dynamicCall and QByteArray - strange characters

[franco.amato]

Hi to all,
doing some test with a com object seems that a com routine that I call with dynamicCall returns a QByteArray or a QString.
Looking at examples of call of such routine seems that it returns an array of bytes where every element is a pointer to a string

I did some tests as this:

QByteArray array = obj->dynamicCall("routine(QString)", "value").toByteArray();
Debugging with visual studio and doing some cout ( qDebug() << array.data() ) I can see very strange characters like this "‰*" in both case, using QByteArray and QString.
The routine called with dymanicCall comunicate with a chinese fingerprint reader. Maybe this is the reason I get such strange characters?

Looking at doc and visual basic example the value returned should be an array of bytes -> returned_value[value1,value2,value3, value4..];

and

value1 = value2 = value3 = should points to a string.

How can I get the value of every value without getting these strange characters?
I hope to get help wysota where are you?

Regards

[ChrisW67]

Can you run the dumpcpp utility against the com object you are working with?

cd somewheresafetowrite
dumpcpp c:\windows\system32\comctl32.ocx

cd somewheresafetowrite
dumpcpp c:\windows\system32\comctl32.ocx

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The resulting cpp and h file should allow you to more directly access the COM objects by simply instantiating them in the typical C++ fashion:

ComctlLib::TreeView m_treeView;
...
m_treeView.SetBorderStyle(ComctlLib::ccFixedSingle);

ComctlLib::TreeView m_treeView;
...
m_treeView.SetBorderStyle(ComctlLib::ccFixedSingle);

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The process can be largely automated by:

client.pro

TEMPLATE = app
CONFIG += qaxcontainer
TARGET = client
DEPENDPATH += .
INCLUDEPATH += .
RC_FILE = client.rc
// {6B7E6392-850A-101B-AFC0-4210102A8DA7} is the TypeLib value from the class concerned.
TYPELIBS = $$system( dumpcpp -getfile {6B7E6392-850A-101B-AFC0-4210102A8DA7} )
isEmpty(TYPELIBS) { 
    message("Tree control type library not found!")
    REQUIRES += COMCTL.TreeView
}
else: {# Input
    SOURCES += main.cpp
}

TEMPLATE = app
CONFIG += qaxcontainer
TARGET = client
DEPENDPATH += .
INCLUDEPATH += .
RC_FILE = client.rc
// {6B7E6392-850A-101B-AFC0-4210102A8DA7} is the TypeLib value from the class concerned.
TYPELIBS = $$system( dumpcpp -getfile {6B7E6392-850A-101B-AFC0-4210102A8DA7} )
isEmpty(TYPELIBS) { 
    message("Tree control type library not found!")
    REQUIRES += COMCTL.TreeView
}
else: {# Input
    SOURCES += main.cpp
}

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[franco.amato]

Can you run the dumpcpp utility against the com object you are working with?

cd somewheresafetowrite
dumpcpp c:\windows\system32\comctl32.ocx

cd somewheresafetowrite
dumpcpp c:\windows\system32\comctl32.ocx

To copy to clipboard, switch view to plain text mode 

The resulting cpp and h file should allow you to more directly access the COM objects by simply instantiating them in the typical C++ fashion:

ComctlLib::TreeView m_treeView;
...
m_treeView.SetBorderStyle(ComctlLib::ccFixedSingle);

ComctlLib::TreeView m_treeView;
...
m_treeView.SetBorderStyle(ComctlLib::ccFixedSingle);

To copy to clipboard, switch view to plain text mode 

The process can be largely automated by:

client.pro

TEMPLATE = app
CONFIG += qaxcontainer
TARGET = client
DEPENDPATH += .
INCLUDEPATH += .
RC_FILE = client.rc
// {6B7E6392-850A-101B-AFC0-4210102A8DA7} is the TypeLib value from the class concerned.
TYPELIBS = $$system( dumpcpp -getfile {6B7E6392-850A-101B-AFC0-4210102A8DA7} )
isEmpty(TYPELIBS) { 
    message("Tree control type library not found!")
    REQUIRES += COMCTL.TreeView
}
else: {# Input
    SOURCES += main.cpp
}

TEMPLATE = app
CONFIG += qaxcontainer
TARGET = client
DEPENDPATH += .
INCLUDEPATH += .
RC_FILE = client.rc
// {6B7E6392-850A-101B-AFC0-4210102A8DA7} is the TypeLib value from the class concerned.
TYPELIBS = $$system( dumpcpp -getfile {6B7E6392-850A-101B-AFC0-4210102A8DA7} )
isEmpty(TYPELIBS) { 
    message("Tree control type library not found!")
    REQUIRES += COMCTL.TreeView
}
else: {# Input
    SOURCES += main.cpp
}

To copy to clipboard, switch view to plain text mode 

Hi,
I executed the dumpcpp on my dll ( the com object) but it doesn't generated any *.h or *.cpp
What can I do?

[ChrisW67]

Did you write the com object yousrself? Using QAxServer? If so you probably have a file ending .tlb as part of the build process, and you can put this file name directly in TYPELIBS.

[franco.amato]

Did you write the com object yousrself? Using QAxServer? If so you probably have a file ending .tlb as part of the build process, and you can put this file name directly in TYPELIBS.

No I didn't write the com object. It com from a finger print sdk I have. I have it in a compiled dll.
I'm not sure now if I have a tlb file as I'm out of office. If I have it what can I do? And if I don't have it?

[ChrisW67]

No I didn't write the com object. It com from a finger print sdk I have. I have it in a compiled dll.
I'm not sure now if I have a tlb file as I'm out of office. If I have it what can I do? And if I don't have it?

You can try

TYPELIBS += C:\path\to\your\fingerprint.dll

TYPELIBS += C:\path\to\your\fingerprint.dll

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which seems to work OK for me for at least some COM objects.

[franco.amato]

You can try

TYPELIBS += C:\path\to\your\fingerprint.dll

TYPELIBS += C:\path\to\your\fingerprint.dll

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which seems to work OK for me for at least some COM objects.

If I also have the *.tlb I have to do

TYPELIBS += C:\path\to\your\fingerprint.dll

TYPELIBS += C:\path\to\your\fingerprint.dll

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And

TYPELIBS += C:\path\to\your\fingerprint.tlb?

TYPELIBS += C:\path\to\your\fingerprint.tlb?

To copy to clipboard, switch view to plain text mode 

[ChrisW67]

If you have the TLB file then list it otherwise try listing the DLL or OCX file itself. One or the other, not both.

[franco.amato]

The resulting cpp and h file should allow you to more directly access the COM objects by simply instantiating them in the typical C++ fashion:

ComctlLib::TreeView m_treeView;
...
m_treeView.SetBorderStyle(ComctlLib::ccFixedSingle);

ComctlLib::TreeView m_treeView;
...
m_treeView.SetBorderStyle(ComctlLib::ccFixedSingle);

To copy to clipboard, switch view to plain text mode 

Hi, I don't understand a thing:
I don't have to use the new operator to instantiate the objects?

[ChrisW67]

Hi, I don't understand a thing: I don't have to use the new operator to instantiate the objects?

That depends on the lifetime you expect the object (m_treeView in my example) to have. On the stack is fine for a short lifespan limited by scope, on the heap would be more typical. The code generated by dumpcpp connects to COM control at the time the wrapper object is constructed and doesn't care how the object came to be.

You have had success with dumpcpp creating some wrappers. The generated classes should manage marshalling COM response into qt and/or C++ structures for you make for more direct access (adjust names as needed):

#include "generated_header.h"
...
terminalLib::oTerminal *comObject;
 
comObject = new terminalLib::oTerminal(this);
QVariant result = oTerminal->GetUserData(QString("some card id thingy"));
delete comObject;

#include "generated_header.h"
...
terminalLib::oTerminal *comObject;

comObject = new terminalLib::oTerminal(this);
QVariant result = oTerminal->GetUserData(QString("some card id thingy"));
delete comObject;

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If you dig around in the generated H and CPP file you might find a definition of "ArrayList" (or it may be intended to be an opaque blob although this seems unlikely). You may also find references to a Windows help file that matches the type library.

Could you post (attach) the generated header file?

[ChrisW67]

If the QVariant returned is of type QByteArray then the COM return was a SAFEARRAY(BYTE) according to the QAxBase documentation.
You might find this useful:
http://www.roblocher.com/whitepapers/oletypes.aspx
http://msdn.microsoft.com/en-us/libr...ROT.13%29.aspx

[franco.amato]

That depends on the lifetime you expect the object (m_treeView in my example) to have. On the stack is fine for a short lifespan limited by scope, on the heap would be more typical. The code generated by dumpcpp connects to COM control at the time the wrapper object is constructed and doesn't care how the object came to be.

You have had success with dumpcpp creating some wrappers. The generated classes should manage marshalling COM response into qt and/or C++ structures for you make for more direct access (adjust names as needed):

#include "generated_header.h"
...
terminalLib::oTerminal *comObject;
 
comObject = new terminalLib::oTerminal(this);
QVariant result = oTerminal->GetUserData(QString("some card id thingy"));
delete comObject;

#include "generated_header.h"
...
terminalLib::oTerminal *comObject;

comObject = new terminalLib::oTerminal(this);
QVariant result = oTerminal->GetUserData(QString("some card id thingy"));
delete comObject;

To copy to clipboard, switch view to plain text mode 

If you dig around in the generated H and CPP file you might find a definition of "ArrayList" (or it may be intended to be an opaque blob although this seems unlikely). You may also find references to a Windows help file that matches the type library.

Could you post (attach) the generated header file?

Dear Chris,
for sure. Tomorrow I'll post the .h file.

Regards

[franco.amato]

Could you post (attach) the generated header file?

I tried to send the files you asked for but the forum says they are bigger than the limit.
If you have a mail address I can send them to you.

Regards

[wysota]

Compress them. Then you will be able to attach them to your post. And only send the relevant file (.h).

[franco.amato]

Compress them. Then you will be able to attach them to your post. And only send the relevant file (.h).

Ok Wysota thank you.
I compressed PallyCom.h in PallyCom.zip ( 8K )

Regards

[franco.amato]

Compress them. Then you will be able to attach them to your post. And only send the relevant file (.h).

Wysota I saw some data calling the routine in a C# console application and I had to do a conversion byte to ascii to see something.
I think if for that that I can not see nothing in Qt. How can I convert the bytearray in ascii?
I also saw that the stream of data contains lots of '\0' and for that maybe I can not see well all characters.

Best

[wysota]

How can I convert the bytearray in ascii?

What did you already try to do it?

[franco.amato]

What did you already try to do it?

Hi,
first I have know how to access to every byte contained in the bytearray and discover how Qt manage the '\0' as in the
returned stream I have lots of such character

[wysota]

Hi,
first I have know how to access to every byte contained in the bytearray and discover how Qt manage the '\0' as in the
returned stream I have lots of such character

Then open the documentation of QByteArray and read it. I can tell you that Qt doesn't "manage" null bytes in any way. They are bytes like any other.

[franco.amato]

Then open the documentation of QByteArray and read it.

This is was I already did many times

I can tell you that Qt doesn't "manage" null bytes in any way. They are bytes like any other.

This is the result of the routine call in a cmd line app written in C#:

"I??\0\0xml;q=0.Franco\0\0\0\0\0\0\0\0\0Amato\0\0 \0\0\0\0\0\0\0\0

\0\0\0\0AAAAAAAAAAAAAAA=0\0\n \n0987654321

`E?\"UF ??\fCQ????O\"D ?\v2??(E??\n2F?D?\fH1\b\vH???\nIae?.???(?`>?/?p<?;M???????:????\"
8??`:?!???PQ?\r??`'?`2 ??Q)\n??#3?????#34????\"34????\"34O???\"34O? ??\"#3D???#4D???
#4D???
#4D???
34D???
\"3DD? ??
#DDE???
4DTE???4UUEo??EUUUo???VffUo???ffff?? ?wwff????wwvg?\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0 \0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0 \0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0 \0\0\0\0\0\0\0\0\0"

You can see many '\0' but why debuggind with visual studio my Qt app I can not see the same string that's should contained in the QByteArray? And also I really don't understand which characteres are these:     ??

I hope you can help me