DESCRIPTION

Each of these functions creates and initializes a new node of a
Panel tree and returns a pointer to the newly created panel.
Existing panels may be reinitialized (for example
to change the label on a button) by functions enumerated in
plinitbutton(2).

The first two arguments of each panel-creation function are a
pointer to the new panel's parent and the flags that control
plpack (see
plinit(2)). Arguments of type
Icon* (a synonym for
void*) are either
Bitmap or text labels. If the
BITMAP bit of the flag word is set, they are of type
Bitmap*. Otherwise, their type is
char*.

plbutton

plcheckbutton

plradiobutton

These three functions create pushbuttons.
Plbutton creates an ordinary button.
Plcheckbutton creates a button with a check mark that toggles
on and off when the button is hit.
Plradiobutton likewise creates a button with a check mark, but
with the additional feature that toggling the
check mark on toggles off the checks of
its siblings in
the
Panel tree.
All three take similar arguments:
label is the text or bitmap drawn on the button, and
hit is the function called when a hit is registered
on the button. Its arguments are a pointer to the button and
the mouse buttons active when the hit occurred.
The
hit functions of
plcheckbutton and
plradiobutton take a third argument that indicates the state of the
button's check mark.

Occasionally, a button or other panel
may wish to take no action on sensing a hit. This is indicated by passing
a null
hit function pointer to the creation function.

plframe

plgroup

These two functions create compound panels that enclose
their children in a rectangular area. The difference is
that
plframe draws a frame around its children, but
plgroup does not.

pllabel

plmessage

These two functions create passive (insensitive to
mouse or keyboard events) panels. The
pllabel entry draws a label containing a text string or
a
Bitmap. Plmessage draws longer messages. Its arguments are the desired
width of the panel, in pixels, and a pointer to the
text to be drawn. The text is displayed on multiple
lines, wrapping around at word boundaries.

plcanvas

creates an empty rectangle in a panel tree.
The
draw argument is a function to be called by
the panel library to redraw the panel.
Draw's argument points to the canvas to be drawn on.
The
hit argument is a function called whenever a mouse event
is registered in the panel. Its arguments are a pointer
to the panel and a pointer to the mouse event.
Hit receives all mouse events with points within the canvas's
rectangle and with a button down.
In addition, an event is sent when the buttons are released
over the canvas, or when the mouse moves out of the canvas's
rectangle. In the latter case, the mouse event's
buttons field has the
OUT bit set.

pledit

creates a panel that displays editable single-font text.
Arguments are the minimum acceptable size for the panel,
a pointer to an array of
Runes that initializes the panel, the number of runes in the
array, and a function to be called every time a selection
is swept out with the mouse. The functions
pleget, plelen, plegetsel, plepaste, plesel, plescroll, and
pleshowsel, described in
plinit(2), manipulate the contents of edit panels.

plentry

creates a single-line text entry panel.
Arguments are the minimum acceptable width of the panel, in pixels,
a string that is the initial contents of the panel,
and a hit function to be called whenever a newline is typed in the panel.
The hit function's arguments are a pointer to the panel and a pointer to
the string entered. Clicking the mouse over an entry makes it the
keyboard focus (the recipient of typed characters), as does calling
plgrabkb (described in
plinit(2)).

pllist

creates a panel containing a scrollable list of text items.
Its arguments are
gen, a pointer to a function that, when passed an integer argument,
returns the text of the appropriate list item,
length, the minimum acceptable number of items to be displayed on the screen, and
hit, a function to be called when an item is selected with the mouse.
Hit's arguments are a pointer to the panel, which mouse buttons were used to
make the selection, and the number of the item selected.

plmenu

calls
plgroup and
plbutton to create an array of buttons.
The
items argument points to an array of strings or
Bitmap pointers,
one per button. A null pointer ends the list.
Itemflags is the flag argument used to create each button.
The
hit function's arguments are the mouse buttons pressed
to register the hit and the button's index in
items.

plpopup

creates a group, as in
plgroup, except that where
plgroup always passes mouse events on to its children,
plpopup may instead temporarily pop up a new panel and
divert mouse events to it. The arguments
left, middle, and
right are pointers to panels to be popped up when the
corresponding mouse button is pushed. A null
pointer causes events to pass through to
plpopup's children.

plpulldown

plmenubar

Plpulldown creates a button that, when triggered by a mouse button push,
temporarily pops up a new panel.
The
label argument points to a Bitmap or text label,
pull points to the panel that appears when the button is pushed, and
side is a flag whose value is one of
PACKN, PACKE, PACKS, or
PACKW, indicating the side of the button on which the pulled-down menu should appear.
The
plmenubar entry calls
plgroup and
plpulldown to create an array of pull-down buttons. Its
itemflags argument gives the flags to be used when creating each pull-down button.
Then follow an indefinite number of pairs giving the labels and pulled-down
panels of the buttons. The list ends with a null label pointer.

plslider

creates a continuously variable slider. The
size argument gives the smallest acceptable size.
If
size.x>.IBsize.y the slider is drawn horizontally, otherwise
vertically.
The
hit function is called whenever a mouse event
changes the slider's value. Its arguments
are a pointer to the slider, the mouse buttons,
the slider's value, and the possible range of
values. The value is always between 0 and
the range.

plscrollbar

creates a scroll bar. If the
flags argument has
PACKE or
PACKW set, the scroll bar slides vertically, otherwise
horizontally. Scroll bars are associated with
the panels that they scroll by a call to
plscroll, described in
plinit(2).

pltextview

creates a panel containing hit-sensitive formatted
multi-font text with bitmap illustrations. Its arguments
are the minimum acceptable size of the panel, in pixels,
a pointer to a data structure describing the text to be
displayed, and a function to be called upon registering a
mouse hit. The arguments of the hit function are a
pointer to the panel, the mouse buttons that caused the hit,
and a pointer to the text element that the mouse pointed
at. The functions
plrtstring and
plrtbitmap, which create the
Rtext data structure that describes the text, are described in
plinit(2).

SOURCE

/sys/src/libpanel

SEE ALSO

plinit(2), plinitbutton(2), graphics(2)
Tom Duff,
``A quick introduction to the panel library''.