GDI双缓冲解决重绘闪屏（非MFC）

#include <windows.h> #include <math.h> #define TWO_PI (2.0 * 3.14159) LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ; HDC hdc1; HBITMAP hBm; int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow) { static TCHAR szAppName[] = TEXT ("Clover") ; HWND hwnd ; MSG msg ; WNDCLASS wndclass ; wndclass.style = CS_HREDRAW | CS_VREDRAW ; wndclass.lpfnWndProc= WndProc ; wndclass.cbClsExtra = 0 ; wndclass.cbWndExtra = 0 ; wndclass.hInstance = hInstance ; wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION) ; wndclass.hCursor = LoadCursor (NULL, IDC_ARROW) ; wndclass.hbrBackground= (HBRUSH) GetStockObject (WHITE_BRUSH) ; wndclass.lpszMenuName = NULL ; wndclass.lpszClassName= szAppName ; if (!RegisterClass (&wndclass)) { MessageBox (NULL, TEXT ("This program requires Windows NT!"), szAppName, MB_ICONERROR) ; return 0 ; } hwnd = CreateWindow (szAppName, TEXT ("Draw a Clover"), WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, 800,800, NULL, NULL, hInstance, NULL) ; ShowWindow (hwnd, iCmdShow) ; UpdateWindow (hwnd) ; SetTimer(hwnd, 1, 1000, NULL); while (GetMessage (&msg, NULL, 0, 0)) { TranslateMessage (&msg) ; DispatchMessage (&msg) ; } return msg.wParam ; } LRESULT CALLBACK WndProc (HWND hwnd, UINT iMsg, WPARAM wParam, LPARAM lParam) { static HRGN hRgnClip ; static int cxClient, cyClient ; double fAngle, fRadius ; HCURSOR hCursor ; HPEN hPen; HDC hdc ; HBRUSH hBrush; HRGN hRgnTemp[6] ; int i ; RECT rcClient; PAINTSTRUCT ps ; switch (iMsg) { case WM_SIZE: cxClient = LOWORD (lParam) ; cyClient = HIWORD (lParam) ; hCursor= SetCursor (LoadCursor (NULL, IDC_WAIT)) ; ShowCursor (TRUE) ; if (hRgnClip) DeleteObject (hRgnClip) ; hRgnTemp[0] = CreateEllipticRgn (0, cyClient / 3, cxClient / 2, 2 * cyClient / 3) ; hRgnTemp[1] = CreateEllipticRgn (cxClient / 2, cyClient / 3, cxClient, 2 * cyClient / 3) ; hRgnTemp[2] = CreateEllipticRgn (cxClient / 3, 0, 2 * cxClient / 3, cyClient / 2) ; hRgnTemp[3] = CreateEllipticRgn (cxClient / 3, cyClient / 2, 2 * cxClient / 3, cyClient) ; hRgnTemp[4] = CreateRectRgn (0, 0, 1, 1) ; hRgnTemp[5] = CreateRectRgn (0, 0, 1, 1) ; hRgnClip = CreateRectRgn (0, 0, 1, 1) ; CombineRgn (hRgnTemp[4], hRgnTemp[0], hRgnTemp[1], RGN_OR) ; CombineRgn (hRgnTemp[5], hRgnTemp[2], hRgnTemp[3], RGN_OR) ; CombineRgn (hRgnClip, hRgnTemp[4], hRgnTemp[5], RGN_XOR) ; for (i = 0 ; i < 6 ; i++) DeleteObject (hRgnTemp[i]) ; SetCursor (hCursor) ; ShowCursor (FALSE) ; return 0 ; case WM_PAINT: hdc = BeginPaint (hwnd, &ps) ; hBm = CreateCompatibleBitmap(hdc,cxClient,cyClient); //创建虚拟位图 hdc1 = CreateCompatibleDC(hdc); //创建和hdc兼容的设备 SelectObject(hdc1,hBm); //选择虚拟画布 hPen = CreatePen(PS_SOLID,1,RGB(rand()%255,rand()%255,rand()%255)); SetViewportOrgEx (hdc1, cxClient / 2, cyClient / 2, NULL) ; SelectClipRgn (hdc1, hRgnClip) ; SelectObject(hdc1,hPen); fRadius = _hypot (cxClient / 2.0, cyClient / 2.0) ; for (fAngle = 0.0 ; fAngle < TWO_PI ; fAngle += TWO_PI / 360) { MoveToEx (hdc1, 0, 0, NULL) ; LineTo (hdc1, (int) ( fRadius * cos (fAngle) + 0.5), (int) (-fRadius * sin (fAngle) + 0.5)) ; } DeleteObject(hPen); BitBlt(hdc,0,0,cxClient,cyClient,hdc1,-cxClient/2,-cyClient/2,SRCCOPY); //源矩形坐标和目标矩形坐标要设置好！把虚拟画布的内容直接拷贝到hdc中。 DeleteObject(hBm); EndPaint (hwnd, &ps) ; return 0 ; case WM_ERASEBKGND : // return 0; break; case WM_TIMER : if (wParam == 1) { InvalidateRect(hwnd,NULL,FALSE); } break; case WM_DESTROY: DeleteObject (hRgnClip) ; PostQuitMessage (0) ; return 0 ; } return DefWindowProc (hwnd, iMsg, wParam, lParam) ; }