Given handle to graphics object, determine which properties are read-only

Sometimes I find I'd like to copy all properties of a graphics object to another object, excluding the ones that are read-only. I.e., I would like to avoid errors like the following where h1 and h2 are both text object handles,

   >> set(h2,get(h1))

Error using set
Attempt to modify a property that is read-only.
Object Name: text
Property Name: 'Annotation'.

Is there an easy way to filter out the read-only properties?

Answer 1

[per isakson]

Yes

    set_properties = set( h2 );
    get_properties = get( h2 );
    read_only_properties = setdiff( fieldnames( get_properties ) ...
                                  , fieldnames( set_properties ) );

See documentation on set, Set Handle Graphics object properties

    a = set(h) returns the user-settable properties and possible values
    for the object identified by h. [...]

and on get

    a = get(h) returns a structure whose field names are the object's
    property names and whose values are the current values of the 
    corresponding properties. [...]

.

In response to comment:

The hack cssm below does nearly implement set(h2,gp). (The functions isflint and dbs are attached.)

    function    cssm(  )
        figure; 
        subplot(121); plot(1:5);    h1=gca; 
        subplot(122); plot(5:-1:1); h2=gca; 

        sp = set( h1 );
        gp = get( h1 );
        rop = setdiff( fieldnames( gp ), fieldnames( sp ) );

        for ii=1:length(rop) %get rid of read-only properties of h1
           gp = rmfield( gp, rop{ii} );
        end

        for name = transpose( fieldnames( gp ) )
            try
                if not(isempty( gp.(name{:}) ))  ...
                   &&  all(all(ishghandle( gp.(name{:}) )))

                    if not(any(isflint( gp.(name{:}) )))
                        copyobj( gp.(name{:}), h2 )
                    else
                        set( h2, name{:}, gp.(name{:}) )
                    end
                else
                    if not(any( strcmpi( name, {'Position' ...
                                               ,'OuterPosition'} ) ))
                        set( h2, name{:}, gp.(name{:}) )
                    end
                end
            catch me 
                dbs
                17;
            end
        end
    end

.

Many properties have the value 0 or 1. ishghandle returns true for both of these (given that figure 1 exists). if not(any(isflint( gp.(name{:}) ))) spots these values.

[Matt J]

That's quite interesting. But then why doesn't the following work, as way to copy axes h1 to axes h2

    figure; 
    subplot(121); plot(1:5); h1=gca; 
    subplot(122); plot(5:-1:1); h2=gca; 

    sp = set( h1 );
    gp = get( h1 );
    rop = setdiff( fieldnames( gp ) ...
                   , fieldnames( sp ) );

       for ii=1:length(rop) %get rid of read-only properties of h1

           gp=rmfield(gp,rop{ii});

       end

    set(h2,gp)

For me this produces the error message,

 Error using set
 Children may only be set to a permutation of itself

[per isakson]

Matlab says

    >> why
    To fool the tall good and smart system manager.

and we have to accept that answer together with the error message ;-)

I'll add a modified version of your code to my answer.

[Cedric]

Interesting, this error cannot be reproduced all the time, because the cause varies..

 >> why
 The bald and not excessively bald and not excessively smart hamster obeyed a  
 terrified and not excessively terrified hamster.

Mine says that this is a large furry bug with big pointy teeth

 :-|

[Matt J]

I'll add a modified version of your code to my answer.

But what is the cause of the error my original version produces? What does " Children may only be set to a permutation of itself " mean?

Once the read-only properties of gp are removed, why doesn't

set(h2,gp)

work directly?

[per isakson]

AKAIK: set( h, 'Children', children_handles ) can only be used to changed the "order" of the children, where "order" affects z-order, tab-order or whatever is applicable.

[Matt J]

OK! Thanks.