Fl_Tabs Class Reference

The Fl_Tabs widget is the "file card tabs" interface that allows you to put lots and lots of buttons and switches in a panel, as popularized by many toolkits. More...

#include <Fl_Tabs.H>

Inheritance diagram for Fl_Tabs:
Fl_Group Fl_Widget

List of all members.

Public Member Functions

void client_area (int &rx, int &ry, int &rw, int &rh, int tabh=0)
 Returns the position and size available to be used by its children.
 Fl_Tabs (int, int, int, int, const char *=0)
 Creates a new Fl_Tabs widget using the given position, size, and label string.
int handle (int)
 Handles the specified event.
int push (Fl_Widget *)
 This is called by the tab widget's handle() method to set the tab group widget the user last FL_PUSH'ed on.
Fl_Widgetpush () const
 Returns the tab group for the tab the user has currently down-clicked on and remains over until FL_RELEASE.
int value (Fl_Widget *)
 Sets the widget to become the current visible widget/tab.
Fl_Widgetvalue ()
 Gets the currently visible widget/tab.
Fl_Widgetwhich (int event_x, int event_y)
 Return the widget of the tab the user clicked on at event_x / event_y.

Protected Member Functions

void draw ()
 Draws the widget.
void redraw_tabs ()

Detailed Description

The Fl_Tabs widget is the "file card tabs" interface that allows you to put lots and lots of buttons and switches in a panel, as popularized by many toolkits.

tabs.png

Clicking the tab makes a child visible() by calling show() on it, and all other children are made invisible by calling hide() on them. Usually the children are Fl_Group widgets containing several widgets themselves.

Each child makes a card, and its label() is printed on the card tab, including the label font and style. The selection color of that child is used to color the tab, while the color of the child determines the background color of the pane.

The size of the tabs is controlled by the bounding box of the children (there should be some space between the children and the edge of the Fl_Tabs), and the tabs may be placed "inverted" on the bottom - this is determined by which gap is larger. It is easiest to lay this out in fluid, using the fluid browser to select each child group and resize them until the tabs look the way you want them to.

The background area behind and to the right of the tabs is "transparent", exposing the background detail of the parent. The value of Fl_Tabs::box() does not affect this area. So if Fl_Tabs is resized by itself without the parent, force the appropriate parent (visible behind the tabs) to redraw() to prevent artifacts.

See "Resizing Caveats" below on how to keep tab heights constant. See "Callback's Use Of when()" on how to control the details of how clicks invoke the callback().

A typical use of the Fl_Tabs widget:

      // Typical use of Fl_Tabs
      Fl_Tabs *tabs = new Fl_Tabs(10,10,300,200);
      {
          Fl_Group *grp1 = new Fl_Group(20,30,280,170,"Tab1");
          {
              ..widgets that go in tab#1..
          }
          grp1->end();
          Fl_Group *grp2 = new Fl_Group(20,30,280,170,"Tab2");
          {
              ..widgets that go in tab#2..
          }
          grp2->end();
      }
      tabs->end();

Default Appearance

The appearance of each "tab" is taken from the label() and color() of the child group corresponding to that "tab" and panel. Where the "tabs" appear depends on the position and size of the child groups that make up the panels within the Fl_Tab, i.e. whether there is more space above or below them. The height of the "tabs" depends on how much free space is available.

tabs_default.png

Fl_Tabs Default Appearance

Highlighting The Selected Tab

The selected "tab" can be highlighted further by setting the selection_color() of the Fl_Tab itself, e.g.

  ..
  tabs = new Fl_Tabs(..);
  tabs->selection_color(FL_DARK3);
  ..

The result of the above looks like:

tabs_selection.png

Highlighting the selected tab

Uniform Tab and Panel Appearance

In order to have uniform tab and panel appearance, not only must the color() and selection_color() for each child group be set, but also the selection_color() of the Fl_Tab itself any time a new "tab" is selected. This can be achieved within the Fl_Tab callback, e.g.

  void MyTabCallback(Fl_Widget *w, void*) {
    Fl_Tabs *tabs = (Fl_Tabs*)w;
    // When tab changed, make sure it has same color as its group
    tabs->selection_color( (tab->value())->color() );
  }
  ..
  int main(..) {
    // Define tabs widget
    tabs = new Fl_Tabs(..);
    tabs->callback(MyTabCallback);

    // Create three tabs each colored differently
    grp1 = new Fl_Group(.. "One");
     grp1->color(9);
     grp1->selection_color(9);
    grp1->end();

    grp2 = new Fl_Group(.. "Two");
     grp2->color(10);
     grp2->selection_color(10);
    grp2->end();

    grp3 = new Fl_Group(.. "Three");
     grp3->color(14);
     grp3->selection_color(14);
    grp3->end();
    ..
    // Make sure default tab has same color as its group
    tabs->selection_color( (tab->value())->color() );
    ..
    return Fl::run();
  }

The result of the above looks like:

tabs_uniform.png

Fl_Tabs with uniform colors

Resizing Caveats

When Fl_Tabs is resized vertically, the default behavior scales the tab's height as well as its children. To keep the tab height constant during resizing, set the tab widget's resizable() to one of the tab's child groups, i.e.

    tabs = new Fl_Tabs(..);
    grp1 = new Fl_Group(..);
    ..
    grp2 = new Fl_Group(..);
    ..
    tabs->end();
    tabs->resizable(grp1);      // keeps tab height constant
Callback's Use Of when()

As of FLTK 1.3.3, Fl_Tabs() supports the following flags for when():

Notes:

  1. The above flags can be logically OR-ed (|) or added (+) to combine behaviors.
  2. The default value for when() is FL_WHEN_RELEASE (inherited from Fl_Widget).
  3. If FL_WHEN_RELEASE is the only flag specified, the behavior will be as if (FL_WHEN_RELEASE|FL_WHEN_CHANGED) was specified.
  4. The value of changed() will be valid during the callback.
  5. If both FL_WHEN_CHANGED and FL_WHEN_NOT_CHANGED are specified, the callback is invoked whether the tab has been changed or not. The changed() method can be used to determine the cause.
  6. FL_WHEN_NOT_CHANGED can happen if someone clicks on an already selected tab, or if a keyboard navigation attempt results in no change to the tabs, such as using the arrow keys while at the left or right end of the tabs.

Constructor & Destructor Documentation

Fl_Tabs::Fl_Tabs ( int  X,
int  Y,
int  W,
int  H,
const char *  l = 0 
)

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

The default boxtype is FL_THIN_UP_BOX.

Use add(Fl_Widget*) to add each child, which are usually Fl_Group widgets. The children should be sized to stay away from the top or bottom edge of the Fl_Tabs widget, which is where the tabs will be drawn.

All children of Fl_Tabs should have the same size and exactly fit on top of each other. They should only leave space above or below where the tabs will go, but not on the sides. If the first child of Fl_Tabs is set to "resizable()", the riders will not resize when the tabs are resized.

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_Tabs and all of its children can be automatic (local) variables, but you must declare the Fl_Tabs widget first so that it is destroyed last.


Member Function Documentation

void Fl_Tabs::client_area ( int &  rx,
int &  ry,
int &  rw,
int &  rh,
int  tabh = 0 
)

Returns the position and size available to be used by its children.

If there isn't any child yet the tabh parameter will be used to calculate the return values. This assumes that the children's labelsize is the same as the Fl_Tabs' labelsize and adds a small border.

If there are already children, the values of child(0) are returned, and tabh is ignored.

Note:
Children should always use the same positions and sizes.

tabh can be one of

  • 0: calculate label size, tabs on top
  • -1: calculate label size, tabs on bottom
  • > 0: use given tabh value, tabs on top (height = tabh)
  • < -1: use given tabh value, tabs on bottom (height = -tabh)
Parameters:
[in] tabh position and optional height of tabs (see above)
[out] rx,ry,rw,rh (x,y,w,h) of client area for children
Since:
FLTK 1.3.0
void Fl_Tabs::draw (  )  [protected, virtual]

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

Reimplemented from Fl_Group.

int Fl_Tabs::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.

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.

int Fl_Tabs::push ( Fl_Widget o  ) 

This is called by the tab widget's handle() method to set the tab group widget the user last FL_PUSH'ed on.

Set back to zero on FL_RELEASE.

As of this writing, the value is mainly used by draw_tab() to determine whether or not to draw a 'down' box for the tab when it's clicked, and to turn it off if the user drags off it.

See also:
push().
Fl_Widget* Fl_Tabs::push (  )  const [inline]

Returns the tab group for the tab the user has currently down-clicked on and remains over until FL_RELEASE.

Otherwise, returns NULL.

While the user is down-clicked on a tab, the return value is the tab group for that tab. But as soon as the user releases, or drags off the tab with the button still down, the return value will be NULL.

See also:
push(Fl_Widget*).
int Fl_Tabs::value ( Fl_Widget newvalue  ) 

Sets the widget to become the current visible widget/tab.

Setting the value hides all other children, and makes this one visible, if it is really a child.

Returns:
1 if there was a change (new value different from previous),
0 if there was no change (new value already set)
Fl_Widget * Fl_Tabs::value (  ) 

Gets the currently visible widget/tab.

The value() is the first visible child (or the last child if none are visible) and this also hides any other children. This allows the tabs to be deleted, moved to other groups, and show()/hide() called without it screwing up.

Fl_Widget * Fl_Tabs::which ( int  event_x,
int  event_y 
)

Return the widget of the tab the user clicked on at event_x / event_y.

This is used for event handling (clicks) and by fluid to pick tabs.

Returns:
The child widget of the tab the user clicked on, or
0 if there are no children or if the event is outside of the tabs area.

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