fltk/FL/Fl_Widget.H

//
// "$Id$"
//
// Widget header file for the Fast Light Tool Kit (FLTK).
//
// Copyright 1998-2008 by Bill Spitzak and others.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Library General Public
// License as published by the Free Software Foundation; either
// version 2 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Library General Public License for more details.
//
// You should have received a copy of the GNU Library General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
// USA.
//
// Please report all bugs and problems on the following page:
//
//     http://www.fltk.org/str.php
//

/** \file
   Fl_Widget, Fl_Label classes . */

#ifndef Fl_Widget_H
#define Fl_Widget_H

#include "Enumerations.H"

class Fl_Widget;
class Fl_Window;
class Fl_Group;
class Fl_Image;

/** Default callback type definition for all fltk widgets (by far the most used) */
typedef void (Fl_Callback )(Fl_Widget*, void*);
/** Default callback type pointer definition for all fltk widgets */
typedef Fl_Callback* Fl_Callback_p; // needed for BORLAND
/** One parameter Callback type definition passing only the widget */
typedef void (Fl_Callback0)(Fl_Widget*);
/** Callback type definition passing the widget and a long data value */
typedef void (Fl_Callback1)(Fl_Widget*, long);


/** This struct stores all information for a text or mixed graphics label.
 *
 *  \todo For FLTK1.3, the Fl_Label type will become a widget by itself. That way
 *        we will be avoiding a lot of code duplication by handling labels in 
 *        a similar fashion to widgets containing text. We also provide an easy
 *        interface for very complex labels, containing html or vector graphics.
 */
struct FL_EXPORT Fl_Label {
  /** label text */
  const char* value;
  /** optional image for an active label */
  Fl_Image* image;
  /** optional image for a deactivated label */
  Fl_Image* deimage;
  /** type of label. \see Fl_Labeltype */
  uchar type;
  /** label font used in text */
  Fl_Font font;
  /** size of label font */
  Fl_Fontsize size;
  /** text color */
  unsigned color;
  /** draw the label aligned to the given box */
  void draw(int,int,int,int, Fl_Align) const ;
  /** measure the size of the label.
   *  \param w, h on input, this is the requested size for the label text plus image;
   *                on return, this will contain the size needed to fit the label
   */
  void measure(int &w, int &h) const ;
};


/** Fl_Widget is the base class for all widgets in FLTK.  
 *
 *  You can't create one of these because the constructor is not public.  However 
 *  you can subclass it.  
 *
 *  All "property" accessing methods, such as color(), parent(), or argument() 
 *  are implemented as trivial inline functions and thus are as fast and small 
 *  as accessing fields in a structure. Unless otherwise noted, the property 
 *  setting methods such as color(n) or label(s) are also trivial inline functions, 
 *  even if they change the widget's appearance.  It is up to the user code to call 
 *  redraw() after these.
 */
class FL_EXPORT Fl_Widget {
  friend class Fl_Group;

  Fl_Group* parent_;
  Fl_Callback* callback_;
  void* user_data_;
  int x_,y_,w_,h_;
  Fl_Label label_;
  int flags_;
  unsigned color_;
  unsigned color2_;
  uchar type_;
  uchar damage_;
  uchar box_;
  Fl_Align align_:8;
  uchar when_;

  const char *tooltip_;

  /** unimplemented copy ctor */
  Fl_Widget(const Fl_Widget &);
  /** unimplemented assignment operator */
  Fl_Widget& operator=(const Fl_Widget &);

protected:

  /** Creates a widget at the given position and size. 
   *  The Fl_Widget is a protected constructor, but all derived widgets have a 
   *  matching public constructor. It takes a value for x(), y(), w(), h(), and 
   *  an optional value for label().
   *
   *  \param[in] x, y the position of the widget relative to the enclosing window
   *  \param[in] w, h size of the widget in pixels
   *  \param[in] label optional text for the widget label
   */
  Fl_Widget(int x, int y, int w, int h, Fl_CString label=0L);

  /** Internal use only. Use position(int,int), size(int, int) or resize(int,int,int,int) instead. */
  void x(int v) {x_ = v;}
  /** Internal use only. Use position(int,int), size(int, int) or resize(int,int,int,int) instead. */
  void y(int v) {y_ = v;}
  /** Internal use only. Use position(int,int), size(int, int) or resize(int,int,int,int) instead. */
  void w(int v) {w_ = v;}
  /** Internal use only. Use position(int,int), size(int, int) or resize(int,int,int,int) instead. */
  void h(int v) {h_ = v;}
  /** Gets the widget flags mask */
  int flags() const {return flags_;}
  /** Sets a flag in the flags mask */
  void set_flag(int c) {flags_ |= c;}
  /** Clears a flag in the flags mask */
  void clear_flag(int c) {flags_ &= ~c;}
  /** flags possible values enumeration.
      See activate(),output(), visible(), changed(), set_visible_focus()
  */
  enum {
        INACTIVE=1,	    ///< the widget can't receive focus, and is disabled but potentially visible
        INVISIBLE=2,	    ///< the widget is not drawn but can receive events
        OUTPUT=4,           ///< for output only
        SHORTCUT_LABEL=64,  ///< the label contains a shortcut we need to draw
        CHANGED=128,	    ///< the widget value changed
        VISIBLE_FOCUS=512,  ///< accepts keyboard focus navigation if the widget can have the focus
        COPIED_LABEL = 1024 ///< the widget label is internally copied, its destruction is handled by the widget
       };
  void draw_box() const;
  void draw_box(Fl_Boxtype, Fl_Color) const;
  void draw_box(Fl_Boxtype, int,int,int,int, Fl_Color) const;
  /** draws a focus rectangle around the widget */
  void draw_focus() {draw_focus(box(),x(),y(),w(),h());}
  void draw_focus(Fl_Boxtype, int,int,int,int) const;
  void draw_label() const;
  void draw_label(int, int, int, int) const;

public:

  /** Destroys the widget. 
   *  Destroying single widgets is not very common, and it is your responsibility 
   *  to either remove() them from any enclosing group or destroy that group 
   *  \em immediately after destroying the children. You almost always want to 
   *  destroy the parent group instead which will destroy all of the child widgets 
   *  and groups in that group.
   */
  virtual ~Fl_Widget();

  /** Draw 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.
   */
  virtual void draw() = 0;

  /** 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 new widget, this function must return 0 if the 
   *  widget does not use the event or 1 otherwise.<BR>
   *  Most of the time, you want to call the inherited handle() method in 
   *  your overriden method so that you don't short-circuit events that you 
   *  don't handle. In this last case you should return the callee retval.
   *
   *  \param[in] event the kind of event received
   *  \retval 0 if the event was not used or understood
   *  \retval 1 if the event was used and can be deleted
   *  \see Fl_Event
   */
  virtual int handle(int event);

  /** Returns a pointer to the parent widget.  
   *  Usually this is a Fl_Group or Fl_Window. 
   *  \retval NULL if the widget has no parent
   *  \see Fl_Group::add(Fl_Widget*)
   */
  Fl_Group* parent() const {return parent_;}

  /** Internal use only. Use Fl_Group::add(Fl_Widget*) instead. */
  void parent(Fl_Group* p) {parent_ = p;} // for hacks only, Fl_Group::add()

  /** Gets the widget type.
   *  Returns the widget type value, which is used for Forms
   *  compatibility and to simulate RTTI.
   */
  uchar type() const {return type_;}

  /** Sets the widget type.
   *  This is used for Forms compatibility.
   */
  void type(uchar t) {type_ = t;}

  /** Gets the widget position in its window.
   *  \return the x position relative to the window
   */
  int x() const {return x_;}

  /** Gets the widget position in its window.
   *  \return the y position relative to the window
   */
  int y() const {return y_;}

  /** Gets the widget width.
   *  \return the width of the widget in pixels.
   */
  int w() const {return w_;}

  /** Gets the widget height.
   *  \return the height of the widget in pixels.
   */
  int h() const {return h_;}

  /** Change the size or position of the widget. 
   *  This is a virtual function so that the widget may implement its 
   *  own handling of resizing. The default version does <I>not</I> 
   *  call the redraw() method, but instead relies on the parent widget 
   *  to do so because the parent may know a faster way to update the 
   *  display, such as scrolling from the old position.  
   *
   *  Some window managers under X11 call resize() a lot more often 
   *  than needed. Please verify that the position or size of a widget 
   *  did actually change before doing any extensive calculations.
   *
   *  position(x,y) is a shortcut for resize(x,y,w(),h()), and size(w,h) is a shortcut for resize(x(),y(),w,h).
   *
   *  \param[in] x, y new position relative to the parent window 
   *  \param[in] w, h new size
   *  \see position(int, int), size(int, int)
   */
  virtual void resize(int x, int y, int w, int h);

  /** Internal use only. */
  int damage_resize(int,int,int,int);

  /** Reposition the window or widget.
   *  position(X,Y) is a shortcut for resize(X,Y,w(),h()).
   *
   *  \param[in] X, Y new position relative to the parent window 
   *  \see resize(int, int, int, int), size(int, int)
   */
  void position(int X,int Y) {resize(X,Y,w_,h_);}

  /** Change the size of the widget.
   *  size(w,h) is a shortcut for resize(x(),y(),w,h).
   *
   *  \param[in] W, H new size
   *  \see position(int, int), resize(int, int, int, int)
   */
  void size(int W,int H) {resize(x_,y_,W,H);}

  /** Gets the label alignment.
   *  \return label alignment
   *  \see label(), align(Fl_Align), Fl_Align
   *  \todo This function should not take uchar as an argument. Apart from the fact that uchar is too short 
   *        with only 8 bits, it does not provide type safety (in which case we don't need to declare Fl_Type
   *        an enum to begin with).
   */
  Fl_Align align() const {return align_;}

  /** Sets the label alignment.
   * This controls how the label is displayed next to or inside the widget. 
   * The default value is FL_ALIGN_CENTER, which centers the label inside the widget.
   * \param[in] alignment new label alignment
   * \see align(), Fl_Align
   */
  void align(Fl_Align alignment) {align_ = alignment;}

  /** Gets the box type for the widget.
   *  \return the current box type
   *  \see box(Fl_Boxtype), Fl_Boxtype
   */
  Fl_Boxtype box() const {return (Fl_Boxtype)box_;}
  
  /** Sets the box type for the widget. 
   *  This identifies a routine that draws the background of the widget. 
   *  See Fl_Boxtype for the available types. The default depends on the widget, 
   *  but is usually FL_NO_BOX or FL_UP_BOX.
   *  \param[in] new_box the new box type
   *  \see box(), Fl_Boxtype
   */
  void box(Fl_Boxtype new_box) {box_ = new_box;}

  /** Gets the background color of the widget.
   *  \return current background color
   *  \see color(unsigned), color(unsigned, unsigned)
   */
  Fl_Color color() const {return (Fl_Color)color_;}

  /** Sets the background color of the widget. 
   *  The color is passed to the box routine. The color is either an index into an 
   *  internal table of RGB colors or an RGB color value generated using fl_rgb_color().
   *  The default for most widgets is FL_BACKGROUND_COLOR. Use Fl::set_color() to 
   *  redefine colors in the color map.
   *  \param[in] bg background color
   *  \see color(), color(unsigned, unsigned), selection_color(unsigned)
   */
  void color(unsigned bg) {color_ = bg;}

  /** Gets the selection color.
   *  \return the current selection color
   *  \see selection_color(unsigned), color(unsigned, unsigned)
   */
  Fl_Color selection_color() const {return (Fl_Color)color2_;}

  /** Gets or sets the selection color.
   *  The selection color is defined for Forms compatibility and is usually 
   *  used to color the widget when it is selected, although some widgets 
   *  use this color for other purposes. You can set both colors at once 
   *  with color(int, int).
   *  \param[in] a the new selection color
   *  \see selection_color(), color(unsigned, unsigned)
   */
  void selection_color(unsigned a) {color2_ = a;}

  /** Sets the background and selection color of the widget. 
   *  The two color form sets both the background and selection colors. 
   *  \param[in] bg background color
   *  \param[in] sel selection color
   *  \see color(unsigned), selection_color(unsigned)
   */
  void color(unsigned bg, unsigned sel) {color_=bg; color2_=sel;}

  /** Get the current label text.
   *  \return a pointer to the current label text
   *  \see label(Fl_CString), copy_label(Fl_CString)
   */
  const char* label() const {return label_.value;}

  /** Get or set the current label pointer. 
   *  The label is shown somewhere on or next to the widget. The passed pointer 
   *  is stored unchanged in the widget (the string is \em not copied), so if 
   *  you need to set the label to a formatted value, make sure the buffer is 
   *  static, global, or allocated. The copy_label() method can be used 
   *  to make a copy of the label string automatically.
   *  \param[in] text pointer to new label text
   *  \see copy_label()
   */
  void label(const char* text);

  /** Sets the current label. 
   *  Unlike label(), this method allocates a copy of the label 
   *  string instead of using the original string pointer.
   *  \param[in] new_label the new label text
   *  \see label()
   */
  void copy_label(Fl_CString new_label);

  /** Shortcut to set the label text and type in one call.
   *  \see label(FL_CString), labeltype(Fl_Labeltype)
   */
  void label(Fl_Labeltype a,const char* b) {label_.type = a; label_.value = b;}

  /** Gets the label type.
   *  \return the current label type.
   *  \see Fl_Labeltype
   */
  Fl_Labeltype labeltype() const {return (Fl_Labeltype)label_.type;}

  /** Sets the label type. 
   *  The label type identifies the function that draws the label of the widget. 
   *  This is generally used for special effects such as embossing or for using 
   *  the label() pointer as another form of data such as an icon. The value 
   *  FL_NORMAL_LABEL prints the label as plain text.
   *  \param a new label type
   *  \see Fl_Labeltype
   */
  void labeltype(Fl_Labeltype a) {label_.type = a;}

  /** Gets the label color. 
   *  The default color is FL_FOREGROUND_COLOR. 
   *  \return the current label color
   */
  Fl_Color labelcolor() const {return (Fl_Color)label_.color;}

  /** Sets the label color. 
   *  The default color is FL_FOREGROUND_COLOR. 
   *  \param[in] c the new label color
   */
  void labelcolor(unsigned c) {label_.color=c;}

  /** Gets the font to use. 
   *  Fonts are identified by indexes into a table. The default value uses a 
   *  Helvetica typeface (Arial for Microsoft&reg; Windows&reg;). The function 
   *  Fl::set_font() can define new typefaces.
   *  \return current font used by the label
   *  \see Fl_Font
   */
  Fl_Font labelfont() const {return label_.font;}

  /** Sets the font to use. 
   *  Fonts are identified by indexes into a table. The default value uses a 
   *  Helvetica typeface (Arial for Microsoft&reg; Windows&reg;). The function 
   *  Fl::set_font() can define new typefaces.
   *  \param[in] f the new font for the label
   *  \see Fl_Font
   */
  void labelfont(Fl_Font f) {label_.font=f;}

  /** Gets the font size in pixels. 
   *  The default size is 14 pixels.
   *  \return the current font size
   */
  Fl_Fontsize labelsize() const {return label_.size;}

  /** Gets or sets the font size in pixels. 
   *  The default size is 14 pixels.
   *  \param[in] pix the new font size
   */
  void labelsize(Fl_Fontsize pix) {label_.size=pix;}

  /** Gets or sets the image to use as part of the widget label.
   *  This image is used when drawing the widget in the active state.
   *  \return the current image
   */
  Fl_Image* image() {return label_.image;}

  /** Gets or sets the image to use as part of the widget label.
   *  This image is used when drawing the widget in the active state.
   *  \param[in] img the new image for the label 
   */
  void image(Fl_Image* img) {label_.image=img;}

  /** Gets or sets the image to use as part of the widget label.
   *  This image is used when drawing the widget in the active state.
   *  \param[in] img the new image for the label 
   */
  void image(Fl_Image& img) {label_.image=&img;}

  /** Gets the image to use as part of the widget label.  
   *  This image is used when drawing the widget in the inactive state.
   *  \return the current deactivated image for this widget
   */
  Fl_Image* deimage() {return label_.deimage;}

  /** Sets the image to use as part of the widget label.  
   *  This image is used when drawing the widget in the inactive state.
   *  \param[in] img the new image for the deactivated widget
   */
  void deimage(Fl_Image* img) {label_.deimage=img;}

  /** Sets the image to use as part of the widget label.  
   *  This image is used when drawing the widget in the inactive state.
   *  \param[in] img the new image for the deactivated widget
   */
  void deimage(Fl_Image& img) {label_.deimage=&img;}

  /** Gets the current tooltip text.
   *  \return a pointer to the tooltip text or NULL
   */
  const char *tooltip() const {return tooltip_;}

  /** Sets the current tooltip text. 
   *  Sets a string of text to display in a popup tooltip window when the user 
   *  hovers the mouse over the widget. The string is <I>not</I> copied, so 
   *  make sure any formatted string is stored in a static, global, 
   *  or allocated buffer.
   * 
   *  If no tooltip is set, the tooltip of the parent is inherited. Setting a 
   *  tooltip for a group and setting no tooltip for a child will show the 
   *  group's tooltip instead. To avoid this behavior, you can set the child's 
   *  tooltip to an empty string ("").
   *  \param[in] t new tooltip
   */
  void tooltip(const char *t);

  /** Gets the current callback function for the widget.
   *  Each widget has a single callback.
   *  \return current callback
   */
  Fl_Callback_p callback() const {return callback_;}

  /** Sets the current callback function for the widget.
   *  Each widget has a single callback.
   *  \param[in] cb new callback
   *  \param[in] p user data
   */
  void callback(Fl_Callback* cb, void* p) {callback_=cb; user_data_=p;}

  /** Sets the current callback function for the widget.
   *  Each widget has a single callback.
   *  \param[in] cb new callback
   */
  void callback(Fl_Callback* cb) {callback_=cb;}

  /** Sets the current callback function for the widget.
   *  Each widget has a single callback.
   *  \param[in] cb new callback
   */
  void callback(Fl_Callback0*cb) {callback_=(Fl_Callback*)cb;}

  /** Sets the current callback function for the widget.
   *  Each widget has a single callback.
   *  \param[in] cb new callback
   *  \param[in] p user data
   */
  void callback(Fl_Callback1*cb, long p=0) {callback_=(Fl_Callback*)cb; user_data_=(void*)p;}

  /** Gets the user data for this widget.
   *  Gets the current user data (void *) argument
   *  that is passed to the callback function.
   *  \return user data as a pointer
   */
  void* user_data() const {return user_data_;}

  /** Sets the user data for this widget.
   *  Sets the new user data (void *) argument
   *  that is passed to the callback function.
   *  \param[in] v new user data
   */
  void user_data(void* v) {user_data_ = v;}

  /** Gets the current user data (long) argument that is passed to the callback function.
   */
  long argument() const {return (long)user_data_;}

  /** Sets the current user data (long) argument that is passed to the callback function.
   *  \todo The user data value must be implemented using a \em union to avoid 64 bit machine incompatibilities.
   */
  void argument(long v) {user_data_ = (void*)v;}

  /**
     Controls when callbacks are done. The following values are useful,
     the default value is FL_WHEN_RELEASE:
  
  <UL>
  
  	<LI>0: The callback is not done, but
  	changed() is turned on.</LI>
  
  	<LI>FL_WHEN_CHANGED: The callback is done each
  	time the text is changed by the user.</LI>
  
  	<LI>FL_WHEN_RELEASE: The callback will be done
  	when this widget loses the focus, including when the
  	window is unmapped. This is a useful value for text
  	fields in a panel where doing the callback on every
  	change is wasteful. However the callback will also
  	happen if the mouse is moved out of the window, which
  	means it should not do anything visible (like pop up an
  	error message). You might do better setting this to
  	zero, and scanning all the items for changed()
  	when the OK button on a panel is pressed.</LI>
  
  	<LI>FL_WHEN_ENTER_KEY: If the user types the
  	Enter key, the entire text is selected, and the callback
  	is done if the text has changed. Normally the Enter key
  	will navigate to the next field (or insert a newline for
  	a Fl_Mulitline_Input), this changes the
  	behavior.</LI>
  
  	<LI>FL_WHEN_ENTER_KEY|FL_WHEN_NOT_CHANGED: The
  	Enter key will do the callback even if the text has not
  	changed. Useful for command fields.</LI>
  
  </UL>
	Return the conditions under which the callback is called.
        \return set of flags
   */
  Fl_When when() const {return (Fl_When)when_;}

  /** Flags used to decide when a callback is called.
   *  Fl_Widget::when() is a set of bitflags used by subclasses of 
   *   Fl_Widget to decide when to do the callback.  If the value 
   *  is zero then the callback is never done.  Other values are described 
   *  in the individual widgets.  This field is in the base class so that 
   *  you can scan a panel and do_callback() on all the ones that 
   *  don't do their own callbacks in response to an "OK" button.
   *  \param[in] i set of flags 
   */
  void when(uchar i) {when_ = i;}

  /** Returns whether a widget is visble.
   *  \retval 0 if the widget is not drawn and hence invisible.
   *  \see show(), hide(), visible_r()
   */
  int visible() const {return !(flags_&INVISIBLE);}
  
  /** Returns whether a widget and all its parents are visible.
   *  \retval 0 if the widget or any of its parents are invisible.
   *  \see show(), hide(), visible()
   */
  int visible_r() const;

  /** Makes a widget visible.
   *  An invisible widget never gets redrawn and does not get events.  
   *  The visible() method returns true if the widget is set to be  
   *  visible. The visible_r() method returns true if the widget and 
   *  all of its parents are visible. A widget is only visible if 
   *  visible() is true on it <I>and all of its parents</I>. 
   * 
   *  Changing it will send FL_SHOW or FL_HIDE events to 
   *  the widget. <I>Do not change it if the parent is not visible, as this 
   *  will send false FL_SHOW or FL_HIDE events to the 
   *  widget</I>. redraw() is called if necessary on this or the parent.
   *  
   *  \see hide(), visible(), visible_r()
   */
  void show();
  
  /** Makes a widget invisible.
   *  \see show(), visible(), visible_r()
   */
  void hide();

  /** Makes the widget visible. 
   *  You must still redraw the parent widget to see a change in the 
   *  window. Normally you want to use the show() method instead.
   */
  void set_visible() {flags_ &= ~INVISIBLE;}

  /** Hides the widget. 
   *  You must still redraw the parent to see a change in the window. 
   *  Normally you want to use the hide() method instead.
   */
  void clear_visible() {flags_ |= INVISIBLE;}

  /** Returns whether the widget is active.
   *  \retval 0 if the widget is inactive
   *  \see active_r(), activate(), deactivate()
   */
  int active() const {return !(flags_&INACTIVE);}

  /** active_r() returns whether the widget and all of its 
   *  parents are active. 
   *  \retval 0 if this or any of the parent widgets are inactive
   *  \see active(), activate(), deactivate()
   */
  int active_r() const;

  /** Activate a widget.
   *  Changing this value will send FL_ACTIVATE to the widget if 
   *  active_r() is true.
   *  \see active(), active_r(), deactivate()
   */
  void activate();

  /** Deactivate a widget.
   *  Inactive widgets will be drawn "grayed out", e.g. with less contrast 
   *  than the active widget. Inactive widgets will not receive any keyboard 
   *  or mouse button events. Other events (including FL_ENTER, FL_MOVE, 
   *  FL_LEAVE, FL_SHORTCUT, and others) will still be sent. A widget is 
   *  only active if active() is true on it <I>and all of its parents</I>.  
   *
   *  Changing this value will send FL_DEACTIVATE to the widget if 
   *  active_r() is true.
   *
   *  Currently you cannot deactivate Fl_Window widgets.
   *
   *  \see activate(), active(), active_r()
   */
  void deactivate();

  /** Return if a widget is used for output only.
   *  output() means the same as !active() except it does not change how the 
   *  widget is drawn. The widget will not receive any events. This is useful 
   *  for making scrollbars or buttons that work as displays rather than input devices.
   *  \retval 0 if the widget is used for input and output
   *  \see set_output(), clear_output() 
   */
  int output() const {return (flags_&OUTPUT);}

  /** Set a widget to output only.
   *  \see output(), clear_output() 
   */
  void set_output() {flags_ |= OUTPUT;}

  /** Set a widget to accept input.
   *  \see set_output(), output() 
   */
  void clear_output() {flags_ &= ~OUTPUT;}

  /** Returns if the widget is able to take events.
   *  This is the same as (active() && !output()
   *  && visible()) but is faster.
   *  \retval 0 if the widget takes no events
   */ 
  int takesevents() const {return !(flags_&(INACTIVE|INVISIBLE|OUTPUT));}

  /** 
   *  Check if the widget value changed since the last callback.
   *  "Changed" is a flag that is turned on when the user changes the value stored 
   *  in the widget. This is only used by subclasses of Fl_Widget that store values, 
   *  but is in the base class so it is easier to scan all the widgets in a panel 
   *  and do_callback() on the changed ones in response to an "OK" button.
   *
   *  Most widgets turn this flag off when they do the callback, and when the program 
   *  sets the stored value.
   *
   * \retval 0 if the value did not change
   * \see set_changed(), clear_changed()`
   */
  int changed() const {return flags_&CHANGED;}

  /** Mark the value of the widget as changed.
   *  \see changed(), clear_changed()
   */
  void set_changed() {flags_ |= CHANGED;}

  /** Mark the value of the widget as unchanged.
   *  \see changed(), set_changed()
   */
  void clear_changed() {flags_ &= ~CHANGED;}

  /** Give the widget the keyboard focus.
   *  Tries to make this widget be the Fl::focus() widget, by first sending 
   *  it an FL_FOCUS event, and if it returns non-zero, setting 
   *  Fl::focus() to this widget.  You should use this method to 
   *  assign the focus to a widget.  
   *  \return true if the widget accepted the focus.
   */
  int take_focus();

  /** Enables keyboard focus navigation with this widget. 
   *  Note, however, that this will not necessarily mean that the widget will 
   *  accept focus, but for widgets that can accept focus, this method enables 
   *  it if it has been disabled.
   *  \see visible_focus(), clear_visible_focus(), visible_focus(int) 
   */
  void set_visible_focus() { flags_ |= VISIBLE_FOCUS; }

  /** Disables keyboard focus navigation with this widget. 
   *  Normally, all widgets participate in keyboard focus navigation.
   *  \see set_visible_focus(), visible_focus(), visible_focus(int) 
   */
  void clear_visible_focus() { flags_ &= ~VISIBLE_FOCUS; }

  /** Modifies keyboard focus navigation. 
   *  \param[in] v set or clear visible focus
   *  \see set_visible_focus(), clear_visible_focus(), visible_focus() 
   */
  void visible_focus(int v) { if (v) set_visible_focus(); else clear_visible_focus(); }
 
  /** Check whether this widget has a visible focus.
   *  \retval 0 if this widget has no visible focus.
   *  \see visible_focus(int), set_visible_focus(), clear_visible_focus()
   */
  int  visible_focus() { return flags_ & VISIBLE_FOCUS; }

  /** Sets the default callback for all widgets.
   *  Sets the default callback, which puts a pointer to the widget on the queue 
   *  returned by Fl::readqueue(). You may want to call this from your own callback.
   *  \param cb the new callback
   *  \param d user data associated with that callback
   *  \see callback(), do_callback(), Fl::readqueu()
   */
  static void default_callback(Fl_Widget *cb, void *d);

  /** Call the widget callback.
   *  Causes a widget to invoke its callback function, optionally
   *  with arbitrary arguments.
   *  \see callback()
   */
  void do_callback() {callback_(this,user_data_); if (callback_ != default_callback) clear_changed();}

  /** Call the widget callback.
   *  Causes a widget to invoke its callback function, optionally
   *  with arbitrary arguments.
   *  \param o call the callback with \em o as the widget argument
   *  \param arg call the callback with \em arg as the user data argument
   *  \see callback()
   */
  void do_callback(Fl_Widget* o,void* arg=0) {callback_(o,arg); if (callback_ != default_callback) clear_changed();}

  /** Call the widget callback.
   *  Causes a widget to invoke its callback function, optionally
   *  with arbitrary arguments.
   *  \param o call the callback with \em o as the widget argument
   *  \param arg call the callback with \em arg as the user data argument
   *  \see callback()
   */
  void do_callback(Fl_Widget* o,long arg) {callback_(o,(void*)arg); if (callback_ != default_callback) clear_changed();}

  /** Internal use only. */
  int test_shortcut();
  /** Internal use only. */
  static char label_shortcut(const char *t);
  /** Internal use only. */
  static int test_shortcut(const char*);

  /** Checks if w is a child of this widget.
   *  \param[in] w potential child widget
   *  \return Returns 1 if \em w is a child of this widget, or is
   *  equal to this widget. Returns 0 if \em w is NULL.
   */
  int contains(const Fl_Widget *w) const ;

  /** Check if this widget is a child of w.
   *  Returns 1 if this widget is a child of \em w, or is
   *  equal to \em w. Returns 0 if \em w is NULL.
   *  \param[in] w the possible parent widget.
   *  \see contains()
   */
  int inside(const Fl_Widget* w) const {return w ? w->contains(this) : 0;}

  /** Schedule the drawing of the widget.
   *  Marks the widget as needing its draw() routine called.
   */
  void redraw();

  /** Schedule the drawing of the label.
   * Marks the widget or the parent as needing a redraw for the label area of a widget.
   */
  void redraw_label();

  /** Returns non-zero if draw() needs to be called. 
   *  The damage value is actually a bit field that the widget 
   *  subclass can use to figure out what parts to draw.
   *  \return a bitmap of flags describing the kind of damage to the widget
   *  \see damage(uchar), clear_damage(uchar)
   */
  uchar damage() const {return damage_;}

  /** Clear damage flags.
   *  Damage flags are cleared when parts of the widget drawing is repaired.
   *  \param[in] c bitmask of flags to clear
   *  \see damage(uchar), damage()
   */
  void clear_damage(uchar c = 0) {damage_ = c;}

  /** Set the damage bits for the widget.
   *  Setting damage bits will schedule the widget for the next redraw.
   *  \param[in] c bitmask of flags to set
   *  \see damage(), clear_damage(uchar)
   */
  void damage(uchar c);

  /** Set the damage bits for an area inside the widget.
   *  Setting damage bits will schedule the widget for the next redraw.
   *  \param[in] c bitmask of flags to set
   *  \param x, y, w, h size of damaged area
   *  \see damage(), clear_damage(uchar)
   */
  void damage(uchar c, int x, int y, int w, int h);

  void draw_label(int, int, int, int, Fl_Align) const;
  /** Sets width ww, height hh accordingly with the labeltype size, label with images will return w() h() of the image. */
  void measure_label(int& ww, int& hh) {label_.measure(ww, hh);}

  /** Returns a pointer to the primary Fl_Window widget.
   *  \retval  NULL if no window is associated with this widget.  
   *  \note for an Fl_Window widget, this returns its <I>parent</I> window (if any), not <I>this</I> window.
   */
  Fl_Window* window() const ;

  /** For back compatibility only. */
  Fl_Color color2() const {return (Fl_Color)color2_;}
  /** For back compatibility only. */
  void color2(unsigned a) {color2_ = a;}
};

/**
    Reserved type numbers (necessary for my cheapo RTTI) start here.
    grep the header files for "RESERVED_TYPE" to find the next available
    number.
*/
#define FL_RESERVED_TYPE 100

#endif

//
// End of "$Id$".
//