画刷练习

先明白一个概念：句柄并不一定是指针， 是资源的索引。。。
句柄  
          通常来说，句柄是对内部对象的索引。  
          它有可能是一个编号，  
          也有可能是一个对象指针，  
          对于不同系统，实现方式是不一样的。  
   
          对于使用者来说，不管句柄是否是指象对象的指针，都不要去当指针来引用。因为，首先，该对象的结构通常是不公开的；其次，即使你知道对象的结构，它也有可能在将来的版本中发生改变。而这些也是设计者使用句柄的原因。  
          《未公开的Winddows技术》一书对于Windows的句柄及其它对象的结构有相当篇幅的描述。

#include <windows.h>

LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain(HINSTANCE hInstance,
                 HINSTANCE hPrevInstance,
                 PSTR szCmdLine,
                 int iCmdShow) {
    static TCHAR szAppName[] = TEXT("MyBrush");
    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 = GetStockObject(WHITE_BRUSH);
    wndclass.lpszMenuName = NULL;
    wndclass.lpszClassName = szAppName;
    
    if(!RegisterClass(&wndclass)) {
        MessageBox(NULL, TEXT("Register failure..."),
            szAppName, MB_ICONERROR);
        return 0;
    }
    
    hwnd = CreateWindow(szAppName,
        szAppName,
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        NULL,
        NULL,
        hInstance,
        NULL);
    
    ShowWindow(hwnd, iCmdShow);
    UpdateWindow(hwnd);
    
    while(GetMessage(&msg, NULL, 0, 0)) {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return msg.wParam;
}

void CreateMyBrush(int i, HBRUSH* hhBrush) {
    LOGBRUSH logBrush;
    switch(i) {
    case 0:
        *hhBrush = CreateSolidBrush(RGB(255, 0, 0));
        break;
    case 1:
        *hhBrush = CreateSolidBrush(RGB(0, 255, 0));
        break;
    case 2:
        *hhBrush = CreateHatchBrush(HS_DIAGCROSS, RGB(0, 0, 255));
        break;
    case 3:
        *hhBrush = CreateHatchBrush(HS_CROSS, RGB(0, 255, 255));
        break;
    case 4:
        *hhBrush = CreateHatchBrush(HS_HORIZONTAL, RGB(255, 255, 0));
        break;
    case 5:
        *hhBrush = CreateHatchBrush(HS_VERTICAL, RGB(122, 23, 32));
        break;
    case 6:
        logBrush.lbStyle = BS_SOLID;
        logBrush.lbColor = RGB(32, 232, 23);
        *hhBrush = CreateBrushIndirect(&logBrush);
        break;
    case 7:
        logBrush.lbStyle = BS_HATCHED;
        logBrush.lbColor = RGB(122, 34, 245);
        logBrush.lbHatch = HS_CROSS;
        *hhBrush = CreateBrushIndirect(&logBrush);
    default:
        *hhBrush = GetStockObject(BLACK_BRUSH);
        break;
    }
}

LRESULT CALLBACK WndProc(HWND hwnd,
                         UINT message,
                         WPARAM wParam,
                         LPARAM lParam) {
    static int cxClient, cyClient;
    PAINTSTRUCT ps;
    HBRUSH hBrush;
    HDC hdc;
    int i, j;
    
    switch(message) {
    case WM_SIZE:
        cxClient = LOWORD(lParam);
        cyClient = HIWORD(lParam);
        return 0;
        
    case WM_PAINT:
        hdc = BeginPaint(hwnd, &ps);
        
        for(i = 0; i < 10; i += 1)
            for(j = 0; j < 10; j += 1) {
                CreateMyBrush((i + j) % 8, &hBrush);
                SelectObject(hdc, hBrush);
                Rectangle(hdc, i * cxClient / 10, j * cyClient / 10,
                    (i + 1) * cxClient / 10, (j + 1) * cyClient / 10);
                DeleteObject(hBrush);
            }
            EndPaint(hwnd, &ps);
            return 0;
            
    case WM_DESTROY:
        PostQuitMessage(0);
        return 0;
    }
    return DefWindowProc(hwnd, message, wParam, lParam);
}