CONTROL(2) CONTROL(2)
NAME
Control, Controlset, activate, closecontrol,
closecontrolset, controlcalled, controlwire, createbox,
createboxbox, createbutton, createcolumn, createentry,
createkeyboard, createlabel, createmenu, createradiobutton,
createrow, createscribble, createslider, createstack,
createtab, createtext, createtextbutton, ctlerror,
ctlmalloc, ctlrealloc, ctlstrdup, ctlprint, deactivate,
freectlfont, freectlimage, initcontrols, 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>
9 typedef struct Control Control;
typedef struct Controlset Controlset;
9 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 */
...
};
9 struct Controlset
{
...
Channel *ctl;
Channel *data;
...
int clicktotype;
...
};
9 void initcontrols(void)
9 Controlset* newcontrolset(Image *i, Channel *kc, Channel *mc, Channel *rc)
9 void closecontrolset(Controlset *cs)
9 int namectlfont(Font *font, char *name)
9 int freectlfont(char *name)
9 int namectlimage(Image *image, char *name)
9 Page 1 Plan 9 (printed 11/24/24)
CONTROL(2) CONTROL(2)
int freectlimage(char *name)
9 Control* createbox(Controlset *cs, char *name)
9 Control* createboxbox(Controlset *cs, char *name)
9 Control* createbutton(Controlset *cs, char *name)
9 Control* createcolumn(Controlset*, char*)
9 Control* createentry(Controlset *cs, char *name)
9 Control* createkeyboard(Controlset *cs, char *name)
9 Control* createlabel(Controlset *cs, char *name)
9 Control* createmenu(Controlset *cs, char *name)
9 Control* createradiobutton(Controlset *cs, char *name)
9 Control* createrow(Controlset*, char*)
9 Control* createscribble(Controlset *cs, char *name)
9 Control* createslider(Controlset *cs, char *name)
9 Control* createstack(Controlset*, char*)
9 Control* createtab(Controlset*, char *)
9 Control* createtext(Controlset *cs, char *name)
9 Control* createtextbutton(Controlset *cs, char *name)
9 void closecontrol(Control *c)
9 int ctlprint(Control*, char*, ...);
9 void ctlerror(char *fmt, ...)
9 Control* controlcalled(char *name)
9 void controlwire(Control *c, char *cname, Channel *ch)
9 void activate(Control *c)
9 void deactivate(Control *c)
9 void resizecontrolset(Controlset *cs)
9 void* ctlmalloc(uint n)
9 void* ctlrealloc(void *p, uint n)
9 char* ctlstrdup(char *s)
9 int ctldeletequits;
DESCRIPTION
This library provides a set of interactive controls for
graphical displays: buttons, sliders, text entry boxes, and
so on. It also provides aggregator Controls: boxes,
columns, rows and stacks of Controls. A stack is a collec-
tion of co-located Controls, of which one is normally visi-
ble. A Controlset collects a group of Controls that share
mouse and keyboard. Each Controlset has a separate thread
Page 2 Plan 9 (printed 11/24/24)
CONTROL(2) CONTROL(2)
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 con-
trol 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 lay-
out: the minimum 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 omitted. 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 channel.
The %q and %Q formats are convenient for properly quoting
string arguments, as in
chanprint(e->event, "value %q", "Don't touch!");
It is wise to use %q always instead of %s when sending mes-
sages, and avoid dealing with the quoting explicitly. In
the other direction, tokenize (see getfields(2)) parses
these messages and interprets the quotes correctly.
Page 3 Plan 9 (printed 11/24/24)
CONTROL(2) CONTROL(2)
The destination of a message can be a named control, or a
set of controls 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 proposal is that a destination of the form "`name1 name2
⋯ type1 type2 ⋯' 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 con-
trolled 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 associated with a Controlset that groups a set of con-
trols sharing mouse, keyboard, and display. Most applica-
tions will need only one Controlset; only those with multi-
ple windows or unusual configurations will need more than
one. The function newcontrolset creates a Controlset. Its
arguments are the image (usually a window) on which its con-
trols 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 channels may be nil, in which case
newcontrolset will call initkeyboard and/or initmouse (see
keyboard(2) and mouse(2)) to initialize the keyboard and
mouse and connect them to the control set. The mouse and
resize channels must both be nil or both be non-nil.
Page 4 Plan 9 (printed 11/24/24)
CONTROL(2) CONTROL(2)
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. Otherwise, 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 chan-
nel causes that 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 refer-
enced in messages. 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 vari-
able 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 calling closecontrol.
Page 5 Plan 9 (printed 11/24/24)
CONTROL(2) CONTROL(2)
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 channel of the Controlset. Multiple com-
mands may be sent in a single message; newline characters
separate commands. For an example, see the implementation
of resizecontrolset in the EXAMPLES section. Note that new-
line is a separator, not a terminator; the final command
does not need a newline.
Messages sent to the ctl channel are delivered to all con-
trols 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 mes-
sages 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 respon-
sive; 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 displays should be
active.
To enable a control, call the activate function, which spec-
ifies that the Control c should respond to mouse and key-
board 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 controls are overlayed,
revealing only the `top' one.
The function controlwire permits rearrangement of the chan-
nels associated 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 reas-
sign all the event channels to a single channel, in effect
multiplexing all the events onto a single channel; or con-
nect the event channel of a slider to the ctl channel for
delivery to a text display (after setting the format for the
slider's messages to name the destination control and the
Page 6 Plan 9 (printed 11/24/24)
CONTROL(2) CONTROL(2)
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 control's behavior, followed by the mes-
sages 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 for-
mat of the draw library is also acceptable for the
coordinates.
size [ minΔx minΔy maxΔx maxΔy ]
Set the minimum and maximum size for automatic lay-
out in columns, rows and stacks. Without its four
arguments, this command is ignored by primitive con-
trols and used by grouping controls to calculate
their minimum and maximum sizes by examining those
of their constituent members. If all primitive con-
trols have been assigned a size, a single size
request addressed to the top of a layout hierarchy
will assign sizes to all grouping Controls.
hide Disable drawing of the control and ignore mouse and
keyboard events until the control is once again
revealed. Grouping Controls (column, row, and
stack) pass the request down to their constituent
Controls.
reveal This is the opposite of hide: the Control is dis-
played 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 (column, 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
Page 7 Plan 9 (printed 11/24/24)
CONTROL(2) CONTROL(2)
presented.
align n Specify the alignment of (some part of) the
Control's display within its rectangle. For
textual controls, the alignment specifies where
the text should appear. For multiline text, the
alignment refers to each line within its box,
and only the horizontal 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: upperleft, 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 rectan-
gle 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 Controls, "%q: value
%d" for integer-valued Control s such as but-
tons, and "%q: value 0x%x" for the keyboard and
scribble Controls. 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 dis-
playing 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 arbitrary string; others an integral
value.
Page 8 Plan 9 (printed 11/24/24)
CONTROL(2) CONTROL(2)
Box
A box is a trivial control that does nothing more than pass
keyboard, mouse, and focus messages back on its event chan-
nel. Keyboard characters 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 structure. 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 specified alignment. The control messages it accepts
are:
align a Controls the placement of the image in the rectan-
gle (unimplemented).
border b
bordercolor name
focus n
hide
image name
rect minx miny maxx maxy
reveal
show
size minΔx minΔy maxΔx maxΔy
Boxbox
A boxbox allows a set of controls (``boxes'') to be dis-
played in rows and columns within the rectangle of the
boxbox. The maximum of the minimum heights of the con-
stituent controls determines the number of rows to be dis-
played. The number of columns is the minimum that allows
all Controls to be displayed. This aggregator works well
for collections 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
possible to add one control to multiple group-
ing controls but the layout of the result will
Page 9 Plan 9 (printed 11/24/24)
CONTROL(2) CONTROL(2)
be quite unpredictable.
border width
bordercolor color
hide This command is passed on to the member con-
trols.
image color Background color displayed between member con-
trols.
reveal This command is passed on to the member con-
trols.
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 rectangle is not
large enough for the minimum a fatal error is
currently 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 propor-
tional to the extra size given by the maximum
until they fit given rectangle. The members
are separated by borders of the width estab-
lished by borderwidth.
remove name Remove the named control from the box.
show This command is passed on to the member con-
trols. Show also (re)displays background and
borders.
size minΔx minΔy maxΔx maxΔy
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 message:
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 sim-
ple color) and illuminates in the standard way when it is
`on'. The control messages it accepts are:
align a Controls the placement of the image in the rectan-
gle (unimplemented).
border b
bordercolor name
focus n
format fmt
hide
Page 10 Plan 9 (printed 11/24/24)
CONTROL(2) CONTROL(2)
image name
light name
mask name
rect minx miny maxx maxy
reveal
show
size minΔx minΔy maxΔx maxΔy
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 con-
trols. 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 con-
trols.
reveal
separation width
Set the separation between member controls to n
pixels.
show These three commands are passed on to the mem-
ber controls. Show also (re)displays the bor-
ders 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 rectangle is not
large enough for the minimum a fatal error is
currently 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 maximum until
they fit given rectangle. The members are sep-
arated by borders of the width established by
borderwidth.
remove name Remove the named control from the column.
Page 11 Plan 9 (printed 11/24/24)
CONTROL(2) CONTROL(2)
size [ minΔx minΔy maxΔx maxΔy ]
Without arguments, this command computes the
minimum and maximum size of a column by adding
the minimum and maximum heights to set minΔy
and maxΔy, and it finds the largest minimum and
maximum widths to set minΔy and maxΔy. When
called with arguments, it simply sets the mini-
mum 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 posi-
tion. Some control characters have special actions:
control-H (backspace) deletes the character before the cur-
sor; 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 contents, 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 characters 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 rectan-
gle.
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
Page 12 Plan 9 (printed 11/24/24)
CONTROL(2) CONTROL(2)
show
size minΔx minΔy maxΔx maxΔy
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 regu-
lar 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 different 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
Page 13 Plan 9 (printed 11/24/24)
CONTROL(2) CONTROL(2)
A label is like a textbutton (q.v.) that does not react,
but whose value is the text it displays. The control mes-
sages it accepts are:
align a Controls the placement of the image in the rectan-
gle.
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 selec-
tions. 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 easiest 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
Page 14 Plan 9 (printed 11/24/24)
CONTROL(2) CONTROL(2)
Set the color in which to highlight selected
lines; default yellow.
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 single control with a numeric value. Its value is -1
if none of the constituent 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 interchanged.
Page 15 Plan 9 (printed 11/24/24)
CONTROL(2) CONTROL(2)
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 [ minΔx minΔy maxΔx maxΔy ]
Scribble
The scribble control provides a region in which strokes
drawn with mouse button 1 are interpreted as characters in
the manner of scribble(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 (unimplemented).
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 rectangle. Only one of these controls will be visi-
ble (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
Page 16 Plan 9 (printed 11/24/24)
CONTROL(2) CONTROL(2)
the n'th added control visible, hiding all oth-
ers.
show
size [ minΔx minΔy maxΔx maxΔy ]
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 standard 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 representing the value of the
slider within its range. For example, if the slider is man-
aging a textual display of 1000 lines, with 18 visible, 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 por-
tion 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: button 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 repre-
sented by the low end.
focus n
Page 17 Plan 9 (printed 11/24/24)
CONTROL(2) CONTROL(2)
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 spec-
ify the orientation 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 radiobut-
ton 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 associ-
ated 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.
Page 18 Plan 9 (printed 11/24/24)
CONTROL(2) CONTROL(2)
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 speci-
fied, 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 yellow.
selectmode s The string s is either single or multi. If
single, the default, only one line may be
Page 19 Plan 9 (printed 11/24/24)
CONTROL(2) CONTROL(2)
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 selec-
tion.
Like a regular button, the value of a textbutton is an inte-
ger; 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 messages it accepts are:
align a Controls the placement of the text in the rectan-
gle.
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
Page 20 Plan 9 (printed 11/24/24)
CONTROL(2) CONTROL(2)
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 ctlerror if they fail to allocate mem-
ory, 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 sen-
sible default appearances for the controls would be useful.
One unusual design goal of this library was to make the con-
trols themselves easy to implement. The reader is encour-
aged to create new controls by adapting the source to exist-
ing ones.
EXAMPLES
This example creates two entry boxes, top and bot, and
copies the contents 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>
9 Controlset *cs;
9 int ctldeletequits = 1;
9 void
resizecontrolset(Controlset*)
{
int i;
Rectangle r, r1, r2;
9 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;
Page 21 Plan 9 (printed 11/24/24)
CONTROL(2) CONTROL(2)
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);
}
9 void
threadmain(int argc, char *argv[])
{
char *s, *args[3];
Channel *c;
Control *top, *bot;
int n;
9 initdraw(0, 0, "example");
initcontrols();
cs = newcontrolset(screen, nil, nil, nil);
cs->clicktotype = 1;
9 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");
9 c = chancreate(sizeof(char*), 0);
controlwire(top, "event", c);
controlwire(bot, "event", c);
9 activate(top);
activate(bot);
resizecontrolset(cs);
9 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");
Page 22 Plan 9 (printed 11/24/24)
CONTROL(2) CONTROL(2)
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");
9 controlwire(top, "event", cs->ctl);
controlwire(bot, "event", cs->ctl);
9 activate(top);
activate(bot);
resizecontrolset(cs);
9 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.
9
Page 23 Plan 9 (printed 11/24/24)