C / C++ / MFC

Blake Miller19-Nov-04 5:25

Blake Miller

19-Nov-04 5:25

GetFileAttributes() check for return of (DWORD)-1

or else

_taccess(<filepath>, 00);

There are others, I use the first one.

22491719-Nov-04 17:19

224917

19-Nov-04 17:19

BOOL FileExists( const char* pszPath );

There is no spoon.

suhredayan

ThatsAlok22-Nov-04 1:18

ThatsAlok

22-Nov-04 1:18

What Happen to Great TOXCCT,Long Time NO SEE

any way Simple Api is

BOOL PathFileExists(<br />
    LPCTSTR pszPath<br />
    );

-----------------------------
"I Think It Will Help"
-----------------------------
Alok Gupta
visit me at http://www.thisisalok.tk

CView derived class in splitter pane

toxcct22-Nov-04 3:06

toxcct

22-Nov-04 3:06

hum, well, could not connect until now... for a short week...

anyway, very thanks to you Mist'Alok Wink | ;)

see you

TOXCCT >>> GEII power

DOC VIEW SDI

act_x19-Nov-04 4:19

act_x

19-Nov-04 4:19

Hi ,
I have a SDI application in which my DOC type is of .xml.

I want to override the standard serialize mechanism to load and Save data but need a handle to the current file (say newDoc1.xml )from within the Doc class as I am externally going to load and save the data using an XML parser object (member of Doc class) . How do I get access to the fileName ?

Thanks

Re: DOC VIEW SDI

David Crow19-Nov-04 5:02

David Crow

19-Nov-04 5:02

act_x wrote:
How do I get access to the fileName ?

Use CDocument::GetPathName().

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

manonthecorner_19-Nov-04 4:06

manonthecorner_

19-Nov-04 4:06

Hi all

i dared to code a simple 3d viewer with my limited iq. Dead | X|

i want to get 2 panes with a vertical static splitter. The left will have a Tree control and right (CMgcCanvas) will draw the model. canvas is derived from CView and OnCreate is overrided. Splitter and tree works well. I added a Messagebox to OnNotify() of CMgcCanvas and CEditorView.

Problem: When i click left pane i can see my messagebox but at right it doesnt work! why?
Note : when i create the tree at right pane, left pane doesnt show messagebox.
Do i create CMgcCanvas wrong? Confused | :confused:

Thanks In Advance,
Burak

At OnCreateClient proc. of mainframe i did it as ;

BOOL CMainFrame::OnCreateClient(LPCREATESTRUCT lpcs, CCreateContext* pContext)
{
// TODO: Add your specialized code here and/or call the base class

//calculate client size
CRect cr;
GetClientRect( &cr);

//Create Splitter
if ( !m_mainSplitter.CreateStatic( this, 1, 2 ) )
{
MessageBox( "Error setting up splitter frames!",
"Init Error!", MB_OK | MB_ICONERROR );
return false;
}

//Create pane views of splitter
//Editor - Tree View
if ( !m_mainSplitter.CreateView( 0, 0,
RUNTIME_CLASS(CMGCEditorView),
CSize(cr.Width()/3, cr.Height()), pContext ) )
{
MessageBox( "Error setting up splitter frames!",
"Init Error!", MB_OK | MB_ICONERROR );
return false;
}

//Canvas View
CRuntimeClass* canvas = RUNTIME_CLASS(CMgcCanvas);
if ( !m_mainSplitter.CreateView( 0, 1,
canvas, CSize(cr.Width()*2/3, cr.Height()), pContext ) )
{
MessageBox( "Error setting up splitter frames!",
"Init Error!", MB_OK | MB_ICONERROR );
return false;
}

m_bInitSplitter = TRUE;

CRect leftrect, rightrect;

m_leftpane = m_mainSplitter.GetPane(0,0);
m_rightpane = m_mainSplitter.GetPane(0,1);
m_leftpane->GetClientRect(&leftrect);
m_rightpane->GetClientRect(&rightrect);

//Create Tree Control
m_MgcTree = new CMgcTree;

if (!m_MgcTree->Create(WS_VISIBLE | WS_TABSTOP | WS_CHILD |
TVS_HASLINES | TVS_HASBUTTONS | TVS_LINESATROOT,
CRect(0, 0, leftrect.Width(), leftrect.Height()),
m_leftpane, IDC_TREE1))
{
TRACE0("Failed to create instant bar child\n");
return -1; // fail to create
}

m_MgcTree->Initialise();

//Create Canvas View -???
m_canvas = new CMgcCanvas;

if (!m_canvas->Create(NULL,"Canvas",WS_VISIBLE | WS_TABSTOP | WS_CHILD ,
CRect(0, 0, rightrect.Width(), rightrect.Height()),
m_rightpane, 143))
{
TRACE0("Failed to create canvas\n");
return -1; // fail to create
}

return true;
}

Re: CView derived class in splitter pane

BlackDice19-Nov-04 4:34

BlackDice

19-Nov-04 4:34

I had a similar problem with a control that I derived from CStatic for displaying 3D Models (See 'My Articles' below, "A beginning DirectX Application using MFC"). The problem was that I didn't have the 'NOTIFY' style set for the class, so it wasn't receiving any messages. I don't know if that's your problem, but maybe look into that.

If I write code in my sleep, does that make me brilliant, or just a lazy programmer?

My articles

www.stillwaterexpress.com

BlackDice - the programmer formerly known as bdiamond

Re: CView derived class in splitter pane

manonthecorner_19-Nov-04 5:15

manonthecorner_

19-Nov-04 5:15

well i found the answer.
Microsoft says ;
The framework calls this member function to inform the parent window of a control that an event has occurred in the control or that the control requires some kind of information.

Tree sended the message as a control but i didnt have any at the view pane.

CMgcCanvas::OnLButtonDown works well.

it didnt help but great code .. thanks BlackDice
i'll send my code first to you if it gets out of stupid class!

Saving data and version handling

Cedric Moonen19-Nov-04 3:55

19-Nov-04 3:55

Hi !

I have a program that saves some data to a file. The data is saved in binary. To make simple (things are a little bit more complicated in my program): I have a structure with some members in it (just regular members, no pointers). To save it, I use fwrite providing the size of the structure (with sizeof(MyStruct)). Of course, several of these objects are saved.

Now, I need to add some new members in my structure, and of course, the files won't be compatible. So I want to have a mechanism that when I need to add new members, things will be compatible without creating the file again.

I was thinking of putting, at the begining of the file, the data size of the structure in the file. Then, when loading data, I make a fread with this size. So, when I add new members to my structure (of, course, I need to add them at the end of the struct), I will read only the data that were saved.

What do you think ? Is there a better suggestion or... ?
Thanks

Navin19-Nov-04 5:29

Navin

19-Nov-04 5:29

Given what you have aleady, that will work. However, how important is it to save all your data in binary? Have you considered a more flexible format, such as XML? Or even just ini-style files (Name=Value pairs inside of [Keys]?)

Somebody will mention MFC serialization. That can work, and it does have versioning abilities, but I'd be careful... if your structures/classes change too much, you could have the same problem you have now.

An expert is somebody who learns more and more about less and less, until he knows absolutely everything about nothing.

Cedric Moonen19-Nov-04 6:34

19-Nov-04 6:34

In fact I was first thinking about ini files but this will be too much complicated and far too less secured (I don't want anybody to change parameters inside). Everything must be configurated inside the program.

Serialization, not because I want to have more access to what I'm doing and I'm not really saving 'pure data'. What I'm saving is configurations (but very complicated configurations Poke tongue | ;-P

Blake Miller19-Nov-04 5:30

Blake Miller

19-Nov-04 5:30

The idea you have is good, or else you can create a keyed file...

[object size][object type][object data]

Your file ends up looking like this sequence of data:
<dword><dword><datastructure><dword><dword><datastructure>

This allow you to add different structures into your file and to skip those you do not recognize.

Of course, you can not randomly seek into your file any more if you do this.

Henry miller19-Nov-04 6:21

Henry miller

19-Nov-04 6:21

I've seen many ways to do this, not all are compatable. Some that I've seen:

Best: don't write out structs. Write XML or some other text format that is [partially] human readable.

Each struct starts with two fields, majic and version. magic is a number (often someone's birthday), choosen so that no two structers magics will ever be reused. Math people sometimes statisticly find some bit pattern that is unlikley to be hit randomly, so they can detect file corruption and the like.

#define MYSTRUCT_MAGIC 0x19540331 // mom's birthday
struct mystuct {
LONG magic;
LONG verion;
... // all data
}

When loading you check magic and version. If they are recognized you load, if the version is old you may reorginize things, and such.

It is a good idea to start your files with a simple string that says what recorded it.

save(struct myDataList *data) {
fd = open(...);
write(fd,"myApp Version 1.x",16);
... // write all the structs out here
}

I don't really like your idea. It doesn't deal with the case where you delete a member, or change the meaning of a member.

Cedric Moonen19-Nov-04 6:37

19-Nov-04 6:37

Henry miller wrote:
It is a good idea to start your files with a simple string that says what recorded it.

Yes I already thought about that (I will add this for future modifications Wink | ;)

).

Henry miller wrote:
I don't really like your idea. It doesn't deal with the case where you delete a member, or change the meaning of a member.

Here this is not a problem because I won't delete any members. Everything will go in the other direction: add member but never delete or change existing memebers.

Henry miller19-Nov-04 7:56

Henry miller

19-Nov-04 7:56

Yeah, thats what they all say. Then someday in the future someone does so anyway. It always happens that the things you least expect to happen are the ones that happen first.

Of course if this is a personal project that isn't much an issue. If this is any bigger though you have to expect that someone else will do something to your code without understanding why you didn't. They will notice that you always write a zero someplace, and never do anything with it so they remove it. And it works until someone trys to load data saved 3 versions ago which had the same size...

Re: Thanks !

Cedric Moonen19-Nov-04 6:39