scummvm/common/rect.h

/* ScummVM - Scumm Interpreter
 * Copyright (C) 2002-2004 The ScummVM project
 *
 * 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 program 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 General Public License for more details.

 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * $Header$
 *
 */

#ifndef COMMON_RECT_H
#define COMMON_RECT_H

#include "common/scummsys.h"
#include "common/util.h"

namespace Common {

/*! 	@brief simple class for handling both 2D position and size

	This small class is an helper for position and size values.
*/
struct Point {
	int16 x;	//!< The horizontal part of the point
	int16 y;	//!< The vertical part of the point

	Point() : x(0), y(0) {};
	Point(const Point & p) : x(p.x), y(p.y) {};
	explicit Point(int16 x1, int16 y1) : x(x1), y(y1) {};
	Point & operator=(const Point & p) { x = p.x; y = p.y; return *this; };
	bool operator==(const Point & p) const { return x == p.x && y == p.y; };
	bool operator!=(const Point & p) const { return x != p.x || y != p.y; };
};

/*! 	@brief simple class for handling a rectangular zone.

	This small class is an helper for rectangles.
	Note: This implementation is built around the assumption that (top,left) is
	part of the rectangle, but (bottom,right) is not! This is reflected in 
	various methods, including contains(), intersects() and others.
	
	Another very wide spread approach to rectangle classes treats (bottom,right)
	also as a part of the rectangle.
	
	Coneptually, both are sound, but the approach we use saves many intermediate
	computations (like computing the height in our case is done by doing this:
	  height = bottom - top;
	while in the alternate system, it would be
	  height = bottom - top + 1;
	
	When writing code using our Rect class, always keep this principle in mind!
*/
struct Rect {
	int16 top, left;		//!< The point at the top left of the rectangle (part of the rect).
	int16 bottom, right;	//!< The point at the bottom right of the rectangle (not part of the rect).

	Rect() : top(0), left(0), bottom(0), right(0) {}
	Rect(int16 w, int16 h) : top(0), left(0), bottom(h), right(w) {}
	Rect(int16 x1, int16 y1, int16 x2, int16 y2) : top(y1), left(x1), bottom(y2), right(x2) {
		assert(isValidRect());
	}
	int16 width() const { return right - left; }
	int16 height() const { return bottom - top; }

	/*!	@brief check if given position is inside this rectangle

		@param x the horizontal position to check
		@param y the vertical position to check	
		
		@return true if the given position is inside this rectangle, false otherwise
	*/
	bool contains(int16 x, int16 y) const {
		return (left <= x) && (x < right) && (top <= y) && (y < bottom);
	}

	/*!	@brief check if given point is inside this rectangle
		
		@param p the point to check
		
		@return true if the given point is inside this rectangle, false otherwise
	*/
	bool contains(const Point & p) const {
		return contains(p.x, p.y);
	}

	/*!	@brief check if given rectangle intersects with this rectangle
		
		@param r the rectangle to check
		
		@return true if the given rectangle is inside the rectangle, false otherwise
	*/
	bool intersects(const Rect & r) const {
		return (left < r.right) && (r.left < right) && (top < r.bottom) && (r.top < bottom);
	}

	/*!	@brief extend this rectangle so that it contains r
		
		@param r the rectangle to extend by
	*/
	void extend(const Rect & r) {
		left = MIN(left, r.left);
		right = MAX(right, r.right);
		top = MIN(top, r.top);
		bottom = MAX(bottom, r.bottom);
	}
	
	/*!	@brief extend this rectangle in all four directions by the given number of pixels
		
		@param offset the size to grow by
	*/
	void grow(int16 offset) {
		top -= offset;
		left -= offset;
		bottom += offset;
		right += offset;
	}
	
	void clip(const Rect & r) {
		assert(isValidRect());
		assert(r.isValidRect());

		if (top < r.top) top = r.top;
		else if (top > r.bottom) top = r.bottom;

		if (left < r.left) left = r.left;
		else if (left > r.right) left = r.right;

		if (bottom > r.bottom) bottom = r.bottom;
		else if (bottom < r.top) bottom = r.top;

		if (right > r.right) right = r.right;
		else if (right < r.left) right = r.left;
	}
	
	void clip(int maxw, int maxh) {
		clip(Rect(0, 0, maxw, maxh));
	}
	
	bool isValidRect() const {
		return (left <= right && top <= bottom);
	}
	
	void moveTo(int16 x, int16 y) {
		bottom += y - top;
		right += x - left;
		top = y;
		left = x;
	}
	
	void moveTo(const Point & p) {
		moveTo(p.x, p.y);
	}
};

}	// End of namespace Common

#endif