listbox.n

linux系统下的音频通信

has several forms, depending on \fIoption\fR:
.RS
.TP
\fIpathName \fBselection anchor \fIindex\fR
Sets the selection anchor to the element given by \fIindex\fR.
.VS 8.0
If \fIindex\fR refers to a non-existent element, then the closest
element is used.
.VE
The selection anchor is the end of the selection that is fixed
while dragging out a selection with the mouse.
The index \fBanchor\fR may be used to refer to the anchor
element.
.TP
\fIpathName \fBselection clear \fIfirst \fR?\fIlast\fR?
If any of the elements between \fIfirst\fR and \fIlast\fR
(inclusive) are selected, they are deselected.
The selection state is not changed for elements outside
this range.
.TP
\fIpathName \fBselection includes \fIindex\fR
Returns 1 if the element indicated by \fIindex\fR is currently
selected, 0 if it isn't.
.TP
\fIpathName \fBselection set \fIfirst \fR?\fIlast\fR?
Selects all of the elements in the range between
\fIfirst\fR and \fIlast\fR, inclusive, without affecting
the selection state of elements outside that range.
.RE
.TP
\fIpathName \fBsize\fR
Returns a decimal string indicating the total number of elements
in the listbox.
.TP
\fIpathName \fBxview \fIargs\fR
This command is used to query and change the horizontal position of the
information in the widget's window.  It can take any of the following
forms:
.RS
.TP
\fIpathName \fBxview\fR
Returns a list containing two elements.
Each element is a real fraction between 0 and 1;  together they describe
the horizontal span that is visible in the window.
For example, if the first element is .2 and the second element is .6,
20% of the listbox's text is off-screen to the left, the middle 40% is visible
in the window, and 40% of the text is off-screen to the right.
These are the same values passed to scrollbars via the \fB\-xscrollcommand\fR
option.
.TP
\fIpathName \fBxview\fR \fIindex\fR
Adjusts the view in the window so that the character position given by
\fIindex\fR is displayed at the left edge of the window.
Character positions are defined by the width of the character \fB0\fR.
.TP
\fIpathName \fBxview moveto\fI fraction\fR
Adjusts the view in the window so that \fIfraction\fR of the
total width of the listbox text is off-screen to the left.
\fIfraction\fR must be a fraction between 0 and 1.
.TP
\fIpathName \fBxview scroll \fInumber what\fR
This command shifts the view in the window left or right according to
\fInumber\fR and \fIwhat\fR.
\fINumber\fR must be an integer.
\fIWhat\fR must be either \fBunits\fR or \fBpages\fR or an abbreviation
of one of these.
If \fIwhat\fR is \fBunits\fR, the view adjusts left or right by
\fInumber\fR character units (the width of the \fB0\fR character)
on the display;  if it is \fBpages\fR then the view adjusts by
\fInumber\fR screenfuls.
If \fInumber\fR is negative then characters farther to the left
become visible;  if it is positive then characters farther to the right
become visible.
.RE
.TP
\fIpathName \fByview \fI?args\fR?
This command is used to query and change the vertical position of the
text in the widget's window.
It can take any of the following forms:
.RS
.TP
\fIpathName \fByview\fR
Returns a list containing two elements, both of which are real fractions
between 0 and 1.
The first element gives the position of the listbox element at the
top of the window, relative to the listbox as a whole (0.5 means
it is halfway through the listbox, for example).
The second element gives the position of the listbox element just after
the last one in the window, relative to the listbox as a whole.
These are the same values passed to scrollbars via the \fB\-yscrollcommand\fR
option.
.TP
\fIpathName \fByview\fR \fIindex\fR
Adjusts the view in the window so that the element given by
\fIindex\fR is displayed at the top of the window.
.TP
\fIpathName \fByview moveto\fI fraction\fR
Adjusts the view in the window so that the element given by \fIfraction\fR
appears at the top of the window.
\fIFraction\fR is a fraction between 0 and 1;  0 indicates the first
element in the listbox, 0.33 indicates the element one-third the
way through the listbox, and so on.
.TP
\fIpathName \fByview scroll \fInumber what\fR
This command adjusts the view in the window up or down according to
\fInumber\fR and \fIwhat\fR.
\fINumber\fR must be an integer.
\fIWhat\fR must be either \fBunits\fR or \fBpages\fR.
If \fIwhat\fR is \fBunits\fR, the view adjusts up or down by
\fInumber\fR lines;  if it is \fBpages\fR then
the view adjusts by \fInumber\fR screenfuls.
If \fInumber\fR is negative then earlier elements
become visible;  if it is positive then later elements
become visible.
.RE

.SH "DEFAULT BINDINGS"
.PP
Tk automatically creates class bindings for listboxes that give them
Motif-like behavior.  Much of the behavior of a listbox is determined
by its \fBselectMode\fR option, which selects one of four ways
of dealing with the selection.
.PP
If the selection mode is \fBsingle\fR or \fBbrowse\fR, at most one
element can be selected in the listbox at once.
In both modes, clicking button 1 on an element selects
it and deselects any other selected item.
In \fBbrowse\fR mode it is also possible to drag the selection
with button 1.
.PP
If the selection mode is \fBmultiple\fR or \fBextended\fR,
any number of elements may be selected at once, including discontiguous
ranges.  In \fBmultiple\fR mode, clicking button 1 on an element
toggles its selection state without affecting any other elements.
In \fBextended\fR mode, pressing button 1 on an element selects
it, deselects everything else, and sets the anchor to the element
under the mouse;  dragging the mouse with button 1
down extends the selection to include all the elements between
the anchor and the element under the mouse, inclusive.
.PP
Most people will probably want to use \fBbrowse\fR mode for
single selections and \fBextended\fR mode for multiple selections;
the other modes appear to be useful only in special situations.
.PP
In addition to the above behavior, the following additional behavior
is defined by the default bindings:
.IP [1]
In \fBextended\fR mode, the selected range can be adjusted by pressing
button 1 with the Shift key down:  this modifies the selection to
consist of the elements between the anchor and the element under
the mouse, inclusive.
The un-anchored end of this new selection can also be dragged with
the button down.
.IP [2]
In \fBextended\fR mode, pressing button 1 with the Control key down
starts a toggle operation: the anchor is set to the element under
the mouse, and its selection state is reversed.  The selection state
of other elements isn't changed.
If the mouse is dragged with button 1 down, then the selection state
of all elements between the anchor and the element under the mouse
is set to match that of the anchor element;  the selection state of
all other elements remains what it was before the toggle operation
began.
.IP [3]
If the mouse leaves the listbox window with button 1 down, the window
scrolls away from the mouse, making information visible that used
to be off-screen on the side of the mouse.
The scrolling continues until the mouse re-enters the window, the
button is released, or the end of the listbox is reached.
.IP [4]
Mouse button 2 may be used for scanning.
If it is pressed and dragged over the listbox, the contents of
the listbox drag at high speed in the direction the mouse moves.
.IP [5]
If the Up or Down key is pressed, the location cursor (active
element) moves up or down one element.
If the selection mode is \fBbrowse\fR or \fBextended\fR then the
new active element is also selected and all other elements are
deselected.
In \fBextended\fR mode the new active element becomes the
selection anchor.
.IP [6]
In \fBextended\fR mode, Shift-Up and Shift-Down move the location
cursor (active element) up or down one element and also extend
the selection to that element in a fashion similar to dragging
with mouse button 1.
.IP [7]
The Left and Right keys scroll the listbox view left and right
by the width of the character \fB0\fR.
Control-Left and Control-Right scroll the listbox view left and
right by the width of the window.
Control-Prior and Control-Next also scroll left and right by
the width of the window.
.IP [8]
The Prior and Next keys scroll the listbox view up and down
by one page (the height of the window).
.IP [9]
The Home and End keys scroll the listbox horizontally to
the left and right edges, respectively.
.IP [10]
Control-Home sets the location cursor to the the first element in
the listbox, selects that element, and deselects everything else
in the listbox.
.IP [11]
Control-End sets the location cursor to the the last element in
the listbox, selects that element, and deselects everything else
in the listbox.
.IP [12]
In \fBextended\fR mode, Control-Shift-Home extends the selection
to the first element in the listbox and Control-Shift-End extends
the selection to the last element.
.IP [13]
In \fBmultiple\fR mode, Control-Shift-Home moves the location cursor
to the first element in the listbox and Control-Shift-End moves
the location cursor to the last element.
.IP [14]
The space and Select keys make a selection at the location cursor
(active element) just as if mouse button 1 had been pressed over
this element.
.IP [15]
In \fBextended\fR mode, Control-Shift-space and Shift-Select
extend the selection to the active element just as if button 1
had been pressed with the Shift key down.
.IP [16]
In \fBextended\fR mode, the Escape key cancels the most recent
selection and restores all the elements in the selected range
to their previous selection state.
.IP [17]
Control-slash selects everything in the widget, except in
\fBsingle\fR and \fBbrowse\fR modes, in which case it selects
the active element and deselects everything else.
.IP [18]
Control-backslash deselects everything in the widget, except in
\fBbrowse\fR mode where it has no effect.
.IP [19]
The F16 key (labelled Copy on many Sun workstations) or Meta-w
copies the selection in the widget to the clipboard, if there is
a selection.

.PP
The behavior of listboxes can be changed by defining new bindings for
individual widgets or by redefining the class bindings.

.SH KEYWORDS
listbox, widget