Win32 RGB三原色

以前看到三原色的图案，一直很好奇是如何画出来。后来终于搞清楚了，其实很简单，实际上就是RGB三个分量的"位与"运算。

下面给出Win32绘制三原色图案的例子，特此记录在此：

 #include <windows.h>

 LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);

 int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTR lpCmdLine,int iCmdShow)

 {

     static TCHAR szAppName[]=TEXT("RGB_SRCPAINT");

     HWND hWnd;

     MSG msg;

     WNDCLASS wc= {sizeof(WNDCLASS)};

     wc.style=CS_HREDRAW|CS_VREDRAW;

     wc.lpfnWndProc=WndProc;

     wc.cbClsExtra=;

     wc.cbWndExtra=;

     wc.hInstance=hInstance;

     wc.hIcon=LoadIcon(NULL,IDI_APPLICATION);

     wc.hCursor=LoadCursor(NULL,IDC_ARROW);

     wc.hbrBackground=(HBRUSH)GetStockObject(WHITE_BRUSH);

     wc.lpszMenuName=NULL;

     wc.lpszClassName=szAppName;

     if(!RegisterClass(&wc)) {

         MessageBox(NULL,TEXT("error"),szAppName,MB_ICONERROR|MB_OK);

         return ;

     }

     hWnd=CreateWindow(szAppName,TEXT("RGB"),WS_OVERLAPPEDWINDOW,

                       ,,,,NULL,NULL,hInstance,NULL);

     //

     ShowWindow(hWnd,iCmdShow);

     UpdateWindow(hWnd);

     while(GetMessage(&msg,NULL,,)) {

         TranslateMessage(&msg);

         DispatchMessage(&msg);

     }

     return msg.wParam;

 }

 //

 void Circle(HDC dc,int ox,int oy,int r)

 {

     Ellipse(dc,ox-r,oy-r,ox+r,oy+r);

 }

 //

 LRESULT CALLBACK WndProc(HWND hWnd,UINT message,WPARAM wParam,LPARAM lParam)

 {

     //

     HDC hdc,hMemDC;

     HBITMAP hBitmap;

     HBRUSH hbrush;

     RECT rc= {,,,};

     PAINTSTRUCT ps;

     int ox=,oy=,r=;

     //

     switch (message) {

     case   WM_PAINT :

         hdc=BeginPaint(hWnd,&ps);

         //MemDC

         hMemDC = CreateCompatibleDC(hdc);

         hBitmap = CreateCompatibleBitmap(hdc,,);

         SelectObject(hMemDC,hBitmap);

         //ClearScreen with  Black

         hbrush = CreateSolidBrush(RGB(, , ));

         SelectObject(hMemDC,hbrush);

         FillRect(hdc,&rc,hbrush);

         //RED

         hbrush = CreateSolidBrush(RGB(, , ));

         SelectObject(hMemDC,hbrush);

         //Ellipse(hMemDC,0+200,0+200+30,100+200,100+200+30);

         Circle(hMemDC,ox,oy+0.8*r,r);

         BitBlt(hdc,,,,,hMemDC,,,SRCPAINT);

         //GREEN

         hbrush = CreateSolidBrush(RGB(, , ));

         SelectObject(hMemDC,hbrush);

         //Ellipse(hMemDC,0+200-26,0+200-15,100+200-26,100+200-15);

         Circle(hMemDC,ox-0.866*0.8*r,oy-0.5*0.8*r,r);

         BitBlt(hdc,,,,,hMemDC,,,SRCPAINT);

         //BLUE

         hbrush = CreateSolidBrush(RGB(, , ));

         SelectObject(hMemDC,hbrush);

         //Ellipse(hMemDC,0+200+26,0+200-15,100+200+26,100+200-15);

         Circle(hMemDC,ox+0.866*0.8*r,oy-0.5*0.8*r,r);

         BitBlt(hdc,,,,,hMemDC,,,SRCPAINT);

         //

         DeleteObject(hBitmap);

         DeleteDC( hMemDC );

         EndPaint (hWnd, &ps) ;

         break;

     case WM_DESTROY :

         PostQuitMessage();

         break ;

     }

     return DefWindowProc (hWnd, message, wParam, lParam) ;

 }