FLTK 1.4.0: Fl_Scroll Class Reference

This container widget lets you maneuver around a set of widgets much larger than your window. More...

#include <Fl_Scroll.H>

Inheritance diagram for Fl_Scroll:

Classes
struct	Fl_Region_LRTB
	A local struct to manage a region defined by left/right/top/bottom. More...

struct	Fl_Region_XYWH
	A local struct to manage a region defined by xywh. More...

struct	Fl_Scrollbar_Data
	A local struct to manage a scrollbar's xywh region and tab values. More...

struct	ScrollInfo
	Structure to manage scrollbar and widget interior sizes. More...

Public Types
enum	{ HORIZONTAL = 1 , VERTICAL = 2 , BOTH = 3 , ALWAYS_ON = 4 , HORIZONTAL_ALWAYS = 5 , VERTICAL_ALWAYS = 6 , BOTH_ALWAYS = 7 }

Public Member Functions
void	clear ()
	Clear all but the scrollbars...

int	delete_child (int n) FL_OVERRIDE
	Removes the widget at `index` from the group and deletes it. More...

	Fl_Scroll (int X, int Y, int W, int H, const char *L=0)
	Creates a new Fl_Scroll widget using the given position, size, and label string. More...

int	handle (int) FL_OVERRIDE
	Handles the specified event. More...

void	resize (int X, int Y, int W, int H) FL_OVERRIDE
	Resizes the Fl_Scroll widget and moves its children if necessary. More...

void	scroll_to (int, int)
	Moves the contents of the scroll group to a new position. More...

int	scrollbar_size () const
	Gets the current size of the scrollbars' troughs, in pixels. More...

void	scrollbar_size (int newSize)
	Sets the pixel size of the scrollbars' troughs to `newSize`, in pixels. More...

int	xposition () const
	Gets the current horizontal scrolling position. More...

int	yposition () const
	Gets the current vertical scrolling position. More...

virtual	~Fl_Scroll ()
	The destructor also deletes all the children. More...

Public Member Functions inherited from Fl_Group
Fl_Widget *&	_ddfdesign_kludge ()
	This is for forms compatibility only.

void	add (Fl_Widget &)
	The widget is removed from its current group (if any) and then added to the end of this group.

void	add (Fl_Widget *o)
	See void Fl_Group::add(Fl_Widget &w)

void	add_resizable (Fl_Widget &o)
	Adds a widget to the group and makes it the resizable widget.

Fl_Widget const	array () const
	Returns a pointer to the array of children. More...

Fl_Group const *	as_group () const FL_OVERRIDE

Fl_Group *	as_group () FL_OVERRIDE
	Returns an Fl_Group pointer if this widget is an Fl_Group. More...

void	begin ()
	Sets the current group so you can build the widget tree by just constructing the widgets. More...

Fl_Widget *	child (int n) const
	Returns array()[n]. More...

int	children () const
	Returns how many child widgets the group has.

void	clear ()
	Deletes all child widgets from memory recursively. More...

unsigned int	clip_children ()
	Returns the current clipping mode. More...

void	clip_children (int c)
	Controls whether the group widget clips the drawing of child widgets to its bounding box. More...

virtual int	delete_child (int n)
	Removes the widget at `index` from the group and deletes it. More...

void	end ()
	Exactly the same as current(this->parent()). More...

int	find (const Fl_Widget &o) const
	See int Fl_Group::find(const Fl_Widget *w) const.

int	find (const Fl_Widget *) const
	Searches the child array for the widget and returns the index. More...

	Fl_Group (int, int, int, int, const char *=0)
	Creates a new Fl_Group widget using the given position, size, and label string. More...

void	focus (Fl_Widget *W)

void	forms_end ()
	This is for forms compatibility only.

int	handle (int) FL_OVERRIDE
	Handles the specified event. More...

void	init_sizes ()
	Resets the internal array of widget sizes and positions. More...

void	insert (Fl_Widget &, int i)
	The widget is removed from its current group (if any) and then inserted into this group. More...

void	insert (Fl_Widget &o, Fl_Widget *before)
	This does insert(w, find(before)). More...

void	remove (Fl_Widget &)
	Removes a widget from the group but does not delete it. More...

void	remove (Fl_Widget *o)
	Removes the widget `o` from the group. More...

void	remove (int index)
	Removes the widget at `index` from the group but does not delete it. More...

Fl_Widget *	resizable () const
	Returns the group's resizable widget. More...

void	resizable (Fl_Widget &o)
	Sets the group's resizable widget. More...

void	resizable (Fl_Widget *o)
	The resizable widget defines both the resizing box and the resizing behavior of the group and its children. More...

void	resize (int, int, int, int) FL_OVERRIDE
	Resizes the Fl_Group widget and all of its children. More...

virtual	~Fl_Group ()
	The destructor also deletes all the children. 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...

Public Attributes
Fl_Scrollbar	hscrollbar

Fl_Scrollbar	scrollbar

Protected Member Functions
void	bbox (int &, int &, int &, int &) const
	Returns the bounding box for the interior of the scrolling area, inside the scrollbars. More...

void	draw () FL_OVERRIDE
	Draws the widget. More...

void	fix_scrollbar_order ()
	Ensure the scrollbars are the last children. More...

int	on_insert (Fl_Widget *, int) FL_OVERRIDE
	Change insert position of a child before it is added. More...

int	on_move (int, int) FL_OVERRIDE
	Change new position of a child before it is moved. More...

void	recalc_scrollbars (ScrollInfo &si) const
	Calculate visibility/size/position of scrollbars, find children's bounding box. More...

Protected Member Functions inherited from Fl_Group
Fl_Rect *	bounds ()
	Returns the internal array of widget sizes and positions. More...

void	draw () FL_OVERRIDE
	Draws the widget. More...

void	draw_child (Fl_Widget &widget) const
	Forces a child to redraw. More...

void	draw_children ()
	Draws all children of the group. More...

void	draw_outside_label (const Fl_Widget &widget) const
	Parents normally call this to draw outside labels of child widgets.

virtual int	on_insert (Fl_Widget *, int)
	Allow derived groups to act when a widget is added as a child. More...

virtual int	on_move (int, int)
	Allow derived groups to act when a widget is moved within the group. More...

virtual void	on_remove (int)
	Allow derived groups to act when a child widget is removed from the group. More...

int *	sizes ()
	Returns the internal array of widget sizes and positions. More...

void	update_child (Fl_Widget &widget) const
	Draws a child only if it needs it. More...

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...

Additional Inherited Members
Static Public Member Functions inherited from Fl_Group
static Fl_Group *	current ()
	Returns the currently active group. More...

static void	current (Fl_Group *g)
	Sets the current group. More...

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

This container widget lets you maneuver around a set of widgets much larger than your window.

If the child widgets are larger than the size of this object then scrollbars will appear so that you can scroll over to them:

If all of the child widgets are packed together into a solid rectangle then you want to set box() to FL_NO_BOX or one of the _FRAME types. This will result in the best output. However, if the child widgets are a sparse arrangement you must set box() to a real _BOX type. This can result in some blinking during redrawing, but that can be solved by using a Fl_Double_Window.

The Fl_Scroll widget calculates the bounding box of all its children by using their widget positions and sizes (x, y, w, h). Outside labels are not considered. If you need outside labels of any widgets or free space outside of this bounding box you can add a tiny invisible Fl_Box at the relevant corner(s) of the Fl_Scroll widget, for instance:

Fl_Scroll scroll(100, 100, 200, 200); // Fl_Scroll at (100, 100)
Fl_Box(100, 100, 1, 1);               // Fl_Box in top left corner
Fl_Input(150, 120, 60, 30, "Input:"); // left most widget with label
// ... more widgets ...
scroll.end();

By default you can scroll in both directions, and the scrollbars disappear if the data will fit in the area of the scroll.

Use Fl_Scroll::type() to change this as follows :

0 - No scrollbars
Fl_Scroll::HORIZONTAL - Only a horizontal scrollbar.
Fl_Scroll::VERTICAL - Only a vertical scrollbar.
Fl_Scroll::BOTH - The default is both scrollbars.
Fl_Scroll::HORIZONTAL_ALWAYS - Horizontal scrollbar always on, vertical always off.
Fl_Scroll::VERTICAL_ALWAYS - Vertical scrollbar always on, horizontal always off.
Fl_Scroll::BOTH_ALWAYS - Both always on.

Use scrollbar.align(int) ( see void Fl_Widget::align(Fl_Align) ) : to change what side the scrollbars are drawn on.

If the FL_ALIGN_LEFT bit is on, the vertical scrollbar is on the left. If the FL_ALIGN_TOP bit is on, the horizontal scrollbar is on the top. Note that only the alignment flags in scrollbar are considered. The flags in hscrollbar however are ignored.

This widget can also be used to pan around a single child widget "canvas". This child widget should be of your own class, with a draw() method that draws the contents. The scrolling is done by changing the x() and y() of the widget, so this child must use the x() and y() to position its drawing. To speed up drawing it should test fl_not_clipped(int x,int y,int w,int h) to find out if a particular area of the widget must be drawn.

Another very useful child is a single Fl_Pack, which is itself a group that packs its children together and changes size to surround them. Filling the Fl_Pack with Fl_Tabs groups (and then putting normal widgets inside those) gives you a very powerful scrolling list of individually-openable panels.

Fluid lets you create these, but you can only lay out objects that fit inside the Fl_Scroll without scrolling. Be sure to leave space for the scrollbars, as Fluid won't show these either.

You cannot use Fl_Window as a child of this since the clipping is not conveyed to it when drawn, and it will draw over the scrollbars and neighboring objects.

Constructor & Destructor Documentation

◆ Fl_Scroll()

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

Creates a new Fl_Scroll widget using the given position, size, and label string.

The default boxtype is FL_NO_BOX.

The destructor also deletes all the children. This allows a whole tree to be deleted at once, without having to keep a pointer to all the children in the user code. A kludge has been done so the Fl_Scroll and all of its children can be automatic (local) variables, but you must declare the Fl_Scroll first, so that it is destroyed last.

◆ ~Fl_Scroll()

Fl_Scroll::~Fl_Scroll ( )

virtual

The destructor also deletes all the children.

See also: Fl_Group::~Fl_Group()

Member Function Documentation

◆ bbox()

void Fl_Scroll::bbox	(	int &	X,
		int &	Y,
		int &	W,
		int &	H
	)		const

protected

Returns the bounding box for the interior of the scrolling area, inside the scrollbars.

This method does not change the scrollbars or their visibility. First the scrollbar positions and visibility are calculated as they should be, according to the positions and sizes of the children. Then the bounding box is calculated.

You may need to call redraw() to make sure the widget gets updated.

See also: recalc_scrollbars()

◆ delete_child()

int Fl_Scroll::delete_child ( int index )

virtual

Removes the widget at index from the group and deletes it.

This method does nothing if index is out of bounds or if Fl_Group::child(index) is one of the scrollbars.

Parameters

[in] index index of child to be removed

Returns: success (0) or error code

Return values

0	success
1	index out of range
2	widget not allowed to be removed (see note)

See also: Fl_Group::delete_child(int index)

Since: FLTK 1.4.0

Reimplemented from Fl_Group.

◆ draw()

void Fl_Scroll::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()

Fl_Widget

Fl_Widget is the base class for all widgets in FLTK.

Definition: Fl_Widget.H:110

Reimplemented from Fl_Group.

◆ fix_scrollbar_order()

void Fl_Scroll::fix_scrollbar_order ( )

protected

Ensure the scrollbars are the last children.

When Fl_Scroll is instantiated the first child of the Fl_Group is the vertical scrollbar scrollbar and the second child is the horizontal scrollbar hscrollbar.

These two widgets must always be the last two widgets and in this order to guarantee the correct drawing order and event delivery.

Since FLTK 1.4.0 the new method on_insert() modifies the insert position of other children if it would be after the scrollbars.

◆ handle()

int Fl_Scroll::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_Group.

◆ on_insert()

int Fl_Scroll::on_insert	(	Fl_Widget *	candidate,
		int	index
	)

protectedvirtual

Change insert position of a child before it is added.

Fix insert position if the new child is planned to be inserted after the scrollbars. We can assume that the scrollbars are always the last two children!

Fl_Group calls this when a new widget is added. We return the new index if the new widget would be added after the scrollbars.

Parameters

[in]	candidate	the candidate will be added to the child array_ after this method returns.
[in]	index	add the child at this position in the array_

Returns: index to position the child as planned; a new index to force the child to a different position; -1 to keep the group from adding the candidate

Version: 1.4.0

See also: Fl_Group::on_insert(Fl_Widget *candidate, int index)

Reimplemented from Fl_Group.

◆ on_move()

int Fl_Scroll::on_move	(	int	old_index,
		int	new_index
	)

protectedvirtual

Change new position of a child before it is moved.

Fix new position if the new child is planned to be moved after the scrollbars. We can assume that the scrollbars are always the last two children!

Fl_Group calls this when a widget is moved within the list of children. We return a new index if the widget would be moved after the scrollbars.

Parameters

old_index	the current index of the child that will be moved
new_index	the new index of the child

Returns: new index, possibly corrected to avoid last two scrollbar entries

Reimplemented from Fl_Group.

◆ recalc_scrollbars()

void Fl_Scroll::recalc_scrollbars ( ScrollInfo & si ) const

protected

Calculate visibility/size/position of scrollbars, find children's bounding box.

The si parameter will be filled with data from the calculations. Derived classes can make use of this call to figure out the scrolling area eg. during resize() handling.

This method does not change the scrollbars or their visibility. It calculates the scrollbar positions and visibility as they should be, according to the positions and sizes of the children.

You may need to call redraw() to make sure the widget gets updated.

Parameters

[in,out] si – ScrollInfo structure, filled with data

See also: bbox()

◆ resize()

void Fl_Scroll::resize	(	int	X,
		int	Y,
		int	W,
		int	H
	)

virtual

Resizes the Fl_Scroll widget and moves its children if necessary.

The Fl_Scroll widget first resizes itself, and then it moves all its children if (and only if) the Fl_Scroll widget has been moved. The children are moved by the same amount as the Fl_Scroll widget has been moved, hence all children keep their relative positions.

Note: Fl_Scroll::resize() does not call Fl_Group::resize(), and child widgets are not resized.

Since children of an Fl_Scroll are not resized, the resizable() widget is ignored (if it is set).

The scrollbars are moved to their proper positions, as given by Fl_Scroll::scrollbar.align(), and switched on or off as necessary.

Note: Due to current (FLTK 1.3.x) implementation constraints some of this may effectively be postponed until the Fl_Scroll is drawn the next time. This may change in a future release.

See also: Fl_Group::resizable(); Fl_Widget::resize(int,int,int,int)

Reimplemented from Fl_Group.

◆ scroll_to()

void Fl_Scroll::scroll_to	(	int	X,
		int	Y
	)

Moves the contents of the scroll group to a new position.

This is like moving the scrollbars of the Fl_Scroll around. For instance:

Fl_Scroll scroll (10,10,200,200);
Fl_Box b1 ( 10, 10,50,50,"b1"); // relative (x,y) = (0,0)
Fl_Box b2 ( 60, 60,50,50,"b2"); // relative (x,y) = (50,50)
Fl_Box b3 ( 60,110,50,50,"b3"); // relative (x,y) = (50,100)
// populate scroll with more children ...
scroll.end();
scroll.scroll_to(50,100);

will move the logical origin of the internal scroll area to (-50,-100) relative to the origin of the Fl_Scroll (10,10), i.e. Fl_Box b3 will be visible in the top left corner of the scroll area.

◆ scrollbar_size() [1/2]

int Fl_Scroll::scrollbar_size ( ) const

inline

Gets the current size of the scrollbars' troughs, in pixels.

If this value is zero (default), this widget will use the Fl::scrollbar_size() value as the scrollbar's width.

Returns: Scrollbar size in pixels, or 0 if the global Fl::scrollbar_size() is being used.

See also: Fl::scrollbar_size(int)

◆ scrollbar_size() [2/2]

void Fl_Scroll::scrollbar_size ( int newSize )

inline

Sets the pixel size of the scrollbars' troughs to newSize, in pixels.

Normally you should not need this method, and should use Fl::scrollbar_size(int) instead to manage the size of ALL your widgets' scrollbars. This ensures your application has a consistent UI, is the default behavior, and is normally what you want.

Only use THIS method if you really need to override the global scrollbar size. The need for this should be rare.

Setting newSize to the special value of 0 causes the widget to track the global Fl::scrollbar_size(), which is the default.

Parameters

[in] newSize Sets the scrollbar size in pixels.
If 0 (default), scrollbar size tracks the global Fl::scrollbar_size()

See also: Fl::scrollbar_size()

◆ xposition()

int Fl_Scroll::xposition ( ) const

inline

Gets the current horizontal scrolling position.

◆ yposition()

int Fl_Scroll::yposition ( ) const

inline

Gets the current vertical scrolling position.

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

Fl_Scroll.H
Fl_Scroll.cxx

Classes

Public Types

Public Member Functions

Public Attributes

Protected Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ Fl_Scroll()

◆ ~Fl_Scroll()

Member Function Documentation

◆ bbox()

◆ delete_child()

◆ draw()

◆ fix_scrollbar_order()

◆ handle()

◆ on_insert()

◆ on_move()

◆ recalc_scrollbars()

◆ resize()

◆ scroll_to()

◆ scrollbar_size() [1/2]

◆ scrollbar_size() [2/2]

◆ xposition()

◆ yposition()