C / C++ / MFC

Re: STL/for_each/templated function question

24-Feb-02 17:37

Some of the features in STL, and C++ for that matter, are convoluted, and I think that is what shys alot of people away from these features in the first place. This is a shame because learning some of these techniques can lead to very elegant solutions.

Joaquín M López Muñoz24-Feb-02 20:03

Joaquín M López Muñoz

24-Feb-02 20:03

In case you wonder, your original code should have worked, but it doesn't due to a limitation of VC++ --it lacks support for so called explicit instantiation of template functions, or better stated, its support is broken. Don't know the status of this bug in VC++ 7.0.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

STL from MS oder SGI?

Travis D. Mathison24-Feb-02 15:46

Travis D. Mathison

24-Feb-02 15:46

Have a little question for you all. In regards to STL -- what distribution of it do you use? (assuming that you use it of course).

Visual C++ 6 has STL support (to a point), it seems incomplete though. I downloaded and started using the SGI STL which is complete (except I found that it only supports the depricated <iostream.h> not the new <iostream> .. what the heck is going on?

I'm a little confused .. maybe I'm just not seeing some obvious small detail here ..

Travis D. Mathison ---
--- After three days without programming, life becomes meaningless ...

Paul M Watt24-Feb-02 15:55

24-Feb-02 15:55

I prefer the SGI STL implementation.

A while back I created a test program to compare STL versus MFC's container classes, and MFC's classes kicked butt over STL, that is the STL that is included with DevStudio. Then I recompiled the program with SGI's version and the competition was feirce depending on the way that the container was used. Sometimes STL was more efficient, others it was MFC container classes, which is to be expected.

The SGI implementation supports other classes that I don't think are in the standard yet. One of my favorite classes in the SGI implementation is the hashmap and hashset, this is used in the exact same way that the map and set are used, but the underlying representation is a hash table rather than a table.

I could not find what you were talking about between depricated and new, could you give more details on that?

Travis D. Mathison24-Feb-02 16:06

Travis D. Mathison

24-Feb-02 16:06

What I meant was that (this is only one instance), the SGI STL has been designed to support the old header file naming style. That is, you would include iostream.h <-- rather than iostream -- if you do include iostream so you can access the new features you will get a lot of errors because it doesn't handle it yet for some reason.

Travis D. Mathison ---
--- After three days without programming, life becomes meaningless ...

Christian Graus24-Feb-02 15:54

Christian Graus

24-Feb-02 15:54

sgi STL is not being built upon, hence the deprecation problem. Use STLPort instead - www.stlport.com, it has the hash table, the additional modifiers, etc., in fact everything the SGI STL has and more.

I believe VC.NET has a better STL - previously they have been stuck with an old Dinkumware implimentation for purely legal reasons.

Christian

The tragedy of cyberspace - that so much can travel so far, and yet mean so little.

CFileDialog and printing different views?

Travis D. Mathison24-Feb-02 16:06

Travis D. Mathison

24-Feb-02 16:06

I just downloaded STLport and am reading about it's use.. thanks for the suggestion.

Travis D. Mathison ---
--- After three days without programming, life becomes meaningless ...

Craig Miller24-Feb-02 13:06

Craig Miller

24-Feb-02 13:06

Hi,

I have an SDI application that has a CFormView derived class as well as a docking window with a CDialog derived class. When the user clicks on the Print command, the message goes to the CFormView derived class where I modified the CFileDialog with two radio buttons to either print the main CFormView or the CDialog window.

Well, when I do this and I call the CDialog derived printing code for some reason, the document gets printed three times and then throws an exception. In actuallity, it should only print one page, I also tried setting the max page to 1 to no evale. I can't figure out why this happens, I guess it could be because the CFormView class is processing the print call but I'm not sure.

Does anyone have any suggestions on how I can fix this peculiure problem?

Thanks in advance,

Craig

Re: CFileDialog and printing different views?

Roger Allen25-Feb-02 3:16

Roger Allen

25-Feb-02 3:16

I would recommend emulating the Doc?view printing procedure for your dialog derived class. I did something similar when printing to PDF files. The whole code for that procedure here is shown, so some of the code will not be relevant to what you are doing, but it will give you some idea of how to progress:

DOCINFO         di ;
CPrintInfo      printInfo ;
CRefinementProDoc       *pDoc = GetDocument() ;
CString         filename ;
CDC             dc ;
CRect           draw_area ;

ASSERT_VALID(pDoc) ;
filename = pDoc->GetPathName() ;
// make sure the compares will match
filename.MakeLower() ;
if (filename == "")
    {
    filename = pDoc->GetTitle() ;
    if (filename.Find(" (modified)") >= 0)
        filename = filename.Left(filename.GetLength() - 11) ;
    }
if (filename.Find(".sds") >= 0)
    filename = filename.Left(filename.GetLength() - 4) ;
if (filename.Find(".mds") >= 0)
    filename = filename.Left(filename.GetLength() - 4) ;
filename += ".pdf" ;

CFileDialog     dlg(FALSE, "PDF", filename, OFN_OVERWRITEPROMPT | OFN_HIDEREADONLY, "Adobe acrobat PDF files (*.pdf)|*.pdf||") ;
dlg.m_ofn.lpstrInitialDir = theApp.g_szLastDirectory ;
// sub-class the window to allow ownerdrawn controls
pView = this ;
dlg.SetTemplate("MYFILEOPEN", "MYFILEOPENEXPLORER") ;
dlg.m_ofn.Flags |= OFN_ENABLEHOOK ;
dlg.m_ofn.lpfnHook = (LPOFNHOOKPROC)OFNHookProcOldStyle ;

if (dlg.DoModal() == IDCANCEL)
    return ;
// copy across the selected pages to print
for (int i = 0 ; i < MAX_DLLS ; i++)
    global_page_status[i] = g_bAllowPrint[i] ;
filename = dlg.GetPathName() ;

HDC hDC = theApp.g_PDF.GetPrinterDC() ;
if (hDC == NULL)
    return ;

OnAboutToPrint() ;
di.cbSize = sizeof(DOCINFO) ;
di.lpszDocName = pDoc->GetPathName() ;
di.lpszOutput = filename ;

// prepare the print information structure
dc.Attach(hDC) ;
printInfo.m_bDirect = TRUE ;
printInfo.m_rectDraw.left = 0 ;
printInfo.m_rectDraw.right = dc.GetDeviceCaps(HORZRES) ;
printInfo.m_rectDraw.top = 0 ;
printInfo.m_rectDraw.bottom = dc.GetDeviceCaps(VERTRES) ;
draw_area = printInfo.m_rectDraw ;

dc.StartDoc(&di) ;
OnPreparePrinting(&printInfo) ;

// start printing the document
for (printInfo.m_nCurPage = 1 ; printInfo.m_nCurPage <= printInfo.GetMaxPage() ; printInfo.m_nCurPage++)
    {
    dc.StartPage() ;
    OnPrint(&dc, &printInfo) ;
    dc.EndPage() ;
    // reset page size as OnPrint may have odified them when
    // header / footers were added to the page
    printInfo.m_rectDraw = draw_area ;
    }
OnEndPrinting(&dc, &printInfo) ;
dc.EndDoc() ;
VERIFY(dc.DeleteDC()) ;
// pop-up the pdf viewer
if (theApp.g_bStartPDF)
    ShellExecute(NULL, NULL, filename, NULL, NULL, SW_SHOWMAXIMIZED) ;
theApp.SetLastDirectory(filename.Left(filename.ReverseFind('\\'))) ;

Roger Allen
Sonork 100.10016

If I'm not breathing, I'm either dead or holding my breath.
A fool jabbers, while a wise man listens. But is he so wise to listen to the fool?

Re: CFileDialog and printing different views?

Craig Miller25-Feb-02 12:03

Craig Miller

25-Feb-02 12:03

Roger,

Thanks so much for your example, I will try it and see if it will solve the problem I am having.

Thanks again,

Craig

OpenGL with MDI application

Rajveer24-Feb-02 10:58

Rajveer

24-Feb-02 10:58

I just created an MDI application using visual studio. I'm trying to draw graphics using openGL in the child window. How exactly do I do this. Am I supposed to attach a function for the child window class where I can draw, or do I declare an instance of the child window class in my drawing function or what?

Re: OpenGL with MDI application

Derek Waters24-Feb-02 11:46

Derek Waters

24-Feb-02 11:46

Hi,

You need to draw the graphics in the OnDraw handler of your CView derived class. However, OpenGL is never that simple, so I would suggest you have a look here for an article that might help you.

------------------------
Derek Waters
derek@lj-oz.com

Subclassing...??

alex.barylski24-Feb-02 9:35

alex.barylski

24-Feb-02 9:35

When subclassing controls is it posible to use a classes member function as the message handler procedure...?

class MyClass : public CWnd
{
  MyHandler() { /* code */ }
  OnCreate()
  { 
    WNDCLASS wc;
    wc.lpfnWndProc = MyHandler;

    HWND hwnd = CreateWindow(blah);
  }
}

The above method didn't work for me, I haven't yet tried actually subclassing using SetWindowLong() but I can't see this working either.

Anybody have any idea's...?

Cheers! Smile | :)

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

Steen Krogsgaard24-Feb-02 10:14

Steen Krogsgaard

24-Feb-02 10:14

Only if you make the member function static. A non-static member will expect to get the hidden this pointer passed, and windows won't do that!

There's a lot of info on methods for using members as callbacks which also applies to this problem. Basically, you can use a static member or a global C-style function.

Cheers
Steen.

"To claim that computer games influence children is rediculous. If Pacman had influenced children born in the 80'ies we would see a lot of youngsters running around in dark rooms eating pills while listening to monotonous music"

alex.barylski24-Feb-02 14:49

alex.barylski

24-Feb-02 14:49

I'm currently using a global C style function, but would prefer to use a more C++ approach.

I'll try static functions and see whats happens...

Cheers!

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

Jeremy Falcon24-Feb-02 15:26

Jeremy Falcon

24-Feb-02 15:26

Steen Krogsgaard wrote:
"To claim that computer games influence children is rediculous. If Pacman had influenced children born in the 80'ies we would see a lot of youngsters running around in dark rooms eating pills while listening to monotonous music"

LOL

Jeremy L. Falcon
"The One Who Said, 'The One Who Said...'"

Paul M Watt24-Feb-02 15:33

Re: Creating 256-color icons

24-Feb-02 15:33

Create a static member function in your class.
Then Call SetWindowLong, and set the GWL_USERDATA field as the this pointer in your
class. Then in your handler, you will get teh window long data and use that as your class pointer.

class MyClass : public CWnd
{  
    HWND m_hWnd;

public:
    static LRESULT MyHandler(HWND hWnd, UINT nMsg, WPARAM wParam, LPARAM lParam) 
    {
        LRESULT lResult;
        MyClass *ThisPtr = dynamic_cast<MyClass*>(::GetWindowLong(hWnd, GWL_USERDATA));
        if (!ThisPtr)
        {
            //Call defwindow proc, this window has not been initialized for this class.
        }

        switch (nMsg)
        {
            case WM_CREATE:
            {
                 lResult = ThisPtr->OnCreate(nMsg, wParam, lParam);
                 ...
            }
            case ...:
            ...
        }

        return lResult;
    }  

    HWND CreateWindow()  
    {     
        WNDCLASS wc;    
        wc.lpfnWndProc = MyHandler;    
        m_hWnd = CreateWindow(blah);  

        ::SetWindowLong(m_hWnd, GWL_USERDATA, (LONG)this);
        
        return m_hWnd;
    }

    // Handler functions
    LRESULT OnCreate (WPARAM wParam, LPARAM lParam)
    {
         //Handle the WM_CREATE message.
    }
};

There are other ways that are possible, I think that this a fairly straight forward technique if you are going to Write your own class framework to manage your windows.

Creating 256-color icons

Kei24-Feb-02 9:36

Kei

24-Feb-02 9:36

Hello,
I've tried using CreateIconIndirect to create a 256-color icon, by applying a 8bit bitmap in hbmColor. However the output icon is a 4-bit icon.. I'd appreciate if anyone can give me some help.

Paul M Watt24-Feb-02 15:20

Printing hex using std::ofstream

24-Feb-02 15:20

After you look at the icon data it is a 4-bit icon, or when you try to display it it is a 4-bit Icon?

nay24-Feb-02 9:36

nay

24-Feb-02 9:36

I'm trying to print out a hex value say b to a file. But instead of printing out b it prints 11. Now I know 11 is B in hex BUT I want the letter b.

Here's one variation I have tried.

object output is a vector of ints.

for(int i = 0; i < objectOutput.size(); i++)
     outfile  << std::hex << objectOutput[i] << std::endl;

I've tried std::hex and std::setiosflags and many different variations and combinations but I still get 11. What am I doing wrong?

nay

Re: Printing hex using std::ofstream

Paul M Watt24-Feb-02 15:40