Usage of virtual functions created and destroyed in the dialog box

The creation and destruction process of a non-Modal Dialog Box differs from that of a modal dialog box.

Let's take a look at the original msdn text:

When you implement a modeless dialog box, always override the oncancel member function and call destroywindow from within it. don't call the base class cdialog: oncancel, because it callenddialog, which will make the dialog box invisible but will not destroy it. you shoshould also override postncdestroy for modeless dialog boxes in order to delete this, since modeless dialog boxes are usually allocated with new. modal Dialog Boxes are usually constructed on the frame and do not need postncdestroy cleanup.

Ms instructions: the non-modal dialog box needs to overload the oncanel function and call destroywindow in this function. The oncancel of the base class cannot be called because the oncancel of the base class calls the enddialog function, which is for the modal dialog box.
Another function that must be overloaded is postncdestroy, which is also a virtual function. The non-modal dialog box is usually created using a class pointer through new, in this case, delete the pointer in the postncdestroy function.

After learning about the theory, we can useCodeTo create and destroy a non-modal dialog box:
// Create
// In the main framework:
Ctestdlg * pdlg = new ctestdlg;
Pdlg-> Create (idd_testdlg, this );
Pdlg-> showwindow (sw_show );

// In the dialog box:
Void ctestdlg: oncancel ()
{
Destroywindow ();
}

Void ctestdlg: postncdestroy ()
{
Cdialog: postncdestroy ();
Delete this;
}

To destroy the non-modal dialog box when you click the button, you only need to map the event of the button to the oncancel function.

The destruction sequence of the non-modal dialog box is as follows:

MFC ApplicationProgramThe order in which messages are processed

1. afxwndproc () This function is used to receive messages, locate the cwnd object to which the message belongs, and then call afxcallwndproc.

2. afxcallwndproc () This function is used to save messages (the content mainly contains message identifiers and message parameters) for future use,
Then call the windowproc () function.

3. windowproc () this function is responsible for sending messages to the onwndmsg () function. If not processed, call the defwindowproc () function.

4. onwndmsg () This function first sorts messages by byte. For wm_command messages, the oncommand () Message
response function is called, and for wm_notify messages
onnotify () message response function. Any missed message is a window message. The onwndmsg () function searches
the message image of the cable class to find a processing function that can process any window message. If the onwndmsg () function cannot find such a processing function,
return the message to the windowproc () function, which sends the message to the defwindowproc () function

5. oncommand () This function checks whether this is a control notification (the lparam parameter is not null. If the lparam parameter is null, it indicates
the message is not a control notification). If it is, the oncommand () function tries to map messages to the control that creates notifications.
if it is not a control notification (or if the control rejects the mapped message) oncommand () the on1_msg () function is called.

6. Based on the class that receives messages, the onreceivmsg () function is potentially used in a process called command routing.
Send command messages and control notifications.
For example, if the class that owns the window is a framework class, the command and notification messages are also transmitted to the view and document class for
Class to find a message processing function

The process of creating an MFC application window

1. precreatewindow () this function is an overload function. You can change the creation parameters in this overload function before the window is created.
(You can set the window style and so on)

2. presubclasswindow (), which is also an overload function that allows subclassification of a window.

3. ongetminmaxinfo () this function is a message response function that responds to a wm_getminmaxinfo message and allows you to set the maximum or
Minimum Size

4. onnccreate () this function is also a message response function. It responds to the wm_nccreate message and sends a message to notify the customer zone of the window.
To be created soon

5. onnccalcsize () this function is also a message response function. It responds to the wm_nccalcsize message and allows you to change the size of the window client.

6. oncreate () this function is also a message response function. It responds to the wm_create message and sends a message to indicate that a window has been created.

7. onsize () this function is also a message response function that responds to the wm_size message and sends the message to indicate that the window size has been
Changed

8. The onmove () Message response function responds to the wm_move message. sending this message indicates that the window is moving

9. onchildnotify () this function is a heavy-duty function and is called as part of message ing to notify the parent window that a window has just been
Create

The order in which the MFC application closes the window (non-modal window)

1. onclose () Message response function. The wm_close message in the response window is sent when the close button is clicked.

2. ondestroy () Message response function, which refers to the wm_destroy message in the response window. When a window is destroyed, this message is sent.

3. onncdestroy () Message response function, which refers to the wm_ncdestroy message in the response window. This message is sent when a window is destroyed.

4. The postncdestroy () overload function is called by cwnd as the final action for processing the onncdestroy () function.

Order of function calls in the open mode dialog box in the MFC Application

1. domodal () overload function, overload domodal () member function

2. The presubclasswindow () overload function allows users to classify a window first.

3. The oncreate () Message response function responds to the wm_create message and sends this message to indicate that a window has been created.

4. The onsize () Message response function responds to the wm_size message and sends the message to notify the window size of the change.

5. The onmove () Message response function responds to the wm_move message and sends the message to notify the window that it is moving.

6. The onsetfont () Message response function responds to the wm_setfont message and sends the message to allow the font of the control in the dialog box to be changed.

7. The oninitdialog () Message response function responds to the wm_initdialog message and sends this message to allow the control in the initialization dialog box,
Or create a new control.

8. The onshowwindow () Message response function responds to the wm_showwindow message, which is called by the showwindow () function.

9. The onctlcolor () Message response function responds to the wm_ctlcolor message and is sent by the parent window to the changed dialog box or the control above the dialog box
Color

10. The onchildnotify () overload function is sent as the result of the wm_ctlcolor message.

Order of the close mode dialog box in the MFC Application

1. The onclose () Message response function responds to the wm_close message. When the "close" button is clicked, the function is called.

2. The onkillfocus () Message response function responds to the wm_killfocus message. It is sent when a window is about to lose the keyboard input focus.

3. The ondestroy () Message response function responds to the wm_destroy message. When a window is about to be destroyed, it is sent.

4. The onncdestroy () Message response function responds to the wm_ncdestroy message and is sent after a window is destroyed.

5. The postncdestroy () overload function is called by cwnd as the final action for processing the onncdestroy () function.

Order of opening the modeless dialog box

1. The presubclasswindow () overload function allows users to subclassify a window first

2. The oncreate () Message response function responds to the wm_create message and sends this message to indicate that a window has been created.

3. The onsize () Message response function responds to the wm_size message and sends the message to notify the window size of the change.

4. The onmove () Message response function responds to the wm_move message and sends the message to notify the window that it is moving.

5. The onsetfont () Message response function responds to the wm_setfont message and sends this message to allow the font of the control in the dialog box to be changed.

All the preceding operations are performed in the given order!