随机画图的实现

#include<windows.h>
#include <time.h>
//声明WndProc()函数
#define IDC_TIMER 100
LRESULT CALLBACK WndProc(
 HWND hwnd,UINT message,
 WPARAM wParam,
 LPARAM lParam);
//编写WinMain()主函数

int randomize();
int random(int);

int WINAPI WinMain(HINSTANCE hInstance,
     HINSTANCE hPrevInstance,
     LPSTR lpCmdLine,
     int nCmdShow)
{
 randomize();
 WNDCLASS wndclass;         //定义窗口类结构变量
 HWND hwnd;            //定义窗口句柄
 MSG msg;           //定义消息结构变量
 char lpszClassName[]="自己创建的窗口";

 //设计窗口类型
 wndclass.style = CS_HREDRAW|CS_VREDRAW;      //改变窗口大小则重画
 wndclass.lpfnWndProc = WndProc;       //窗口函数为WndProc
 wndclass.cbClsExtra = 0;         //窗口类无扩展
 wndclass.cbWndExtra = 0;        //窗口实例无扩展
 wndclass.hInstance = hInstance;        //注册窗口类实例句柄
 wndclass.hIcon = LoadIcon(NULL,IDI_APPLICATION);   //用箭头光标
 wndclass.hCursor = LoadCursor(NULL,IDC_ARROW); 
 wndclass.hbrBackground = (HBRUSH)(COLOR_WINDOW+1); //背景为白色
 wndclass.lpszMenuName = NULL;        //窗口默认无菜单
 wndclass.lpszClassName =lpszClassName;
int SW_XFS = GetSystemMetrics(SM_CXSCREEN);
 int SW_YFS = GetSystemMetrics(SM_CYSCREEN);
 //注册窗口类型
 if(! RegisterClass(&wndclass))
 return FALSE;

 
 //创建窗口
 hwnd = CreateWindow(lpszClassName,
   "window窗口创建",
   WS_OVERLAPPEDWINDOW,
   CW_USEDEFAULT, CW_USEDEFAULT, 
   CW_USEDEFAULT, CW_USEDEFAULT,
   NULL,
   NULL,
   hInstance,
   NULL);
 //显示并刷新窗口
 ShowWindow(hwnd,nCmdShow); 
 //显示窗口
SetTimer(hwnd,IDC_TIMER,500,NULL);

 UpdateWindow (hwnd);          //更新窗口的客户区
 //消息循环
 while(GetMessage (&msg,NULL,0,0)) 
 {
  TranslateMessage (&msg);         //键盘消息转换
  DispatchMessage (&msg);         //派送消息给窗口函数
 }
 return msg.wParam;           //返回退出值
}
//响应窗口消息
LRESULT CALLBACK WndProc(HWND   hWnd,
    UINT   message,
    WPARAM wParam,
    LPARAM lParam)
{
 static RECT rect;
 static int ww,wh;
 HPEN hOldPen,hNewPen;
 HBRUSH hOldBrush,hNewBrush;
 LOGBRUSH LogBrush;
 HDC hDC;
 COLORREF color;

switch (message)
 {
  case WM_CREATE:
   GetClientRect(hWnd,&rect);
   ww = rect.right-rect.left;
   wh = rect.bottom-rect.top;
   break;
  case WM_SIZE:
   ww = LOWORD(lParam);
   wh = HIWORD(lParam);
   break;

case WM_TIMER:
   hDC = GetDC(hWnd);
   color = RGB(250*random(2),250*random(2),250*random(2));
   hNewPen = CreatePen(PS_SOLID,0,color);
   hOldPen = (HPEN)SelectObject(hDC,hNewPen);
   LogBrush.lbStyle = BS_SOLID;
   LogBrush.lbHatch = HS_CROSS;
   LogBrush.lbColor = color;
   hNewBrush = CreateBrushIndirect(&LogBrush);
   hOldBrush = (HBRUSH)SelectObject(hDC,hNewBrush);
   Ellipse(hDC,random(ww),random(wh),random(ww),random(wh));
   hNewPen = (HPEN)SelectObject(hDC,hOldPen);
   hNewBrush = (HBRUSH)SelectObject(hDC,hOldBrush);

DeleteObject(hNewPen);
   DeleteObject(hNewBrush);
   ReleaseDC(hWnd,hDC);  
   break;
  case WM_DESTROY:
   PostQuitMessage(0);
   break;
  default:
   return DefWindowProc(hWnd,message,wParam,lParam);
 }

return 0;
}

int randomize()
{
 srand((unsigned int)time(NULL));
 return 0;
}

int random(int number)
{
 int rn;
 rn = (int)(((long)rand()*number)/(RAND_MAX+1));
 return rn;
}