//设置映像与使用映像模式实例，本例中的程序运行时，初始阶段按模式MM_TEXT绘图,图形为一个坐标系,
//以逻辑坐标系的原点为原点,X,Y轴分别是逻辑坐标系的X,Y轴.当用户按下'A'键,'B'键或'C'键时,产生
//WM_CHAR消息,将映像模式分别设置为ISOTROPIC,ANISOTROPIC或LOMETRIC,同时调用InvalidateRect函数
//刷新用户区。

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

int WINAPI WinMain
       (
    HINSTANCE hInstance,
    HINSTANCE hPrevInst,
    LPSTR lpszCmdLine,
    INT nCmdShow
    )
{
 HWND hwnd;
 MSG Msg;
 WNDCLASS wndclass;
 char lpszClassName[]="Drawing";
 char lpszTitle[]="My_Drawing";

 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=(HBRUSH)GetStockObject(WHITE_BRUSH);
 wndclass.lpszClassName=lpszClassName;
 wndclass.lpszMenuName=NULL;
 wndclass.style=0;

 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);
 UpdateWindow(hwnd);

 while(GetMessage(&Msg,NULL,0,0))
 {
  TranslateMessage(&Msg);
  DispatchMessage(&Msg);
 }
    return Msg.wParam;
}
LRESULT CALLBACK WndProc(HWND hwnd,UINT message,WPARAM wParam,LPARAM lParam)
{
 HDC hdc;
 PAINTSTRUCT ps;
 HPEN hPen;
 
 switch(message)
 {
 case WM_CHAR:
  if(wParam=='a'||wParam=='A') nMode=MM_ISOTROPIC;
  if(wParam=='b'||wParam=='B') nMode=MM_ANISOTROPIC;
  if(wParam=='c'||wParam=='C') nMode=MM_LOMETRIC;
  if(wParam=='s'||wParam=='S') nMode=MM_LOENGLISH;
  if(wParam=='d'||wParam=='D') nMode=MM_TWIPS;
  InvalidateRect(hwnd,NULL,1);
  break;
 case WM_PAINT:
  hdc=BeginPaint(hwnd,&ps);
  SetMapMode(hdc,nMode);
  SetWindowExtEx(hdc,15,15,NULL);
  SetViewportExtEx(hdc,15,10,NULL);
  SetViewportOrgEx(hdc,120,120,NULL);
   hPen=CreatePen(PS_SOLID,2,RGB(255,0,0));
  SelectObject(hdc,hPen);
  LineTo(hdc,200,0);
  LineTo(hdc,195,-5);
  MoveToEx(hdc,200,0,NULL);
  LineTo(hdc,195,5);
  MoveToEx(hdc,0,0,NULL);
  LineTo(hdc,0,200);
  LineTo(hdc,-5,195);
  MoveToEx(hdc,0,200,NULL);
  LineTo(hdc,5,195);
  DeleteObject(hPen);
  EndPaint(hwnd,&ps);
  break;
 case WM_DESTROY:
  PostQuitMessage(0);
  break;
 default:
  return DefWindowProc(hwnd,message,wParam,lParam);
  break;
    }
 return 0;
}