Fl_Button Class Reference

Buttons generate callbacks when they are clicked by the user. More...

#include <Fl_Button.H>

Inheritance diagram for Fl_Button:

Public Member Functions
int	clear ()
	Same as value(0). More...
uchar	compact ()
	Return true if buttons are rendered as compact buttons. More...
void	compact (uchar v)
	Decide if buttons should be rendered in compact mode. More...
Fl_Boxtype	down_box () const
	Returns the current down box type, which is drawn when value() is non-zero. More...
void	down_box (Fl_Boxtype b)
	Sets the down box type. More...
Fl_Color	down_color () const
	(for backwards compatibility)
void	down_color (unsigned c)
	(for backwards compatibility)
	Fl_Button (int X, int Y, int W, int H, const char *L=0)
	The constructor creates the button using the given position, size, and label. More...
int	handle (int) FL_OVERRIDE
	Handles the specified event. More...
int	set ()
	Same as value(1). More...
void	setonly ()
	Turns on this button and turns off all other radio buttons in the group (calling value(1) or set() does not do this).
int	shortcut () const
	Returns the current shortcut key for the button. More...
void	shortcut (const char *s)
	(for backwards compatibility)
void	shortcut (int s)
	Sets the shortcut key to s. More...
char	value () const
	Returns the current value of the button (0 or 1).
int	value (int v)
	Sets the current value of the button. More...
Public Member Functions inherited from Fl_Widget
void	_clear_fullscreen ()
void	_set_fullscreen ()
void	activate ()
	Activates the widget. More...
unsigned int	active () const
	Returns whether the widget is active. More...
int	active_r () const
	Returns whether the widget and all of its parents are active. More...
Fl_Align	align () const
	Gets the label alignment. More...
void	align (Fl_Align alignment)
	Sets the label alignment. More...
long	argument () const
	Gets the current user data (long) argument that is passed to the callback function. More...
void	argument (long v)
	Sets the current user data (long) argument that is passed to the callback function. More...
virtual class Fl_Gl_Window *	as_gl_window ()
	Returns an Fl_Gl_Window pointer if this widget is an Fl_Gl_Window. More...
virtual class Fl_Gl_Window const *	as_gl_window () const
virtual Fl_Group *	as_group ()
	Returns an Fl_Group pointer if this widget is an Fl_Group. More...
virtual Fl_Group const *	as_group () const
virtual Fl_Window *	as_window ()
	Returns an Fl_Window pointer if this widget is an Fl_Window. More...
virtual Fl_Window const *	as_window () const
void	bind_deimage (Fl_Image *img)
	Sets the image to use as part of the widget label when in the inactive state. More...
void	bind_deimage (int f)
	Bind the inactive image to the widget, so the widget will delete the image when it is no longer needed. More...
void	bind_image (Fl_Image *img)
	Sets the image to use as part of the widget label when in the active state. More...
void	bind_image (int f)
	Bind the image to the widget, so the widget will delete the image when it is no longer needed. More...
Fl_Boxtype	box () const
	Gets the box type of the widget. More...
void	box (Fl_Boxtype new_box)
	Sets the box type for the widget. More...
Fl_Callback_p	callback () const
	Gets the current callback function for the widget. More...
void	callback (Fl_Callback *cb)
	Sets the current callback function for the widget. More...
void	callback (Fl_Callback *cb, Fl_Callback_User_Data *p, bool auto_free)
	Sets the current callback function and managed user data for the widget. More...
void	callback (Fl_Callback *cb, void *p)
	Sets the current callback function and data for the widget. More...
void	callback (Fl_Callback0 *cb)
	Sets the current callback function for the widget. More...
void	callback (Fl_Callback1 *cb, long p=0)
	Sets the current callback function for the widget. More...
unsigned int	changed () const
	Checks if the widget value changed since the last callback. More...
void	clear_active ()
	Marks the widget as inactive without sending events or changing focus. More...
void	clear_changed ()
	Marks the value of the widget as unchanged. More...
void	clear_damage (uchar c=0)
	Clears or sets the damage flags. More...
void	clear_output ()
	Sets a widget to accept input. More...
void	clear_visible ()
	Hides the widget. More...
void	clear_visible_focus ()
	Disables keyboard focus navigation with this widget. More...
Fl_Color	color () const
	Gets the background color of the widget. More...
void	color (Fl_Color bg)
	Sets the background color of the widget. More...
void	color (Fl_Color bg, Fl_Color sel)
	Sets the background and selection color of the widget. More...
Fl_Color	color2 () const
	For back compatibility only. More...
void	color2 (unsigned a)
	For back compatibility only. More...
int	contains (const Fl_Widget *w) const
	Checks if w is a child of this widget. More...
void	copy_label (const char *new_label)
	Sets the current label. More...
void	copy_tooltip (const char *text)
	Sets the current tooltip text. More...
uchar	damage () const
	Returns non-zero if draw() needs to be called. More...
void	damage (uchar c)
	Sets the damage bits for the widget. More...
void	damage (uchar c, int x, int y, int w, int h)
	Sets the damage bits for an area inside the widget. More...
int	damage_resize (int, int, int, int)
	Internal use only.
void	deactivate ()
	Deactivates the widget. More...
Fl_Image *	deimage ()
	Gets the image that is used as part of the widget label when in the inactive state. More...
const Fl_Image *	deimage () const
	Gets the image that is used as part of the widget label when in the inactive state. More...
void	deimage (Fl_Image &img)
	Sets the image to use as part of the widget label when in the inactive state. More...
void	deimage (Fl_Image *img)
	Sets the image to use as part of the widget label when in the inactive state. More...
int	deimage_bound () const
	Returns whether the inactive image is managed by the widget. More...
void	do_callback (Fl_Callback_Reason reason=FL_REASON_UNKNOWN)
	Calls the widget callback function with default arguments. More...
void	do_callback (Fl_Widget *widget, long arg, Fl_Callback_Reason reason=FL_REASON_UNKNOWN)
	Calls the widget callback function with arbitrary arguments. More...
void	do_callback (Fl_Widget *widget, void *arg=0, Fl_Callback_Reason reason=FL_REASON_UNKNOWN)
	Calls the widget callback function with arbitrary arguments. More...
virtual void	draw ()=0
	Draws the widget. More...
void	draw_label (int, int, int, int, Fl_Align) const
	Draws the label in an arbitrary bounding box with an arbitrary alignment. More...
int	h () const
	Gets the widget height. More...
virtual int	handle (int event)
	Handles the specified event. More...
virtual void	hide ()
	Makes a widget invisible. More...
int	horizontal_label_margin ()
	Get the spacing between the label and the horizontal edge of the widget. More...
void	horizontal_label_margin (int px)
	Set the spacing between the label and the horizontal edge of the widget. More...
Fl_Image *	image ()
	Gets the image that is used as part of the widget label when in the active state. More...
const Fl_Image *	image () const
	Gets the image that is used as part of the widget label when in the active state. More...
void	image (Fl_Image &img)
	Sets the image to use as part of the widget label when in the active state. More...
void	image (Fl_Image *img)
	Sets the image to use as part of the widget label when in the active state. More...
int	image_bound () const
	Returns whether the image is managed by the widget. More...
int	inside (const Fl_Widget *wgt) const
	Checks if this widget is a child of wgt. More...
int	is_label_copied () const
	Returns whether the current label was assigned with copy_label(). More...
const char *	label () const
	Gets the current label text. More...
void	label (const char *text)
	Sets the current label pointer. More...
void	label (Fl_Labeltype a, const char *b)
	Shortcut to set the label text and type in one call. More...
int	label_image_spacing ()
	Return the gap size between the label and the image. More...
void	label_image_spacing (int gap)
	Set the gap between the label and the image in pixels. More...
Fl_Color	labelcolor () const
	Gets the label color. More...
void	labelcolor (Fl_Color c)
	Sets the label color. More...
Fl_Font	labelfont () const
	Gets the font to use. More...
void	labelfont (Fl_Font f)
	Sets the font to use. More...
Fl_Fontsize	labelsize () const
	Gets the font size in pixels. More...
void	labelsize (Fl_Fontsize pix)
	Sets the font size in pixels. More...
Fl_Labeltype	labeltype () const
	Gets the label type. More...
void	labeltype (Fl_Labeltype a)
	Sets the label type. More...
void	measure_label (int &ww, int &hh) const
	Sets width ww and height hh accordingly with the label size. More...
bool	needs_keyboard () const
	Returns whether this widget needs a keyboard. More...
void	needs_keyboard (bool needs)
	Sets whether this widget needs a keyboard. More...
unsigned int	output () const
	Returns if a widget is used for output only. More...
Fl_Group *	parent () const
	Returns a pointer to the parent widget. More...
void	parent (Fl_Group *p)
	Internal use only - "for hacks only". More...
void	position (int X, int Y)
	Repositions the window or widget. More...
void	redraw ()
	Schedules the drawing of the widget. More...
void	redraw_label ()
	Schedules the drawing of the label. More...
virtual void	resize (int x, int y, int w, int h)
	Changes the size or position of the widget. More...
Fl_Color	selection_color () const
	Gets the selection color. More...
void	selection_color (Fl_Color a)
	Sets the selection color. More...
void	set_active ()
	Marks the widget as active without sending events or changing focus. More...
void	set_changed ()
	Marks the value of the widget as changed. More...
void	set_output ()
	Sets a widget to output only. More...
void	set_visible ()
	Makes the widget visible. More...
void	set_visible_focus ()
	Enables keyboard focus navigation with this widget. More...
int	shortcut_label () const
	Returns whether the widget's label uses '&' to indicate shortcuts. More...
void	shortcut_label (int value)
	Sets whether the widget's label uses '&' to indicate shortcuts. More...
virtual void	show ()
	Makes a widget visible. More...
void	size (int W, int H)
	Changes the size of the widget. More...
int	take_focus ()
	Gives the widget the keyboard focus. More...
unsigned int	takesevents () const
	Returns if the widget is able to take events. More...
int	test_shortcut ()
	Returns true if the widget's label contains the entered '&x' shortcut. More...
const char *	tooltip () const
	Gets the current tooltip text. More...
void	tooltip (const char *text)
	Sets the current tooltip text. More...
Fl_Window *	top_window () const
	Returns a pointer to the top-level window for the widget. More...
Fl_Window *	top_window_offset (int &xoff, int &yoff) const
	Finds the x/y offset of the current widget relative to the top-level window. More...
uchar	type () const
	Gets the widget type. More...
void	type (uchar t)
	Sets the widget type. More...
int	use_accents_menu ()
	Returns non zero if MAC_USE_ACCENTS_MENU flag is set, 0 otherwise.
void *	user_data () const
	Gets the user data for this widget. More...
void	user_data (Fl_Callback_User_Data *v, bool auto_free)
	Sets the user data for this widget.
void	user_data (void *v)
	Sets the user data for this widget.
int	vertical_label_margin ()
	Get the spacing between the label and the vertical edge of the widget. More...
void	vertical_label_margin (int px)
	Set the spacing between the label and the vertical edge of the widget. More...
unsigned int	visible () const
	Returns whether a widget is visible. More...
unsigned int	visible_focus () const
	Checks whether this widget has a visible focus. More...
void	visible_focus (int v)
	Modifies keyboard focus navigation. More...
int	visible_r () const
	Returns whether a widget and all its parents are visible. More...
int	w () const
	Gets the widget width. More...
Fl_When	when () const
	Returns the conditions under which the callback is called. More...
void	when (uchar i)
	Sets the flags used to decide when a callback is called. More...
Fl_Window *	window () const
	Returns a pointer to the nearest parent window up the widget hierarchy. More...
int	x () const
	Gets the widget position in its window. More...
int	y () const
	Gets the widget position in its window. More...
virtual	~Fl_Widget ()
	Destroys the widget. More...

Protected Member Functions
void	draw () FL_OVERRIDE
	Draws the widget. More...
void	simulate_key_action ()
Protected Member Functions inherited from Fl_Widget
void	clear_flag (unsigned int c)
	Clears a flag in the flags mask.
void	draw_backdrop () const
	If FL_ALIGN_IMAGE_BACKDROP is set, the image or deimage will be drawn.
void	draw_box () const
	Draws the widget box according its box style.
void	draw_box (Fl_Boxtype t, Fl_Color c) const
	Draws a box of type t, of color c at the widget's position and size.
void	draw_box (Fl_Boxtype t, int x, int y, int w, int h, Fl_Color c) const
	Draws a box of type t, of color c at the position X,Y and size W,H.
void	draw_focus () const
	Draws a focus rectangle around the widget. More...
void	draw_focus (Fl_Boxtype t, int X, int Y, int W, int H) const
	Draws a focus rectangle around the widget. More...
void	draw_focus (Fl_Boxtype t, int x, int y, int w, int h, Fl_Color bg) const
	Draws a focus box for the widget at the given position and size. More...
void	draw_label () const
	Draws the widget's label at the defined label position. More...
void	draw_label (int, int, int, int) const
	Draws the label in an arbitrary bounding box. More...
	Fl_Widget (int x, int y, int w, int h, const char *label=0L)
	Creates a widget at the given position and size. More...
unsigned int	flags () const
	Gets the widget flags mask.
void	h (int v)
	Internal use only. More...
void	set_flag (unsigned int c)
	Sets a flag in the flags mask.
void	w (int v)
	Internal use only. More...
void	x (int v)
	Internal use only. More...
void	y (int v)
	Internal use only. More...

Static Protected Member Functions
static void	key_release_timeout (void *)

Static Protected Attributes
static Fl_Widget_Tracker *	key_release_tracker = 0

Additional Inherited Members
Static Public Member Functions inherited from Fl_Widget
static void	default_callback (Fl_Widget *widget, void *data)
	The default callback for all widgets that don't set a callback. More...
static unsigned int	label_shortcut (const char *t)
	Returns the Unicode value of the '&x' shortcut in a given text. More...
static int	test_shortcut (const char *, const bool require_alt=false)
	Returns true if the given text t contains the entered '&x' shortcut. More...
Protected Types inherited from Fl_Widget
enum	{   INACTIVE = 1<<0 , INVISIBLE = 1<<1 , OUTPUT = 1<<2 , NOBORDER = 1<<3 ,   FORCE_POSITION = 1<<4 , NON_MODAL = 1<<5 , SHORTCUT_LABEL = 1<<6 , CHANGED = 1<<7 ,   OVERRIDE = 1<<8 , VISIBLE_FOCUS = 1<<9 , COPIED_LABEL = 1<<10 , CLIP_CHILDREN = 1<<11 ,   MENU_WINDOW = 1<<12 , TOOLTIP_WINDOW = 1<<13 , MODAL = 1<<14 , NO_OVERLAY = 1<<15 ,   GROUP_RELATIVE = 1<<16 , COPIED_TOOLTIP = 1<<17 , FULLSCREEN = 1<<18 , MAC_USE_ACCENTS_MENU = 1<<19 ,   NEEDS_KEYBOARD = 1<<20 , IMAGE_BOUND = 1<<21 , DEIMAGE_BOUND = 1<<22 , AUTO_DELETE_USER_DATA = 1<<23 ,   MAXIMIZED = 1<<24 , POPUP = 1<<25 , USERFLAG3 = 1<<29 , USERFLAG2 = 1<<30 ,   USERFLAG1 = 1<<31 }
	flags possible values enumeration. More...

Detailed Description

Buttons generate callbacks when they are clicked by the user.

You control exactly when and how by changing the values for type(uchar) and when(uchar). Buttons can also generate callbacks in response to FL_SHORTCUT events. The button can either have an explicit shortcut(int s) value or a letter shortcut can be indicated in the label() with an '&' character before it. For the label shortcut it does not matter if Alt is held down, but if you have an input field in the same window, the user will have to hold down the Alt key so that the input field does not eat the event first as an FL_KEYBOARD event.

See also

Fl_Widget::shortcut_label(int)

For an Fl_Button object, the type() call returns one of:

• FL_NORMAL_BUTTON (0): value() remains unchanged after button press.
• FL_TOGGLE_BUTTON: value() is inverted after button press.
• FL_RADIO_BUTTON: value() is set to 1 after button press, and all other buttons in the current group with type() == FL_RADIO_BUTTON are set to zero.

For an Fl_Button object, the following when() values are useful, the default being FL_WHEN_RELEASE:

• 0: The callback is not done, instead changed() is turned on.
• FL_WHEN_RELEASE: The callback is done after the user successfully clicks the button, or when a shortcut is typed. The reason is FL_REASON_RELEASED.
• FL_WHEN_CHANGED: The callback is done each time the value() changes (when the user pushes and releases the button, and as the mouse is dragged around in and out of the button). The reason is set to FL_REASON_CHANGED
• FL_WHEN_NOT_CHANGED: The callback is done when the mouse button is released, but the value did not changed. The reason is set to FL_REASON_SELECTED

Constructor & Destructor Documentation

Fl_Button()

Fl_Button::Fl_Button	(	int	X,
		int	Y,
		int	W,
		int	H,
		const char *	L = 0
	)

The constructor creates the button using the given position, size, and label.

The default box type is box(FL_UP_BOX).

You can control how the button is drawn when ON by setting down_box(). The default is FL_NO_BOX (0) which will select an appropriate box type using the normal (OFF) box type by using fl_down(box()).

Derived classes may handle this differently.

A button may request callbacks with when() FL_WHEN_CHANGED, FL_WHEN_NOT_CHANGED, and FL_WHEN_RELEASE, triggering the callback reasons FL_REASON_CHANGED, FL_REASON_SELECTED, and FL_REASON_DESELECTED.

Parameters

[in]	X,Y,W,H	position and size of the widget
[in]	L	widget label, default is no label

Member Function Documentation

clear()

int Fl_Button::clear ( )

inline

Same as value(0).

See also

value(int v)

compact() [1/2]

uchar Fl_Button::compact ( )

inline

Return true if buttons are rendered as compact buttons.

Returns

0 if compact mode is off, 1 if it is on

See also

compact(bool)

compact() [2/2]

void Fl_Button::compact

(

uchar

v

)

Decide if buttons should be rendered in compact mode.

compact button keypad using GTK+ Scheme

compact buttons in Gleam

In compact mode, the button's surrounding border is altered to visually signal that multiple buttons are functionally linked together. To ensure the correct rendering of buttons in compact mode, all buttons must be part of the same group, positioned close to each other, and aligned with the edges of the group. Any button outlines not in contact with the parent group's outline will be displayed as separators.

Parameters

[in]

v

switch compact mode on (1) or off (0)

down_box() [1/2]

Fl_Boxtype Fl_Button::down_box ( ) const

inline

Returns the current down box type, which is drawn when value() is non-zero.

Return values

Fl_Boxtype

down_box() [2/2]

void Fl_Button::down_box ( Fl_Boxtype  b )

inline

Sets the down box type.

The default value of 0 causes FLTK to figure out the correct matching down version of box().

Some derived classes (e.g. Fl_Round_Button and Fl_Light_Button use down_box() for special purposes. See docs of these classes.

Parameters

[in]

b

down box type

draw()

void Fl_Button::draw ( )

protectedvirtual

Draws the widget.

Never call this function directly. FLTK will schedule redrawing whenever needed. If your widget must be redrawn as soon as possible, call redraw() instead.

Override this function to draw your own widgets.

If you ever need to call another widget's draw method from within your own draw() method, e.g. for an embedded scrollbar, you can do it (because draw() is virtual) like this:

Fl_Widget *s = &scrollbar; // scrollbar is an embedded Fl_Scrollbar
s->draw();                 // calls Fl_Scrollbar::draw()

Implements Fl_Widget.

Reimplemented in Fl_Light_Button, Fl_Return_Button, and Fl_Shortcut_Button.

handle()

int Fl_Button::handle ( int  event )

virtual

Handles the specified event.

You normally don't call this method directly, but instead let FLTK do it when the user interacts with the widget.

When implemented in a widget, this function must return 0 if the widget does not use the event or 1 otherwise.

Most of the time, you want to call the inherited handle() method in your overridden method so that you don't short-circuit events that you don't handle. In this last case you should return the callee retval.

One exception to the rule in the previous paragraph is if you really want to override the behavior of the base class. This requires knowledge of the details of the inherited class.

In rare cases you may want to return 1 from your handle() method although you don't really handle the event. The effect would be to filter event processing, for instance if you want to dismiss non-numeric characters (keypresses) in a numeric input widget. You may "ring the bell" or show another visual indication or drop the event silently. In such a case you must not call the handle() method of the base class and tell FLTK that you consumed the event by returning 1 even if you didn't do anything with it.

Parameters

[in]

event

the kind of event received

Return values

0	if the event was not used or understood
1	if the event was used and can be deleted

See also

Fl_Event

Reimplemented from Fl_Widget.

Reimplemented in Fl_Light_Button, Fl_Repeat_Button, Fl_Return_Button, and Fl_Shortcut_Button.

set()

int Fl_Button::set ( )

inline

Same as value(1).

See also

value(int v)

shortcut() [1/2]

int Fl_Button::shortcut ( ) const

inline

Returns the current shortcut key for the button.

Return values

int

shortcut() [2/2]

void Fl_Button::shortcut ( int  s )

inline

Sets the shortcut key to s.

Setting this overrides the use of '&' in the label(). The value is a bitwise OR of a key and a set of shift flags, for example: FL_ALT | 'a', or FL_ALT | (FL_F + 10), or just 'a'. A value of 0 disables the shortcut.

The key can be any value returned by Fl::event_key(), but will usually be an ASCII letter. Use a lower-case letter unless you require the shift key to be held down.

The shift flags can be any set of values accepted by Fl::event_state(). If the bit is on, that shift key must be pushed. Meta, Alt, Ctrl, and Shift must be off if they are not in the shift flags (zero for the other bits indicates a "don't care" setting).

Parameters

[in]

s

bitwise OR of key and shift flags

value()

int Fl_Button::value

(

int

v

)

Sets the current value of the button.

A non-zero value sets the button to 1 (ON), and zero sets it to 0 (OFF).

Parameters

[in]

v

button value.

See also

set(), clear()

---

The documentation for this class was generated from the following files:

• Fl_Button.H
• Fl_Button.cxx