Windows GDI 映射模式（出自：Windows程序设计第5版－珍藏版）

GDI映射模式(mapping mode):
和映射模式紧密相关的还有4个其它的设备环境属性：
1.窗口原点(window origin)
2.视口原点(viewport origin)
3.窗口范围(window extents)
4.视口范围(viewport extents)
所有GDI函数中(如TextOut),参数坐标值都是“逻辑单位(logical unit)”, Windows必须将逻辑单位转换为“设备单位(device unit)”
Windows定义了8种映射模式。他们在WINGDI.H中定义的标识符如下表示.

映射模式被定义为从“窗口”(window)(逻辑坐标)到“视口”(viewport)(设备坐标)的映射。

测试代码：

//
//  FUNCTION: WndProc(HWND, UINT, WPARAM, LPARAM)
//
//  PURPOSE:  Processes messages for the main window.
//
//  WM_COMMAND	- process the application menu
//  WM_PAINT	- Paint the main window
//  WM_DESTROY	- post a quit message and return
//
//
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	static int cxClient,cyClient;
	int wmId, wmEvent;
	PAINTSTRUCT ps;
	HDC hdc;

	switch (message)
	{
	case WM_SIZE:
		cxClient = LOWORD(lParam);
		cyClient = HIWORD(lParam);
		return 0;
	case WM_COMMAND:
		wmId    = LOWORD(wParam);
		wmEvent = HIWORD(wParam);
		// Parse the menu selections:
		switch (wmId)
		{
		case IDM_ABOUT:
			DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About);
			break;
		case IDM_EXIT:
			DestroyWindow(hWnd);
			break;
		default:
			return DefWindowProc(hWnd, message, wParam, lParam);
		}
		break;
	case WM_PAINT:
		hdc = BeginPaint(hWnd, &ps);
		// TODO: Add any drawing code here...

		/*
		//SetMapMode(hdc,MM_ISOTROPIC);
		SetMapMode(hdc,MM_ANISOTROPIC);		//会拉伸
		SetWindowExtEx(hdc, 32767,32767,NULL);
		SetViewportExtEx(hdc,cxClient,-cyClient,NULL);
		SetViewportOrgEx(hdc,0,cyClient,NULL);
		//MoveToEx(hdc,0,0,NULL);
		LineTo(hdc,32767,32767);
		*/

		SetMapMode(hdc,MM_ISOTROPIC);
		SetWindowExtEx(hdc,1000,1000,NULL);
		SetViewportExtEx(hdc,cxClient/2,-cyClient/2,NULL);
		//(xWinOrg,yWinOrg),(xViewOrg,yViewOrg) 均默认为(0,0)
		//SetWindowOrgEx(hdc,cxClient/2,cyClient/2,NULL);
		SetViewportOrgEx(hdc,cxClient/2,cyClient/2,NULL);

		Rectangle(hdc,-200,-200,200,200);
		MoveToEx(hdc,-200,-200,NULL);
		LineTo(hdc,200,200);

		//Window偏移
		SetWindowOrgEx(hdc,-50,-50,NULL);
		Rectangle(hdc,-200,-200,200,200);

		EndPaint(hWnd, &ps);
		break;
	case WM_DESTROY:
		PostQuitMessage(0);
		break;
	default:
		return DefWindowProc(hWnd, message, wParam, lParam);
	}
	return 0;
}