Develop Reference

Losing AWT DrawingSurface when Canvas is hidden

I am writing 3d rendering module for an AWT/Swing application.
To provide good FPS, I can't draw using Swing/AWT methods and graphics. Instead, I obtain the Drawing Surface from the Canvas element, and then render directly to it. Something like this:
public class Window {
private Component canvas;
private JAWTDrawingSurface ds;
public static final JAWT awt;
static {
awt = JAWT.calloc();
awt.version(JAWT_VERSION_1_4);
if (!JAWT_GetAWT(awt))
throw new AssertionError("GetAWT failed");
}
public void lock() throws AWTException {
int lock = JAWT_DrawingSurface_Lock(ds, ds.Lock());
if ((lock & JAWT_LOCK_ERROR) != 0)
throw new AWTException("JAWT_DrawingSurface_Lock() failed");
}
public void unlock() throws AWTException {
JAWT_DrawingSurface_Unlock(ds, ds.Unlock());
}
public void Init2()
{
this.ds = JAWT_GetDrawingSurface(canvas, awt.GetDrawingSurface());
try
{
lock();
// Create GL Capabilities
unlock();
}
}
It works fine when I call it the first time.
But when I hide the canvas for any reason (for example minimizing window or displaying another panel instead of Canvas), the ds variable remains the same, but it doesn't work after that.
Basically, even if I make sure I call the variable only when it is visible and on top - any call using ds will throw an exception. For example lock() function stops working.
I'm wondering why's that?
Also I tried to basically obtain a new DS if I minimize and then maximize the window again, but this also doesn't work - the new DS address is returned as it should, but I can't use that new object just as I couldn't use the original one.
There's probably something stupid I'm missing here, but I can't figure out what.
Please help me sort this out. Thank you!

The solution:
When the Canvas is hidden, call eglMakeCurrent(eglDisplay,EGL_NO_SURFACE,EGL_NO_SURFACE,EGL_NO_CONTEXT) to unbind the current context.
When you need to start drawing again, you need to do something like this:
public void Reinit()
{
System.err.println("Context Reinit()");
this.ds = JAWT_GetDrawingSurface(canvas, awt.GetDrawingSurface());
try
{
lock();
try
{
JAWTDrawingSurfaceInfo dsi = JAWT_DrawingSurface_GetDrawingSurfaceInfo(ds, ds.GetDrawingSurfaceInfo());
JAWTX11DrawingSurfaceInfo dsiWin = JAWTX11DrawingSurfaceInfo.create(dsi.platformInfo());
this.display = dsiWin.display();
this.drawable = dsiWin.drawable();
eglDisplay = eglGetDisplay(display);
surface = eglCreateWindowSurface(eglDisplay,fbConfigs.get(0),drawable,(int[])null);
eglMakeCurrent(eglDisplay,surface,surface,context);
GLES.setCapabilities(glesCaps);
JAWT_DrawingSurface_FreeDrawingSurfaceInfo(dsi, ds.FreeDrawingSurfaceInfo());
}
finally
{
unlock();
System.err.printf("Unlock \n");
}
}
catch (Exception e)
{
System.err.println("JAWT Failed" + e.getMessage());
}
}
As You can see, I re-create the display and surface, but I use the previously created context for rendering, without needing to re-create it.

How to detect keypress

I am using java and trying to write a simple sudo mouse recorder that will store the mouse position when the space key is pressed. The only key I need to detect is the space key (Although if another key is easier, that will work).
I need the whole mouse recorder to be written in java, but it is OK if the function for the keypress is in another language. And I will be runing this in Windows 7.
What is the simplest way to do what has been described? All of the methods I have found require at minimum 20 lines of code. This is OK, except I don't understand how to implement them. I have an example source below:
import java.awt.MouseInfo;
import javax.swing.JOptionPane;
public class MouseRecorder {
public static void main (String[] args)
{
int slot = 0;
int xLoc[10];
int yLoc[10];
while (slot <= 10)
{
if (keyPressed(KEY_SPACE)) //<<<<This obviously won't work, but I'm looking for the simplest way to code this
{
xLoc[slot] = MouseInfo.getPointerInfo().getLocation().x;
yLoc[slot] = MouseInfo.getPointerInfo().getLocation().y;
slot++;
}
}
//The mouse information can now be utilized
}
}

Again your question is not clear since you have not addressed my comment:
It smells like to me that you might want a system-wide key logger that only responds to one key press, and that doesn't need a GUI. If this is so, then your best solution is to not use Java to create your application but to use a tool that can get closer to the OS. AutoIt comes to mind if this is for a Windows project. Please define your needs better.
and this forces us to guess at the problem and its solution.
If you are interested in creating a Swing GUI, having it take focus, and have it listen to key events, then the solution is to do this:
Create your Swing GUI and display it, leaving it as the active windowed application while your application is running.
Using Key Bindings have it listen for space bar presses
And then log the mouse location when the space bar is pressed.
As noted, this will not be achievable in 5 lines of code, so put that idea to the side.
If on the other hand your desire is to not have a GUI but rather listen for hot-key presses while any and all applications are running, then
The possible platforms used will be critical since your solution will require OS-specific code since creating a hot-key means having to create a keyboard handler routine, often in C, and doing this for each platform, and then linking it in to Java using JNI or JNA.
Or as noted another way is to link your Java program with an OS specific utility program or script such as AutoIt.
If you need more specific help, then please clarify your question.
Edit
You state:
Thank you for the answer, but as I have described above: "Changing languages is out of the question although it seems like that might be easier." and "I dont want a gui, if I can avoid it"
Then my second answer is what you're looking for. How adept are you at C/C++, JNI or JNA, and how good is your knowledge of operating system libraries? If you want a Java only solution, I would consider your requirements far above beginner or intermediate Java and into the realm of advanced -- or at least beyond my abilities at the moment, although I am sure that I could come up with some solutions after several days to a week or two of study.
... or consider getting rid of your "changing languages" requirement and instead allow at least meshing Java together with a scripting utility, like AutoIt. That could allow creation of solutions in a shorter period of time, at least for me. A limitation though is that these would be platform specific solutions. What is your purpose behind all of this? Could this be an XY problem in disguise?
Edit 2
I decided to try to solve this with a small AutoIt utility that I meshed with Java, and this is what I came up with.
My AutoIt program is called CaptureHotKey.au3, and it is compiled to an exe before use:
$key = $CmdLine[1]
HotKeySet($key, "hotKeyFunction")
While 1
Sleep(100)
WEnd
Func hotKeyFunction()
ConsoleWrite(#CRLF)
EndFunc
There's not much to it. All it does is set a hot-key from the first command line parameter, provides an endless while loop so that it will continue to run, and a hotkey function that is quite simple and only sends a carriage-return/line-feed to the console (which will be the standard output).
Then a Java class to help interact with this. It uses SwingPropertyLanguageSupport to allow addition of PropertyChangeListeners that respond on the Swing thread (in case I want to use this with a GUI).
import java.beans.PropertyChangeListener;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import javax.swing.event.SwingPropertyChangeSupport;
public class CaptureHotKey implements Runnable {
public static final String HOT_KEY = "hot key";
private String hotKey;
private SwingPropertyChangeSupport pcSupport = new SwingPropertyChangeSupport(
this);
private Scanner scanner;
private CaptureHotKeyFromAutoIt capture;
public CaptureHotKey(final String hotKey) throws IOException {
this.hotKey = hotKey;
capture = new CaptureHotKeyFromAutoIt(hotKey);
scanner = new Scanner(capture.getReadable());
}
public void startCapturing() {
new Thread(this).start();
}
public void exit() {
if (capture != null) {
capture.exit();
}
if (scanner != null) {
scanner.close();
}
}
public void addPropertyChangeListener(PropertyChangeListener listener) {
pcSupport.addPropertyChangeListener(listener);
}
public void removePropertyChangeListener(PropertyChangeListener listener) {
pcSupport.removePropertyChangeListener(listener);
}
public String getHotKey() {
return hotKey;
}
#Override
public void run() {
while (scanner != null && scanner.hasNextLine()) {
scanner.nextLine();
pcSupport.firePropertyChange(HOT_KEY, true, false);
}
}
private static class CaptureHotKeyFromAutoIt {
public static final String AUTO_IT_APP_PATH = "CaptureHotKey.exe";
private Process process = null;
private ProcessBuilder pb;
public CaptureHotKeyFromAutoIt(String hotKey) throws IOException {
List<String> cmdList = new ArrayList<>();
cmdList.add(AUTO_IT_APP_PATH);
cmdList.add(hotKey);
pb = new ProcessBuilder(cmdList);
pb.redirectErrorStream(true);
process = pb.start();
}
public void exit() {
if (process != null) {
process.destroy();
}
}
public Readable getReadable() {
if (process != null) {
return new InputStreamReader(process.getInputStream());
}
return null;
}
}
}
Finally a Java class to test this set up:;
This adds a PropertyChangeListener to the class above to allow it to be notified if the hot-key is pressed:
import java.awt.MouseInfo;
import java.awt.PointerInfo;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.io.IOException;
import java.util.Scanner;
public class CaptureHotKeyTest {
public static final String CTRL_R = "^r"; // "{SPACE}" works for spacebar
private static final String EXIT = "exit";
private CaptureHotKey capture;
public CaptureHotKeyTest() {
try {
capture = new CaptureHotKey(CTRL_R);
capture.addPropertyChangeListener(new HotKeyPropertyChngListener());
capture.startCapturing();
Scanner scan = new Scanner(System.in);
System.out.println("Press control-r to get mouse position.");
System.out.println("Type \"exit\" to exit program");
while (scan.hasNextLine()) {
String line = scan.nextLine();
if (line.equalsIgnoreCase(EXIT)) {
scan.close();
capture.exit();
break;
}
}
} catch (IOException e) {
e.printStackTrace();
}
}
private class HotKeyPropertyChngListener implements PropertyChangeListener {
#Override
public void propertyChange(PropertyChangeEvent evt) {
if (evt.getPropertyName().equals(CaptureHotKey.HOT_KEY)) {
System.out.println("hot key pressed");
PointerInfo pointerInfo = MouseInfo.getPointerInfo();
System.out.println("Mouse: " + pointerInfo.getLocation());
}
}
}
public static void main(String[] args) {
new CaptureHotKeyTest();
}
}

You should use KeyListener: http://docs.oracle.com/javase/tutorial/uiswing/events/keylistener.html
It works fine with Swing

Eclipse Plug-in Counting Click / Listening To Click

I am writing a plugin for MagicDraw an IDE based on eclipse. I want the application to close after 15 minutes of idle time to release the license.
What i first did implement a counter that will check the mouse position every 1000 ms. And each time the mouse location remained the same i decreased the counter. And when the counter reached 0 i closed the application. And each time to position changed i reset the counter.
The problem here was that if the application is open and the user is just moving his mouse around in a different window he is not categorized as idle.
My second approach was to count the number of clicks. But the problem that i am facing is i am not getting how to add a listener to the full IDE window.
Here is what i have so far.
package myplugin;
import java.awt.event.MouseListener;
public class CheckAct implements MouseListener{
private int timeleft;
private int permtime ;
public CheckAct(int initialTime){
this.setPermtime(initialTime);
this.setTimeleft(initialTime) ;
//Missing Addlistener Code
}
#Override
public void mouseClicked(java.awt.event.MouseEvent e) {
// TODO Auto-generated method stub
this.resetTime();
}
}
where i have the //missing addlistenercode is where i believe i should add the listener to the full eclipse window to be able to use the mouseClicked event.
But how do i do that ?
Please note i only showed relevant code.

Cause you are using eclipse you can use SWT to capure mouse events. The easies way is to register a Listener on the Display-Instance to get all events of all application windows.
PlatformUI.getWorkbench().getDisplay().addListener(SWT.MouseDown, new Listener() {
#Override
public void handleEvent(Event event) {
//TODO
}
});

java sound, fadeIn effect, using FloatControl

Im trying to implement fade in effect to my mp3 player.
I´m using
FloatControl volumeControl = (FloatControl) line.getControl(FloatControl.Type.MASTER_GAIN);
because FloatControl.Type.VOLUME throws an exception(Unavaliable Control) I dont know why.
I need some help with the algorithm, because its not working ok.
Heres the code:
public class FloatControlFader
{
public static void fadeIn(final FloatControl control, final float from,
final float to, final int seconds)
{
final float vps = ((to-from) / (seconds*10));//Volume incrased/100millisecond
control.setValue(from);
Thread t = new Thread(new Runnable(){
public void run() {
for(int i=0; i < seconds*10; i++)
{
try
{
Thread.sleep(100);
}
catch (InterruptedException ex)
{
}
System.out.println(control.getValue()); //for DEBUG
control.setValue(control.getValue() + vps);
}
}
});
t.start();
}
}
Would appreciate any help, thanks!

Remember the human ear does not hear linearly so increasing by a steady X vps is not going to sound like a smooth fade. You need to put a log function in there. Then you need to map the linear increases to log values. This is of course all assuming the volume control units are not in decibels. If you're increasing by db then you're fine.

Real-time graphing in Java

I have an application which updates a variable about between 5 to 50 times a second and I am looking for some way of drawing a continuous XY plot of this change in real-time.
Though JFreeChart is not recommended for such a high update rate, many users still say that it works for them. I've tried using this demo and modified it to display a random variable, but it seems to use up 100% CPU usage all the time. Even if I ignore that, I do not want to be restricted to JFreeChart's ui class for constructing forms (though I'm not sure what its capabilities are exactly). Would it be possible to integrate it with Java's "forms" and drop-down menus? (as are available in VB) Otherwise, are there any alternatives I could look into?
EDIT: I'm new to Swing, so I've put together a code just to test the functionality of JFreeChart with it (while avoiding the use of the ApplicationFrame class of JFree since I'm not sure how that will work with Swing's combo boxes and buttons). Right now, the graph is being updated immediately and CPU usage is high. Would it be possible to buffer the value with new Millisecond() and update it maybe twice a second? Also, can I add other components to the rest of the JFrame without disrupting JFreeChart? How would I do that? frame.getContentPane().add(new Button("Click")) seems to overwrite the graph.
package graphtest;
import java.util.Random;
import javax.swing.JFrame;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.axis.ValueAxis;
import org.jfree.chart.plot.XYPlot;
import org.jfree.data.time.Millisecond;
import org.jfree.data.time.TimeSeries;
import org.jfree.data.time.TimeSeriesCollection;
public class Main {
static TimeSeries ts = new TimeSeries("data", Millisecond.class);
public static void main(String[] args) throws InterruptedException {
gen myGen = new gen();
new Thread(myGen).start();
TimeSeriesCollection dataset = new TimeSeriesCollection(ts);
JFreeChart chart = ChartFactory.createTimeSeriesChart(
"GraphTest",
"Time",
"Value",
dataset,
true,
true,
false
);
final XYPlot plot = chart.getXYPlot();
ValueAxis axis = plot.getDomainAxis();
axis.setAutoRange(true);
axis.setFixedAutoRange(60000.0);
JFrame frame = new JFrame("GraphTest");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
ChartPanel label = new ChartPanel(chart);
frame.getContentPane().add(label);
//Suppose I add combo boxes and buttons here later
frame.pack();
frame.setVisible(true);
}
static class gen implements Runnable {
private Random randGen = new Random();
public void run() {
while(true) {
int num = randGen.nextInt(1000);
System.out.println(num);
ts.addOrUpdate(new Millisecond(), num);
try {
Thread.sleep(20);
} catch (InterruptedException ex) {
System.out.println(ex);
}
}
}
}
}

If your variable is updating that fast, there's no point in updating a chart every time.
Have you thought about buffering the variable changes, and refreshing the chart on a different thread, say, every 5s ? You should find that JFreeChart can handle such update rates well.
Since JFreeChart is a normal desktop library, you can integrate it with a standard Swing application very easily. Or, you can use it to chart via a web application (by rendering to a JPEG/PNG etc. JFreeChart can generate image maps automatically as well, so you can use mouseovers etc.)

In order to get your CPU well below 100% and allow your GUI to remain responsive, you have to throttle back your chart updating rate. A maximum update rate of around 24 frames per second makes sense for a real-time chart; any faster is more or less indistinguishable anyway. If your data is coming in faster than that rate, you just need to buffer it in the background and update your chart in the foreground at your desired update rate. In the following example, I use XChart along with a SwingWorker background thread. The data capture is simulated at a rate of one per every 5 ms and the chart is updated at 24 frames per second. This concept should work with JFreeCharts or any other charting library as well with slight modification. Disclaimer: I'm the lead developer of XChart.
import java.util.LinkedList;
import java.util.List;
import javax.swing.SwingWorker;
import org.knowm.xchart.QuickChart;
import org.knowm.xchart.SwingWrapper;
import org.knowm.xchart.XYChart;
/**
* Creates a real-time chart using SwingWorker
*/
public class SwingWorkerRealTime {
MySwingWorker mySwingWorker;
SwingWrapper<XYChart> sw;
XYChart chart;
public static void main(String[] args) throws Exception {
SwingWorkerRealTime swingWorkerRealTime = new SwingWorkerRealTime();
swingWorkerRealTime.go();
}
private void go() {
// Create Chart
chart = QuickChart.getChart("SwingWorker XChart Real-time Demo", "Time", "Value", "randomWalk", new double[] { 0 }, new double[] { 0 });
chart.getStyler().setLegendVisible(false);
chart.getStyler().setXAxisTicksVisible(false);
// Show it
sw = new SwingWrapper<XYChart>(chart);
sw.displayChart();
mySwingWorker = new MySwingWorker();
mySwingWorker.execute();
}
private class MySwingWorker extends SwingWorker<Boolean, double[]> {
LinkedList<Double> fifo = new LinkedList<Double>();
public MySwingWorker() {
fifo.add(0.0);
}
#Override
protected Boolean doInBackground() throws Exception {
while (!isCancelled()) {
fifo.add(fifo.get(fifo.size() - 1) + Math.random() - .5);
if (fifo.size() > 500) {
fifo.removeFirst();
}
double[] array = new double[fifo.size()];
for (int i = 0; i < fifo.size(); i++) {
array[i] = fifo.get(i);
}
publish(array);
try {
Thread.sleep(5);
} catch (InterruptedException e) {
// eat it. caught when interrupt is called
System.out.println("MySwingWorker shut down.");
}
}
return true;
}
#Override
protected void process(List<double[]> chunks) {
System.out.println("number of chunks: " + chunks.size());
double[] mostRecentDataSet = chunks.get(chunks.size() - 1);
chart.updateXYSeries("randomWalk", null, mostRecentDataSet, null);
sw.repaintChart();
long start = System.currentTimeMillis();
long duration = System.currentTimeMillis() - start;
try {
Thread.sleep(40 - duration); // 40 ms ==> 25fps
// Thread.sleep(400 - duration); // 40 ms ==> 2.5fps
} catch (InterruptedException e) {
}
}
}
}

According to this blog post:
http://jonathanwatmough.com/2008/02/prototyping-code-in-clojure/
its possible to implement 'real-ish time' display of audio spectrums using the KJ DSP library:
http://sirk.sytes.net/software/libs/kjdss/index.htm
so if you can get by with fairly simple charts it might be an alternative to JFreeChart.

If the data is updating more often than you can generate the chart, then you should have a task in a separate thread that regenerates the chart, and starts another regeneration when it's done. There's little point in running it ore often than that, but if it turns out to be too much of a cpu load, you can throttle back the frequency with which it restarts. If updates don't come in, you don't trigger the re-generate. I did something like that in my Zocalo project recently. It does everything but the throttling back.
package net.commerce.zocalo.freechart;
// Copyright 2009 Chris Hibbert. All rights reserved.
// This software is published under the terms of the MIT license, a copy
// of which has been included with this distribution in the LICENSE file.
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Callable;
import java.util.concurrent.Future;
import java.util.Map;
import java.util.HashMap;
/** Schedule a task like generating a price history graph. Multiple requests may come
in sporadically. We want to ensure that only one is being processed at a time. If we're
busy processing when a request comes in, we'll remember to start another when this one is
done. Multiple requests that come in while processing will spur a single restart. */
public class ChartScheduler {
static private Logger log = Logger.getLogger(ChartScheduler.class);
static private Map<String, ChartScheduler> schedulers = new HashMap<String, ChartScheduler>();
private AtomicBoolean generating = new AtomicBoolean(false);
private AtomicBoolean requested = new AtomicBoolean(false);
private ExecutorService threads = Executors.newCachedThreadPool();
private Callable<Boolean> callable;
private int runs = 0;
private String name;
private ChartScheduler(String name, final Runnable worker) {
this.name = name;
callable = new Callable<Boolean>() {
public Boolean call() throws Exception {
worker.run();
runs++;
restartIfNeeded();
return true;
}
};
}
public static ChartScheduler create(String name, Runnable worker) {
ChartScheduler sched = find(name);
if (sched == null) {
sched = new ChartScheduler(name, worker);
schedulers.put(name, sched);
}
return sched;
}
public static ChartScheduler find(String name) {
return schedulers.get(name);
}
public boolean generateNewChart() {
requested.set(true);
if (generating.compareAndSet(false, true)) {
startNewThread();
return true;
} else {
return false;
}
}
private Future<Boolean> startNewThread() {
generating.set(true);
requested.set(false);
return threads.submit(callable);
}
private boolean restartIfNeeded() {
generating.set(false);
if (requested.get()) {
return generateNewChart();
} else {
return false;
}
}
public boolean isBusy() {
return generating.get();
}
public int runs() {
return runs;
}
}

Answered before here. Your variable changes up to 50 times per second, but in most cases you won't need to update every time a change is made. Instead you could update the graph at regular intervals (every 100ms for instance).

Well I am also using JFreechart for high updates. JFreeChart updates up to 10 to 15 frame/second but using 100% CPU usage. But if I want to update it at a much higher frequency it wont be updated. If you find any any library which can be updated at abt 20 fps and can be used to develop a application in Java then please suggest me also. I have seen many library JFreeChart FAQ but I am not sure if anyone could be use for updates at about 20 fps.

You should try out charts from VisualVM (part of JDK).
Intro on it: http://java.dzone.com/news/real-time-charts-java-desktop

Maybe you can use two threads. One for the updating of your variable witch priority equals to 10.
And a second thread who paints so fast as posible witch priority equals to 5.
I had to do the same in a game I'm writing.
It's possible I didn't understand your question.