canvas.h

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#ifndef CANVAS_CLASS
#define CANVAS_CLASS

/*****************************************************************************\
*                                                                             *
*  Name   : canvas                                                            *
*  Author : Chris Koeritz                                                     *
*                                                                             *
*  Purpose:                                                                   *
*                                                                             *
*    Models a rectangular worker object on which paintable objects can        *
*  be placed.                                                                 *
*                                                                             *
*******************************************************************************
* Copyright (c) 1991-$now By Author.  This program is free software; you can  *
* redistribute it and/or modify it under the terms of the GNU General Public  *
* License as published by the Free Software Foundation; either version 2 of   *
* the License or (at your option) any later version.  This is online at:      *
*     http://www.fsf.org/copyleft/gpl.html                                    *
* Please send any updates to: fred@gruntose.com                               *
\*****************************************************************************/

#include "manager.h"
#include "picture.h"
#include "resources.h"
#include "worker.h"

const c_rectangle default_world = c_rectangle(0, 0, 1000, 1000);

class WP_PASSIVE_CLASS_STYLE canvas : public worker, private c_rectangle_warper
{
public:
  canvas(manager &root, const c_rectangle &initial_size,
          const c_rectangle &initial_world = default_world,
          const color &foreground = colors::WHITE,
          const color &background = colors::BLACK,
          origin_vertex world_corner = BOTTOM_LEFT);
    // Creates a canvas attached to the "root".  The location of the canvas
    // in universal coordinates is "position".  The world coordinate system
    // is specified by "initial_world", where an implicit ordering is used
    // to define the coordinate system: the first vertex of the rectangle is
    // the origin, while the second is the extent of the world coordinates
    // away from that origin.  When one is manipulating the canvas itself,
    // this is in terms of universal coordinates, but when things on the
    // canvas are referred to, those things are in world coordinates.

  virtual ~canvas();

  IMPLEMENT_CLASS_NAME("canvas");

// Contents Redisplaying Methods:

  void redraw();
    // Causes the canvas to repaint its entire contents.

  virtual void redraw_part(const c_rectangle &to_redraw);
    // Causes the portion of the canvas that intersects with the rectangle
    // (in universal coordinates) to be redrawn.

// Coordinate System Methods:

  c_rectangle world() const;
    // observes the frame of reference for the things internal to this canvas
    // (such as the things painted on it).
  c_rectangle universe() const;
    // observes the frame of reference that is external to this object.

  // the "device" coordinates below are relative to the origin of the canvas.
  c_point world_to_device(const c_point &in_world) const;
  c_point device_to_world(const c_point &in_device) const;

  c_rectangle world_to_device(const c_rectangle &in_world) const;
  c_rectangle device_to_world(const c_rectangle &in_device) const;

// Contents Management Functions:

  int elements();
    // the number of paintables currently attached to this canvas.
  void add(drawable *to_add);
    // attaches a new object (hopefully a paintable one, but drawables are
    // allowed since we want to allow pictures to be added).
  void remove(drawable *to_add);
    // detaches an object from the canvas.  the request is ignored if the
    // object is not found.
  void update();
    // reorders the set of paintables attached to the canvas so that the
    // layers are accurate.  a call to draw() is required to make sure that
    // any changes are displayed.

// Miscellaneous Methods:

  resources &details();
    // Accesses the repository for windowing system dependent information.

  static void exposer(window_handle, canvas *me, XmAnyCallbackStruct *parms);
  static void resizer(window_handle, canvas *me, XmAnyCallbackStruct *parms);
  static void inputer(window_handle, canvas *me, XmAnyCallbackStruct *parms);

private:
  resources _details;
  picture contents;

  window_handle create_canvas_handle(manager &root, const c_point &origin);
};

#endif

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