puzzling question about pointers - *char - C / C++ / MFC Discussion Boards

Re: How do I change OnDraw??

NickOne24-Jul-02 11:34

NickOne

24-Jul-02 11:34

Cool! Thanks!

Does this apply as well (making an OnDraw/OnPaint handler) if I make a new MDI child class?

NickOne

Re: How do I change OnDraw??

C^hris L^osinger24-Jul-02 11:37

C^hris L^osinger

24-Jul-02 11:37

yep. pretty much anytime you want a view window to show something, you have to draw it yourself in OnDraw. the exceptions are the formview and tree/listview things where you're really just using standard controls as a view.

for dialogs and most other controls, you do the drawing in the OnPaint function.

i find the best way to do image drawing in a dialog is to take a static rectangle control and fence off an area within the dialog. then, when it's time to draw (in nPaint) i find that control's rectangle, deflate it a little and draw inside of it. that way, you a) have a nice rectangluar border around the image and b) you can design around the image area, if you need other controls in the dialog.

-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

Fractals!

Re: How do I change OnDraw??

Paul M Watt24-Jul-02 19:39

Paul M Watt

24-Jul-02 19:39

I would like to give you one more piece of information that you might find helpful as to why the OnDraw and OnPaint methods exist and when to use them.

OnPaint is a message handler that handles an actual message from windows (WM_PAINT). Every window will get a WM_PAINT message, and in turn the OnPaint handler will be called when a window needs to be repainted. This includes buttons, static controls, treeview controls, dialogs and so on, even the MDI children that you are handling the OnDraw method.

The OnDraw method is a method in MFC that is usually used for windows that represent documents. The default action for the OnPaint handler of a document window prepares a HDC and calls the OnDraw handler. All of your painting that is required for your document should go in the OnDraw handler. This is because MFC also has the OnPrint or WM_PRINT message call the same OnDraw handler that you used to draw your window. The only difference is that it passes you a HDC that is for a printer rather than your monitor. This allows you to perform the painting code for your document in one place, and the MFC framework can take advantage of that.

Build a man a fire, and he will be warm for a day
Light a man on fire, and he will be warm for the rest of his life!

How do l execute a program from within the code?

citress24-Jul-02 10:38

citress

24-Jul-02 10:38

Hi everyone, l'm currently working on linking a program to its GUI application. And l was wondering if executing the program from within the GUI code is the correct way to approach it. lf it is, can someone give me some suggestions as to how l should go about it? l've tried calling the system command in my code (eg. system("program < inputDataFile") ), but doing so will result in a black window popping up. l do not want to see a black window flash for a couple of seconds everytime l run my program, so l hope there is another way to do this.
Any comments will be appreciated, thanks!

Re: How do l execute a program from within the code?

Ravi Bhavnani24-Jul-02 10:51

Ravi Bhavnani

24-Jul-02 10:51

See this article.

/ravi

Let's put "civil" back into "civilization"
http://www.ravib.com
ravib@ravib.com

Re: How do l execute a program from within the code?

Georg Haan24-Jul-02 10:54

Georg Haan

24-Jul-02 10:54

To keep the black window from popping up, try WinExec with the SW_HIDE flag.
Even better would be to redirect output entirely, not to a file, but to a pipe. Nothing gets written to a drive this way... Microsoft has sample code for this, you'l find ithere.

Georg Haan

Re: How do l execute a program from within the code?

Todd Smith24-Jul-02 14:00

Todd Smith

24-Jul-02 14:00

Try CreateProcess

Todd Smith

puzzling question about pointers - *char

ns24-Jul-02 10:37

24-Jul-02 10:37

For the following code

int DLLGetKeywords( char* keyBuf)<br />
{<br />
char buffer[] = " type1,depth,type2,range,type3*";<br />
*strchr(buffer,'*') = 0; //double null now<br />
AfxMessageBox(buffer);  //////msgbox1<br />
<br />
///////////////////////////////////////////////////////////////<br />
	char *pc,*pc1;<br />
  for (pc = buffer ; *pc ; pc = strchr(pc,0) + 1) <br />
 {<br />
	// if we got here there must be a word<br />
 <br />
 	char* pc1 = strchr(pc,','); // search for a comma, returns a null pointer if not found<br />
	if (pc1) *pc1 = 0; <br />
  }<br />
<br />
<br />
  //////////////////////////////////////////////////<br />
strcpy(keyBuf,buffer);<br />
AfxMessageBox(buffer);

//////////////msgbox2

The first msgbox has an output as expected: " type1,depth,type2,range,type3*"
The second msgbox has an output of "type1". Thats all.

ALl thats happening in the routine is that commas are being replaced by nulls. I thought that its because the msgbox only "reads" upto the first null. But when I go to populate a listbox with this buffer, (post messagebox2), i only get "type1" in it.

Any light on this mystery?

Thanks,
ns

Re: puzzling question about pointers - *char

David Chamberlain24-Jul-02 10:42

David Chamberlain

24-Jul-02 10:42

ns wrote:
ALl thats happening in the routine is that commas are being replaced by nulls.

When you do this, you terminate the string. The array is filled with characters and nulls, but when you output them from the beginning, it only goes as far as the first null.

Dave

"You can say that again." -- Dept. of Redundancy Dept.

Thank you.- another related question:

ns24-Jul-02 10:58

24-Jul-02 10:58

I suspected this. So how does one extract the words buried in a string which has nulls between words?

I have stuff like "abc\0aaa\0ddd\0" which is my attempt at saying I've got nulls between words? I'm using this:

<br />
void CTrain1View::popDisplayList(int popDisplayFlag, char * buffer)<br />
{<br />
//keywords are stored in a string returned by the dll.delimited with nulls.<br />
//lets extract them<br />
if (popDisplayFlag)<br />
{<br />
char* pc;<br />
 <br />
CString string;<br />
int nListIndex = 0;<br />
  for (pc = buffer ; *pc ; pc = strchr(pc,0) + 1) <br />
 {<br />
	// if we got here there must be a word<br />
 //////////////////////////////////////////////////////////////////////////////////////////////<br />
 char* pc1 = strchr(pc,','); // search for a comma, returns a null pointer if not found<br />
	if (pc1) *pc1 = 0; // if we find a comma we replace it with a null character, if we didn't find a comma then the word is already null-terminated<br />
 //////////////////////////////////////////////////////////////////////////////////////////////////////<br />
	string = pc;<br />
	int nItem = m_listdisplay.InsertItem(nListIndex,string);<br />
<br />
 }<br />
<br />

but my listbox gets one extra line of garbage after the first five (buffer has five words in it, commma delimited)entries. I dont see why.

Any clues? I do thank you for confirming my suspicion regarding the buffers condition after putting in the nulls.

Re: Thank you.- another related question:

David Chamberlain24-Jul-02 11:05

David Chamberlain

24-Jul-02 11:05

My suggestion would be to use the 'strtok' function (string to token) on the original string with the commas. On the first call, you specify the source string and a set of delimiters (a comma, in your case) and the function returns a pointer (I think) to the first sequence of characters up to the specified delimiter. On subsequent calls, the source string is specified as NULL, as the function maintains its own buffer. Each consecutive call will return a pointer (I think) to the next sequence of characters up to the specified delimiter. When strtok returns NULL, there are no more tokens.

Two things:
1) strtok replaces the found delimiter with a NULL, which you don't have to worry at all about.
2) the set of delimiters can be changed on each call, if desired. This is handy for parsing a sequence where things are not always the same.

Dave

"You can say that again." -- Dept. of Redundancy Dept.

Re: Thank you.- another related question:

ns25-Jul-02 1:19

25-Jul-02 1:19

Thank you very much for the strtok - i didnt know about it. I appreciate your responses - they are most helpful! Smile | :)

Re: puzzling question about pointers - *char

Ravi Bhavnani24-Jul-02 10:49

Ravi Bhavnani

24-Jul-02 10:49

Ugh, code like this is difficult to maintain and won't pass a review. Now back to our regularly scheduled broadcast...

The first msgbox has an output as expected: " type1,depth,type2,range,type3*"
This surprises me. The output shouldn't include the trailing asterisk.

The second msgbox has an output of "type1". Thats all.
That makes sense, because you've happened to have (eventually) replaced the first comma with a null byte. Btw, the loop logic (specifically the increment) is suspect. What do you want to have happen?

/ravi

Let's put "civil" back into "civilization"
http://www.ravib.com
ravib@ravib.com

Re: puzzling question about pointers - *char

ns25-Jul-02 1:18

25-Jul-02 1:18

I was trying to extract words out of a buffer which has null terminators between words. I was supplying myself with a fake buffer of the sort I expect to get, to see if my code would process the buffer correctly. You are right - there was of course no * in the messageBox. In this thread char * got much clearer to me. I like CStrings better but I have to use whatever someone elses dll supplies. Thanks much.

Re: puzzling question about pointers - *char

Ravi Bhavnani25-Jul-02 2:36

Ravi Bhavnani

25-Jul-02 2:36

Consider using strtok() to extract tokens from a C string. The tokens need to be delimited by a non-null char. If you're creating the string yourself, then this is easy. I usually use '`' or '~' as delimiters, because they stand out while debugging. Hope this helps!

/ravi

Let's put "civil" back into "civilization"
http://www.ravib.com
ravib@ravib.com

Never mind...

Ravi Bhavnani25-Jul-02 2:37

Ravi Bhavnani

25-Jul-02 2:37

I just saw David's response to your email. Never mind... Smile | :)

/ravi

Let's put "civil" back into "civilization"
http://www.ravib.com
ravib@ravib.com

Can you create two CDialogBars in a frame window?

JohnnyG24-Jul-02 10:28

JohnnyG

24-Jul-02 10:28

I didn't see any documentation that you couldn't. I'd like one at the top and one at the bottom essentially taking up all of the client area. Is that possible?

Question Mark Handling in ADO

newlogsign24-Jul-02 9:52

newlogsign

24-Jul-02 9:52

Has anyone seen this problem with ADO query:

select /*?*/ 1 from dual

Basically it seems if the query / proc / function contains question mark, ADO query will return "Wrong number of parameters" error message. Change ? to '?' will be fine, but that alter the code as well.

For instance, the following code will cause problem:

create or replace function aaa return number
value number;
is
begin
value := select sum(amount) /*Total Amount?*/ from bill_info;
return value;
end;

Has anyone know what is the right escape for question mark?

Thanks.;P

How do I prevent my application showing a button on the taskbar?

adara24-Jul-02 8:09

adara

24-Jul-02 8:09

How do I prevent my application showing a button on the taskbar?
Thanx Rose | [Rose]

Re: How do I prevent my application showing a button on the taskbar?

Ravi Bhavnani24-Jul-02 10:54

Ravi Bhavnani

24-Jul-02 10:54

See this article.

/ravi

Let's put "civil" back into "civilization"
http://www.ravib.com
ravib@ravib.com

Re: How do I prevent my application showing a button on the taskbar?

J Patel24-Jul-02 10:57

J Patel

24-Jul-02 10:57

Check out the style WS_EX_TOOLWINDOW. But this creates a smaller title bar.

[edit]
Check out http://msdn.microsoft.com/msdnmag/issues/0500/c/c0500.asp

Jignesh

Re: How do I prevent my application showing a button on the taskbar?

Paul M Watt24-Jul-02 20:02

Paul M Watt

24-Jul-02 20:02

Simply remove the WS_EX_APPWINDOW style from your window.

MFC:
pWnd->ModifyStyleEx(WS_EX_APPWINDOW, 0);

Win32 API:
LONG lStyle = ::GetWindowLong(hWnd, GWL_EXSTYLE);
lStyle &= ~WS_EX_APPWINDOW;
::SetWindowLong(hWnd, GWL_EXSTYLE, lStyle);

Build a man a fire, and he will be warm for a day
Light a man on fire, and he will be warm for the rest of his life!

method executing too many times

mgriffith24-Jul-02 8:08

mgriffith

24-Jul-02 8:08

i have 2 methods that are using IWebBrowser2 to execute a print method from a com object that is hosted on a webpage. here is the code for the methods:

---------------------------------

STDMETHODIMP CTemplatePrinter::IEPrintNoPrompt(VARIANT varTemplateURL)
{
CComPtr<iolecontainer> spContainer;
CComPtr<iserviceprovider> spSP;
CComPtr<iwebbrowser2> spWB;
CComPtr<idispatch> spDisp;
CComPtr<ihtmldocument2> spDoc;
CComPtr<iolecommandtarget> spCT;
CComVariant vPTPath = varTemplateURL;

m_spClientSite->GetContainer(&spContainer);
spContainer->QueryInterface(IID_IServiceProvider, (void**)&spSP);
spSP->QueryService(SID_SWebBrowserApp, IID_IWebBrowser, (void**)&spWB);
spWB->get_Document(&spDisp);
spDisp->QueryInterface(IID_IHTMLDocument2, (void**)&spDoc);
spDoc->QueryInterface(IID_IOleCommandTarget, (void**)&spCT);

// ******* THIS IS WHERE IT'S GOING CRAZY!!!! ******* //
spCT->Exec(&CGID_MSHTML, IDM_PRINT, OLECMDEXECOPT_DONTPROMPTUSER, &vPTPath, NULL);

return S_OK;
}

---------------------------------------

STDMETHODIMP CTemplatePrinter::IEPrint(VARIANT varTemplateURL)
{
CComPtr<iolecontainer> spContainer;
CComPtr<iserviceprovider> spSP;
CComPtr<iwebbrowser2> spWB;
CComPtr<idispatch> spDisp;
CComPtr<ihtmldocument2> spDoc;
CComPtr<iolecommandtarget> spCT;
CComVariant vPTPath = varTemplateURL;

m_spClientSite->GetContainer(&spContainer);
spContainer->QueryInterface(IID_IServiceProvider, (void**)&spSP);
spSP->QueryService(SID_SWebBrowserApp, IID_IWebBrowser, (void**)&spWB);
spWB->get_Document(&spDisp);
spDisp->QueryInterface(IID_IHTMLDocument2, (void**)&spDoc);
spDoc->QueryInterface(IID_IOleCommandTarget, (void**)&spCT);

// ***** IT CALLS THIS 2 TIMES? ******** //
spCT->Exec(&CGID_MSHTML, IDM_PRINT, OLECMDEXECOPT_PROMPTUSER, &vPTPath, NULL);

return S_OK;
}
--------------------------

my question is: does anyone have any idea why the IOleCommandTarget::Exec method it going berzerk? when i call the method from a script, the first one keeps spooling pages into the printer, and the second one opens 2 print dialogs in a row...i also have another function for opening a print preview window that works fine....the only difference is my call to Exec is as follows:
spCT->Exec(&CGID_MSHTML, IDM_PRINTPREVIEW, OLECMDEXECOPT_PROMPTUSER, &vPTPath, NULL);

i've tried all that i can see...if i replace spCT->Exec(...) with
spWB->ExecWB(OLECMD_PRINT, OLECMDEXECOPY_PROMPTUSER, &vPTPath, NULL);
it still does the same thing...i've even tryied without passing in the &vPTPath (printing template path) argument

i also know that the method is only getting called once...i tested this by also using spDoc to write some stuff out to pop up a message box every time it got called, and the message box only came up once, but the printing kept going...

any suggestions?
Confused | :confused:

michael griffith
--------------------
mgriffith@lauren.com
mdg12@po.cwru.edu

Fonts

Anonymous24-Jul-02 8:06

Anonymous

24-Jul-02 8:06

I would like to set the font size of a dialog based on the screen resolution of the user's PC. Does anyone have a quick function to do this???

Thanks,

FL

error LNK2001??

Jh324-Jul-02 7:11

Jh3

24-Jul-02 7:11

i'm using a class from another program, but if i compile i get the a *.obj : error LNK2001:unresolved external symbol error, __imp__waveOutWrite@12. (waveOutWrite is the function declared in mmsystem.h) how can i fix this?

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