints ques as a prompt and reads a single line of text,
		   up to a newline.  The string entered is returned without the
		   newline.  ESC is used to cancel, in which case the string
		   "\033\000" is returned.
		-- getlin() must call flush_screen(1) before doing anything.
		-- This uses the top line in the tty window-port, other
		   ports might use a popup.
int get_ext_cmd(void)
		-- Get an extended command in a window-port specific way.
		   An index into extcmdlist[] is returned on a successful
		   selection, -1 otherwise.
player_selection()
		-- Do a window-port specific player type selection.  If
		   player_selection() offers a Quit option, it is its
		   responsibility to clean up and terminate the process.
		   You need to fill in pl_character[0].
display_file(str, boolean complain)
		-- Display the file named str.  Complain about missing files
		   iff complain is TRUE.
update_inventory()
		-- Indicate to the window port that the inventory has been
		   changed.
		-- Merely calls display_inventory() for window-ports that
		   leave the window up, otherwise empty.
doprev_message()
		-- Display previous messages.  Used by the ^P command.
		-- On the tty-port this scrolls WIN_MESSAGE back one line.

update_positionbar(char *features)
		-- Optional, POSITIONBAR must be defined. Provide some 
		   additional information for use in a horizontal
		   position bar (most useful on clipped displays).
		   Features is a series of char pairs.  The first char
		   in the pair is a symbol and the second char is the
		   column where it is currently located.
		   A '<' is used to mark an upstairs, a '>'
		   for a downstairs, and an '@' for the current player
		   location. A zero char marks the end of the list.
			

C.  Window Utility Routines

init_nhwindows(int* argcp, char** argv)
		-- Initialize the windows used by NetHack.  This can also
		   create the standard windows listed at the top, but does
		   not display them.
		-- Any commandline arguments relevant to the windowport
		   should be interpreted, and *argcp and *argv should
		   be changed to remove those arguments.
		-- When the message window is created, the variable
		   iflags.window_inited needs to be set to TRUE.  Otherwise
		   all plines() will be done via raw_print().
		** Why not have init_nhwindows() create all of the "standard"
		** windows?  Or at least all but WIN_INFO?	-dean
exit_nhwindows(str)
		-- Exits the window system.  This should dismiss all windows,
		   except the "window" used for raw_print().  str is printed
		   if possible.
window = create_nhwindow(type)
		-- Create a window of type "type."
clear_nhwindow(window)
		-- Clear the given window, when appropriate.
display_nhwindow(window, boolean blocking)
		-- Display the window on the screen.  If there is data
		   pending for output in that window, it should be sent.
		   If blocking is TRUE, display_nhwindow() will not
		   return until the data has been displayed on the screen,
		   and acknowledged by the user where appropriate.
		-- All calls are blocking in the tty window-port.
		-- Calling display_nhwindow(WIN_MESSAGE,???) will do a
		   --more--, if necessary, in the tty window-port.
destroy_nhwindow(window)
		-- Destroy will dismiss the window if the window has not
		   already been dismissed.
start_menu(window)
		-- Start using window as a menu.  You must call start_menu()
		   before add_menu().  After calling start_menu() you may not
		   putstr() to the window.  Only windows of type NHW_MENU may
		   be used for menus.
add_menu(windid window, int glyph, const anything identifier,
				char accelerator, char groupacc,
				int attr, char *str, boolean preselected)
		-- Add a text line str to the given menu window.  If identifier
		   is 0, then the line cannot be selected (e.g. a title).
		   Otherwise, identifier is the value returned if the line is
		   selected.  Accelerator is a keyboard key that can be used
		   to select the line.  If the accelerator of a selectable
		   item is 0, the window system is free to select its own
		   accelerator.  It is up to the window-port to make the
		   accelerator visible to the user (e.g. put "a - " in front
		   of str).  The value attr is the same as in putstr().
		   Glyph is an optional glyph to accompany the line.  If
		   window port cannot or does not want to display it, this
		   is OK.  If there is no glyph applicable, then this
		   value will be NO_GLYPH.
		-- All accelerators should be in the range [A-Za-z].
	        -- It is expected that callers do not mix accelerator
		   choices.  Either all selectable items have an accelerator
		   or let the window system pick them.  Don't do both.
		-- Groupacc is a group accelerator.  It may be any character
		   outside of the standard accelerator (see above) or a
		   number.  If 0, the item is unaffected by any group
		   accelerator.  If this accelerator conflicts with
		   the menu command (or their user defined alises), it loses.
		   The menu commands and aliases take care not to interfere
		   with the default object class symbols.
		-- If you want this choice to be preselected when the
		   menu is displayed, set preselected to TRUE.

end_menu(window, prompt)
		-- Stop adding entries to the menu and flushes the window
		   to the screen (brings to front?).  Prompt is a prompt
		   to give the user.  If prompt is NULL, no prompt will
		   be printed.
		** This probably shouldn't flush the window any more (if
		** it ever did).  That should be select_menu's job.  -dean
int select_menu(windid window, int how, menu_item **selected)
		-- Return the number of items selected; 0 if none were chosen,
		   -1 when explicitly cancelled.  If items were selected, then
		   selected is filled in with an allocated array of menu_item
		   structures, one for each selected line.  The caller must
		   free this array when done with it.  The "count" field
		   of selected is a user supplied count.  If the user did
		   not supply a count, then the count field is filled with
		   -1 (meaning all).  A count of zero is equivalent to not
		   being selected and should not be in the list.  If no items
		   were selected, then selected is NULL'ed out.  How is the
		   mode of the menu.  Three valid values are PICK_NONE,
		   PICK_ONE, and PICK_N, meaning: nothing is selectable,
		   only one thing is selectable, and any number valid items
		   may selected.  If how is PICK_NONE, this function should
		   never return anything but 0 or -1.
		-- You may call select_menu() on a window multiple times --
		   the menu is saved until start_menu() or destroy_nhwindow()
		   is called on the window.
		-- Note that NHW_MENU windows need not have select_menu()
		   called for them. There is no way of knowing whether
		   select_menu() will be called for the window at
		   create_nhwindow() time.
char message_menu(char let, int how, const char *mesg)
		-- tty-specific hack to allow single line context-sensitive
		   help to behave compatibly with multi-line help menus.
		-- This should only be called when a prompt is active; it
		   sends `mesg' to the message window.  For tty, it forces
		   a --More-- prompt and enables `let' as a viable keystroke
		   for dismissing that prompt, so that the original prompt
		   can be answered from the message line "help menu".
		-- Return value is either `let', '\0' (no selection was made),
		   or '\033' (explicit cancellation was requested).
		-- Interfaces which issue prompts and messages to separate
		   windows typically won't need this functionality, so can
		   substitute genl_message_menu (windows.c) instead.

D.  Misc. Routines

make_sound(???) -- To be determined later.  THIS IS CURRENTLY UN-IMPLEMENTED.
nhbell()	-- Beep at user.  [This will exist at least until sounds are
		   redone, since sounds aren't attributable to windows anyway.]
mark_synch()	-- Don't go beyond this point in I/O on any channel until
		   all channels are caught up to here.  Can be an empty call
		   for the moment
wait_synch()	-- Wait until all pending output is complete (*flush*() for
		   streams goes here).
		-- May also deal with exposure events etc. so that the
		   display is OK when return from wait_synch().
delay_output()	-- Causes a visible delay of 50ms in the output.
		   Conceptually, this is similar to wait_synch() followed
		   by a nap(50ms), but allows asynchronous operation.
askname()	-- Ask the user for a player name.
cliparound(x, y)-- Make sure that the user is more-or-less centered on the
		   screen if the playing area is larger than the screen.
		-- This function is only defined if CLIPPING is defined.
number_pad(state)
		-- Initialize the number pad to the given state.
suspend_nhwindows(str)
		-- Prepare the window to be suspended.
resume_nhwindows()
		-- Restore the windows after being suspended.

start_screen()	-- Only used on Unix tty ports, but must be declared for
		   completeness.  Sets up the tty to work in full-screen
		   graphics mode.  Look at win/tty/termcap.c for an
		   example.  If your window-port does not need this function
		   just declare an empty function.
end_screen()	-- Only used on Unix tty ports, but must be declared for
		   completeness.  The complement of start_screen().

outrip(winid, int)
		-- The tombstone code.  If you want the traditional code use
		   genl_outrip for the value and check the #if in rip.c.

III.  Global variables

The following global variables are defined in decl.c and must be used by
the window interface to the rest of NetHack.

char toplines[BUFSZ]	Contains the last message printed to the WIN_MESSAGE
			window, used by Norep().
winid WIN_MESSAGE, WIN_MAP, WIN_STATUS, WIN_INVEN
			The four standard windows.
char *AE, *AS;		Checked in options.c to see if we should switch
			to DEC_GRAPHICS.  It is #ifdefed VMS and UNIX.
int LI, CO;		Set in sys/unix/ioctl.c.

The following appears to be Unix specific.  Other ports using the tty
window-port should also declare this variable in one of your sys/*.c files.

short ospeed;		Set and declared in sys/unix/unixtty.c (don't
			know about other sys files).

IV.  New or respecified common, high level routines

These are not part of the interface, but mentioned here for your information.

char display_inventory(lets, want_reply)
		-- Calls a start_menu()/add_menu()/select_menu() sequence.
		   It returns the item selected, or '\0' if none is selected.
		   Returns '\033' if the menu was canceled.
raw_printf(str, ...)
		-- Like raw_print(), but accepts arguments like printf().  This
		   routine processes the arguments and then calls raw_print().
		-- The mac version #defines error raw_printf.  I think this
		   is a reasonable thing to do for most ports.
pline(str, ...)
		-- Prints a string to WIN_MESSAGE using a printf() interface.
		   It has the variants You(), Your(), Norep(), and others
		   in pline.c which all use the same mechanism.  pline()
		   requires the variable "char toplines[]" be defined; Every
		   putstr() on WIN_MESSAGE must copy str to toplines[] for use
		   by Norep() and pline().  If the window system is not active
		   (!iflags.window_inited) pline() uses raw_print().


V.  Game startup

The following is the general order in which calls from main() should be made,
as they relate to the window system.  The actual code may differ, but the
order of the calls should be the same.


choose_windows(DEFAULT_WINDOW_SYS) /* choose a default window system */
initoptions()			   /* read the resource file */
init_nhwindows()		   /* initialize the window system */
process_options(argc, argv)	   /* process command line options or equiv */
if(save file is present) {
  display_gamewindows()		   /* create & display the game windows */
  dorestore()			   /* restore old game; pline()s are OK */
} else {
  player_selection()		   /* select a player type using a window */
  display_gamewindows()		   /* create & display the game windows */
}
pline("Hello, welcome...");

Choose_windows() is a common routine, and calling it in main() is necessary
to initialize the function pointer table to _something_ so that calls to
raw_print() will not fail.  Choose_windows() should be called almost
immediately upon entering main().  Look at unixmain.c for an example.

Display_gamewindows() is a common routine that displays the three standard
game windows (WIN_MESSAGE, WIN_MAP, and WIN_STATUS).  It is normally called
just before the "Hello, welcome" message.

Process_options() is currently still unique to each port.  There may be need
in the future to make it possible to replace this on a per window-port basis.


VI.  Conventions

init_nhwindows() is expected to display a gee-whiz banner window, including
the Copyright message.  It is recommended that the COPYRIGHT_BANNER_A,
COPYRIGHT_BANNER_B, and COPYRIGHT_BANNER_C macros from patchlevel.h be used
for constructing the Copyright message.  COPYRIGHT_BANNER_A is a 
quoted string that has the NetHack copyright declaration, 
COPYRIGHT_BANNER_B is a quoted string that states who the copyright 
belongs to, and COPYRIGHT_BANNER_C simply says "See License for
details." Be sure to #include "patchlevel.h" to define these macros.
Using the macros will prevent having to update the Copyright information
in each window-port prior to each release.

Ports (MSDOS, TOS, MAC, etc) _may_ use window-port specific routines in
their port specific files, _AT_THEIR_OWN_RISK_.  Since "port" and
"window-port" are orthogonal, you make your "port" code less portable by
using "window-port" specific routines.  Every effort should be made to
use window-port interface routines, unless there is something port
specific that is better suited (e.g. msmsg() for MSDOS).

The tty window-port is contained in win/tty, the X window port is contained
in win/X11.  The files in these directories contain _only_ window port code,
and may be replaced completely by other window ports.


VII.  Implementation and Multi-window support

NetHack 3.2 supports multiple window systems in the same binary.  When
writing a new window-port, you need to follow the following guidelines:

1) Pick a unique prefix to identify your window-port.  For example, the tty
   window port uses "tty"; the X11 window-port uses "X11".
2) When declaring your interface function, precede the function names with
   your unique prefix.  E.g:

	void tty_init_nhwindows()
	{
		/* code for initializing windows in the tty port */
	}

   When calling window functions from within your port code, we suggest
   calling the prefixed version to avoid unnecessary overhead.  However,
   you may safely call the non-prefixed version (e.g. putstr() rather than
   tty_putstr()) as long as you #include "hack.h".  If you do not
   include hack.h and use the non-prefixed names, you will get compile
   or link-time errors.

   We also suggest declaring all functions and port-specific data with
   this prefix to avoid unexpected overlaps with other window-ports.
   The tty and X11 ports do not currently follow this suggestion, but do
   use separate non-overlapping convention for naming data and internal
   functions.

3) Declare a structure, "struct window_procs prefix_procs", (with your
   prefix instead of "prefix") and fill in names of all of your
   interface functions.  The first entry in this structure is the name
   of your window-port, which should be the prefix.  The other entries
   are the function addresses.

   Assuming that you followed the convention in (2), you can safely copy
   the structure definition from an existing window-port and just change
   the prefixes.  That will guarantee that you get the order of your
   initializations correct (not all compilers will catch out-of-order
   function pointer declarations).

4) Add a #define to config.h identifying your window-port in the
   "Windowing systems" section.  Follow the "prefix_GRAPHICS" convention
   for your window-port.

5) Add your prefix to the list of valid prefixes listed in the "Known
   systems are" comment.

6) Edit makedefs.c and add a string for your windowing system to window_opts
   inside an #ifdef prefix_GRAPHICS.

7) Edit windows.c and add an external reference to your prefix_procs inside
   an #ifdef prefix_GRAPHICS.  Also add an entry to the win_choices
   structure for your window-port of the form:

    #ifdef prefix_GRAPHICS
	{ &prefix_procs, prefix_init_function },
    #endif

   The init_function is necessary for some compilers and systems to force
   correct linking.  If your system does not need such massaging, you
   may put a null pointer here.

   You should declare prefix_procs and prefix_init_function as extern's
   in your win*.h file, and #include that file at the beginning of
   windows.c, also inside an #ifdef prefix_GRAPHICS.  Some win*.h files
   are rather sensitive, and you might have to duplicate your
   prefix_procs and prefix_init_function's instead of including win*.h.
   The tty port includes wintty.h, the X11 port duplicates the declarations.

8) If your port uses Makefile.src, add the .c and .o files and an
   appropriate comment in the section on "WINSRC" and "WINOBJ".  See
   Makefile.src for the style to use.  If you don't use Makefile.src,
   we suggest using a similar convention for the make-equivalent used
   on your system.  Also add your new source and binaries to WINSRC and
   WINOBJ (if you want the NetHack binary to include them, that is).

9) Look at your port's portmain.c (the file containing main()) and make
   sure that all of the calls match the the requirements laid out in
   Section V.

Now, proceed with compilation and installation as usual.  Don't forget
to edit Makefile.src (or its equivalent) and config.h to set the
window-ports you want in your binary, the default window-port to use,
and the .o's needed to build a valid game.

One caveat.  Unfortunately, if you incorrectly specify the
DEFAULT_WINDOW_SYS, NetHack will dump core (or whatever) without
printing any message, because raw_print() cannot function without first
setting the window-port.