Setting status-bar components

I last week’s post, Setting status-bar text, I showed how to set the status-bar text in Matlab figures and the main desktop. But Matlab status-bars are Java containers in which we can add GUI controls, not just simple text labels. In this post I will show how to do this for Matlab 7 figures.

Let’s return to the two alternatives I’ve presented in my previous post for setting a Matlab 7 figure status-bar text:

% Alternative #1 (hFig = requested figure's handle)
jFrame = get(hFig,'JavaFrame');
jFigPanel = get(jFrame,'FigurePanelContainer');
jRootPane = jFigPanel.getComponent(0).getRootPane;
jRootPane = jRootPane.getTopLevelAncestor;
statusbarObj = jRootPane.getStatusBar;
% Alternative #2
jFrame = get(hFig,'JavaFrame');
jRootPane = jFrame.fFigureClient.getWindow;
statusbarObj = com.mathworks.mwswing.MJStatusBar;

The first alternative uses the default status-bar (a com.mathworks.mwswing.MJStatusBar object) which Matlab automatically creates with each figure. This object is created as invisible, so we need to set its text (via its setText method), and then make it visible (via its ancestor’s root-pane’s setStatusBarVisible method – setting the object itself to visible is not enough). The alternative is to replace the default status-bar object with a user-specified container (in this case, we use a new instance of com.mathworks.mwswing.MJStatusBar).

Last week I forgot to mention that only the second alternative works in the general case – it appears that the first alternative often fails because figures are not created with the default statusbar on many platforms/Matlab release (I’m not sure exactly which). My StatusBar utility on the MathWorks File Exchange, which I mentioned in last week’s post, takes care of these nuances, and automatically creates the status bar object if it is missing.

In any case, using these two code snippets as a baseline, we can customize any Java container that we wish. We are not limited to text labels. The default ststusbar container, MJStatusBar, only includes a single JLabel-derived component that stores the text message. We can add other components to this container. For example, let’s add a simple progress-bar:

jFrame = get(hFig,'JavaFrame');
jRootPane = jFrame.fFigureClient.getWindow;
statusbarObj = com.mathworks.mwswing.MJStatusBar;
% Add a progress-bar to left side of standard MJStatusBar container
jProgressBar = javax.swing.JProgressBar;
set(jProgressBar, 'Minimum',0, 'Maximum',500, 'Value',234);
statusbarObj.add(jProgressBar,'West');  % 'West' => left of text; 'East' => right
% Beware: 'East' also works but doesn't resize automatically
% Set this container as the figure's status-bar
% Note: setting setStatusBarVisible(1) is not enough to display the status-bar
% - we also need to call setText(), even if only with an empty string ''
statusbarObj.setText('testing 123...');

Status bar with a simple progress-bar

Status bar with a simple progress-bar

We can of course use the progress-bar and status-bar handles to modify their appearance within our code, for example within some loop. For example:

numIds = length(allIds);
set(jProgressBar, 'StringPainted','on', 'Maximum',numIds, 'Value',0);
for id = 1 : numIds
   % Update status bar
   set(jProgressBar, 'StringPainted','on', 'Value',id);
   msg = 'Processing %d of %d (%.1f%%)...';
   % do something useful...
end  % for all Ids
% Some final status-bar updates...
% Hide the progress-bar
% Hide the corner grip
cornerGrip = statusbarObj.getParent.getComponent(0);
cornerGrip.setVisible(0);  % or: set(cornerGrip,'Visible','off')
% Set a red foreground & yellow background to status bar text
statusbarObj.setText('All done - congratulations!!!');
statusbarTxt = statusbarObj.getComponent(0);
set(statusbarTxt,'Background',[1,1,0]);  % an alternative…

Modifying status bar properties in run-timer

Modifying status bar properties in run-time

The progress-bar component was just a simple example of how to present non-intrusive controls/information in the figure status bar. Other controls (buttons, checkboxes etc.) can similarly be added.

Note that the status-bar’s corner-grip (at its far right) is not a sub-component of the statusbarObj object like the label, but rather of its parent JPanel container. This is easily be seen using my FindJObj utility on the MathWorks File Exchange:

Status bar with a simple progress-bar

Status bar with a simple progress-bar

One final note: The status bar is 20 pixels high across the entire bottom of the figure. It hides everything between pixel heights 0-20, even parts of uicontrols, regardless of who was created first or the relative ComponentZOrder in the frame’s ContentPane:

% Add a "Next phase" button to the right of the text
jb = javax.swing.JButton('Next phase >');
jbh = handle(jb,'CallbackProperties');
set(jbh, 'ActionPerformedCallback', @nextPhaseFunction);
%note: we might need jRootPane.setStatusBarVisible(0)
% followed by jRootPane.setStatusBarVisible(1) to repaint
% Add a simple Matlab uicontrol, obscured by the status-bar
hb = uicontrol('string','click me!', 'position',[10,15,70,30]);

Adding controls inside and outside the status-bar

Adding controls inside and outside the status-bar

If you have made interesting use of Matlab’s status-bar, please share them in the comments section below.

Related posts:

  1. Setting status-bar text The Matlab desktop and figure windows have a usable statusbar which can only be set using undocumented methods. This post shows how to set the status-bar text....
  2. Figure toolbar components Matlab's toolbars can be customized using a combination of undocumented Matlab and Java hacks. This article describes how to access existing toolbar icons and how to add non-button toolbar components....
  3. Date selection components The JIDE package, pre-bundled in Matlab, contains several GUI controls for selecting dates - this article explains how they can be used...
  4. Color selection components Matlab has several internal color-selection components that can easily be integrated in Matlab GUI...
  5. Plot-type selection components Several built-in components enable programmatic plot-type selection in Matlab GUI - this article explains how...
  6. Setting line position in an edit-box uicontrol Matlab uicontrols have many useful features that are only available via Java. Here's how to access them....

Categories: Figure window, GUI, Java, Medium risk of breaking in future versions

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7 Responses to Setting status-bar components

  1. Hello Yair,

    I am using statusbar in my codes since I prefer waitbar docked. I wanted to know how to delete this object in a safe way.
    In the help, I can read that the command


    deletes status bar from current figure. But I had to comment the line 263 :


    to prevent the message : Property Name already in use . It happens each time I recreate a statusbar or when I display a dialog box.

    I guess that :


    is not enough to delete this object.


    • Aurélien – you are correct: For performance reasons, the statusbar object is not really deleted when you issue


      Instead, it is simply made invisible using the root-pane’s setStatusBarVisible(0) method in line #222. Then, when you recreate the statusbar, adding the internal handles to the CornerGrip, TextPanel and ProgressBar fails, since these properties already exist in the old (previously-hidden) statusbar object.

      Your solution, to comment line #263, is probably the easiest and best.

  2. nir S. says:

    Hi Yair,

    It seems that matlab won’t support JavaFrame in future versions of Matlab.
    are there any other way to intgrated the waitbar in my GUI?

  3. luis camilo says:

    How can I modify the position of the statusbar in a GUIDE, for example [10,10, 150, 200]? thanks!

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