C / C++ / MFC

2-Aug-02 20:18

did you try looking at this site?? there are like 10 different image classes here.

-c

To explain Donald Knuth's relevance to computing is like explaining Paul's relevance to the Catholic Church. He isn't God, he isn't the Son of God, but he was sent by God to explain God to the masses.
/. #3848917

Re: URL for bmp to jpeg

-Dy5-Aug-02 0:41

-Dy

5-Aug-02 0:41

suresh_sathya wrote:
Anybody knows site for free dll's

Either here on CP, or try the Free Image project at http://www.6ixsoft.com[^] - very handy!

Dylan Kenneally
London, UK

CPP question???

alex.barylski2-Aug-02 20:00

alex.barylski

2-Aug-02 20:00

I am trying to use a PVOID to store a dynamic array of pointers to various objects which will change from time to time so static casts won't work I don't think.

For example I have created a pure virtual base class which all objects SHOULD derive from if they wish to be added to the PVOID memory mentioned above.

Initially I tried using the base class as a cast and paramters for functions.

AddObject(CGenericItem* pItem)
{
    static UINT nIndex = 0;                          
    // m_pStack is a PVOID member of this class
    *(m_pStack+nIndex) = (PVOID)pItem;	                      
    nIndex++;
}

The above doesn't work? I'm getting a void * 'unknown size' WTF | :WTF:

does that mean...??? I figured any pointer would be 4 bytes or does it mean the size of the object..???

static casts won't work because the object passed to the above function will never be the same object (ALL derived from the same base, but not the same final class)

So:

*(m_pStack+nIndex) = (UINT)pItem;

or something to that effect isn't gonna do...

Is there any way I can use RTTI and determine the class of the object and perform a cast at run time using dynamic_cast???

Thanx alot

cheers Poke tongue | ;-P

"An expert is someone who has made all the mistakes in his or her field" - Niels Bohr

C^hris L^osinger2-Aug-02 20:07

2-Aug-02 20:07

Hockey wrote:
*(m_pStack+nIndex) = (PVOID)pItem;

when you add a value to a pointer, you are actually adding a multiple of the pointed-to object's size. ie. if m_pStack was an int*, you would be adding nIndex*4 to the ptr address, allowing you to get to item m_pStack[nIndex].

or, as K&R puts it "if p is a pointer to an element of an array, p++ increments p to point to the next element".

but, void has no size, so you can't multiply by it, and you can't have an array of them.

Hockey wrote:
Is there any way I can use RTTI and determine the class of the object and perform a cast at run time using dynamic_cast???

yes. Smile | :)

-c

alex.barylski2-Aug-02 20:49

alex.barylski

2-Aug-02 20:49

I can't have an array of void *'s...???

How does CPtrList work then...???

thanx again.

"An expert is someone who has made all the mistakes in his or her field" - Niels Bohr

Christian Graus2-Aug-02 21:08

Christian Graus

2-Aug-02 21:08

The answer comes in two parts.

1. a list is not an array, it is a data structure where each element knows about it's own data and ( at least ) the location of the next piece of data. Some lists also know the location of the prior item. Advantages of lists: they are quick if you want to add and remove from the middle. Disadvantages: they are slow for lookup of items.

2. How does CPtrList work ? Like all MFC container classes, that is, barely. Use std::list or std::vector instead.

Christian

We're just observing the seasonal migration from VB to VC. Most of these birds will be killed by predators or will die of hunger. Only the best will survive - Tomasz Sowinski 29-07-2002 ( on the number of newbie posters in the VC forum )

alex.barylski2-Aug-02 22:30

alex.barylski

2-Aug-02 22:30

It took me a while, but I finally figure that out or so i thought I did, so it's good to hear someone else tell me what a list is and how it differs from an array.

I never cared to think there was a difference before, but now I know there is a crucial difference...

Thanx for clearing that up for me CG...

Cheers Smile | :)

"An expert is someone who has made all the mistakes in his or her field" - Niels Bohr

C^hris L^osinger3-Aug-02 5:07

3-Aug-02 5:07

you can't have an array of "void"'s.

-c

Problem in Detecting System Idle time

Prateeti2-Aug-02 19:38

Prateeti

2-Aug-02 19:38

I have developed a chat server. In that I want to detect system idle time, if idle time is greater than 10 min then the server should disconnect the client application automatically. For this purpose I am using Idle Time tracker suggested by Sidney, this code I got from codeproject, but its not working fine its disconnecting the client even if the user is using the system.
What could be the problem....I am not getting it. Can anybody help me ?
Prateeti

Plug in architecture - how to create a good one?

Hiusing2-Aug-02 17:45

Hiusing

2-Aug-02 17:45

Hello,
I'm building an image viewer that would like to use plug-in architecture to extend the functionality of the image format it supports and tools. I also would like to able to provide some basic image manipulation functions to plug-in writers. Anyone can give me some idea how to do it?

Thanks!

Re: Plug in architecture - how to create a good one?

C^hris L^osinger2-Aug-02 20:12

2-Aug-02 20:12

here's how i answered this question last week: http://www.codeproject.com/script/comments/forums.asp?forumid=1647&app=50&select=249957&df=100&fr=1151#xx244157xx
-c

Re: CDhtmlDialog (VS.NET)

CDhtmlDialog (VS.NET)

Roman Nurik2-Aug-02 17:34

Roman Nurik

2-Aug-02 17:34

hey, how do i add controls like treeview and listview for example, or a richedit to a CDhtmlDialog without having to place it on the dialog resource instead of the HTML... i was thinking of putting some <OBJECT> or some type of code into the HTML to create a control but i don't know how to do that

any ideas?

<div style="width: 100%; background-color: #efefef; border: 1px solid #999999; padding: 2px; margin: 5px; filter: progid:DXImageTransform.Microsoft.Shadow(color=#808080,direction=135,strength=3); text-align: center;">- <b style="font-variant:small-caps">Roman</b> -</div>

ColinDavies2-Aug-02 21:14

ColinDavies

2-Aug-02 21:14

Roman Nurik wrote:
any ideas?

I don't know if this will work.
But if you use the IHTMLDocument Interface you should be create Frames in the View and put your control into that.

Regardz
Colin J Davies

Sonork ID 100.9197:Colin

You are the intrepid one, always willing to leap into the fray! A serious character flaw, I might add, but entertaining.
Said by Roger Wright about me.

MDI question

RK_20002-Aug-02 17:18

RK_2000

2-Aug-02 17:18

Hi,

I have an MDI application. Suppose the user starts searching for something on one view. Then he/she switches over to another view. Obisouly, since the find dialog was launched with the other view, it won't be associated with the new one. But what if I wanted this to be the case? how do I make a find dialog launched in one view, to be associated with another view whenever the second view becomes active?

thanks

Re: MDI question

Pavel Klocek3-Aug-02 2:46

Pavel Klocek

3-Aug-02 2:46

The dialog communicates with the application using Windows Messages. Define the message handlers on the level of views, then the messages from the search dialog will be received by the current top view.

Sonork 100.15206;PavelK

SQL anyone?

nss2-Aug-02 17:08

nss

2-Aug-02 17:08

I am trying to add records using INSERT INTO

pCommand->CommandText="INSERT INTO tblTest (Color, Texture) VALUES ('navy blue', 'rusty') "; 
_RecordsetPtr pRecordset; 

hr = pRecordset.CreateInstance (__uuidof (Recordset)); 

if (FAILED (hr)) 
{ 
AfxMessageBox ("Can't create an instance of Recordset"); 
return; 
} 
AfxMessageBox("LLL"); 

pRecordset->CursorLocation = adUseClient; 
pRecordset->Open ((IDispatch *) pCommand, vtMissing, adOpenDynamic, adLockBatchOptimistic, adCmdTable);

i get an exception at the Open statement so theres something it doesnt like about the SQL i guess.
ANy ideas wil be appreciated!
Thanks,
ns

RK_20002-Aug-02 17:15

RK_2000

2-Aug-02 17:15

Just out of curosity, since this is an insert, why would you use a recordset for? Try using ExecuteSQL on the connection object.

Also, make sure that pRecordset is not 0 when you are calling the open.

nss2-Aug-02 18:16

nss

2-Aug-02 18:16

Heres what I tried: stil exception on execute

LPCTSTR lpstrExec ="INSERT  INTO tblTest  VALUES ('navy blue', 'rusty','aa,'aa,'aa,'aa') ";
		m_pConn->CursorLocation = adUseClient;
		m_pConn->Execute(_bstr_t(lpstrExec), NULL, adExecuteNoRecords);

Of course I'm justguessing...new at this stuff.
Thank you so much for replying,
ns

RK_20002-Aug-02 18:26

RK_2000

2-Aug-02 18:26

Your latest SQL statement is incorrect btw...the first one was ok.in this one you're missing your column names..You either have to go insert into x(yy,yyy,yyy) values ('','','') or insert into x select x,x,x

This usually works for me as far as inserts go. Remember that you are dealing with COM, so everything is _bstr_t..so you can't just use strings...
Here m_pConnection and varQuery are defined as

const std::string & varQuery
static _Connection * m_pConnection;

then here is my functin which receives the varQuery...BTW, for USES_CONVERSION, you need to include atlconv.h file!

BOOL CDBClass::ExecuteQuery(const std::string & szQuery)
{
USES_CONVERSION;

BOOL bRet = TRUE;
HRESULT hRes = 0;

_variant_t varQuery;
varQuery = A2W(szQuery.c_str());

if(m_pConnection == 0)
CreateConnection();

if(m_pConnection != 0)
{
try {
hRes = m_pConnection->Execute(varQuery.bstrVal, NULL, NULL, NULL);
}

catch (...)
{

bRet = FALSE;
}

if(hRes != 0)
GetError();

hRes == 0 ? bRet = 1 : bRet = 0;
}

return bRet;
}