Re: TPad::WaitPrimitive comments

Maxim,

OK, I understand the problem now and I fixed TPad::WaitPrimitive in CVS. Thanks for having reported the problem with a very short script.

Rene Brun

On
Wed, 26 Apr 2006, Maxim Nikulin wrote:

> Hi Rene,
>
> I'm sorry that my message was not clear enough.
>
> Rene Brun wrote:
>>
>> -Could you indicate what type of problems you faced?
>> -What is the problem that you are trying to solve?
>
> Sometimes I want to have a look at intermediate results and then
> continue calculation. Adding the statement gPad->WaitPrimitive() to a
> script I expect to get pause at that point. The problem is that in some
> cases ROOT continues execution of the script. E.g. this script doesn't
> stop at all:
>
> {
> h = new TH1F ("h", "h", 10, 0, 1);
> h->Draw();
> t = new TText(0.5, 0.5, "Text");
> t->Draw();
> for (Int_t i = 0; i < 10; ++i)
> {
> h->Fill(i/10. + 0.01);
> c1->Modified();
> c1->Update();
> c1->WaitPrimitive();
> }
> }
>
> Another case is more subtle. Let's remove TText object:
> {
> h = new TH1F ("h", "h", 10, 0, 1);
> h->Draw();
> for (Int_t i = 0; i < 10; ++i)
> {
> h->Fill(i/10. + 0.01);
> c1->Modified();
> c1->Update();
> c1->WaitPrimitive();
> }
> }
> During the first iteration the script always stops. If I press a key
> (E.g. [space]) the next 9 steps are passed without pauses. In case of
> double clicks the script usually passes two or three iterations. I think
> that actually it runs until double click events is replaced by mouse move.
>
> Another issue that closing of the window during processing of
> WaitPrimitive() obviously leads to segmentation violation.
>
>> What you show is certainly not a solution to any problem.
>> If you just want to interact with the window while filling the histograms
>> simply call gSystem->ProcessEvents();
>
> No, the goal is to stop calculation until user presses a key. Fill() was
> added just to have different plots.
>
>> On Mon, 24 Apr 2006, Maxim Nikulin wrote:
>>
>>> Hi,
>>>
>>> I faced several problems during my attempts to use the
>>> TPad::WaitPrimitive() method and I think these issues should be mentioned
>>> in the documentation. I've written a script demonstrating a possible
>>> solution, I hope it will be useful for someone.
>>>
>>> {
>>> h = new TH1F ("h", "h", 10, 0, 1);
>>> h->Draw();
>>> t = new TText(0.5, 0.5, "Text");
>>> t->SetName("t"); // otherwise it has empty name ""
>>> // and WaitPrimitive() returns immediately
>>> // TText is not the only class having the empty
>>> // name by default
>>> t->Draw();
>>> for (Int_t i = 0; i < 10; ++i)
>>> {
>>> h->Fill(i/10. + 0.01);
>>> c1->Modified();
>>> c1->Update();
>>> c1->WaitPrimitive();
>>> c1->HandleInput(kNoEvent, 0, 0); // next call of WaitPrimitive()
>>> // often receives the same event
>>> // so no pause happens
>>> cout << i << endl;
>>> }
>>> }
>>>
>>> Another point is that the canvas can be closed while WaitPrimitive() is
>>> executed. Probably the code should handle this case.
>>>
>>> I don't think input event processing significantly varies for different
>>> window managers, but just to be precise. I use Black box window manager,
>>> ROOT 5.10/00 and Fedora Core 2 on a Pentium 4 box.
>
>
Received on Sat Apr 29 2006 - 19:53:35 MEST