Determine if using HG2

How can I determine if MATLAB or the current figure is using the new graphics pipeline, HG2? I need a function

   tf = ishg2(figure_handle)

which should be backwards compatible, say to MATLAB 7.0, and also account for the fact that people can choose which rendering pipeline to use (HG1 or HG2) in newer MATLAB releases, so simply checking version number is not sufficient.

[Oliver Woodford]

The

get(gcf, 'usehg2')

property described here appears not to work in R2014b prerelease.

[Robert Berglin]

It's so simple you may not want to bother to create a function:

function result = ishg2(figure_handle)
  if isnumeric(figure_handle)
    result=false;
  else
    result=true;
  end
end

[Walter Roberson]

figure handles are permitted to be numeric in hg2.

Answer 1

[Oliver Woodford]

I've ended up using the undocumented function, graphicsversion():

function tf = ishg2(fig)
try
    tf = ~graphicsversion(fig, 'handlegraphics');
catch
    tf = false;
end

[Oliver Woodford]

graphicsversion is undocumented and may disappear in the future. Cris Luengo's first suggestion might be a better option.

Answer 2

[Jan]

A summary of the solutions posted here, which use a figure handle h:

exist('graphicsversion', 'builtin') && ~graphicsversion(h, 'handlegraphics')
isgraphics(h) && isa(h,'handle')
isa(h, 'handle')
~isnumeric(h)
isa(h, 'matlab.ui.Figure')
~graphicsversion(h, 'handlegraphics')   % Not documented
get(h, 'usehg2')                        % Not working in some versions

A version without using a figure handle:

~verLessThan('matlab', '8.4')
[100, 1] * sscanf(version, '%d.', 2) < 804  % 170 times faster than verLessThan method

The function ishg2figure was part of Matlab2006a already, but it is private and not documented.

Many codes depend on the used handle graphics version. Therefore a reliable an efficient identification is required and the corresponding tool should not be determined by a discussion in the forum, but by an officially documented Matlablab function. In addition this function must be available for older Matlab versions also, such that I need a download e.g. in the FileExchange or the knowledge base.

Answer 3

[Oliver Woodford]

Currently I'm using the version checking approach:

function tf = ishg2()
try
    tf = ~verLessThan('matlab', '8.4');
catch
    tf = false;
end

Answer 4

[Cris Luengo]

You can simply check the class of the figure handle:

function tf = ishg2(fig)
   tf = isa(h,'matlab.ui.Figure');

or:

function tf = ishg2(fig)
   tf = ~isnumeric(fig);

In the second case you are not checking whether the input is a figure handle or not, buyer beware.

Answer 5

[Markus Leuthold]

For any handle returned by a plot command,

isa(h,'handle')

returns true if HG2 is used, false otherwise. The command does not check if h is still a valid handle. If you need that, then

isgraphics(h) && isa(h,'handle')

Works on both 2014b and older versions

[Mike Garrity]

That version's actually not safe. To help keep old code running in 14b, it's possible to cast a handle to a graphics object into a double.

The following returns false

ax = gca
h = double(ax)
if isgraphics(h) && isa(h,'handle')
  disp('is')
else
  disp('aint')
end

Similarly there were some tricky cases in earlier versions where you could cast the double value for a graphics object into a handle.

The graphicsversion function is actually the safest way to do this because it knows all of the different combinations.

If you need to run in an old version which didn't have the graphicsversion command, then you can assume that you don't have a new graphics object. So you could either use try/catch as Oliver showed, or do something like this:

exist('graphicsversion','builtin') && ~graphicsversion(h,'handlegraphics')

Answer 6

[Cris Luengo]

Revisiting this issue.

The best method discussed here is using `graphics` version. However, you currently get a warning when you use it, since it's deprecated. The help to that function suggests you compare the version number to 8.4:

 verLessThan('matlab','8.4.0')

Jan Simon suggested this as a faster alternative:

 [100, 1] * sscanf(version, '%d.', 2) < 804

However, since it's possible to turn off HG2 in at least some versions of MATLAB, this is not a fool-proof method.

An alternative could be:

 try, hg2 = strcmp(get(fig,'GraphicsSmoothing'),'on'); catch, hg2 = false; end

The 'GraphicsSmoothing' is a property that only exists for HG2 figures.

The solution I had given earlier,

 ~isnumeric(fig)

only works if `fig` has not been converted to double. So you can use it on the result of `figure` or `gcf`, but if you write a function that takes a figure handle as input, and you want your uses to be able to simply type the figure number, then that method fails.