glenda.party
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term% cat index.txt
CONTROL(2)                    System Calls Manual                   CONTROL(2)



NAME
       Control,  Controlset, activate, closecontrol, closecontrolset, control‐
       called, controlwire, createbox, createboxbox, createbutton,  createcol‐
       umn,  createentry,  createkeyboard,  createlabel, createmenu, createra‐
       diobutton, createrow, createscribble, createslider,  createstack,  cre‐
       atetab,  createtext, createtextbutton, ctlerror, ctlmalloc, ctlrealloc,
       ctlstrdup, ctlprint, deactivate,  freectlfont,  freectlimage,  initcon‐
       trols,  namectlfont,  namectlimage,  newcontrolset,  resizecontrolset -
       interactive graphical controls

SYNOPSIS
       #include <u.h>
       #include <libc.h>
       #include <draw.h>
       #include <thread.h>
       #include <keyboard.h>
       #include <mouse.h>
       #include <control.h>
       typedef struct Control Control;
       typedef struct Controlset Controlset;
       struct Control
       {
           char        *name;
           Rectangle   rect;   /* area on screen */
           Rectangle   size;   /* min/max Dx, Dy (not a rect) */
           Channel *event; /* chan(char*) to client */
           Channel *data;  /* chan(char*) to client */
           ...
       };
       struct Controlset
       {
           ...
           Channel     *ctl;
           Channel     *data;
           ...
           int clicktotype;
           ...
       };
       void        initcontrols(void)
       Controlset* newcontrolset(Image *i, Channel *kc, Channel *mc, Channel *rc)
       void        closecontrolset(Controlset *cs)
       int     namectlfont(Font *font, char *name)
       int     freectlfont(char *name)
       int     namectlimage(Image *image, char *name)
       int     freectlimage(char *name)
       Control*    createbox(Controlset *cs, char *name)
       Control*    createboxbox(Controlset *cs, char *name)
       Control*    createbutton(Controlset *cs, char *name)
       Control*    createcolumn(Controlset*, char*)
       Control*    createentry(Controlset *cs, char *name)
       Control*    createkeyboard(Controlset *cs, char *name)
       Control*    createlabel(Controlset *cs, char *name)
       Control*    createmenu(Controlset *cs, char *name)
       Control*    createradiobutton(Controlset *cs, char *name)
       Control*    createrow(Controlset*, char*)
       Control*    createscribble(Controlset *cs, char *name)
       Control*    createslider(Controlset *cs, char *name)
       Control*    createstack(Controlset*, char*)
       Control*    createtab(Controlset*, char *)
       Control*    createtext(Controlset *cs, char *name)
       Control*    createtextbutton(Controlset *cs, char *name)
       void        closecontrol(Control *c)
       int     ctlprint(Control*, char*, ...);
       void        ctlerror(char *fmt, ...)
       Control*    controlcalled(char *name)
       void        controlwire(Control *c, char *cname, Channel *ch)
       void        activate(Control *c)
       void        deactivate(Control *c)
       void        resizecontrolset(Controlset *cs)
       void*       ctlmalloc(uint n)
       void*       ctlrealloc(void *p, uint n)
       char*       ctlstrdup(char *s)
       int     ctldeletequits;

DESCRIPTION
       This library provides a set of interactive controls for graphical  dis‐
       plays: buttons, sliders, text entry boxes, and so on.  It also provides
       aggregator Controls: boxes, columns, rows and stacks  of  Controls.   A
       stack  is a collection of co-located Controls, of which one is normally
       visible.  A Controlset collects a group of Controls  that  share  mouse
       and  keyboard.   Each  Controlset has a separate thread of control that
       processes keyboard and mouse events as well as commands to be passed on
       to  the  Controls.  Since each Controlset uses a thread, programs using
       the control library must be linked with the thread library, thread(2).

       Controls are manipulated by reading and writing to the control channel,
       ctl,  of  their  Controlset.   Channels are defined in thread(2).  Each
       Control has two output channels: Event delivers messages about  actions
       within  the  control  (such  as  a  button press) and data delivers (if
       requested by an appropriate write to ctl) control-specific data such as
       the contents of a field.

       The library provides a simple mechanism for automatic layout: the mini‐
       mum and maximum sizes of each simple control can be specified.  Boxbox,
       row,  column  and  stack Controls then use these sizes to lay out their
       constituent Controls when called upon to do so.  See the description of
       these grouping Controls for further details.

   Message format
       All  messages  are represented as UTF-8 text.  Numbers are formatted in
       decimal, and strings are transmitted in the quoted form of quote(2).

       Messages sent to a Controlset are of the form,

              sender: destination verb [argument ... ]

       The sender (and the colon following it) may be ommitted.  For  example,
       the  initial field of a text entry control called entry could be set by
       sending the message,

              entry value 'Hello, world!'

       to its Controlset's ctl file.  This message contains the verb value and
       the single argument Hello, world!

       To  make  it  easy  to  write  messages,  the  function  chanprint (see
       thread(2)) can be used to print formatted text to a Controlset's  chan‐
       nel.

       The  %q and %Q formats are convenient for properly quoting string argu‐
       ments, as in

              chanprint(e->event, "value %q", "Don't touch!");

       It is wise to use %q always instead of %s when  sending  messages,  and
       avoid  dealing  with  the  quoting explicitly.  In the other direction,
       tokenize (see getfields(2)) parses these messages  and  interprets  the
       quotes correctly.

       The  destination  of a message can be a named control, or a set of con‐
       trols identified by name or type.  The command

              'entry slider' show

       (note the quotation) sends the `show' command to the entry named  entry
       and  all  controls  of type slider.  If there were a control whose name
       was slider that control would also be shown.

        Note that we are still experimenting with destination names.  One pro‐
       posal  is  that  a destination of the form "`name1 name2 ⯠type1 type2
       â¯' selects all controls of the named types in the control  hierarchies
       (of columns, rows and stacks) whose names precede the types.

       Messages sent by a control on its event channel are of the form

              sender: event

       The  sender  is  the name of the control sending the message; the event
       describes the event.  Its format can often be controlled by setting the
       Control's format string.  For example, when the user types a newline at
       a text entry Control named entry, the control sends the message

              entry: value 'Hello again!'  on its event channel.

   Initialization and Control sets
       After initdraw (see graphics(2)) is called, the  function  initcontrols
       should  be  called to initialize the library.  It calls quotefmtinstall
       to install the %q and %Q formats; see quote(2).

       Each control is represented by a Control data structure and is  associ‐
       ated  with  a  Controlset  that groups a set of controls sharing mouse,
       keyboard, and display.  Most  applications  will  need  only  one  Con‐
       trolset;  only  those  with  multiple windows or unusual configurations
       will need more than one.  The function  newcontrolset  creates  a  Con‐
       trolset.   Its  arguments are the image (usually a window) on which its
       controls will  appear,  typically  the  screen  variable  in  the  draw
       library,  and three channels: kc, a channel of Runes from the keyboard;
       mc, a channel of Mouse structures from the mouse; and rc, a channel  of
       int  that indicates when the window has been resized.  Any of the chan‐
       nels may be nil, in which case  newcontrolset  will  call  initkeyboard
       and/or  initmouse (see keyboard(2) and mouse(2)) to initialize the key‐
       board and mouse and connect them to the control  set.   The  mouse  and
       resize channels must both be nil or both be non-nil.

       The  function closecontrolset frees all the controls in the control set
       and tears down all the associated threads.  It does not close the mouse
       and keyboard.

       The  public  elements of a Controlset are the flag clicktotype, and the
       ctl and data channels.

       Clicktotype is zero by default.  If it is set to non-zero, the controls
       in  the set will acquire `focus' by the click-to-type paradigm.  Other‐
       wise, focus is always given to the control under the mouse.

       Commands for controls are sent through the  Controlset's  ctl  channel.
       One  special  command  is recognized by the Controlset itself:  Sending
       the string sync to the ctl channel causes tha string to  be  echoed  to
       the  Controlset's data channel when all commands up to the sync command
       have been processed.  The string is allocated and must  be  freed  (see
       malloc(2)).   Synchronization  is  necessary between sending a command,
       for example, to resize all controls, and using their rect fields.

       The function resizecontrolset must be provided by the user.   When  the
       associated  window  is  resized, the library will call resizecontrolset
       with the affected Controlset; the  function  should  reconnect  to  and
       redraw the window.

       If  all  windows are organized in a hierachy of boxboxes, columns, rows
       and stacks, and minimum and maximum sizes have already  been  supplied,
       only the top control needs to be resized (see the rect command below).

   Fonts and images
       Fonts  and images must be given names so they may be referenced in mes‐
       sages.  The functions namectlfont and namectlimage associate a (unique)
       name  with  the specified font or image.  The association is removed by
       freectlfont and freectlimage.  The font or image is not freed by  these
       functions, however.

       The  function initcontrols establishes name bindings for all the colors
       mentioned in <draw.h>, such as black, white, red, yellow, etc., as well
       as  masks  transparent and opaque.  It also sets the name font to refer
       to the default font variable set up by initdraw.

   Creation
       Each type of control has an associated creation function: createbutton,
       createentry,  etc.,  whose arguments are the Controlset to attach it to
       and a globally unique name for it.  A control may be destroyed by call‐
       ing closecontrol.

       The  function  controlcalled  returns a pointer to the Control with the
       given name, or nil if no such control exists.

   Configuration
       After a control is created, it must be configured  using  the  control-
       specific commands documented below.  Commands are sent to the ctl chan‐
       nel of the Controlset.  Multiple commands may be sent in a single  mes‐
       sage;  newline  characters  separate commands.  For an example, see the
       implementation of resizecontrolset in the EXAMPLES section.  Note  that
       newline  is  a  separator, not a terminator; the final command does not
       need a newline.

       Messages sent to the ctl channel are delivered  to  all  controls  that
       match the destination field.  This field is a set of names separated by
       spaces, tabs or newlines.  A control matches  the  destination  if  its
       name or its type is among the set.

       The  recipient  of  a  message ignores the initial sender: field of the
       message, if present, making it possible to send messages  generated  on
       an event channel directly to another control's ctl channel.

   Activation
       When  they  are  created, controls are disabled: they do not respond to
       user input.  Not all controls  need  to  be  responsive;  for  example,
       labels  are  static and a text display might show a log of messages but
       not be useful to edit.  But buttons, entry boxes, and other  text  dis‐
       plays should be active.

       To  enable  a control, call the activate function, which specifies that
       the Control c should respond to mouse and keyboard  events;  deactivate
       turns it off again.

       Controls can be either revealed (default) or hidden.  When a control is
       hidden, it will not receive mouse or keyboard events and state  changes
       or  show  commands  will  be  ignored  until  the control is once again
       revealed.  Control hiding is particularly useful  when  different  con‐
       trols are overlayed, revealing only the `top' one.

       The  function controlwire permits rearrangement of the channels associ‐
       ated with a Control.  The channel cname (one of "data" or  "event")  of
       Control  c is reassigned to the channel ch.  There are several uses for
       this operation: one may reassign all the event  channels  to  a  single
       channel,  in  effect multiplexing all the events onto a single channel;
       or connect the event channel of a slider to the ctl channel for  deliv‐
       ery  to  a text display (after setting the format for the slider's mes‐
       sages to name the destination control and the  appropriate  syntax  for
       the  rest of the command) to let the slider act as a scroll bar for the
       text without rerouting the messages explicitly.

   Controls
       The following sections document the individual controls in alphabetical
       order.   The  layout of each section is a brief description of the con‐
       trol's behavior, followed by the messages it sends on  event,  followed
       by the messages it accepts via the ctl channel.  The event messages are
       triggered only by mouse or keyboard action; messages to the ctl file do
       not cause events to be generated.

       All controls accept the following messages:

       rect minx miny maxx maxy
              Set  the bounding rectangle for the control on the display.  The
              syntax generated by the %R print format of the draw  library  is
              also acceptable for the coordinates.

       size [ minÎx minÎy maxÎx maxÎy ]
              Set  the  minimum  and maximum size for automatic layout in col‐
              umns, rows and stacks.  Without its four arguments, this command
              is  ignored  by primitive controls and used by grouping controls
              to calculate their minimum and maximum sizes by examining  those
              of  their  constituent  members.  If all primitive controls have
              been assigned a size, a single size request addressed to the top
              of  a  layout  hierarchy  will assign sizes to all grouping Con‐
              trols.

       hide   Disable drawing of the control and  ignore  mouse  and  keyboard
              events  until the control is once again revealed.  Grouping Con‐
              trols (column, row, and stack) pass the request  down  to  their
              constituent Controls.

       reveal This is the opposite of hide: the Control is displayed and mouse
              and keyboard operations resume.  Grouping Controls (column, row,
              and  stack) pass the request down to their constituent Controls.
              The reveal command for stacks takes an optional argument  naming
              the Control to be revealed; all other Controls will be hidden.

       show   Display  the  Control on its screen if not hidden.  Some actions
              will also cause the Controls to  show  themselves  automatically
              (but never when the control is hidden).  Grouping Controls (col‐
              umn, row, and stack) pass the request down to their  constituent
              Controls.

       Many  messages are common between multiple Controls.  Such messages are
       described in detail  here  to  avoid  repetition.   In  the  individual
       descriptions, only the syntax is presented.

       align n
              Specify  the  alignment  of (some part of) the Control's display
              within its rectangle.  For textual controls, the alignment spec‐
              ifies  where  the  text  should appear.  For multiline text, the
              alignment refers to each line within its box, and only the hori‐
              zontal  part  is  honored.   For  other  Controls, the alignment
              affects the appearance of the display in a reasonable way.   The
              valid  alignments are words with obvious interpretations: upper‐
              left, uppercenter, upperright, centerleft, center,  centerright,
              lowerleft, lowercenter, and lowerright.

       border n
              Inset  the  Control (or separate constituent Controls in boxbox,
              column and row Controls after the next rect command) within  its
              rectangle by n pixels, default zero.

       bordercolor name
              Paint  the  border  of the control with the named color, default
              black.

       focus n
              The Control now has (if n is non-zero) or does not have (  if  n
              is  zero)  focus.   Most  Controls ignore the message; there are
              plans to make them react.

       format fmt
              Set the format of `value' messages sent on  the  event  channel.
              By  default, the format is "%q: value %q" for string-valued Con‐
              trols, "%q: value %d" for integer-valued Control s such as  but‐
              tons,  and  "%q:  value 0x%x" for the keyboard and scribble Con‐
              trols.  The %q prints the name of  the  Control;  the  rest  the
              value.   Any  supplied  format string must be type-equivalent to
              the default for that Control.

       image name

       light name

       mask name
              Many controls set a background image or color for display.   The
              image  message  sets  the  image.   The  mask  and  light images
              together specify how the Control shows it is enabled: the  light
              is printed through the mask when the state is `on' or `pressed'.
              Otherwise, the image appears unmodified.  The default  image  is
              white; mask opaque; light yellow.

       font name

       textcolor name
              These  commands set the font and color for displaying text.  The
              defaults are the default font set up by the  draw  library,  and
              black.

       value v
              Set  the  value  of the Control.  Textual images accept an arbi‐
              trary string; others an integral value.

   Box
       A box is a trivial control that does nothing more than  pass  keyboard,
       mouse,  and focus messages back on its event channel.  Keyboard charac‐
       ters are sent in the format

              boxname: key 0xnn

       where nn is the hexadecimal value of the character.  Mouse messages are
       sent in the format

              boxname: mouse [x y] but msec

       where  x,  y,  but, and msec are the various fields of the Mouse struc‐
       ture.  The focus message is just

              boxname: focus n

       where n is 0 if the box has lost focus, 1 if it has acquired it.

       The box displays within its rectangle an image, under mask, with speci‐
       fied alignment.  The control messages it accepts are:

       align a
              Controls  the  placement of the image in the rectangle (unimple‐
              mented).

       border b

       bordercolor name

       focus n

       hide

       image name

       rect minx miny maxx maxy

       reveal

       show

       size minÎx minÎy maxÎx maxÎy

   Boxbox
       A boxbox allows a set of controls (``boxes'') to be displayed  in  rows
       and  columns  within  the  rectangle of the boxbox.  The maximum of the
       minimum heights of the constituent controls determines  the  number  of
       rows to be displayed.  The number of columns is the minimum that allows
       all Controls to be displayed.  This aggregator works well  for  collec‐
       tions of buttons, labels, or textbuttons that all have a fixed height.

       add name ...
              adds  the  named  control  to  the box of controls.  The display
              order is determined by the order of  adding.   The  first  named
              control  is top left, the second goes below it, etc.  It is pos‐
              sible to add one control to multiple grouping controls  but  the
              layout of the result will be quite unpredictable.

       border width

       bordercolor color

       hide   This command is passed on to the member controls.

       image color
              Background color displayed between member controls.

       reveal This command is passed on to the member controls.

       separation width
              Set the separation between member controls to n pixels.

       rect minx miny maxx maxy
              The  member  controls  are  layed out within the given rectangle
              according to the minimum and maximum sizes given.  If  the  rec‐
              tangle is not large enough for the minimum a fatal error is cur‐
              rently generated.  If the controls at their maximum size are not
              big  enough to fit, they are top-left justified at their maximum
              size in the space given.  Otherwise,  controls  will  get  their
              minimum  size  and  be  enlarged  proportional to the extra size
              given by the maximum until they fit given rectangle.   The  mem‐
              bers  are  separated by borders of the width established by bor‐
              derwidth.

       remove name
              Remove the named control from the box.

       show   This command is passed on to the  member  controls.   Show  also
              (re)displays background and borders.

       size minÎx minÎy maxÎx maxÎy

   Button
       A button is a simple control that toggles its state when mouse button 1
       is pressed on its rectangle.  Each state change triggers an event  mes‐
       sage:

              buttonname: value n
              where n encodes the mouse buttons used to make the selection.

       The  button  displays  an image (which may of course be a simple color)
       and illuminates in the standard way when it is `on'.  The control  mes‐
       sages it accepts are:

       align a
              Controls  the  placement of the image in the rectangle (unimple‐
              mented).

       border b

       bordercolor name

       focus n

       format fmt

       hide

       image name

       light name

       mask name

       rect minx miny maxx maxy

       reveal

       show

       size minÎx minÎy maxÎx maxÎy

       value n
              Set the button to `on' (if n is non-zero)  or  `off'  (if  n  is
              zero).

   Column
       A  column  is a grouping control which lays out its members vertically,
       from top to bottom.   Currently,  columns  ignore  mouse  and  keyboard
       events,  but  there  are plans to allow dragging the borders (when they
       have non-zero width) between constituent members.

       add name ...
              adds the named control to the column of controls.  The  vertical
              order  is  determined  by  the order of adding.  The first named
              control goes at the top.  It is possible to add one  control  to
              multiple  grouping controls but the layout of the result will be
              quite unpredictable.

       border width
              Set the border between members to the width given.

       bordercolor color

       hide

       image color
              Background color displayed between member controls.

       reveal

       separation width
              Set the separation between member controls to n pixels.

       show   These three commands are passed on to the member controls.  Show
              also (re)displays the borders between members.

       rect minx miny maxx maxy
              The  member  controls  are  layed out within the given rectangle
              according to the minimum and maximum sizes given.  If  the  rec‐
              tangle is not large enough for the minimum a fatal error is cur‐
              rently generated.  However, see the example at the end  of  this
              man  page.   If  the  controls at their maximum size are not big
              enough to fit, they are centered at their maximum  size  in  the
              space  given.   Otherwise,  controls will get their minimum size
              and be enlarged proportional to the extra size given by the max‐
              imum  until they fit given rectangle.  The members are separated
              by borders of the width established by borderwidth.

       remove name
              Remove the named control from the column.

       size [ minÎx minÎy maxÎx maxÎy ]
              Without arguments, this command computes the minimum and maximum
              size  of  a  column by adding the minimum and maximum heights to
              set minÎy and maxÎy, and it finds the largest minimum and  maxi‐
              mum  widths to set minÎy and maxÎy.  When called with arguments,
              it simply sets the minimum and maximum sizes to those given.

   Entry
       The entry control manages a single line of  editable  text.   When  the
       user hits a carriage return anywhere in the text, the control generates
       the event message,

              entryname: value s

       with s the complete text of the entry box.

       The cursor can be moved by clicking button 1; at the moment,  there  is
       no  way  to  select  characters,  only a typing position.  Some control
       characters have special  actions:  control-H  (backspace)  deletes  the
       character  before  the cursor; control-U clears the line; and control-V
       pastes the snarf buffer at the typing position.  Most  important,  car‐
       riage return sends the text to the event channel.

       To  enter  passwords  and other secret text without displaying the con‐
       tents, set the font to one in which all characters are the  same.   The
       easiest way to do this is to make a font containing only one character,
       at position 0 (NUL), since that position is used to render all  charac‐
       ters  not  otherwise  defined  in  the  font  (see  draw(2)).  The file
       /lib/font/bit/lucm/passwd.9.font defines such a font.

       The control messages the entry control accepts are:

       align a
              Controls the placement of the text in the rectangle.

       border b

       bordercolor name

       data   After receiving this message, the entry will send its  value  to
              its data channel as an unadorned, unquoted string.

       focus n
              When  it receives focus, the entry box displays a typing cursor.
              When it does not have focus, the cursor is not displayed.

       font name

       format fmt

       hide

       image name

       rect minx miny maxx maxy

       reveal

       show

       size minÎx minÎy maxÎx maxÎy

       textcolor name

       value s
              Set the string displayed in the entry box.

   Keyboard
       The keyboard control implements a simulated keyboard useful on  palmtop
       devices.   Keystrokes,  generated  by  mouse  button 1 on the simulated
       keys, are sent as event messages:

              keyboardname: value 0xnn

       where nn is the hexadecimal Unicode value  of  the  character.   Shift,
       control,  and  caps  lock  are  handled by the keyboard control itself;
       shift and control affect only the next regular keystroke.  The Alt  key
       is  unimplemented; it will become equivalent to the standard Plan 9 key
       for synthesizing non-ASCII characters.

       There are two special keys, Scrib and Menu, which return values 0x10000
       and 0x10001.

       The  image,  mask,  light  rules  are  used  to  indicate that a key is
       pressed, but to aid clumsy fingers the keystroke is not generated until
       the  key  is released, so it is possible to slide the pointer to a dif‐
       ferent key to correct for bad aim.

       The control messages the keyboard accepts are:

       border b

       bordercolor name

       focus n

       font name1 name2
              Sets the font for the keys.  If only one font is  named,  it  is
              used for all keys.  If two are named, the second is used for key
              caps with special names such as Shift and Enter.  (Good  choices
              on  the Bitsy are /lib/font/bit/lucidasans/boldlatin1.6.font for
              the first and  /lib/font/bit/lucidasans/unicode.6.font  for  the
              second  argument.)  If neither is specified, both will be set to
              the default global font.

       format fmt

       hide

       image name

       light name

       mask name

       rect minx miny maxx maxy

       reveal

       show

       size minx miny maxx maxy

   Label
       A label is like a textbutton (q.v.)  that does  not  react,  but  whose
       value is the text it displays.  The control messages it accepts are:

       align a
              Controls the placement of the image in the rectangle.

       border b

       bordercolor name

       focus n

       font name

       hide

       image name

       rect minx miny maxx maxy

       reveal

       show

       size minx miny maxx maxy

       textcolor name

       value s
              The  value is a string that can be modified only by sending this
              message to the ctl file.

   Menu
       A menu is a pop-up window containing a set of textual selections.  When
       a  selection is made, it removes itself from the screen and reports the
       selection by value:

              menuname: value n

       If no selection is made, no message is reported.  Because it creates  a
       window,  programs  using  a  menu  must have their screen variable (see
       graphics(2) and window(2)) set up to be refreshed properly.  The  easi‐
       est way to do this is to call getwindow with refresh argument Refbackup
       (see graphics(2)); most programs use Refnone.

       The control messages accepted by a menu are:

       add text
              Add a line of text to the end of the menu.

       align a
              Controls the left-right placement of the text in its rectangle.

       border b

       bordercolor name

       focus n

       font name

       format fmt

       hide

       image name

       rect minx miny maxx maxy

       reveal

       size minx miny maxx maxy
              Only the origin of the rectangle is significant; menus calculate
              the appropriate size.

       selectcolor name
              Set the color in which to highlight selected lines; default yel‐
              low.

       selecttextcolor name
              Set the color in which to  draw  the  text  in  selected  lines;
              default black.

       show   Display  the menu. Not usually needed unless the menu is changed
              while visible; use window instead.

       window

       window n
              With no arguments, toggle the menu's visibility; otherwise  make
              it  visible  (1)  or invisible (0).  When the selection is made,
              the menu will remove its window automatically.

   Radiobutton
       The radiobutton assembles a group of buttons or textbuttons into a sin‐
       gle  control with a numeric value.  Its value is -1 if none of the con‐
       stituent buttons is pressed; otherwise it is  the  index,  starting  at
       zero,  of  the button that is pressed.  Only one button may be pressed;
       the radiobutton manipulates  its  buttons  to  guarantee  this.   State
       changes trigger an event message:

              radiobuttonname: value n

       Buttons  are  added to the radio button using the add message; there is
       no way to remove them, although they may be  turned  off  independently
       using  deactivate.   The  index reported in the value is defined by the
       order in which the buttons are added.  The constituent  buttons  should
       be  configured  and  layed  out  in the usual way; the rectangle of the
       radiobutton is used only to `catch'  mouse  events  and  should  almost
       always  correspond  to the bounding box of the constituent buttons.  In
       other words, the geometry is not maintained automatically.

       The control messages the radiobutton accepts are:

       add name
              Add the control with the specified name to the radiobutton.

       focus n

       format fmt

       hide

       rect minx miny maxx maxy

       reveal

       size minx miny maxx maxy

       show

       value n

   Row
       A row groups a number of member controls left to right in a  rectangle.
       Rows  behave  exactly  like  columns  with  the roles of x and y inter‐
       changed.

       The control messages it accepts are:

       add name ...

       border width

       bordercolor color

       hide

       image color

       rect minx miny maxx maxy

       remove name

       reveal

       separation width

       show

       size [ minÎx minÎy maxÎx maxÎy ]

   Scribble
       The scribble control provides a region  in  which  strokes  drawn  with
       mouse  button  1  are interpreted as characters in the manner of scrib‐
       ble(2).  In most respects, including the format of its event  messages,
       it is equivalent to a keyboard control.

       The control messages it accepts are:

       align a
              Controls  the  placement of the image in the rectangle (unimple‐
              mented).

       border b

       bordercolor name

       focus n

       font name
              Used to display the indicia.

       hide

       image name

       linecolor name
              The color in which to draw the strokes; default black.

       rect minx miny maxx maxy

       reveal

       size minx miny maxx maxy

       show

   Stack
       A stack groups a number of member controls in the same  shared  rectan‐
       gle.  Only one of these controls will be visible (revealed), the others
       are hidden.

       The control messages it accepts are:

       hide

       rect minx miny maxx maxy

       remove name

       reveal [ n ]
              Without argument, reveal is the opposite of hide: it  makes  its
              selected control visible after it was hidden.  With an argument,
              it makes the n'th added control visible, hiding all others.

       show

       size [ minÎx minÎy maxÎx maxÎy ]
              Without argument, size computes the maximum of the  minimum  and
              maximum  sizes  of its constituent controls.  With arguments, it
              sets the size to the given values.

   Slider
       A slider controls an integer value by dragging the mouse with a button.
       Configured  appropriately,  it can serve as a scroll bar with the stan‐
       dard Plan 9 behavior.  When the value  changes,  an  event  message  is
       sent:

              slidername: value n

       The  slider  is  a  good candidate for connecting to another control by
       setting its format and rewiring its event channel to  the  other's  ctl
       channel.

       The geometry of the slider is defined by three numbers: max is a number
       representing the range of the slider; vis is a number representing  how
       much of what is being controlled is visible; and value is a number rep‐
       resenting the value of the slider within its range.   For  example,  if
       the  slider  is managing a textual display of 1000 lines, with 18 visi‐
       ble, and the first visible line (numbered starting form 0) is 304,  max
       will  be 1000, vis will be 18, and value will be 304.  The indicator is
       the visual representation of the vis portion of the controlled object.

       The control messages the slider accepts are:

       absolute n
              If n is zero, the slider behaves like a Plan 9 scroll bar:  but‐
              ton  2 sets absolute position, button 1 decreases the value, and
              button 3 increases it.  If n is  non-zero,  all  buttons  behave
              like button 2, setting the absolute value.

       border b

       bordercolor name

       clamp end n
              The  end is either the word high or low; n sets whether that end
              is clamped or not.  If it is clamped, that end of the  indicator
              is  always  at  its supremum.  A standard scroll bar has neither
              end clamped; a volume slider would have its low end clamped.  If
              the  low  end is clamped, the value of the slider is represented
              by the high end of the indicator; otherwise it is represented by
              the low end.

       focus n

       format fmt

       hide

       image name

       indicatorcolor name
              Set the color in which to draw the indicator; default black.

       max n  Set the maximum value of the range covered by the slider.

       orient dir
              The  string dir begins either hor or ver to specify the orienta‐
              tion of the slider.  The default is vertical.  The value  always
              increases  to the right for horizontal sliders and downwards for
              vertical sliders.

       rect minx miny maxx maxy

       reveal

       size minx miny maxx maxy

       show

       value n

       vis n  Set the visible area shown by the indicator.

   Tab
       A tab control combines radiobottuns with a stack of windows giving  the
       appearance  of  tabbed controls.  Currently, the tabs are positioned at
       the top of the stack.  The radiobutton  consists  of  textbuttons,  the
       stack can be composed of any type of control.

       Control messages are

       add button control button control ...
              Adds  a  button to the radiobutton, and an associated control to
              the stack.  Buttons and controls are numbered in  the  order  of
              addition.  There is no remove operation.

       border b

       bordercolor color

       focus n

       format fmt
              When  a  format string is defined, the tab control reports which
              tab is selected using the format  string  (which  must  print  a
              char* and an int).

       image color
              Color between member controls.

       separation n
              Spacing  between  buttons in the radiobutton and between the row
              of buttons and the stack below it.

       rect n n n n

       hide

       reveal

       size n n n n

       show

       value n
              Value must be an integer indicating which tab to  bring  to  the
              top.

   Text
       A  text  control  presents  a set of lines of text.  The text cannot be
       edited with the keyboard, but can be changed by control  messages.   (A
       more  interactive  text control will be created eventually.)  The mouse
       can be used to select lines of text.  The only event message reports  a
       state change in the selection of a line:

              textname: select n s

       states  that  line  n has changed its selection state to s, either zero
       (unselected) or non-zero (selected).  The non-zero  value  encodes  the
       mouse buttons that were down when the selection occurred.

       The control messages the text control accepts are:

       accumulate s

       accumulate n s

       add s

       add n s
              With one argument, append the string s as a new last line of the
              control; if n is specified, add the line before the current line
              n, making the new line number n.  The lines are zero indexed and
              n can be no greater than  the  current  number  of  lines.   Add
              refreshes  the  display,  but  accumulate  does not, to avoid n-
              squared behavior when assembling a piece of text.

       align a
              Controls the placement of each line of text left-to-right in its
              rectangle.  Vertically, lines are tightly packed with separation
              set by the font's interline spacing.

       border b

       bordercolor name

       clear  Delete all text.

       delete n
              Delete line n.

       focus n

       font name

       image name

       rect minx miny maxx maxy

       replace n s
              Replace line n by the string s.

       reveal

       scroll n
              If n is non-zero, the text will automatically scroll so the last
              line is always visible when new text is added.

       select n m
              Set the selection state of line n to m.

       selectcolor name
              Set the color in which to highlight selected lines; default yel‐
              low.

       selectmode s
              The string s is either single or multi.  If single, the default,
              only  one  line  may  be  selected  at  a  time;  when a line is
              selected, other lines are unselected.  If multi,  the  selection
              state of individual lines can be toggled independently.

       size minx miny maxx maxy

       show

       textcolor name

       topline n
              Scroll the text so the top visible line is number n.

       value s
              Delete  all the text in the control and then add the single line
              s.

   Textbutton
       A textbutton is a textual variant of a plain button.  Each state change
       triggers an event message:

              textbuttonname: value n

       where n encodes the mouse buttons used to make the selection.

       Like  a  regular  button,  the value of a textbutton is an integer; the
       text is the string that appears in the  button.   It  uses  the  image,
       light,  mask method of indicating its state; moreover, the color of the
       text can be set to change when the button is pressed.  The control mes‐
       sages it accepts are:

       align a
              Controls the placement of the text in the rectangle.

       border b

       bordercolor name

       focus n

       font name

       format fmt

       hide

       image name

       light name

       mask name

       pressedtextcolor name
              Set  the  color  in which to display text when the textbutton is
              pressed.

       rect minx miny maxx maxy

       reveal

       size minx miny maxx maxy

       show

       text s Set the text displayed in the button.

       textcolor name

       value n
              Set the button to `on' (if n is non-zero)  or  `off'  (if  n  is
              zero).

   Helper functions
       The  function  ctlerror is called when the library encounters an error.
       It prints the formatted message and exits the program.

       The functions ctlmalloc, ctlrealloc, ctlstrdup, and  ctlrunestrdup  are
       packagings  of the corresponding C library functions.  They call ctler‐
       ror if they fail to allocate memory, and ctlmalloc zeros the memory  it
       returns.

       Finally, for debugging, if the global variable ctldeletequits is set to
       a non-zero value, typing a DEL will cause the program to call

              ctlerror("delete");

   Caveat
       This library is very new and is still missing  a  number  of  important
       features.   The  details  are  all subject to change.  Another level of
       library that handles geometry and has sensible default appearances  for
       the controls would be useful.

       One  unusual design goal of this library was to make the controls them‐
       selves easy to implement.  The reader is encouraged to create new  con‐
       trols by adapting the source to existing ones.

EXAMPLES
       This  example creates two entry boxes, top and bot, and copies the con‐
       tents of one to the other whenever a newline is typed.

       #include <u.h>
       #include <libc.h>
       #include <thread.h>
       #include <draw.h>
       #include <mouse.h>
       #include <keyboard.h>
       #include <control.h>
       Controlset *cs;
       int ctldeletequits = 1;
       void
       resizecontrolset(Controlset*)
       {
           int i;
           Rectangle r, r1, r2;
           if(getwindow(display, Refnone) < 0)
               sysfatal("resize failed: %r");
           r = insetrect(screen->r, 10);
           r1 = r;
           r2 = r;
           r1.max.y = r1.min.y+1+font->height+1;
           r2.min.y = r1.max.y+10;
           r2.max.y = r2.min.y+1+font->height+1;
           chanprint(cs->ctl, "top rect %R\ntop show", r1);
           chanprint(cs->ctl, "bot rect %R\nbot show", r2);
       }
       void
       threadmain(int argc, char *argv[])
       {
           char *s, *args[3];
           Channel *c;
           Control *top, *bot;
           int n;
           initdraw(0, 0, "example");
           initcontrols();
           cs = newcontrolset(screen, nil, nil, nil);
           cs->clicktotype = 1;
           top = createentry(cs, "top");
           chanprint(cs->ctl, "top image paleyellow");
           chanprint(cs->ctl, "top border 1");
           bot = createentry(cs, "bot");
           chanprint(cs->ctl, "bot image paleyellow");
           chanprint(cs->ctl, "bot border 1");
           c = chancreate(sizeof(char*), 0);
           controlwire(top, "event", c);
           controlwire(bot, "event", c);
           activate(top);
           activate(bot);
           resizecontrolset(cs);
           for(;;){
               s = recvp(c);
               n = tokenize(s, args, nelem(args));
               if(n==3 && strcmp(args[1], "value")==0){
                   if(strcmp(args[0], "top:") == 0)
                       chanprint(cs->ctl, "bot value %q", args[2]);
                   else
                       chanprint(cs->ctl, "top value %q", args[2]);
               }
           }
           threadexitsall(nil);
       }

       A richer variant couples a text entry box to a slider.  Since the value
       of  a  slider  is  its numerical setting, as a decimal number, all that
       needs changing is the setup of bot:

           bot = createslider(cs, "bot");
           chanprint(cs->ctl, "bot border 1");
           chanprint(cs->ctl, "bot image paleyellow");
           chanprint(cs->ctl, "bot indicatorcolor red");
           chanprint(cs->ctl, "bot max 100");
           chanprint(cs->ctl, "bot clamp low 1");
           chanprint(cs->ctl, "bot orient horizontal");

       The rest is the same.  Of course, the value of the entry  box  is  only
       meaningful to the slider if it is also a decimal number.

       Finally,  we  can  avoid processing events altogether by cross-coupling
       the controls.  Replace the rest of threadmain with this:

           chanprint(cs->ctl, "bot format %q", "%q: top value %q");
           chanprint(cs->ctl, "top format %q", "%q: bot value %q");
           controlwire(top, "event", cs->ctl);
           controlwire(bot, "event", cs->ctl);
           activate(top);
           activate(bot);
           resizecontrolset(cs);
           for(;;)
               yield();
           threadexitsall(nil);

SOURCE
       /sys/src/libcontrol

SEE ALSO
       draw(2), frame(2), graphics(2), quote(2), thread(2)

BUGS
       The library is strict about matters of formatting,  argument  count  in
       messages,  etc.,  and calls ctlerror in situations where it may be fine
       to ignore the error and continue.



                                                                    CONTROL(2)