ASImage problem in TASImage child class

ROOT
1

Hello,

I want to create a child class of TASImage and when I try to overwrite the ExecuteEvent function I run into the following problems:

Any ideas on how to resolve this? A minimal example is attached. If you comment out the ExecuteEvent function the code compiles fine. In the example, the function is a simple copy of TASImage::ExecuteEvent without any new code.

Thanks,
Gregor
MyGui.zip (112 KB)

2

In your “MyGui.cxx” file:

  1. replace all “->fImage” occurrences with “->GetImage()”
  2. in the beginning, add appropriate include files which are required in order to define the “ASImage” structure, which originates in the “libAfterImage” (warning: ROOT usually builds and uses its own version of the “libAfterImage”, so you cannot use the one that comes with your operating system -> see how the “libASImage” is built)
3

Thanks! “->GetImage()” works, even though I’m still wondering why I shouldn’t be able to access a protected base class member from a child class…

Anyway, I have decided to make do with

void MyTASImage::ExecuteEvent(Int_t event, Int_t px, Int_t py){
   TASImage::ExecuteEvent(event,px,py);

   // Do my own stuff afterwards:
   // ...
}

instead of messing with all the includes and copying files manually from build tree to install directory, particularly since other people are using the code on other machines.

4

Hi,

One of the error messages was:
…
…/MyGui.cxx:38:43: error: within this context
if (fScaledImage) image = fScaledImage->fImage;

So the complain is accessing fImage via the pointer fScaledImage.

MyTASImage can access its own base classes data member but not those
from a different object.
but an object can access its own protected member in both itself and a
different object of the same type.
(See paragraph 11.5 ; it would have worked if fScaledImage was a
MyTASImage*)

Cheers,
Philippe.