Re: question about ordering of visible/hidden children in graphics objects (was: rearranging 'children' in a graphics handle)

[John W. Eaton]

On 10-Feb-2010, Ben Abbott wrote:

| On Feb 10, 2010, at 1:56 PM, John W. Eaton wrote:
| 
| > On 10-Feb-2010, Ben Abbott wrote:
| > 
| > | Its not clear to me if the discussion is about hidden handles or
| > | hidden objects.
| > 
| > Hidden handles.  For example, what does Matlab do for the following?
| > 
| >  h1 = line (rand (3, 1), rand (3, 1))
| >  h2 = line (rand (3, 1), rand (3, 1))
| >  h3 = line (rand (3, 1), rand (3, 1))
| >  set (0, 'showhiddenhandles', 'on')
| >  get (gca (), 'children')             ## expect [h3; h2; h1; hidden...]
| >  set (0, 'showhiddenhandles', 'off')
| >  set (h2, 'handlevisibility', 'off');
| >  kids = get (gca (), 'children')      ## should only get [h3; h1]
| >  set (0, 'showhiddenhandles', 'on')
| >  get (gca (), 'children')             ## expect [h3; h2; h1; other 
hidden...]
| >  set (0, 'showhiddenhandles', 'off')
| >  set (gca (), 'children', flipud (kids))
| >  get (gca (), 'children')             ## expect [h1; h3]
| >  set (0, 'showhiddenhandles', 'on')
| >  get (gca (), 'children')
| > 
| > Should the result of the last command above be
| > 
| >  [h1; h3; h2; other hidden...]
| > 
| > or
| > 
| >  [h1; h2; h3; other hidden...]
| > 
| > Currently, Octave returns the first list above.
| > 
| > BTW,
| > 
| >  findall (gca ())
| > 
| > does not seem to be equivalent to
| > 
| >  set (0, 'showhiddenhandles', 'on')
| >  get (gca (), 'children')
| > 
| > With findall, the handles appear to be sorted.  Is that required for
| > compatibility with Matlab?
| > 
| > What does Matlab do?  The order of the handles might matter in how
| > things are displayed, so we probably need to be compatible with the
| > Matlab behavior.
| > 
| > jwe
| 
| I've attached the results.
| 
| The portion below ...
| 
| >  get (gca (), 'children')             ## expect [h3; h2; h1; other 
hidden...]
| 
| was ordered as [other hidden handles; h3; h2; h1]
| 
| The last part was ordered as ... [other hidden handles; h2; h1; h3]

Then I think this part of our current implementation is OK, except
that the order of the handles is apparently reversed.  Does that
matter?  I thought we already switched the order of children once for
Matlab compatibility.  Did we get the ordering wrong?

Also, what about the order of the hidden objects, and what are they?
xlabel, ylabel, zlabel and what else?  Are they ordered the same in
Octave and Matlab?  Should they be the same?  Should we even care
about this detail?

| Regarding findall and get(gca,'children'), the list only differs by the 
handle for the current axis. However, the order is the same for each. See below.
| 
| >> findall(gca())
| 
| ans =
| 
|           171
|           177
|           176
|           175
|           174
|           172
|    0.00097656
|           173
| 
| >> set(0,'showhiddenHandles','on')
| >> get(gca,'children')
| 
| ans =
| 
|           177
|           176
|           175
|           174
|           172
|    0.00097656
|           173

OK, so should we fix Octave so that it does not sort the resutls of
findall?

jwe