API简单绘图2

#include<windows.h>
#include<string.h>
#include<stdlib.h>
#include<stdio.h>
LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);

int WINAPI WinMain
(
 HINSTANCE hInstance,
 HINSTANCE hPrevInst,
 LPSTR lpszCmdLine,
 int nCmdShow
 )
{
 HWND hwnd;
 MSG Msg;
 WNDCLASS wndclass;
 char lpszClassName[]="映象模式";
 char lpszTitle[]="My_Map_Mode";

 wndclass.style=0;
 wndclass.lpfnWndProc=WndProc;
 wndclass.cbClsExtra=0;
 wndclass.cbClsExtra=0;
 wndclass.hInstance=hInstance;
 wndclass.hIcon=LoadIcon(NULL,IDI_APPLICATION);
 wndclass.hCursor=LoadCursor(NULL,IDC_ARROW);
 wndclass.hbrBackground=(HBRUSH)(GetStockObject(WHITE_BRUSH));
 wndclass.lpszClassName=NULL;
 wndclass.lpszClassName=lpszClassName;

 if(!RegisterClass(&wndclass))
 {
  MessageBeep(0);
  return FALSE;
 }

 hwnd=CreateWindow
  (
  lpszClassName,
  lpszTitle,
  WS_OVERLAPPEDWINDOW,
  CW_USEDEFAULT,
  CW_USEDEFAULT,
  CW_USEDEFAULT,
  CW_USEDEFAULT,
  NULL,
  NULL,
  hInstance,
  NULL
  );
 ShowWindow(hwnd,nCmdShow);//显示窗口
 UpdateWindow(hwnd);//绘制用户区
 while(GetMessage(&Msg,NULL,0,0)) //消息循环
 {
  TranslateMessage(&Msg);
  DispatchMessage(&Msg);
 }
 return Msg.wParam;//消息循环结束时将消息返回系统
}

LRESULT CALLBACK WndProc  //窗口函数
(HWND hwnd,
 UINT message,
 WPARAM wParam,
 LPARAM lParam
 )
{
 HDC hdc;
 PAINTSTRUCT ps;
 HBRUSH hB1,hB2;
 int nMode;  //定义映象模式变量nMode

 switch(message)
 {
 case WM_CREATE:     //窗口创建时设置映象模式为MM_TEXT
  nMode=MM_TEXT;
 case WM_LBUTTONDOWN: //单击鼠标左键更改映象模式为MM_ISOTROPIC
  nMode=MM_ISOTROPIC;
  InvalidateRect(hwnd,NULL,1);//刷新用户区
  break;
 case WM_RBUTTONDOWN://单击鼠标右键更改显示模式为MM_ANISOTROPIC
  nMode=MM_ANISOTROPIC;
  InvalidateRect(hwnd,NULL,1);//刷新用户区
 case WM_PAINT:
  hdc=BeginPaint(hwnd,&ps);//取得设备环境句柄
  SetMapMode(hdc,nMode);//设置映象模式
  SetWindowExtEx(hdc,150,150,NULL);//设置窗口区域
  SetViewportExtEx(hdc,150,100,NULL);//设置视口原点
  hB1=(HBRUSH)(GetStockObject(WHITE_BRUSH));//定义白色画刷
  hB2=(HBRUSH)(GetStockObject(BLACK_BRUSH));//定义黑色画刷
  SelectObject(hdc,hB1);//将黑白画刷选入设备环境
  RoundRect(hdc,0,0,150,150,30,30);//使用当前画笔绘制一个带圆角的矩形，并用当前画刷填充

  SelectObject(hdc,hB2);//更改当前画刷为黑色画刷
  Ellipse(hdc,0,10,150,140);//使用当前画笔绘制椭圆
                            //并用当前画刷填充
  EndPaint(hwnd,&ps);//释放设备环境句柄
  break;
 case WM_DESTROY:
  DeleteObject(hB1);  //退出窗口时删除画刷
  DeleteObject(hB2);
  PostQuitMessage(0);
  break;
 default:
  return DefWindowProc(hwnd,message,wParam,lParam);
 }
 return 0;
}