An CALLBACK function could be member of an class ?

I am trying to use CDC::EnumObjects method just like this:

Code:

---

        CDC dc;
        dc.Attach(hDC);
        dc.EnumObjects(OBJ_PEN, EnumObjectHandler, 0);

---

from here: https://msdn.microsoft.com/en-us/lib...or=-2147217396

and

Code:

---

BOOL CALLBACK EnumObjectHandler(LPVOID lpLogObject, LPARAM lpData)
{
        return TRUE;
}

---

and it works.

My question is, can I move this function, in an class, as member function (method), but, most important, without changing as static ? Yes, I can put here my trials, but none of them had worked ... perhaps it is not possible what I am trying to do :)

If you move EnumObjectHandler() into a class as a member function then it needs to be static.

Quote:

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Originally Posted by mesajflaviu

I am trying to use CDC::EnumObjects method just like this:

Code:

---

        CDC dc;
        dc.Attach(hDC);
        dc.EnumObjects(OBJ_PEN, EnumObjectHandler, 0);

---

from here: https://msdn.microsoft.com/en-us/lib...or=-2147217396

and

Code:

---

BOOL CALLBACK EnumObjectHandler(LPVOID lpLogObject, LPARAM lpData)
{
        return TRUE;
}

---

and it works.

My question is, can I move this function, in an class, as member function (method), but, most important, without changing as static ? Yes, I can put here my trials, but none of them had worked ... perhaps it is not possible what I am trying to do :)

---

Yes, you can.
for example, you can pass the this pointer as a lpData parameter.
Then from within this static Callback function you'll be able to call any of your class members using the passed in this pointer.

Good point, my goal is to move the callback function inside of an class, as a member method ... and I understand that there is no alternative but declare as static. Sometime this solution could be a workaround. Kindly thank you all of you !

An alternative to member functions is to use lambdas, introduced by C++11.
Example:

Code:

---

void CEnumDialog::EnumPens(CDC& dc)
{
    dc.EnumObjects(OBJ_PEN,
        [](LPVOID lpLogObject, LPARAM lParam)->BOOL
    {
        LOGPEN* pPen = (LOGPEN*)lpLogObject;
        CEnumDialog* pDlg = (CEnumDialog*)lParam;
                    // Do something cool here...
        return TRUE; // ...then continue the enumeration.
    }, (LPARAM)this);
}

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See also Using Lambdas in MFC Applications – Replacing Callback Functions