How to trap mouse middle button clicks on a Histogram in a TCanvas

[Abyroot2014]

TRAPPING MOUSE MIDDLE BUTTON CLICKS ON A HISTOGRAM IN A TCanvas

I have a window in which I have a TCanvas embedded in a TRootEmbeddedCanvas.
I then draw a histogram using TH1I in the TCanvas.
Now my software is a standalone executable using ROOT libraries and
also has the following function where the window messages are processed :
Bool_t HistWin::ProcessMessage (Long_t msg, Long_t parm1, Long_t parm2)
Now I want to trap the mouse middle button clicks made on the histogram
and want to capture the index i.e the x-axis value of the point and
print the corresponding y-axis value.
I had a look at the files :
1.root/tutorials/gui/exec3.c
2.root/tutorials/hist/exec2.c
3.root/tutorials/hist/exec1.c
I could not locate the corresponding demo file.
I tried to understand it to incorporate the code in my program without much progress.
I guess I need help to make progress.

[couet]

See:

gPad->GetEventX() to axis range

Have a look at $ROOTSYS/tutorials/graphics/mandelbrot.C

How too find out which bin was clicked in a TH2D histogram

Hi, You can take a look at these tutorials: graphics/triangles.C, hist/exec2.C, hist/DynamicSlice.C and graphics/mandelbrot.C Cheers, Bertrand.

Mandelbrot macro

Dear all, while preparing a small ROOT course, I have written the following macro, that draws the fractal Mandelbrot set, and allows for zoom/unzoom operations. Runs with root mandelbrot.C+ I attach the macro and a screenhsot, just in case someone is interested (maybe a new ROOT tutorial on TExec/TComplex ? [8)] ) Bye Luigi [image] mandelbrot.C (3.24 KB)

[Abyroot2014]

Hi, I made some progress as can be seen by running attached code.
BUT now a new problem : after closing the histogram window if i re-open it again and then if I CLICK the middle button then the following error messages appear :

Error in : BadDrawable (invalid Pixmap or Window parameter) (TGCompositeFrame XID: 71303530, XREQ: 62)
TGCompositeFrame: 71303530
TGViewPort: 71303521
TRootEmbeddedCanvas: 71303520
TGVerticalFrame: 71303519
TGCompositeFrame: 71303518
HistWin: 71303564
Error in : BadWindow (invalid Window parameter) (TGCompositeFrame XID: 71303530, XREQ: 2)
TGCompositeFrame: 71303530
TGViewPort: 71303521
TRootEmbeddedCanvas: 71303520
TGVerticalFrame: 71303519
TGCompositeFrame: 71303518
…
To compile attached code do as follows:

1. make clean
2. make dict
3. make
4. ./nscope to run the code

Kindly teach how to debug such error messages , can gdb be used ? or any other ? like ddd ?
or any other debugging method kindly suggest so I can debug on my own.
Help and guidance greatly appreciated. THANKS VERY MUCH.
nscopeIJuly2015.tar.gz (16.5 KB)

[bellenot]

Hi,

You should add: delete fRootEmbeddedCanvas799;in the destructor (TRootEmbeddedCanvas is not properly deleted by the Cleaup() method).
And you can use gdb, or your preferred debugger to debug your application…

Cheers, Bertrand.

[Abyroot2014]

Hi,
The code was still crashing sometimes when the HistWin window was closed.
So I added the line as follows and now it is much more stable:
…
In Destructor
…
if (fRootEmbeddedCanvas799)
delete fRootEmbeddedCanvas799;
}

Thank you Bertrand for solving my problem.
Cheers, Abraham