Re: uimenu implementation, 2nd version [octave_execution_exception]

[Ben Abbott]

On Oct 29, 2010, at 4:31 PM, Kai Habel wrote:

> Am 29.10.2010 10:11, schrieb Ben Abbott:
>> On Oct 29, 2010, at 3:16 PM, Kai Habel wrote:
>> 
>>> Am 27.10.2010 09:56, schrieb Ben Abbott:
>>> 
>>> Ben,
>>> 
>>> I don't think the error is related to the call of error (msg). Can you 
>>> check this, by commenting out this line or placing an input('press enter') 
>>> before this line.
>> You are correct. When I comment out this line, the crash still occurs.
>> 
>>> I think the FLTK-GUI runs in "parallel" and is catching an mouse event.
>>> 
>>> When looking at the backtrace, I see that  at #18 plot_window::handle() is 
>>> called with event==1 (FL_PUSH?) and after that 
>>> plot_window::pixel2axes_or_ca (this=0x19123970, px=35,py=52). This looks 
>>> like valid pixel coordinates. Can you confirm that the error happens during 
>>> pixel2axes_or_ca. That should be possible with a debugger, or you can place 
>>> some debug statements in there e.g. printf("before\n"); printf("after\n");
>>> 
>>> The crash seems to happen later in:
>>> #14 0x001ccadd in screen_size_pixels () at graphics.cc:541
>>> 
>>> where we have
>>> 
>>> #13 0x017b67ea in Matrix::extract_n (this=0xbfff85e8, r1=0, c1=2, nr=1, 
>>> nc=2)
>>> 
>>> ----------graphics.cc-----------
>>> // This function always returns the screensize in pixels
>>> 
>>> static Matrix
>>> screen_size_pixels (void)
>>> {
>>>   graphics_object obj = gh_manager::get_object (0);
>>>   Matrix sz = obj.get ("screensize").matrix_value ();
>>>   return convert_position (sz, obj.get ("units").string_value (), "pixels", 
>>> sz.extract_n (0, 2, 1, 2)).extract_n (0, 2, 1, 2);
>>> }
>>> -------------------------------------------------
>>> 
>>> It seems convert_position() is never called, because one of those 
>>> xxx.extract_n() calls fail.
>>> 
>>> Can you check there if all variables are ok there?
>>> 
>>> Kai
>> I'm a c++ flunky. It may be necessary for  you give me the commands I need 
>> to check the variables are ok.
>> 
>> I realize I should start with ...
>> 
>>      break graphics.cc:541
>> 
>> ... which stops at "return convert_position (...)"
>> 
>> Is it enough to then to ..
>> 
>>      print sz
>> 
>> Which gives ..
>> 
>> $1 = {
>>     <Array<double>>  = {
>>       rep = 0x2d6b7e0,
>>       dimensions = {
>>         rep = 0x2d7c6c8
>>       },
>>       slice_data = 0x4955440,
>>       slice_len = 4
>>     },<No data fields>},<No data fields>}
>> 
>> I can "continue" several times until the plot window appears with the 
>> uimenu, but then I'm unable to select the "clf" option since I have to go 
>> back to the command line and type "continue" again... hmm, I'm not being 
>> very clear. Hopefully you understand my problem with the debugger.
>> 
>> Is the a c++ command I can insert into the code to print the contents of 
>> "sz" to the command liine?
>> 
>> Ben
> I don't use gdb much, so I don't how to access sz from there. But if you put 
> in something like:
> 
> std::cout << "sz(0): " << sz(0)<< ", sz(1): " << sz(1)<< ", sz(2):" << 
> sz(2)<< ", sz(3):" << sz(3) << std::endl;
> 
> that should give you the content of sz, with:
> sz(0) x0?
> sz(1) y0?
> sz(2) width
> sz(3) heigth
> 
> Kai

Ok. good call!

sz(0): 1, sz(1): 1, sz(2):1680, sz(3):1050
sz(0): 1, sz(1): 1, sz(2):1680, sz(3):1050
sz(0): 1, sz(1): 1, sz(2):1680, sz(3):1050
sz(0): 1, sz(1): 1, sz(2):1680, sz(3):1050
error: Invalid call to clf.  Correct usage is:

 -- Function File:  clf ()
 -- Function File:  clf ("reset")
 -- Function File:  clf (HFIG)
 -- Function File:  clf (HFIG, "reset")


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sz(0): 1.93148e-288, sz(1): 2.122e-314, sz(2):0, sz(3):0
terminate called after throwing an instance of 'octave_execution_exception'
panic: Abort trap -- stopping myself...
attempting to save variables to `octave-core'...
save to `octave-core' complete

The last one is full of nonsense.

What next?

Ben