Group Class Reference

Inherits Widget.

Inherited by AlignGroup, BarGroup, ColorChooser, HelpView, Menu, PackedGroup, ScrollGroup, StatusBarGroup, TabGroup, TextDisplay, TiledGroup, Window, and WizardGroup.

List of all members.

Public Member Functions
int	children () const
Widget *	child (int n) const
void	draw ()
void	layout ()
int	handle (int)
void	begin ()
void	end ()
int	find (const Widget *) const
int	find (const Widget &o) const
	Group (int, int, int, int, const char *=0, bool begin=false)
virtual	~Group ()
void	add (Widget &)
void	add (Widget *o)
void	insert (Widget &, int index)
void	insert (Widget &o, Widget *before)
void	remove (int index)
void	remove (Widget &o)
void	remove (Widget *o)
void	remove_all ()
void	replace (int index, Widget &)
void	replace (Widget &old, Widget &o)
void	swap (int indexA, int indexB)
void	clear ()
void	resizable (Widget &o)
void	resizable (Widget *o)
Widget *	resizable () const
void	add_resizable (Widget &o)
void	init_sizes ()
bool	resize (int, int, int, int)
bool	resize (int w, int h)
void	focus_index (int v)
void	set_focus (Widget *w)
int	focus_index () const
void	fix_old_positions ()
Flags	resize_align () const
void	resize_align (Flags f)
Static Public Member Functions
Group *	current ()
void	current (Group *g)
int	navigation_key ()
Protected Member Functions
void	draw_child (Widget &) const
void	update_child (Widget &) const
void	draw_outside_label (Widget &) const
int *	sizes ()
void	layout (const Rectangle &, int layout_damage)
Friends
void	end_group ()

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Detailed Description

The Group class is the FLTK container widget. It maintains an array of child widgets. These children can themselves be any widget including Group, nesting groups allows much more control over layout and resize behavior. Nested groups are also necessary to group radio buttons together.

By default Group preserves the positions and sizes of all it's children, they do not move no matter what sizes or other children are added or removed.

Setting resizable() will change the layout behavior so that it responds to resizing by moving or resizing the children to fit. See below for details.

You may want to use an Pack or a Scroll to get other common layout behavior that can respond to changes in the sizes of child widgets.

The most-used subclass of Group is Window, all the rules about resizing apply to windows. Setting resizable() on a window will allow the user to resize it. If you want different behavior (such as from Pack) for your window you should make the window have that as a single resizable child that fills it.

Menu is a subclass and thus all menus and browsers are groups and the items in them are widgets.

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Constructor & Destructor Documentation

Group::Group (  int  X, int  Y, int  W, int  H, const char *  l = 0, bool  begin = false )

Creates a new Group widget using the given position, size, and label string. The default boxtype is NO_BOX.

Group::~Group (   )  [virtual]

Calls clear(), and thus deletes all child widgets

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Member Function Documentation

void Group::add (  Widget &  o  )

The widget is removed from it's current group (if any) and then added to the end of this group.

void Group::begin (   )  [inline]

begin() sets the current group so you can build the widget tree by just constructing the widgets. begin() is exactly the same as current(this). Don't forget to end() the group or window!

Widget * Group::child (  int  n  )  const [inline]

Returns a child, n >= 0 && n < children(). No range checking is done! Reimplemented in Menu.

int Group::children (   )  const [inline]

Returns how many child widgets the group has. Reimplemented in Menu.

void Group::clear (   )

Deletes all children from the group and makes it empty. This calls the destructor on all the children!!! Reimplemented from Widget.

Group * Group::current (   )  [inline, static]

Returns the group being currently built. The Widget constructor automatically does current()->add(widget) if this is not null. To prevent new widgets from being added to a group, call Group::current(0).

void Group::draw_child (  Widget &  w  )  const [protected]

Force a child to draw, by turning on DAMAGE_ALL and DAMAGE_EXPOSE, and calling it's draw() after temporarily translating so 0,0 in drawing coordinates is the upper-left corner. It's damage is then set to 0.

void Group::draw_outside_label (  Widget &  w  )  const [protected]

Groups normally call this to draw the label() outside a widget. This uses the flags() to determine where to put the label. If the ALIGN flags are all zero, or if ALIGN_INSIDE is turned on, then nothing is done. Otherwise the align is used to select a rectangle outside the widget and the widget's label() is formatted into that area. The font is set to labelfont()/labelsize(), and labelcolor() is used to color the text. The flags are passed to the draw() function, but with the alignment changed to put the text against the widget, and INACTIVE is added if active_r() is false. The image() of the widget is not drawn by this. It is always drawn inside the widget.

void Group::end (   )  [inline]

end() is exactly the same as current(this->parent()). Any new widgets added to the widget tree will be added to the parent of the group.

int Group::find (  const Widget *  widget  )  const

Searches the children for widget, returns the index of widget or of a parent of widget that is a child() of this. Returns children() if the widget is NULL or not found.

void Group::fix_old_positions (   )

If this is a Group and not a Window, subtract x() and y() from the position of all children. This will fix the positions of widgets created for fltk1.1 that are inside a group.

int Group::focus_index (   )  const [inline]

The index of the widget that contains the focus. You can initialize this before the group is displayed. Changing it while it is displayed does not work, use widget->take_focus() instead. For some subclasses such as TabGroup, a negative number indicates that the group itself has the focus. In most cases any illegal value means it will search for any widget that accepts focus. This is also used by Menu to locate the item selected by the user. See Menu::get_item(). Reimplemented in Browser.

int Group::handle (  int  event  )  [virtual]

Calls send() on some or all of the children widgets. Reimplemented from Widget. Reimplemented in ItemGroup.

void Group::init_sizes (   )

Indicate that all the remembered child sizes should be reinitialized. The group remembers the initial size of itself and all it's children, so that the layout can be restored even if the group is resized so that some children go to zero or negative sizes. Normally these sizes are calculated the first time layout() is called, though you can do so by calling sizes() directly. Though this makes sense it often results in unexpected behavior when a program wants to rearrange the child widgets or change the size of a group to surround a new arrangement of child widgets. The widgets tend to snap back to a previous size. Calling init_sizes() "resets" the sizes array to the current group and children positions. Actually it just deletes the sizes array, and it is not recreated until the next time layout is called. Call this if you manually adjust the sizes of the children, or attempt to change the size of the group without wanting the children to scale. This is automatically done when any child is added or removed.

void Group::insert (  Widget &  o, int  index )

This does insert(w, find(beforethis)). This will append the widget if beforethis is not in the group.

void Group::layout (  const Rectangle &  r, int  layout_damage )  [protected]

Inner implementation of layout(). The child widgets are resized and positioned so that the area that was initially surrounded by this widget now fits inside the rectangle. r is a rectangle, in the coordinate system of this Group (ie 0,0 is the top-left corner of the Group). layout_damage controls what is done. If LAYOUT_W or LAYOUT_H are off then no resizing or moving of widgets in that direction is done. This is used by ScrollGroup to resize the widgets to fit inside the scrollbars.

int Group::navigation_key (   )  [static]

Turn Tab into Right or Left for keyboard navigation

void Group::remove (  Widget &  widget  )  [inline]

Removes a widget from the group. This does nothing if the widget is not currently a child of this group.

void Group::remove (  int  index  )

Remove the indexed widget from the group.

void Group::remove_all (   )

Removes all widgets from the group. This does not call the destructor on the child widget (see clear()).

void Group::replace (  Widget &  old, Widget &  nu )  [inline]

Find the old widget and remove it and insert the nu one. If old is not a child, the new widget is appended to the end of the list.

void Group::replace (  int  index, Widget &  o )

Remove the indexed widget and insert the passed widget in it's place.

Widget * Group::resizable (   )  const [inline]

The resizable widget defines the resizing box for the group. When the group is resized it calculates a new size and position for all of its children. Widgets that are horizontally or vertically inside the dimensions of the box are scaled to the new size. Widgets outside the box are moved. Orignal size, the gray area is the resizable(): And here is the same Group resized larger: The resizable may be set to the group itself, in which case all the contents are resized. If the resizable is NULL (the default) then all widgets remain a fixed size and distance from the top-left corner. It is possible to achieve any type of resize behavior by using an InvisibleBox as the resizable and/or by using a hierarchy of child Group's.

bool Group::resize (  int  x, int  y, int  w, int  h )

This non-virtual override is for programs that set up a group's layout and then call resize() on it to set the correct size before it is displayed. What it does is remember the current sizes (the thing the init_sizes() method makes it forget) before calling the normal widget resize(). This is a non-virtual override because in normal use fltk will call layout() anyway before any use of the widget, and Group's layout() initializes the sizes. This is only for programs that use resize() directly. Reimplemented from Widget.

int * Group::sizes (   )  [protected]

Returns array of initial sizes of the widget and it's children. The sizes() array stores the initial positions of widgets as left,right,top,bottom quads. The first quad is the group, the second is the resizable (clipped to the group), and the rest are the children. This is a convienent order for the algorithim. This array is not calculated until the first time sizes() is called. It then returns the same array from then on. Calling init_sizes() deletes the array so the next call of this creates a new one.

void Group::update_child (  Widget &  w  )  const [protected]

If the child's damage() is not zero, force it to update calling it's draw() after temporarily translating so 0,0 in drawing coordinates is the upper-left corner. It's damage is then set to 0.

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

• fltk/Group.h
• src/Group.cxx
• src/Widget_draw.cxx

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