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：

 1 #include <windows.h>
 2
 3 LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);
 4
 5
 6 int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTR lpCmdLine,int iCmdShow)
 7 {
 8     static TCHAR szAppName[]=TEXT("RGB_SRCPAINT");
 9     HWND hWnd;
10     MSG msg;
11     WNDCLASS wc= {sizeof(WNDCLASS)};
12     wc.style=CS_HREDRAW|CS_VREDRAW;
13     wc.lpfnWndProc=WndProc;
14     wc.cbClsExtra=0;
15     wc.cbWndExtra=0;
16     wc.hInstance=hInstance;
17     wc.hIcon=LoadIcon(NULL,IDI_APPLICATION);
18     wc.hCursor=LoadCursor(NULL,IDC_ARROW);
19     wc.hbrBackground=(HBRUSH)GetStockObject(WHITE_BRUSH);
20     wc.lpszMenuName=NULL;
21     wc.lpszClassName=szAppName;
22     if(!RegisterClass(&wc)) {
23         MessageBox(NULL,TEXT("error"),szAppName,MB_ICONERROR|MB_OK);
24         return 0;
25     }
26     hWnd=CreateWindow(szAppName,TEXT("RGB"),WS_OVERLAPPEDWINDOW,
27                       320,120,500,500,NULL,NULL,hInstance,NULL);
28
29     //
30     ShowWindow(hWnd,iCmdShow);
31     UpdateWindow(hWnd);
32     while(GetMessage(&msg,NULL,0,0)) {
33         TranslateMessage(&msg);
34         DispatchMessage(&msg);
35     }
36     return msg.wParam;
37 }
38 //
39 void Circle(HDC dc,int ox,int oy,int r)
40 {
41     Ellipse(dc,ox-r,oy-r,ox+r,oy+r);
42 }
43 //
44 LRESULT CALLBACK WndProc(HWND hWnd,UINT message,WPARAM wParam,LPARAM lParam)
45 {
46     //
47     HDC hdc,hMemDC;
48     HBITMAP hBitmap;
49     HBRUSH hbrush;
50     RECT rc= {0,0,500,500};
51     PAINTSTRUCT ps;
52     int ox=250,oy=210,r=100;
53     //
54     switch (message) {
55     case   WM_PAINT :
56         hdc=BeginPaint(hWnd,&ps);
57         //MemDC
58         hMemDC = CreateCompatibleDC(hdc);
59         hBitmap = CreateCompatibleBitmap(hdc,500,500);
60         SelectObject(hMemDC,hBitmap);
61         //ClearScreen with  Black
62         hbrush = CreateSolidBrush(RGB(0, 0, 0));
63         SelectObject(hMemDC,hbrush);
64         FillRect(hdc,&rc,hbrush);
65         //RED
66         hbrush = CreateSolidBrush(RGB(255, 0, 0));
67         SelectObject(hMemDC,hbrush);
68         //Ellipse(hMemDC,0+200,0+200+30,100+200,100+200+30);
69         Circle(hMemDC,ox,oy+0.8*r,r);
70         BitBlt(hdc,0,0,500,500,hMemDC,0,0,SRCPAINT);
71         //GREEN
72         hbrush = CreateSolidBrush(RGB(0, 255, 0));
73         SelectObject(hMemDC,hbrush);
74         //Ellipse(hMemDC,0+200-26,0+200-15,100+200-26,100+200-15);
75         Circle(hMemDC,ox-0.866*0.8*r,oy-0.5*0.8*r,r);
76         BitBlt(hdc,0,0,500,500,hMemDC,0,0,SRCPAINT);
77         //BLUE
78         hbrush = CreateSolidBrush(RGB(0, 0, 255));
79         SelectObject(hMemDC,hbrush);
80         //Ellipse(hMemDC,0+200+26,0+200-15,100+200+26,100+200-15);
81         Circle(hMemDC,ox+0.866*0.8*r,oy-0.5*0.8*r,r);
82         BitBlt(hdc,0,0,500,500,hMemDC,0,0,SRCPAINT);
83         //
84         DeleteObject(hBitmap);
85         DeleteDC( hMemDC );
86         EndPaint (hWnd, &ps) ;
87
88         break;
89     case WM_DESTROY :
90         PostQuitMessage(0);
91         break ;
92     }
93     return DefWindowProc (hWnd, message, wParam, lParam) ;
94 }