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>
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 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 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 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 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 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 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 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 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 associated with a Controlset that groups a set of controls sharing mouse, keyboard, and display. Most applications will need only one Controlset; only those with multiple 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 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 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.

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 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 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 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 calling 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 channel of the Controlset. Multiple commands 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 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 displays 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 controls are overlayed, revealing only the `top' one.

The function controlwire permits rearrangement of the channels 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 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 delivery to a text display (after setting the format for the slider's messages 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 control'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 [ minΔx minΔy maxΔx maxΔy ]
Set the minimum and maximum size for automatic layout in columns, 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 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 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 (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 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 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 Controls, "%q: value %d" for integer–valued Control s such as buttons, 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 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 arbitrary 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 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 rectangle (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 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 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 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 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 proportional to the extra size given by the maximum 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 box.
show          This command is passed on to the member controls. 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 simple 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 rectangle (unimplemented).
border b
bordercolor name
focus n
format fmt
hide
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 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 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 separated by borders of the width established by borderwidth.
remove name    Remove the named control from the column.
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 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, carriage 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 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
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 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 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
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 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
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.

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 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
[ 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 managing 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 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: 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 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 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 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 nSpacing 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 yellow.
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 messages 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 ctlerror 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 themselves easy to implement. The reader is encouraged to create new controls by adapting the source to existing 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>
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.
Copyright © 2019 Alcatel-Lucent. All rights reserved.