% R2018a
hFig = figure; 
hAxes = axes(hFig);
plot(rand(100,1),'Parent',hAxes);

% JavaSceneServerGLJPanel=get(hAxes.NodeParent.JavaComponent,'Component')
% hJavaSceneServerGLJPanel=handle(JavaSceneServerGLJPanel,'CallbackProperties');
%  
% set(hJavaSceneServerGLJPanel,'FocusGainedCallback',@(x,y)disp('in focus'));
% set(hJavaSceneServerGLJPanel,'FocusLostCallback',  @(x,y)disp('... out'));

drawnow

jf=get(hFig,'JavaFrame');
jw=handle(jf.getFigurePanelContainer.getTopLevelAncestor,'CallbackProperties');
 
set(jw,'WindowGainedFocusCallback',@(x,y)disp('in focus'));
set(jw,'WindowLostFocusCallback',  @(x,y)disp('... out'));

   

% R2018a
hFig = figure; 
hAxes = axes(hFig);
plot(rand(100,1),'Parent',hAxes);

JavaSceneServerGLJPanel=get(hAxes.NodeParent.JavaComponent,'Component')
hJavaSceneServerGLJPanel=handle(JavaSceneServerGLJPanel,'CallbackProperties');
 
set(hJavaSceneServerGLJPanel,'FocusGainedCallback',@(x,y)disp('in focus'));
set(hJavaSceneServerGLJPanel,'FocusLostCallback',  @(x,y)disp('... out'));
   

Well, I found a solution (R2016b) by trial and error for very simple situations, i.e., just one axes inside the figure.
I just check the number of components in jAxis and grab the last one.

hFig = figure; 
h = axes(hFig);
plot(rand(100,1),'Parent',h);
jFig = get(hFig, 'JavaFrame');
jAxis = jFig.getAxisComponent;

n = jAxis.getComponentCount;
disp(n);
jAxis.grabFocus();
drawnow; % will not work without this
n = jAxis.getComponentCount;
disp(n);

set(jAxis.getComponent(n-1),'FocusGainedCallback',@(x,y)disp('in focus'));
set(jAxis.getComponent(n-1),'FocusLostCallback',  @(x,y)disp('... out'));

Note that this is mainly cargo cult: I have no idea why I need to grab the focus and force a redraw for this to work. Still would be thankful if somebody comes up with a better, explainable solution, because the one I suggest here does not work for more complicated situations, such as GUIs with multiple panels and changing number of elements…

Same problem here 🙁 … so frustrating, as other callbacks as for instance:

set(jAxis.getComponent(0),'MouseMovedCallback',@(x,y)disp('ab'));

work fine after adding axes to the figure. I really hope that somebody comes up with a solution.

@Paul & @Yvon – in HG2 (R2014b onward), you can simply set the Focus events (FocusGained, FocusLost etc.) on the direct child of the AxisComponent, as follows:

set(jAxis.getComponent(0),'FocusGainedCallback',{@myMatlabFunc,hFig});

Paul, I’m facing the same problem as you have in R2014b. By any chance, did you find any solution to this?

Yvon

The mechanism described above for detecting windows focus event does not work in R2014b. I believe the issue is related in changes in the figure’s AxisComponent. In R2013b, jFrame.getAxisComponent returns:

com.mathworks.hg.peer.FigureAxisComponentProxy$_AxisCanvas[fAxisComponentProxy,0,0,560x420]

In R2014b, it returns:

com.mathworks.hg.peer.HeavyweightLightweightContainerFactory$FigurePanelContainerLight[fFigurePanel,0,0,560x420,layout=...]

If you have a solution for this problem, please post it.

Paul

 
% Snippet used to test focus callbacks
hFig = figure('name', 'FocusGainTest');  % etc. - prepare the figure

% Get the underlying Java reference
warning off MATLAB:HandleGraphics:ObsoletedProperty:JavaFrame
jFrame = get(hFig, 'JavaFrame');
hFrame = handle(jFrame,'CallbackProperties');

jAxis = jFrame.getAxisComponent 
hAxis = handle(jAxis,'CallbackProperties');

% Set the focus event callback
set(hAxis,'FocusGainedCallback', @(a,b) disp('FocusGainedCallback'));
set(hAxis,'FocusLostCallback', @(a,b) disp('FocusLostCallback'));

Solution found – thanks for undoc’d documentation – brilliant.

(1) overload figure.m (place this function in your path)

%% fix the annoying focus follows mouse bug
%% (c) GPL SA 2013
function h=figure(n);
    global hasfocus;
    if(~exist('n'))
        n=1;
        end;
    h = builtin('figure',n);
    jFig = get(h,'JavaFrame');
    jAxis = jFig.getAxisComponent;
    set(jAxis,'FocusGainedCallback',{@setfocus,h});
    hasfocus = h;

(2) catch the mouse focus events (place this function in your path)

%% fix the annoying focus follows mouse bug
%% (c) GPL SA 2013
function setfocus(jAxis, jEventData, hFig)
    global hasfocus;
    set(0,'currentfigure',hasfocus)
end

(3) If you are bothered by warning messages spamming up your console put this line in your matlab start up files:

warning off MATLAB:dispatcher:nameConflict

Works for me on matlab 2007something

Can I modify the question – I’d like to capture all focus events for all figures (then I can reset “currentfigure”). Is there a way to do this?