TK(2) TK(2)
NAME
Tk: toplevel, namechan, cmd, pointer, keyboard, imageget,
imageput, quote, rect - graphics toolkit
SYNOPSIS
include "draw.m";
include "tk.m";
tk := load Tk Tk->PATH;
Image: import Draw;
Toplevel: adt
{
display: ref Draw->Display;
wreq: chan of string;
image: ref Image;
ctxt: ref Draw->Wmcontext;
screenr: Draw->Rect;
};
toplevel: fn(display: ref Draw->Display, arg: string): ref Toplevel;
namechan: fn(top: ref Toplevel, c: chan of string, n: string): string;
cmd: fn(top: ref Toplevel, arg: string): string;
pointer: fn(top: ref Toplevel, p: Draw->Pointer);
keyboard: fn(top: ref Toplevel, key: int);
getimage: fn(top: ref Toplevel, name: string):
(ref Image, ref Image, string);
putimage: fn(top: ref Toplevel, name: string, i, m: ref Image): string;
rect: fn(top: ref Toplevel, name: string, flags: int): Draw->Rect;
quote: fn(s: string): string;
color: fn(s: string): int;
DESCRIPTION
The Tk module provides primitives for building user inter-
faces, based on Ousterhout's Tcl/TK. The interface to the
toolkit itself is primarily the passing of strings to and
from the elements of the toolkit using the cmd function; see
section 9 of this manual for more information about the syn-
tax of those strings. Tkclient(2) is conventionally used to
create tk windows that interact correctly with a running
window manager.
Toplevel creates a new window called a Toplevel, which is
under the control of the Tk toolkit, on an existing display,
usually one inherited from the graphics Context (see draw-
context(2)). The Toplevel is passed to cmd and namechan
(q.v.) to drive the widgets in the window. Arg is a string
containing creation options (such as -borderwidth 2) that
are applied when creating the toplevel window.
Cmd passes command strings to the widgets in the Toplevel t
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and returns the string resulting from their execution. For
example, given a canvas .c in the Toplevel t,
x := int tk->cmd(t, ".c cget -actx");
returns the integer x coordinate of the canvas.
Bindings can be created in a Toplevel that trigger strings
to be sent on Limbo channels. Such channels must be
declared to the Tk module using namechan. For example, to
create a button that sends the word Ouch when it is pressed:
hitchannel := chan of string;
tk->namechan(t, hitchannel, "channel");
tk->cmd(t,
"button .b.Hit -text Hit -command {send channel Ouch}");
expl := <-hitchannel; # will see Ouch when button pressed
Pointer and keyboard pass mouse and keyboard events to a Tk
window for delivery to widgets; they must be called by each
application, which usually receives them via a Wmcontext
structure (see draw-context(2)) obtained from the window
manager, often via tkclient(2).
Putimage passes an image and a mask into Tk. If name is the
name of a Tk widget, it must be either a panel(9) widget, or
a top level widget (ie, ``.'') or a menu widget, in which
case the associated image or window image is set to i. (m is
ignored for menu and top-level widgets.) Otherwise, name
must be the name of an existing image(9) which has its image
and mask set to copies of i and m respectively.
Initially, a Tk toplevel has no image to draw on. Tk uses
wreq to request new images of an external authority, and to
inform said authority when the images are to be deleted.
The requests are formatted as per quoted in string(2), and
hold one of the following:
!reshape name reqid minx miny maxx
A new image for name is requested (name is either the
toplevel widget or a menu). The desired rectangle for
the new image is given by [minx miny maxx maxy], and
the application should respond by creating a new image
and using putimage to pass it to Tk. Reqid is used by
Tk to filter out responses to out-of-date requests;
when responding to a reshape request, the name passed
to putimage should have a space and reqid appended.
Tkclient(2) usually deals with the details of this.
delete name
The image name has been deleted. This is generated for
menu(9) widgets when they are unmapped.
raise name
Tk widget name should be raised above other windows on
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the same screen.
lower name
Tk widget name should be lowered beneath other windows
on the same screen.
Wreq may be set to nil if an application is not prepared to
read requests sent on this channel.
Rect returns the bounding rectangle of widget name in top.
Flags determines the form of rectangle returned. If flags
is zero, the actual rectangle of name in screen coordinates,
not including its border, is returned. The bitmask flags
that can change this are:
Border
Include the widget's border.
Required
Return the rectangle required by the widget, rather
than the rectangle that has been actually allocated to
it.
Local
Return the rectangle in coordinates relative to the
logical origin of the actual top level image.
Quote returns a string that is the same as its arguments,
but enclosed in curly braces and with internal curly braces
escaped. This can be used to make an arbitrary string into
a word suitable as an argument to a Tk function.
Color returns a colour in 32-bit RGBA format corresponding
to the tk colour name s. (see types(9) for details).
Screenr gives the rectangle of the screen containing the
toplevel window. Tk has no a priori way of knowing what
this is; it is initially set to the rectangle of the display
image, and may be set by the application if it knows better
(e.g. from the wmrect file served by wm(1)).
SOURCE
/libinterp/tk.c
/libtk/*.c
SEE ALSO
intro(9), image(9), panel(9), tkcmd(1), sh-tk(1), draw-
context(2), tkclient(2), wmlib(2)
`An Overview of Limbo/Tk', this manual, Volume 2.
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