1.画线方法
*1.捕获鼠标按下和弹起消息，获取两个点
*2.消息响应，画线
2.在CMainFrame类中的鼠标左键事件得不到响应的原因是CNameView覆盖了CMainFrame
3.注释宏
4.画线方法
*1.HDC
*2.CDC(MFC封装)
*3.CClientDC(不用显式释放资源)
*4.CWindowDC(可以画到非客户区)
5.画线步骤
*1.获取DC
*2.MoveTo到原点
*3.LineTo到目标点
*4.释放DC
6.CPen
构造函数参数：
线类型PS_SOLID等
宽度
颜色
RGB宏，三个参数：红绿蓝颜色值
7.SelectObject
添加设备到设备描述表，返回旧的设备指针，DC成员函数
8.FillRect
画矩形
9.CBrush
画刷，构造函数参数可以是颜色，位图
10.CBitMap
LoadBitmap:
The LoadBitmap function loads the specified bitmap resource from a module's executable file.
HBITMAP LoadBitmap(
HINSTANCE hInstance, // handle of application instance
LPCTSTR lpBitmapName // address of bitmap resource name
);
Parameters
hInstance
Identifies the instance of the module whose executable file contains the bitmap to be loaded.
lpBitmapName
Points to a null-terminated string that contains the name of the bitmap resource to be loaded. Alternatively, this parameter can consist of the resource identifier in the low-order word and zero in the high-order word. The MAKEINTRESOURCE macro can be used to create this value.
Return Values
If the function succeeds, the return value is the handle of the specified bitmap.
If the function fails, the return value is NULL.
Remarks
If the bitmap pointed to by the lpBitmapName parameter does not exist or there is insufficient memory to load the bitmap, the function fails.
An application can use the LoadBitmap function to access the predefined bitmaps used by the Win32 API. To do so, the application must set the hInstance parameter to NULL and the lpBitmapName parameter to one of the following values:
OBM_BTNCORNERS OBM_OLD_RESTORE
OBM_BTSIZE OBM_OLD_RGARROW
OBM_CHECK OBM_OLD_UPARROW
OBM_CHECKBOXES OBM_OLD_ZOOM
OBM_CLOSE OBM_REDUCE
OBM_COMBO OBM_REDUCED
OBM_DNARROW OBM_RESTORE
OBM_DNARROWD OBM_RESTORED
OBM_DNARROWI OBM_RGARROW
OBM_LFARROW OBM_RGARROWD
OBM_LFARROWD OBM_RGARROWI
OBM_LFARROWI OBM_SIZE
OBM_MNARROW OBM_UPARROW
OBM_OLD_CLOSE OBM_UPARROWD
OBM_OLD_DNARROW OBM_UPARROWI
OBM_OLD_LFARROW OBM_ZOOM
OBM_OLD_REDUCE OBM_ZOOMD
Bitmap names that begin with OBM_OLD represent bitmaps used by Windows versions earlier than 3.0.
For an application to use any of the OBM_ constants, the constant OEMRESOURCE must be defined before the WINDOWS.H header file is included.
The application must call the DeleteObject function to delete each bitmap handle returned by the LoadBitmap function.
See Also
CreateBitmap, DeleteObject, LoadCursor, LoadIcon, MAKEINTRESOURCE
11.Rectangle画矩形
12.GetStockObject可以通过NULL_BRUSH获取透明画刷，使矩形不被覆盖
GetStockObject返回画刷句柄，通过CBrush::FromHandle转为CBrush对象指针
13.SetROP2
设置绘画模式
