Does CClientDC represent the device environment of the entire window?

You're talking about DC, right, the device environment is commonly said to be the attributes of drawing or entering text and other operations, such as background color, brush color, background mode, text color, etc., there is a default at the beginning, you can change it, such as the default text color is black, you can change it to red, etc.

You're talking about the Device Description Table (DC), a struct that contains information about the device!

It's nothing to do with MFC. CclientDC ends up using the GDI library, which is not very performant, but can also be used for games. The main thing is that you have to do double cushioning.

You can make a background buffer in memory, where you can draw everything you want to draw, and then bitblt it to the window. This can significantly improve performance.

It's about it, but it doesn't matter much to you.

The program you're writing isn't powerful enough to run on a graphics card.

It's your design that's problematic with double cushioning or something

3. Wrong. The exception is static member functions. Whether a parent or derived class pointer, you must point to an instantiated object in order to call a non-static member function of a class.

9. The same three truths. Except for static members.

1.Right.

2.Right. 3.False, a pointer to the parent class can also operate on the derived class, polymorphic 4Right.

5.Right. 6.Wrong.

7.Wrong. 8.Wrong.

9.Right. 10.Right.

1As long as there is an invalid field, it will be redrawn, there is wm paint, endpaint() is to eliminate the invalid field, the priority of wm paint message is very low, the system will superimpose several wm paint invalid fields, 2The most common program of the windows system, composed of two windows, one is the main window, the other is the view window, which is the white part in the middle of the notepad, the view window is in front, covering the main window, and the menu title bar is not covered, So you see most of the view windows.

cwindowdc gets the upper left corner of the title bar, and cclientdc gets the view window, which is the white upper left corner in the middle of notepad.

getdc() is based on the class, and the main window gets the windowdc

Isn't it those toolbars, menu bars and even title bars that will be doodled by me.

Yes, but not elsewhere.

The reason for this is that the view window is in front, covering the main window.

1: It will be sent when it needs to be redrawn, such as window zoom, masking, etc. 2: Represents the upper left corner of the responsive window (including the title bar).

3: getdc only gets the client area of the given window, and gets the whole window with getwindowdc

4: View window refers to the CVIEW client area window.

What you mean by this is that when the left mouse button is pressed, get the invalid area of the current window 62616964757a686964616fe58685e5aeb931333332393362

From the above literal understanding Since you want to get the invalid area of a window, you first have to have a window, right? Which window is the window of your cmyview class This class is derived from the cwnd class, so it's a window class Now that we know which window it is, we have to notify the program (here it's actually the device context object) What I want to get is the invalid area of this window The thing that represents a window in windows is the handle hwnd this thing Each of these things points to a window, and when the window is generated, That is, when creating a window with create, it will return a hwnd This hwnd represents this window, just like a pointer In c the handle is encapsulated by the class, in other words, each window class derived from cwnd has its own m hwnd member, which holds the handle of the window represented by the object defined by the class, and to put it simply, to find this class member, that is, to find this handle, to find this handle, that is, to find this window And this is a pointer to the class itself, and if you have learned C++**, then you should understand that if you have a pointer to an object, then you will naturally find this object

cclientdc dc(this);Establish a device context object to get an invalid area of a window Which window? The window represented by the object that this points to Each object saves a m hwnd member, pointing to the window created by this object When you call dc(this), the class will automatically give this m hwnd member to the device context So this here is actually passing itself, in order to get the m hwnd in its own object in order to get which window you want to operate

If you still don't understand, then don't ask.

This represents the BAI object.

pointer, du

In the ** you posted, zha is the pointer to the cmyview object. DAOCCendudDc DC(this) stands for a device context object that creates a reply back to the object associated with this pointer, i.e., the device context object associated with CMYVIEW.

A pointer to the window object.

Device Context = Device Context

device is the associated device. An object that is necessary to interact with the hardware or software environment during programming. To acquire him, to access him, to modify him, is to operate hardware or software.