fltk/FL/Fl_Button.H

//
// Button header file for the Fast Light Tool Kit (FLTK).
//
// Copyright 1998-2014 by Bill Spitzak and others.
//
// This library is free software. Distribution and use rights are outlined in
// the file "COPYING" which should have been included with this file. If this
// file is missing or damaged, see the license at:
//
//     https://www.fltk.org/COPYING.php
//
// Please see the following page on how to report bugs and issues:
//
//     https://www.fltk.org/bugs.php
//

/* \file
   Fl_Button widget . */

#ifndef Fl_Button_H
#define Fl_Button_H

#ifndef Fl_Widget_H
#include "Fl_Widget.H"
#endif

// values for type()
#define FL_NORMAL_BUTTON        0   /**< value() will be set to 1 during the press of the button and
                                         reverts back to 0 when the button is released */
#define FL_TOGGLE_BUTTON        1   ///< value() toggles between 0 and 1 at every click of the button
#define FL_RADIO_BUTTON         (FL_RESERVED_TYPE+2) /**< is set to 1 at button press, and all other
                                         buttons in the same group with <tt>type() == FL_RADIO_BUTTON</tt>
                                         are set to zero.*/
#define FL_HIDDEN_BUTTON        3   ///< for Forms compatibility

extern FL_EXPORT Fl_Shortcut fl_old_shortcut(const char*);

class Fl_Widget_Tracker;

/**
  \class Fl_Button
  \brief 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 \c 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 \e Alt is held
  down, but if you have an input field in the same window, the user will have
  to hold down the \e Alt key so that the input field does not eat the event
  first as an \c FL_KEYBOARD event.
  \see Fl_Widget::shortcut_label(int)

  For an Fl_Button object, the type() call returns one of:
  \li \c FL_NORMAL_BUTTON (0): value() remains unchanged after button press.
  \li \c FL_TOGGLE_BUTTON: value() is inverted after button press.
  \li \c FL_RADIO_BUTTON: value() is set to 1 after button press, and all other
         buttons in the current group with <tt>type() == FL_RADIO_BUTTON</tt>
         are set to zero.

  For an Fl_Button object, the following when() values are useful, the default
  being \c FL_WHEN_RELEASE:
  \li \c 0: The callback is not done, instead changed() is turned on.
  \li \c FL_WHEN_RELEASE: The callback is done after the user successfully
         clicks the button, or when a shortcut is typed. The reason is
         \p FL_REASON_RELEASED.
  \li \c 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
         \p FL_REASON_CHANGED
  \li \c 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
         \p FL_REASON_SELECTED
*/

class FL_EXPORT Fl_Button : public Fl_Widget {

  int shortcut_;
  char value_;
  char oldval;
  uchar down_box_;

protected:

  static Fl_Widget_Tracker *key_release_tracker;
  static void key_release_timeout(void*);
  void simulate_key_action();

  void draw() FL_OVERRIDE;

public:

  int handle(int) FL_OVERRIDE;

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

  int value(int v);

  /**
    Returns the current value of the button (0 or 1).
   */
  char value() const {return value_;}

  /**
    Same as \c value(1).
    \see value(int v)
   */
  int set() {return value(1);}

  /**
    Same as \c value(0).
    \see value(int v)
   */
  int clear() {return value(0);}

  void setonly(); // this should only be called on FL_RADIO_BUTTONs

  /**
    Returns the current shortcut key for the button.
    \retval int
   */
  int shortcut() const {return shortcut_;}

  /**
    Sets the shortcut key to \c 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:
    <tt>FL_ALT | 'a'</tt>, or
    <tt>FL_ALT | (FL_F + 10)</tt>, or just
    <tt>'a'</tt>.
    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).
    \param[in] s bitwise OR of key and shift flags
   */
  void shortcut(int s) {shortcut_ = s;}

  /**
    Returns the current down box type, which is drawn when value() is non-zero.
    \retval Fl_Boxtype
   */
  Fl_Boxtype down_box() const {return (Fl_Boxtype)down_box_;}

  /**
    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.

    \param[in] b down box type
   */
  void down_box(Fl_Boxtype b) {down_box_ = b;}

  /// (for backwards compatibility)
  void shortcut(const char *s) {shortcut(fl_old_shortcut(s));}

  /// (for backwards compatibility)
  Fl_Color down_color() const {return selection_color();}

  /// (for backwards compatibility)
  void down_color(unsigned c) {selection_color(c);}
};

#endif