Применение Windows API
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Легалов А. И.
Шрифт:

 _timer.Set (100);

}

Once set, the timer sends our program timer messages and we have to process them.

LRESULT CALLBACK MainWndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam) {

 Controller* pCtrl = WinGetLong<Controller*>(hwnd);

 switch (message) {

 ...

 case WM_TIMER:

pCtrl->Timer(wParam);

return 0;

 ...

 }

 return ::DefWindowProc(hwnd, message, wParam, lParam);

}

void Controller::Timer(int id) {

 _timer.Kill;

 _view.Step;

 UpdateCanvas canvas(_hwnd);

 _view.Update(canvas);

 ::InvalidateRect(_hwnd, 0, FALSE);

 _timer.Set(50);

}

void Controller::Paint {

 PaintCanvas canvas(_hwnd);

 _view.Paint(canvas);

}

The Update method of View is the workhorse of our program. It creates the image in the buffer. We then call InvalidateRectangle to force the repaint of our window (the last parameter, FALSE, tells Windows not to clear the previous image — we don't want it to flash white before every frame).

Here's the class View, with the three bitmaps.

class View {

public:

 View(HINSTANCE hInst);

 void SetSize(int cxNew, int cyNew) {

_cx = cxNew;

_cy = cyNew;

 }

 void Step { ++_tick; }

 void Update(Canvas& canvas);

 void Paint(Canvas& canvas);

private:

 int _cx, _cy;

 int _tick;

 Bitmap _bitmapBuf; // for double buffering

 Bitmap _background;

 int _widthBkg, _heightBkg;

 Bitmap _sprite;

 Bitmap _mask;

 int _widthSprite, _heightSprite;

};

View::View(HINSTANCE hInst) : _tick (0) {

 // Load bitmap from file

 _background.Load("picture.bmp");

 // Load bitmap from resource

 _background.GetSize(_widthBkg, _heightBkg);

 // Load bitmaps from resources

 _sprite.Load(hInst, IDB_FANNY);

 _mask.Load(hInst, IDB_MASK);

 _sprite.GetSize(_widthSprite, _heightSprite);

 DesktopCanvas canvas;

 _bitmapBuf.CreateCompatible(canvas, 1, 1);

 _cx = 1;

 _cy = 1;

}

And here's the implementation of Update. We create a bitmap canvas in memory, making it compatible with the current display canvas. We blit the background image into it, then blit the mask and the sprite (notice the change of position for each frame). Finally, we transfer the complete bitmap into our buffer (overloaded assignment operator at work!).

void View::Update(Canvas& canvas) {

 const double speed = 0.01;

 Bitmap bmp(canvas, _cx, _cy);

 BitmapCanvas bmpCanvas(canvas, bmp);

 RECT rect = { 0, 0, _cx, _cy };

 bmpCanvas.WhiteWash(rect);

 // Do the off-line drawing

 Blitter bltBkg(_background);

 bltBkg.BlitTo(bmpCanvas);

 int xRange = (_widthBkg - _widthSprite) / 2;

 int yRange = (_heightBkg - _heightSprite) / 2;

 int x = xRange + static_cast<int>(xRange * sin(speed * _tick));