MATLAB GUI programming (code level) 2.0 – Undocumented MATLAB – JAVA codes in MATLAB M-files

This is something I found really interesting in MATLAB. We can write m-scripts with JAVA codes, this is very useful when designing UI components for MATLAB applications. In this article I will share my experience on creating GUI in MATLAB using JAVA and also an implementation of video cropping software (backend part will be discussed on my next article).

For more information on Undocumented MATLAB, please visit Undocumented MATLAB official web page.

When using JAVA codes in *.m files we do not use “new” keywords to initiate any objects.  I am not sure the usage of import keyword in MATLAB/JAVA. Therefore JFrame must be used as  java.swing.JFrame. It is quite different from JAVA.

JFrame frame = new JFrame; // Java Syntax

frame = javax.swing.JFrame; % matlab syntax

Creating a JFrame, Adding title, setting size and layout is as follows,

frame = javax.swing.JFrame;
frame.setSize(1200,800);
frame.setTitle( 'Movie Maker');
frame.setLayout(java.awt.GridBagLayout);

We can use Java Border Factory as well. Setting up a JPanel can be done as follows,

playerPanel = javax.swing.JPanel;
playerPanel.setBorder( ...
  javax.swing.BorderFactory.createTitledBorder( ...
  javax.swing.BorderFactory.createEtchedBorder(), 'Video' ...
  ) ...
);
playerPanel.setLayout(java.awt.GridBagLayout);
playerPanel.setMinimumSize(java.awt.Dimension(800,600));
playerPanel.setMaximumSize(java.awt.Dimension(800,600));
playerPanel.setPreferredSize(java.awt.Dimension(800,600));

Setting actions can be done using the MATLAB keyword “ActionPerformedCallback” , we can set another *m file or function to call then action is triggered as follows,

set(pauseButton, 'ActionPerformedCallback',@playControlListener);

Even in positioning UI components, we can use GridbagLayout.

playerButtonPanel.add( ...
  captureButton, ...
  java.awt.GridBagConstraints( ...
    0, 0, 1, 1, 1.0, 1.0, java.awt.GridBagConstraints.NORTHWEST,
    java.awt.GridBagConstraints.NONE,...
    java.awt.Insets(6, 12, 6, 6), 1, 1));

In order to crop and to snap video frames I created Movie maker application using MATLAB and I used this kind of an implementation using JAVA for the GUI component. Complete code for the GUI is as below.

% Thilina S. Ambagahawaththa
% 2012/05/30
clc;
clear all;
close all;
%% Frame
frame = javax.swing.JFrame;
frame.setSize(1200,800);
frame.setTitle( 'Movie Maker');
frame.setLayout(java.awt.GridBagLayout);
%% Video Player Panel
playerPanel = javax.swing.JPanel;
  playerPanel.setBorder( ...
    javax.swing.BorderFactory.createTitledBorder( ...
    javax.swing.BorderFactory.createEtchedBorder(), 'Video' ...
  ) ...
);

playerPanel.setLayout(java.awt.GridBagLayout);
playerPanel.setMinimumSize(java.awt.Dimension(800,600));
playerPanel.setMaximumSize(java.awt.Dimension(800,600));
playerPanel.setPreferredSize(java.awt.Dimension(800,600));

viewPan = javax.swing.JScrollPane;
viewPan.setMinimumSize(java.awt.Dimension(800,600));
viewPan.setMaximumSize(java.awt.Dimension(800,600));
viewPan.setPreferredSize(java.awt.Dimension(800,600));

%% Player Button Panel
playerButtonPanel = javax.swing.JPanel;
  playerButtonPanel.setBorder( ...
    javax.swing.BorderFactory.createTitledBorder( ...
    javax.swing.BorderFactory.createEtchedBorder(), 'Control' ...
  ) ...
);
playerPanel.setLayout(java.awt.GridBagLayout);

%% Player Window
playerWindowLabel = javax.swing.JLabel;

%% Buttons
stateButton = javax.swing.JButton;
stateButton.setMinimumSize(java.awt.Dimension(60,25));
stateButton.setMaximumSize(java.awt.Dimension(60,25));
stateButton.setPreferredSize(java.awt.Dimension(60,25));

captureButton = javax.swing.JButton;
captureButton.setMinimumSize(java.awt.Dimension(120,25));
captureButton.setMaximumSize(java.awt.Dimension(120,25));
captureButton.setPreferredSize(java.awt.Dimension(120,25));
captureButton.setText( 'SaveFrame');
captureButton.setToolTipText( 'SF');
set(captureButton, 'ActionPerformedCallback',@playControlListener);

playButton = javax.swing.JButton(javax.swing.ImageIcon('D:\Projects\Self\MovieMaker\project\icons\1_play.jpg' ));
playButton.setMinimumSize(java.awt.Dimension(25,25));
playButton.setMaximumSize(java.awt.Dimension(25,25));
playButton.setPreferredSize(java.awt.Dimension(25,25));
playButton.setToolTipText( 'Play');
set(playButton, 'ActionPerformedCallback',@playControlListener);

pauseButton = javax.swing.JButton(javax.swing.ImageIcon('D:\Projects\Self\MovieMaker\project\icons\1_pause.jpg' ));
pauseButton.setMinimumSize(java.awt.Dimension(25,25));
pauseButton.setMaximumSize(java.awt.Dimension(25,25));
pauseButton.setPreferredSize(java.awt.Dimension(25,25));
pauseButton.setToolTipText( 'Pause');
set(pauseButton, 'ActionPerformedCallback',@playControlListener);

stopButton = javax.swing.JButton(javax.swing.ImageIcon('D:\Projects\Self\MovieMaker\project\icons\1_stop.jpg' ));
stopButton.setMinimumSize(java.awt.Dimension(25,25));
stopButton.setMaximumSize(java.awt.Dimension(25,25));
stopButton.setPreferredSize(java.awt.Dimension(25,25));
stopButton.setToolTipText( 'Stop');
set(stopButton, 'ActionPerformedCallback',@playControlListener);

revButton = javax.swing.JButton(javax.swing.ImageIcon('D:\Projects\Self\MovieMaker\project\icons\1_rev.jpg' ));
revButton.setMinimumSize(java.awt.Dimension(25,25));
revButton.setMaximumSize(java.awt.Dimension(25,25));
revButton.setPreferredSize(java.awt.Dimension(25,25));
revButton.setToolTipText( 'Rev');
set(revButton, 'ActionPerformedCallback',@playControlListener);

fwdButton = javax.swing.JButton(javax.swing.ImageIcon('D:\Projects\Self\MovieMaker\project\icons\1_fwd.jpg' ));
fwdButton.setMinimumSize(java.awt.Dimension(25,25));
fwdButton.setMaximumSize(java.awt.Dimension(25,25));
fwdButton.setPreferredSize(java.awt.Dimension(25,25));
fwdButton.setToolTipText( 'Fwd');
set(fwdButton, 'ActionPerformedCallback',@playControlListener);

sbkButton = javax.swing.JButton(javax.swing.ImageIcon('D:\Projects\Self\MovieMaker\project\icons\1_skipBck.jpg' ));
sbkButton.setMinimumSize(java.awt.Dimension(25,25));
sbkButton.setMaximumSize(java.awt.Dimension(25,25));
sbkButton.setPreferredSize(java.awt.Dimension(25,25));
sbkButton.setToolTipText( 'SBK');
set(sbkButton, 'ActionPerformedCallback',@playControlListener);

sfdButton = javax.swing.JButton(javax.swing.ImageIcon('D:\Projects\Self\MovieMaker\project\icons\1_skipFwd.jpg' ));
sfdButton.setMinimumSize(java.awt.Dimension(25,25));
sfdButton.setMaximumSize(java.awt.Dimension(25,25));
sfdButton.setPreferredSize(java.awt.Dimension(25,25));
sfdButton.setToolTipText( 'SFD');
set(sfdButton, 'ActionPerformedCallback',@playControlListener);

ejtButton = javax.swing.JButton(javax.swing.ImageIcon('D:\Projects\Self\MovieMaker\project\icons\1_ejt.jpg' ));
ejtButton.setMinimumSize(java.awt.Dimension(25,25));
ejtButton.setMaximumSize(java.awt.Dimension(25,25));
ejtButton.setPreferredSize(java.awt.Dimension(25,25));
ejtButton.setToolTipText( 'EJT');
set(ejtButton, 'ActionPerformedCallback',@playControlListener);

scrButton = javax.swing.JButton(javax.swing.ImageIcon('D:\Projects\Self\MovieMaker\project\icons\1_scr.jpg' ));
scrButton.setMinimumSize(java.awt.Dimension(25,25));
scrButton.setMaximumSize(java.awt.Dimension(25,25));
scrButton.setPreferredSize(java.awt.Dimension(25,25));
scrButton.setToolTipText( 'Start Crop');
set(scrButton, 'ActionPerformedCallback',@playControlListener);

ecrButton = javax.swing.JButton(javax.swing.ImageIcon('D:\Projects\Self\MovieMaker\project\icons\1_ecr.jpg' ));
ecrButton.setMinimumSize(java.awt.Dimension(25,25));
ecrButton.setMaximumSize(java.awt.Dimension(25,25));
ecrButton.setPreferredSize(java.awt.Dimension(25,25));
ecrButton.setToolTipText( 'End Crop');
set(ecrButton, 'ActionPerformedCallback',@playControlListener);

sveButton = javax.swing.JButton(javax.swing.ImageIcon('D:\Projects\Self\MovieMaker\project\icons\1_sve.jpg' ));
sveButton.setMinimumSize(java.awt.Dimension(25,25));
sveButton.setMaximumSize(java.awt.Dimension(25,25));
sveButton.setPreferredSize(java.awt.Dimension(25,25));
sveButton.setToolTipText( 'Save');
set(sveButton, 'ActionPerformedCallback',@playControlListener);

%% Sliders
playPointSlider = javax.swing.JSlider;
playPointSlider.setMinimum(1);
playPointSlider.setMaximum(10);
playPointSlider.setValue(1);
set(playPointSlider, 'MouseReleasedCallback',@playControlListener);

%% player Panel setup
viewPan.getViewport().add(playerWindowLabel);
playerPanel.add( ...
  viewPan, ...
  java.awt.GridBagConstraints( ...
  0, 0, 1, 1, 1.0, 1.0, java.awt.GridBagConstraints.NORTHWEST, java.awt.GridBagConstraints.BOTH,...
  java.awt.Insets(6, 12, 6, 6), 1, 1));

%% Button Panel Setup
% SB Rv Ps Pl St FF SF EJ
playerButtonPanel.add( ...
  stateButton, ...
  java.awt.GridBagConstraints( ...
  0, 0, 1, 1, 1.0, 1.0, java.awt.GridBagConstraints.NORTHWEST, java.awt.GridBagConstraints.NONE,...
  java.awt.Insets(6, 12, 6, 6), 1, 1));
playerButtonPanel.add( ...
  captureButton, ...
  java.awt.GridBagConstraints( ...
  0, 0, 1, 1, 1.0, 1.0, java.awt.GridBagConstraints.NORTHWEST, java.awt.GridBagConstraints.NONE,...
  java.awt.Insets(6, 12, 6, 6), 1, 1));
playerButtonPanel.add( ...
  sbkButton, ...
  java.awt.GridBagConstraints( ...
  1, 0, 1, 1, 1.0, 1.0, java.awt.GridBagConstraints.NORTHWEST, java.awt.GridBagConstraints.NONE,...
  java.awt.Insets(6, 12, 6, 6), 1, 1));
playerButtonPanel.add( ...
  revButton, ...
  java.awt.GridBagConstraints( ...
  2, 0, 1, 1, 1.0, 1.0, java.awt.GridBagConstraints.NORTHWEST, java.awt.GridBagConstraints.NONE,...
  java.awt.Insets(6, 12, 6, 6), 1, 1));
playerButtonPanel.add( ...
  pauseButton, ...
  java.awt.GridBagConstraints( ...
  3, 0, 1, 1, 1.0, 1.0, java.awt.GridBagConstraints.NORTHWEST, java.awt.GridBagConstraints.NONE,...
  java.awt.Insets(6, 12, 6, 6), 1, 1));
playerButtonPanel.add( ...
  playButton, ...
  java.awt.GridBagConstraints( ...
  4, 0, 1, 1, 1.0, 1.0, java.awt.GridBagConstraints.NORTHWEST, java.awt.GridBagConstraints.NONE,...
  java.awt.Insets(6, 12, 6, 6), 1, 1));
playerButtonPanel.add( ...
  stopButton, ...
  java.awt.GridBagConstraints( ...
  5, 0, 1, 1, 1.0, 1.0, java.awt.GridBagConstraints.NORTHWEST, java.awt.GridBagConstraints.NONE,...
  java.awt.Insets(6, 12, 6, 6), 1, 1));
playerButtonPanel.add( ...
  fwdButton, ...
  java.awt.GridBagConstraints( ...
  6, 0, 1, 1, 1.0, 1.0, java.awt.GridBagConstraints.NORTHWEST, java.awt.GridBagConstraints.NONE,...
  java.awt.Insets(6, 12, 6, 6), 1, 1));
playerButtonPanel.add( ...
  sfdButton, ...
  java.awt.GridBagConstraints( ...
  7, 0, 1, 1, 1.0, 1.0, java.awt.GridBagConstraints.NORTHWEST, java.awt.GridBagConstraints.NONE,...
  java.awt.Insets(6, 12, 6, 6), 1, 1));
playerButtonPanel.add( ...
  ejtButton, ...
  java.awt.GridBagConstraints( ...
  8, 0, 1, 1, 1.0, 1.0, java.awt.GridBagConstraints.NORTHWEST, java.awt.GridBagConstraints.NONE,...
  java.awt.Insets(6, 12, 6, 6), 1, 1));
playerButtonPanel.add( ...
  scrButton, ...
  java.awt.GridBagConstraints( ...
  8, 0, 1, 1, 1.0, 1.0, java.awt.GridBagConstraints.NORTHWEST, java.awt.GridBagConstraints.NONE,...
  java.awt.Insets(6, 12, 6, 6), 1, 1));
playerButtonPanel.add( ...
  ecrButton, ...
  java.awt.GridBagConstraints( ...
  8, 0, 1, 1, 1.0, 1.0, java.awt.GridBagConstraints.NORTHWEST, java.awt.GridBagConstraints.NONE,...
  java.awt.Insets(6, 12, 6, 6), 1, 1));
playerButtonPanel.add( ...
  sveButton, ...
  java.awt.GridBagConstraints( ...
  8, 0, 1, 1, 1.0, 1.0, java.awt.GridBagConstraints.NORTHWEST, java.awt.GridBagConstraints.NONE,...
  java.awt.Insets(6, 12, 6, 6), 1, 1));

frame.add( ...
  playerPanel, ...
  java.awt.GridBagConstraints( ...
  0, 0, 1, 1, 1.0, 1.0, java.awt.GridBagConstraints.NORTHWEST, java.awt.GridBagConstraints.BOTH,...
  java.awt.Insets(6, 12, 6, 6), 1, 1));
frame.add( ...
  playPointSlider, ...
  java.awt.GridBagConstraints( ...
  0, 1, 1, 1, 1.0, 1.0, java.awt.GridBagConstraints.NORTHWEST, java.awt.GridBagConstraints.BOTH,...
  java.awt.Insets(6, 12, 6, 6), 1, 1));
frame.add( ...
  playerButtonPanel, ...
  java.awt.GridBagConstraints( ...
  0, 2, 1, 1, 1.0, 1.0, java.awt.GridBagConstraints.NORTHWEST, java.awt.GridBagConstraints.BOTH,...
  java.awt.Insets(6, 12, 6, 6), 1, 1));
  frame.setVisible(true);

Final GUI is as follows,

I will discuss the implementation of the backend of this application in my next article. Hope you have some basic idea on using JAVA UI components with *.m scripts. Thank you very much for reading.