windowss编程之旋转风车

#include<windows.h>
#include<math.h>
#include<string.h>
#include<stdio.h>
const double PI = 3.1415926;

LRESULT CALLBACK WndProc(
  HWND hwnd,      // handle to window
  UINT uMsg,      // message identifier
  WPARAM wParam,  // first message parameter
  LPARAM lParam   // second message parameter
);

int WINAPI WinMain(
  HINSTANCE hInstance,      // handle to current instance
  HINSTANCE hPrevInstance,  // handle to previous instance
  LPSTR lpCmdLine,          // command line
  int nCmdShow              // show state
)
{
	WNDCLASS wndclass;

	wndclass.cbClsExtra = 0;
	wndclass.cbWndExtra = 0;
	wndclass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
	wndclass.hCursor = LoadCursor(NULL, IDC_ARROW);
	wndclass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
	wndclass.hInstance = hInstance;
	wndclass.lpfnWndProc = WndProc;
	wndclass.lpszClassName = "我的窗口";
	wndclass.lpszMenuName = NULL;
	wndclass.style = CS_HREDRAW | CS_VREDRAW;
	RegisterClass(&wndclass); //注册窗口类

	HWND hwnd;
	hwnd = CreateWindow("我的窗口", "窗口", WS_OVERLAPPEDWINDOW, 
		0, 0, 640, 480, NULL, NULL, hInstance, NULL);

	ShowWindow(hwnd, SW_SHOWNORMAL);
	UpdateWindow(hwnd);

	MSG Msg;
	while(GetMessage(&Msg, NULL, 0, 0))
	{
		TranslateMessage(&Msg); 
        DispatchMessage(&Msg); 
	}

	return 0;
}

LRESULT CALLBACK WndProc(
  HWND hwnd,      // handle to window
  UINT uMsg,      // message identifier
  WPARAM wParam,  // first message parameter
  LPARAM lParam   // second message parameter
)
{
	HDC hdc;
	PAINTSTRUCT ps;
	HPEN hpen;
	HBRUSH hbrush;
	int nlength = 100, nwidth = 40;
	static int j = 0;
	switch(uMsg)
	{
	case WM_PAINT:	
		{
			hdc = BeginPaint(hwnd, &ps);
			hpen = (HPEN)GetStockObject(BLACK_PEN);
			hbrush = (HBRUSH)GetStockObject(BLACK_BRUSH);
		
			MoveToEx(hdc, 300 , 200, NULL);
			int k, nxl, nyl, nxw, nyw;
			for(k=0; k<4; k++)
			{
				nxl = 300 + nwidth * cos(j/5+(90-90*k)*PI/180);
				nyl = 200 - nwidth * sin(j/5+(90-90*k)*PI/180);
				nxw = 300 + nlength * cos(j/5+(-90*k)*PI/180);
				nyw = 200 - nlength * sin(j/5+(-90*k)*PI/180);
				POINT point[3];
				point[0].x = nxl; point[0].y = nyl;
				point[1].x = nxw; point[1].y = nyw;
				point[2].x = 300; point[2].y = 200;
				hbrush = CreateSolidBrush(RGB(25+50*k, 240-40*k, 45+60*k));
				SelectObject(hdc, hpen);
				SelectObject(hdc, hbrush);
				Polygon(hdc, point, 3);
				LineTo(hdc, nxl, nyl);
				LineTo(hdc, nxw, nyw);
				LineTo(hdc, 300, 200);
			}	
			j += 5;	
			Sleep(500);
			InvalidateRect(hwnd, NULL, 1);//重绘窗口区域

			EndPaint(hwnd, &ps);
			DeleteObject(hpen);
			DeleteObject(hbrush);
		}
		break;

	case WM_CLOSE:
		DestroyWindow(hwnd);
		break;

	case WM_DESTROY:
		PostQuitMessage(0);
	break;

	default:
		return DefWindowProc(hwnd, uMsg, wParam, lParam);
	}

	return 0;
}

总结：

要实现风车转动关键有两点：

1.InvalidateRect(hwnd, NULL, 1)//重绘窗口区域；

2.一个静态局部变量j，不断的改变风车顶点的坐标；