.\" Copyright (c) 2002-2022 Julien Nadeau Carriere <vedge@csoft.net>
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.Dd December 21, 2022
.Dt AG_CHECKBOX 3
.Os Agar 1.7
.Sh NAME
.Nm AG_Checkbox
.Nd agar checkbox widget
.Sh SYNOPSIS
.Bd -literal
#include <agar/core.h>
#include <agar/gui.h>
.Ed
.Sh DESCRIPTION
.\" IMAGE(/widgets/AG_Checkbox.png, "Two checkboxes")
The
.Nm
widget controls a boolean variable (i.e., an
.Ft int
or a set of bits in an integer).
If a text label is specified, it is displayed next to the control.
.Sh INHERITANCE HIERARCHY
.Xr AG_Object 3 ->
.Xr AG_Widget 3 ->
.Nm .
.Sh INITIALIZATION
.nr nS 1
.Ft "AG_Checkbox *"
.Fn AG_CheckboxNew "AG_Widget *parent" "Uint flags" "const char *format" "..."
.Pp
.Ft "AG_Checkbox *"
.Fn AG_CheckboxNewS "AG_Widget *parent" "Uint flags" "const char *label"
.Pp
.Ft "AG_Checkbox *"
.Fn AG_CheckboxNewFn "AG_Widget *parent" "Uint flags" "const char *label" "AG_EventFn fn" "const char *fmt" "..."
.Pp
.Ft "AG_Checkbox *"
.Fn AG_CheckboxNewInt "AG_Widget *parent" "Uint flags" "const char *label" "int *pBool"
.Pp
.Ft "AG_Checkbox *"
.Fn AG_CheckboxNewUint "AG_Widget *parent" "Uint flags" "const char *label" "Uint *pBool"
.Pp
.Ft "AG_Checkbox *"
.Fn AG_CheckboxNewFlag "AG_Widget *parent" "Uint flags" "const char *label" "Uint *pFlags" "Uint bitmask"
.Pp
.Ft "void"
.Fn AG_CheckboxSetFromFlags "AG_Widget *parent" "Uint flags" "Uint *pFlags" "const AG_FlagDescr *flagsDescr"
.Pp
.Ft "void"
.Fn AG_CheckboxSetFromFlagsFn "AG_Widget *parent" "Uint flags" "Uint *pFlags" "const AG_FlagDescr *flagsDescr" "AG_EventFn fn" "const char *fmt" "..."
.Pp
.Ft "int"
.Fn AG_CheckboxGetState "AG_Checkbox *checkbox"
.Pp
.Ft "void"
.Fn AG_CheckboxSetState "AG_Checkbox *checkbox" "int enable"
.Pp
.Ft "void"
.Fn AG_CheckboxToggle "AG_Checkbox *checkbox"
.Pp
.nr nS 0
The
.Fn AG_CheckboxNew
function allocates, initializes, and attaches a
.Nm
widget.
.Fn AG_CheckboxNew
accepts an optional text label argument.
The
.Fn AG_CheckboxNewFn
variant also assigns the specified callback function to the
.Sq checkbox-changed
event.
.Pp
Acceptable values for the
.Fa flags
argument include:
.Bl -tag -width "AG_CHECKBOX_EXPAND "
.It AG_CHECKBOX_INVERT
Invert the logical interpretation of "state".
.It AG_CHECKBOX_SET
Set default "state" to 1 (default = 0).
.It AG_CHECKBOX_EXCL
Advise that this checkbox is the only widget accessing "state"
(so periodic updates are not needed).
.It AG_CHECKBOX_HFILL
Expand horizontally in parent container.
.It AG_CHECKBOX_VFILL
Expand vertically in parent container.
.It AG_CHECKBOX_EXPAND
Shorthand for
.Dv AG_CHECKBOX_HFILL | AG_CHECKBOX_VFILL .
.El
.Pp
The
.Fn AG_CheckboxNewInt
constructor binds "state" to a natural integer.
.Fn AG_CheckboxNewFlag
binds "state" to one or more bits in the natural integer at
.Fa pFlags ,
according to
.Fa bitmask a.
.Pp
.\" MANLINK(AG_FlagDescr)
.Fn AG_CheckboxSetFromFlags
creates a set of checkboxes for the given set of flags, described
by an array of
.Ft AG_FlagDescr
structures:
.Bd -literal
.\" SYNTAX(c)
typedef struct ag_flag_descr {
	Uint bitmask;			/* Bitmask */
	const char *descr;		/* Bit(s) description */
	int writeable;			/* User-editable */
} AG_FlagDescr;
.Ed
.Pp
The
.Fn AG_CheckboxSetFromFlagsFn
variant sets the event handler for
.Sq checkbox-changed
to the given function
.Fa fn
and optional arguments
.Fa fmt .
.Pp
.Fn AG_CheckboxGetState
returns the current state of the checkbox.
.Fn AG_CheckboxSetState
sets the of the checkbox, where 0=inactive and 0=active.
.Fn AG_CheckboxToggle
inverts the state atomically.
.Sh BINDINGS
The
.Nm
widget provides the following bindings:
.Pp
.Bl -tag -compact -width "FLAGS32 *state "
.It Va BOOL *state
Value (1/0) of natural integer
.It Va INT *state
Value (1/0) of natural integer
.It Va UINT8 *state
Value (1/0) of 8-bit integer
.It Va UINT16 *state
Value (1/0) of 16-bit integer
.It Va UINT32 *state
Value (1/0) of 32-bit integer
.It Va FLAGS *state
Bits in an int
.It Va FLAGS8 *state
Bits in 8-bit word
.It Va FLAGS16 *state
Bits in 16-bit word
.It Va FLAGS32 *state
Bits in 32-bit word
.El
.Sh EVENTS
The
.Nm
widget generates the following events:
.Bl -tag -width 2n
.It Fn checkbox-changed "int state"
Checkbox state changed (1=enabled, 0=disabled).
The
.Sq state
binding remains locked during the event handler's execution.
.El
.Sh STRUCTURE DATA
For the
.Ft AG_Checkbox
object:
.Bl -tag -width "AG_Label *lbl "
.It Ft int invert
Invert the logical interpretation of the
.Sq state
binding.
.It Ft AG_Label *lbl
Pointer to the
.Xr AG_Label 3
displaying the caption text.
.El
.Sh EXAMPLES
The following code fragment ties an
.Nm
to a boolean variable represented by an
.Ft int :
.Bd -literal -offset indent
.\" SYNTAX(c)
int someOption = 0;

AG_Window *win = AG_WindowNew(0);
AG_CheckboxNewInt(win, 0, "Some option", &someOption);
AG_WindowShow(win);
.Ed
.Pp
The following code fragment uses an
.Nm
to trigger a callback function:
.Bd -literal -offset indent
.\" SYNTAX(c)
static void
MyCallback(AG_Event *event)
{
	AG_TextInfo(NULL, "Callback invoked");
}

AG_Window *win = AG_WindowNew(0);
AG_CheckboxNewFn(win, 0, "Execute callback", MyCallback, NULL);
AG_WindowShow(win);
.Ed
.Pp
The following code fragment creates an array of checkboxes, each tied to
a specific bit in a word:
.Bd -literal -offset indent
.\" SYNTAX(c)
#define FLAG_FOO	0x01
#define FLAG_BAR	0x02
#define FLAG_BAZ	0x04

int myWord = 0;

AG_FlagDescr myFlagDescr[] = {
	{ FLAG_FOO,	"foo flag",		1 },
	{ FLAG_BAR,	"bar flag",		1 },
	{ FLAG_BAZ,	"baz flag (readonly)",	0 },
	{ 0,		NULL,			0 }
};

AG_Window *win = AG_WindowNew(0);
AG_CheckboxSetFromFlags(win, 0, &myWord, myFlagDescr);
AG_WindowShow(win);
.Ed
.Sh SEE ALSO
.Xr AG_Button 3 ,
.Xr AG_Event 3 ,
.Xr AG_Intro 3 ,
.Xr AG_Radio 3 ,
.Xr AG_Widget 3 ,
.Xr AG_Window 3
.Sh HISTORY
The
.Nm
widget first appeared in Agar 1.0.
.Fn AG_CheckboxToggle ,
.Fn AG_CheckboxGetState
and
.Fn AG_CheckboxSetState
appeared in Agar 1.6.0.