ball.h

画一个小球

#include <windows.h>
#include <math.h>

TCHAR szAppName[] = TEXT("Bounce");
#define PI 3.14159
#define TWO_PI 2*PI

class MovableObject{
public:
	virtual void Draw(HDC hdc) = 0;
	virtual void GetUpdateRect(RECT *rc) = 0;
	virtual void SetImage(HDC hdc) = 0;
	virtual ~MovableObject(){DeleteObject(_image);}
	void Move();
	void SetDirection(double direction)
		{_direction = direction;}
	void SetSpeed(LONG x,LONG y)
		{_speed.x = x;_speed.y = y;}
	void SetPosition(LONG x,LONG y)
		{_position.x = x;_position.y = y;}
	void GetPostion(POINT &pos)
		{pos = _position;}
//protected:
protected:
	POINT	_speed;
	/*Distance object can move in x and y direction
	  every time interval*/
	HBITMAP _image;
	POINT	_position;
	double	_direction;	//in arc
};


void MovableObject::Move(){
	_position.x += _speed.x;
	_position.y += _speed.y;
}

class Ball : public MovableObject{
public:
	~Ball(){DeleteObject(_image);}
	void SetColor(COLORREF color)
		{_color = color;}
	void Draw(HDC hdc);
	void SetRadius(UINT radius)
		{_radius = radius;}
	void GetUpdateRect(RECT *rc);
	void CheckCollide(Ball &ball2);
	void AdjustSpeed(UINT cxClient, UINT cyClient);
	void SetImage(HDC hdc);
private:
	UINT _radius;
	COLORREF _color;
};
void Ball::SetImage(HDC hdc){

	HDC hdcMem = CreateCompatibleDC(hdc);
	_image = CreateCompatibleBitmap(hdc,2*_radius,2*_radius);
	SelectObject(hdcMem, _image);
	Rectangle(hdcMem,-1,-1,2*_radius+1,2*_radius+1);

	HBRUSH hBrush = CreateSolidBrush(_color);
	hBrush = (HBRUSH)SelectObject(hdcMem,hBrush);
	SetBkColor(hdcMem,RGB(0,0,0));
	SelectObject(hdcMem,GetStockObject(NULL_PEN));
	Ellipse(hdcMem,0,0,2*_radius,2*_radius);

	DeleteObject(SelectObject(hdcMem,hBrush));
	DeleteDC(hdcMem);
}

void Ball::Draw(HDC hdc){

	HDC hdcMem = CreateCompatibleDC(hdc);
	SelectObject(hdcMem,_image);
	BitBlt(hdc,_position.x-_radius,_position.y-_radius,
			2*_radius,2*_radius,hdcMem,0,0,SRCCOPY);
	DeleteDC(hdcMem);
}

void Ball::GetUpdateRect(RECT *rc){
	rc->left = _position.x-_radius;
	rc->top = _position.y-_radius;
	rc->right = _position.x+_radius;
	rc->bottom = _position.y+_radius;
}


void Ball::CheckCollide(Ball &ball2){
	UINT distance = sqrt(pow((_position.x-ball2._position.x),2)+
		pow((_position.y-ball2._position.y),2));
	if(distance <= _radius+ball2._radius){
		//exchange speed
		POINT speed_tmp;
		speed_tmp.x = _speed.x;
		speed_tmp.y = _speed.y;
		

		_speed.x = ball2._speed.x;
		_speed.y = ball2._speed.y;
		ball2._speed.x = speed_tmp.x;
		ball2._speed.y = speed_tmp.y;
	}
}

void Ball::AdjustSpeed(UINT cxClient, UINT cyClient){
	//adjust speed for specified ball to keep it in the client area
	if(_position.x+_radius>=cxClient ||
		int(_position.x-_radius)<=0){
		_speed.x = -_speed.x;
		_position.x =  min(cxClient-_radius,
			max(_radius,(int)_position.x));
	}
	if(_position.y+_radius>=cyClient ||
		int(_position.y-_radius)<=0){
		_speed.y = -_speed.y;
		_position.y =  min(cyClient-_radius,
			max(_radius,(int)_position.y));
	}
}