listbox.n

linux系统下的音频通信

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'\" Copyright (c) 1990 The Regents of the University of California.
'\" Copyright (c) 1994-1997 Sun Microsystems, Inc.
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'\" SCCS: @(#) listbox.n 1.38 97/10/31 12:58:47
'\" 
.so man.macros
.TH listbox n 8.0 Tk "Tk Built-In Commands"
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
listbox \- Create and manipulate listbox widgets
.SH SYNOPSIS
\fBlistbox\fR \fIpathName \fR?\fIoptions\fR?
.SO
\-background	\-foreground	\-relief	\-takefocus
\-borderwidth	\-height	\-selectbackground	\-width
\-cursor	\-highlightbackground	\-selectborderwidth	\-xscrollcommand
\-exportselection	\-highlightcolor	\-selectforeground	\-yscrollcommand
\-font	\-highlightthickness	\-setgrid
.SE
.SH "WIDGET-SPECIFIC OPTIONS"
.OP \-height height Height
Specifies the desired height for the window, in lines.
If zero or less, then the desired height for the window is made just
large enough to hold all the elements in the listbox.
.OP \-selectmode selectMode SelectMode
Specifies one of several styles for manipulating the selection.
The value of the option may be arbitrary, but the default bindings
expect it to be either \fBsingle\fR, \fBbrowse\fR, \fBmultiple\fR,
or \fBextended\fR;  the default value is \fBbrowse\fR.
.OP \-width width Width
Specifies the desired width for the window in characters.
If the font doesn't have a uniform width then the width of the
character ``0'' is used in translating from character units to
screen units.
If zero or less, then the desired width for the window is made just
large enough to hold all the elements in the listbox.
.BE

.SH DESCRIPTION
.PP
The \fBlistbox\fR command creates a new window (given by the
\fIpathName\fR argument) and makes it into a listbox widget.
Additional
options, described above, may be specified on the command line
or in the option database
to configure aspects of the listbox such as its colors, font,
text, and relief.  The \fBlistbox\fR command returns its
\fIpathName\fR argument.  At the time this command is invoked,
there must not exist a window named \fIpathName\fR, but
\fIpathName\fR's parent must exist.
.PP
A listbox is a widget that displays a list of strings, one per line.
When first created, a new listbox has no elements.
Elements may be added or deleted using widget commands described
below.  In addition, one or more elements may be selected as described
below.
If a listbox is exporting its selection (see \fBexportSelection\fR
option), then it will observe the standard X11 protocols
for handling the selection.
Listbox selections are available as type \fBSTRING\fR;
the value of the selection will be the text of the selected elements, with
newlines separating the elements.
.PP
It is not necessary for all the elements to be
displayed in the listbox window at once;  commands described below
may be used to change the view in the window.  Listboxes allow
scrolling in both directions using the standard \fBxScrollCommand\fR
and \fByScrollCommand\fR options.
They also support scanning, as described below.

.SH "INDICES"
.PP
Many of the widget commands for listboxes take one or more indices
as arguments.
An index specifies a particular element of the listbox, in any of
the following ways:
.TP 12
\fInumber\fR
Specifies the element as a numerical index, where 0 corresponds
to the first element in the listbox.
.TP 12
\fBactive\fR
Indicates the element that has the location cursor.  This element
will be displayed with an underline when the listbox has the
keyboard focus, and it is specified with the \fBactivate\fR
widget command.
.TP 12
\fBanchor\fR
Indicates the anchor point for the selection, which is set with the
\fBselection anchor\fR widget command.
.TP 12
\fBend\fR
Indicates the end of the listbox.
.VS 8.0
For most commands this refers to the last element in the listbox,
but for a few commands such as \fBindex\fR and \fBinsert\fR
it refers to the element just after the last one.
.VE
.TP 12
\fB@\fIx\fB,\fIy\fR
Indicates the element that covers the point in the listbox window
specified by \fIx\fR and \fIy\fR (in pixel coordinates).  If no
element covers that point, then the closest element to that
point is used.
.LP
In the widget command descriptions below, arguments named \fIindex\fR,
\fIfirst\fR, and \fIlast\fR always contain text indices in one of
the above forms.

.SH "WIDGET COMMAND"
.PP
The \fBlistbox\fR command creates a new Tcl command whose
name is \fIpathName\fR.  This
command may be used to invoke various
operations on the widget.  It has the following general form:
.CS
\fIpathName option \fR?\fIarg arg ...\fR?
.CE
\fIOption\fR and the \fIarg\fRs
determine the exact behavior of the command.  The following
commands are possible for listbox widgets:
.TP
\fIpathName \fBactivate\fR \fIindex\fR
Sets the active element to the one indicated by \fIindex\fR.
.VS 8.0
If \fIindex\fR is outside the range of elements in the listbox
then the closest element is activated.
.VE
The active element is drawn with an underline when the widget
has the input focus, and its index may be retrieved with the
index \fBactive\fR.
.TP
\fIpathName \fBbbox\fR \fIindex\fR
Returns a list of four numbers describing the bounding box of
the text in the element given by \fIindex\fR.
The first two elements of the list give the x and y coordinates
of the upper-left corner of the screen area covered by the text
(specified in pixels relative to the widget) and the last two
elements give the width and height of the area, in pixels.
If no part of the element given by \fIindex\fR is visible on the
screen,
.VS 8.0
or if \fIindex\fR refers to a non-existent element,
.VE
then the result is an empty string;  if the element is
partially visible, the result gives the full area of the element,
including any parts that are not visible.
.TP
\fIpathName \fBcget\fR \fIoption\fR
Returns the current value of the configuration option given
by \fIoption\fR.
\fIOption\fR may have any of the values accepted by the \fBlistbox\fR
command.
.TP
\fIpathName \fBconfigure\fR ?\fIoption\fR? ?\fIvalue option value ...\fR?
Query or modify the configuration options of the widget.
If no \fIoption\fR is specified, returns a list describing all of
the available options for \fIpathName\fR (see \fBTk_ConfigureInfo\fR for
information on the format of this list).  If \fIoption\fR is specified
with no \fIvalue\fR, then the command returns a list describing the
one named option (this list will be identical to the corresponding
sublist of the value returned if no \fIoption\fR is specified).  If
one or more \fIoption\-value\fR pairs are specified, then the command
modifies the given widget option(s) to have the given value(s);  in
this case the command returns an empty string.
\fIOption\fR may have any of the values accepted by the \fBlistbox\fR
command.
.TP
\fIpathName \fBcurselection\fR
Returns a list containing the numerical indices of
all of the elements in the listbox that are currently selected.
If there are no elements selected in the listbox then an empty
string is returned.
.TP
\fIpathName \fBdelete \fIfirst \fR?\fIlast\fR?
Deletes one or more elements of the listbox.  \fIFirst\fR and \fIlast\fR
are indices specifying the first and last elements in the range
to delete.  If \fIlast\fR isn't specified it defaults to
\fIfirst\fR, i.e. a single element is deleted.
.TP
\fIpathName \fBget \fIfirst\fR ?\fIlast\fR?
If \fIlast\fR is omitted, returns the contents of the listbox
element indicated by \fIfirst\fR,
.VS 8.0
or an empty string if \fIfirst\fR refers to a non-existent element.
.VE
If \fIlast\fR is specified, the command returns a list whose elements
are all of the listbox elements between \fIfirst\fR and \fIlast\fR,
inclusive.
Both \fIfirst\fR and \fIlast\fR may have any of the standard
forms for indices.
.TP
\fIpathName \fBindex \fIindex\fR
Returns the integer index value that corresponds to \fIindex\fR.
.VS 8.0
If \fIindex\fR is \fBend\fR the return value is a count of the number
of elements in the listbox (not the index of the last element).
.VE
.TP
\fIpathName \fBinsert \fIindex \fR?\fIelement element ...\fR?
Inserts zero or more new elements in the list just before the
element given by \fIindex\fR.  If \fIindex\fR is specified as
\fBend\fR then the new elements are added to the end of the
list.  Returns an empty string.
.TP
\fIpathName \fBnearest \fIy\fR
Given a y-coordinate within the listbox window, this command returns
the index of the (visible) listbox element nearest to that y-coordinate.
.TP
\fIpathName \fBscan\fR \fIoption args\fR
This command is used to implement scanning on listboxes.  It has
two forms, depending on \fIoption\fR:
.RS
.TP
\fIpathName \fBscan mark \fIx y\fR
Records \fIx\fR and \fIy\fR and the current view in the listbox
window;  used in conjunction with later \fBscan dragto\fR commands.
Typically this command is associated with a mouse button press in
the widget.  It returns an empty string.
.TP
\fIpathName \fBscan dragto \fIx y\fR.
This command computes the difference between its \fIx\fR and \fIy\fR
arguments and the \fIx\fR and \fIy\fR arguments to the last
\fBscan mark\fR command for the widget.
It then adjusts the view by 10 times the
difference in coordinates.  This command is typically associated
with mouse motion events in the widget, to produce the effect of
dragging the list at high speed through the window.  The return
value is an empty string.
.RE
.TP
\fIpathName \fBsee \fIindex\fR
Adjust the view in the listbox so that the element given by \fIindex\fR
is visible.
If the element is already visible then the command has no effect;
if the element is near one edge of the window then the listbox
scrolls to bring the element into view at the edge;  otherwise
the listbox scrolls to center the element.
.TP
\fIpathName \fBselection \fIoption arg\fR
This command is used to adjust the selection within a listbox.  It