MFC 随机矩形

while (GetMessage(&msg, NULL, 0, 0))
    {
        if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
    }

    while(TRUE)
    {
        if(PeekMessage(&msg,NULL,0,0,PM_REMOVE))
        {
            if(msg.message == WM_QUIT)
                break;
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
        else
            DrawRctangle(hWnd);
    }

// peekmessage.cpp : 定义应用程序的入口点。
//

#include "stdafx.h"
#include "peekmessage.h"
#include <Windows.h>
#include <stdlib.h>

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

int cxClient,cyClient;

int WINAPI  WinMain(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     LPTSTR    lpCmdLine,
                     int       nCmdShow)
{
     // TODO: 在此放置代码。
    HWND hWnd;
    static TCHAR szAppName[] = TEXT("RandRect");
    MSG msg;
    WNDCLASS wcex;

    wcex.style            = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc    = WndProc;
    wcex.cbClsExtra        = 0;
    wcex.cbWndExtra        = 0;
    wcex.hInstance        = hInstance;
    wcex.hIcon            = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_PEEKMESSAGE));
    wcex.hCursor        = LoadCursor(NULL, IDC_ARROW);
    wcex.hbrBackground    = (HBRUSH)(COLOR_WINDOW+1);
    wcex.lpszMenuName    = NULL;
    wcex.lpszClassName    = szAppName;

    if (!RegisterClass(&wcex))
    {
        MessageBox(NULL,TEXT("this program requires Windows ",szAppName,MB_ICONERROR);
        return 0;
    }
    
    hWnd = CreateWindow(szAppName,TEXT("Random Rectangles"),WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT,CW_USEDEFAULT,CW_USEDEFAULT,CW_USEDEFAULT,NULL,NULL,hInstance,NULL);

    ShowWindow(hWnd,nCmdShow);
    UpdateWindow(hWnd);

    
    while(TRUE)
    {
        if(PeekMessage(&msg,NULL,0,0,PM_REMOVE))
        {
            if(msg.message == WM_QUIT)
                break;
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
        else
            DrawRctangle(hWnd);
    }

    return (int) msg.wParam;
}

void DrawRctangle(HWND hWnd)
{
    HBRUSH hBrush;
    HDC hdc;
    RECT rect;

    if(cxClient == 0 || cyClient == 0)
        return;
    SetRect(&rect,rand()%cxClient,rand()%cyClient,rand()%cxClient,rand()%cyClient);
    hBrush = CreateSolidBrush(
            RGB(rand()%256,rand()%256,rand()%256)
        );
    hdc = GetDC(hWnd);
    FillRect(hdc,&rect,hBrush);
    ReleaseDC(hWnd,hdc);
    DeleteObject(hBrush);
}

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch(message)
    {
    case WM_SIZE:
        cxClient = LOWORD(lParam);
        cyClient = HIWORD(wParam);
        return 0;
    case WM_DESTROY:
        PostQuitMessage(0);
        return 0;
    }
    return DefWindowProc(hWnd,message,wParam,lParam);
}