How do you set the focus to a specific uiaxes

I am designing an app with the new App Designer format and would like to be able to set the focus of my uifigure to draw on a specific set of uiaxes when I activate a particular callback.

When I attempt to target the axis for plotting using

axes(app.UIAxes)

I get the following error:

Error using axes
Functionality not supported with figures created with the uifigure function.

And calling:

uiaxes(app.UIAxes)

yields:

Error using uiaxes (line 32)
UIAxes cannot be a child of UIAxes.

Is it possible to set the current axes/panel of a uifigure object via their handle? How do I go back add a plot to uiaxes after having created them and subsequently edited other components on the uifigure?

Answer 1

[Cris LaPierre]

I would recommend using the plot(ax,___) syntax.

" plot(ax,___) creates the line in the axes specified by ax instead of in the current axes (gca). The option ax can precede any of the input argument combinations in the previous syntaxes."

What I typically do is create a startup function that generates the initial plot

function startupFcn(app)
   ...
   app.p1 = plot(app.UIAxes,x,y1)
   ...
end

Then, when I want to update my line, my app just updates the XData and YData properties of app.p1

% Update line
app.p1.XData = x_new;
app.p1.YData = y1_new;

Of course, this all depends on what type of plot you want to create.

BTW, startup function is a callback of the app canvas. See this page for how to add/create it.

[James Kirk]

Thank you for this solution!

[zhehao.nkd]

Great solution ! But what if I am not using plot, instead I am using spectogram, imshow or whatever self-defined functions without (ax,___) syntax?

[Cris LaPierre]

Check the documentation for that function to see if there is a 'Parent' name-value pair. If there is, use that syntax. You might also need to check the properites of the graphics object to see what the equivalent XData and YData properties are.

Here's a link for imshow.

imshow('peppers.png','Parent',app.UIAxes);

[Matt J]

Unfortunately, some 3rd party code from before the days of appdesigner do not support an "ax" input. Are we really forced to rewrite the 3rd party code? Is there really no equivalent to axes(ax) for forcing a uiaxes into focus?

[Sylvia Ludwig]

+1

[Wes Baldwin]

+1

[Walter Roberson]

Note with respect to spectrogram() :

spectrogram() has no way of passing in a figure / uifigure or an axes / uiaxes

spectogram() does a gcf() . By default, HandleVisibility is off for uifigure(), so by default uifigure are skipped over. Probably a new figure() will be created to satisfy the gcf(). However, you can deliberately set HandleVisibility to on for uifigure, in which case gcf() will find the uifigure

spectogram() does a nextplot() with no parameters. If the nextplot is marked as replace or replacechildren then nextplot() will clf(), which will destroy the current axes. Otherwise nextplot is marked as new or add. If an axes is found then it is cla() . If no axes is found then nextplot uses axes('parent', fig) to create one.

So... by manipulating HandleVisibility you can get spectogram to plot inside a uifigure, and it will be able to find the current uiaxes. It will cla() the uiaxes, but that will leave the position intact.

Answer 2

[Walter Roberson]

Somewhere around R2020b (possibly R2020a) it became possible to axes() the handle to a uiaxes to bring it into focus.

(It did not work in R2019b; I do not happen to have R2020a installed to test with.)