I have done some digging around on this, however, I still can't seem to figure it out. Please excuse me, I haven't been programming for long.
Background: When I click on my run button it should create a second JFrame and update the background colours of JPanels on the second frame, periodically, once per iteration, throughout the run that the JButton starts.
Problem: The second frame is created, but stays blank until the loop, started by the JButton is finished, and it only displays the final state.
I have tried: invalidate(), validate(), repaint(), setVisible(true).
I have tried to run it in a separate thread.
I have even tried sleep(), in case it doesn't have enough time to update. Is there something else that I can try?
I think I would have overwritten the void paint(Graphics g) method which is called by the OS when redrawing is needed and add your drawing routine there. Don't forget the super.paint(g) call. You can then manually trigger redrawing (from inside your loop) by a call to void update (Graphics g); (calling void repaint() should work too)
The second frame is created, but stays blank until the loop, started by the JButton is finished, and it only displays the final state
If your ActionListener attached to the JButton (or the Action) is implemented like
public void actionPerformed( ActionEvent e ){
updateColor();
...
updateColor();
...
updateColor();
}
then the behavior you are seeing is exactly as expected.
Swing is a single threaded framework. When your ActionListener updates the background color, a repaint will be scheduled (emphasis on schedule, which is something different from performed). Since your loop in the ActionListener is still occupying the single thread (the EDT), the repaint cannot be executed.
As such, the first time the repaint can be executed is after you have released the EDT by finishing your loop. At that moment, the background color has already changed to its final color, and that is all what you will be seeing.
A possible solution to be able to see the background change is to use a javax.swing.Timer (and not the java.util version). A click on the JButton can start the timer, and each time the timer is triggered you change the background color to the next color. The moment the final color is reached, you stop the timer.
Related
Is the setBounds() method of a Component like JPanel called on the Event Dispatch Thread? I am asking this because I am writing a program that draws platforms and uses a Swing Timer to move them up. I override the setBounds() method so that every time the JPanel is resized, the platforms will resize too. I just want to make sure that setBounds() doesn't resize the platforms while the Timer is moving them. Also, would it be better to use a WindowListener to check if the JPanel was resized?
setBounds() will be called on the EDT by Swing code, but you have to ensure your code's own invocations of setBounds() also only calls it on the EDT. If you can ensure all calls of setBounds() occur on the EDT, then you shouldn't have to worry about setBounds() being executed while your SwingTimer is being executed because SwingTimers also execute on the EDT by default (so they won't execute at the same time).
Also I never seen someone override setBounds() so I do wonder if there's not an alternative solution such as just querying the bounds every time your SwingTimer executes. Using a listener listening for window resizes like you say does sound much better.
I am making something that resembles a subtitle player that will go over a video.
I would like to make the background transparent so that the box that the text is in will not interfere with the movie/TV show playing behind it. I have tried 2 ways to do this and each way results in the same problem. The text does not disappear when the next sentence appears. If the background is a color (Eg: Color.red), then this works fine. After a certain time, I call text.setText("next sentence"), but this does not work with a transparent background. The relevant code is as follows. text is a JTextField
I should mention the video is not in this program. This program is ONLY subtitles.
First way:
text.setBackground(new Color(0,0,0,0));
Second way: (using a transparent image)
Graphics c = myPicture.getGraphics();
text.paintAll(c);
I update the text like this.
Thread.sleep(Graphix.subtitles.get(counter).getStart());
text.setText(Graphix.subtitles.get(counter).getText());
This also makes it overlap.
text.setForeground(Color.blue);
text.setBackground(new Color(0,0,0,0));
text.setOpaque(false);
The relevant code from Main is as follows.
final JFrame JFwindow = new JFrame("Subtitles");
JFwindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JFwindow.getContentPane().add(new Subtitles());
JFwindow.setSize(1300, 150);
JFwindow.setUndecorated(true);
JFwindow.setBackground(new Color(0,0,0,0f));
JFwindow.pack();
JFwindow.setVisible(true);
Transparency is achieved by calling JPanel#setOpaque and passing it false.
You should NEVER be calling getGraphics. getGraphics and return null and is, at best, only as snap shot. Once the RepaintManager starts a new paint cycle, the results of painting to it will be overridden.
Using a tarnsparent color will only confuse the RepaintManager as it won't know that it needs to paint under the component
Sleeping within the Event Dispatching Thread (EDT) will stop Swing from performing any updates (as well as process any events). Instead I'd recommend using a javax.swing.Timer. See Concurrency in Swing for more details.
If you're using the VLC bindings, then it can't be achieved
Don't forget to make all the parent containers that the sub titles are contained in transparent as well
So I have this problem. I have a program that creates and load files.
When I load a file into my program, I rely on a component listener that tells me when is the specific component "full", and then moves all of the components according to that.
I add each component on the top, and then listener register when parent component is "filled" and moves the bottom compoennt to a new parent it also creates. Think of it as adding a new line of text to the begining of a houndred page MSWord document.
That listener also relys on the GUI setup - if everything in memory is not painted to the screen, it grabs wrong component heights (usually being 0) and uses them in it's calculations which then come out wrong, and everything gets messed up.
Here is a flow chart of that part of my program:
(everytning happens on a JPanel in a JFrame)
trigger opening method:
{
repeat this x (lets say e.g. 100) times:
{
trigger addComponent method
{
add component
{
adding component triggers the component listner 8if there is no more room in parent)
{
move all of the components one place down, move the ones out of bounds to next "page"
repaint and revalidate whole JFrame (inside listener)
}
}
repaint and revalidate whole JFrame (part of addComponent method)
}
repaint and revalidate whole JFrame(part of opening methid, after component addition)
}
repaint and revalidate whole JFrame (as a part of opening method, final repaint/validate)
}
The reason for this may repaint/validate is that addComponent method, as well as the listener has other functions and is called in other places where that is the only (optimal) place for repainting/validating.
The problem is that JFrame doesn't get repainted until the very last(final) validate/repaint call in opeoning method. I tried adding Thread.sleep(1000) to several places in the code (after validate/repaint) to proved this.
Also, as far a I know, when a component listener is triggered, it stops at the line which triggerd it, then executes itself, and then continues from that line, right?
How do I fix this? How do I force my program to repaint/validate after each new component was added ant then again after the listener did it's job?
Reply to the first two comments:
Firstly, Thread.sleep(1000) was just to diagnose the problem. Right before Thread.sleep(1000) method was repaint/validate method, so I thought if I pause the program right after reapint() was called, after every pause, GUI would be repainted ad I would see new element added, which was not the case.
Secondly, regarding to the lengthy calculations, those calculations aren't that long (executing this with 20 components gets momentary results, though not ones that are desired). Also, that calculations require removing and adding components to the GUI quite often (every 10-20 lines), so Incorporating SwingWorker in that is close to impossible, and not needed.
Thirdly, I think you missed the whole point. Length of execution is not the real problem here, nor the freezing of the GUI (whic doesn't really occurr, not long enough to be noticable, anyway). The problem is that repaint/validate was called in the loop for total of 3-4 times for every component (cca. 60-80 times if I open a file with 20 components), and the only time I saw it being executed is when the last time it was called, after the loop...
I even put System.out.println("something") method right before and right after the repaint/validate. It printed out "something" twice, but repaint/validate never happened.
I can see any issue with add / remove / modify JComponents in the container (JFrame --> JPanel e.i.)
depends if container (JPanel e.i.) is placed in JScrollPane
depends if you need to call pack() after add / remove / modify JComponents in the container, and then to change size of JFrame (for example) on the screen
(In my applicaton with Swing GUI) I want to display GlassPane during some work performed in a loop or method, which is called after clicking JButton.
For example:
(action performed after clicking a button)
if (item.equals(button)) {
glassPane.setVisible(true);
someTimeConsumingMethod();
glassPane.setVisible(false);
}
Running this code results in not showing the glassPane during execution of someTimeConsumingMethod() - GUI just freezes for a moment, before result is displayed. Removing last line in that loop (glassPane.setVisible(false);) results in showing glassPane after the method is done (when GUI unfreezes).
Is there a simple way to show that glassPane before GUI freezes, or I need to use some advanced knowledge here? (threads?)
UPDATE1:
I've updated my code according to davidXYZ answer (with two changes):
(action performed after clicking a button)
if (item.equals(button)) {
glassPane.setVisible(true);
new Thread(new Runnable(){
public void run(){
someTimeConsumingMethod(); // 1st change: running the someTimeConsumingMethod in new Thread
// instead of setting glassPane to visible
}
}).start();
// 2nd change: moved glassPane.setVisible(false); inside the someTimeConsumingMethod(); (placed at the end of it).
}
The point of 1st change is that setting glassPane visible in new thread right before running someTimeConsumingMethod in my GUI thread was revealing the glassPane after someTimeConsumingMethod finished (double-checked this).
Now it works fine, thank you for all answers. I will definitely check all the links you provided to actually understand threads!
UPDATE2:
Some more info: someTimeConsumingMethod(); in my application is prepering new Swing Components accoriding to the XML data (cards builded from JButtons and JLabels with few JPanels where needed, and adding them in correct places).
UPDATE3:
I am trying to make it work using SwingWorker's invokeLater method. Now it looks like that:
(action performed after clicking a button)
if (item.equals(button)) {
glassPane.setVisible(true);
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
someTimeConsumingMethod();
glassPane.setVisible(false);
}
});
}
It works not that good as code from UPDATE1 (but still - it works). Problems are:
glassPane loads without .gif animation (file is setted up in custom glassPane class - it works with UPDATE1 code)
there is small delay at the end of "working" process - first cursor changes to normal (from the WAIT_CURSOR), and after very short moment glassPane disappear.
Cursor is changed by the custom glassPane class on activation/deactivation (no delay using new Thread way).
Is it correct way of using SwingWorker's invokeLater method?
EDIT: My mistake, I confused SwingWorker with SwingUtilities.invokeLater(). I guess the image issue is due to GUI freezing when the someTimeCOnsumingMethod starts.
GUI just freezes for a moment, before result is displayed. Removing last line in that loop (glassPane.setVisible(false);) results in showing glassPane after the method is done (when GUI unfreezes).
this is common issue about Event Dispath Thread, when all events in EDT are flushed to the Swing GUI in one moment, then everything in the method if (item.equals(button)) { could be done on one moment,
but your description talking you have got issue with Concurency in Swing, some of code blocking EDT, this is small delay, for example Thread.sleep(int) can caused this issue, don't do that, or redirect code block to the Backgroung taks
Is there a simple way to show that glassPane before GUI freezes, or I need to use some advanced knowledge here? (threads?)
this question is booking example why SwingWorker is there, or easier way is Runnable#Thread
methods implemented in SwingWorker quite guarante that output will be done on EDT
any output from Runnable#Thread to the Swing GUI should be wrapped in invokeLater()
easiest steps from Jbuttons Action could be
show GlassPane
start background task from SwingWorker (be sure that listening by PropertyChangeListener) or invoke Runnable#Thread
in this moment ActionListener executions is done rest of code is redirected to the Backgroung taks
if task ended, then to hide GlassPane
create simple void by wrapping setVisible into invokeLater() for Runnable#Thread
in the case that you use SwingWorker then you can to hide the GlassPane on proper event from PropertyChangeListener or you can to use any (separate) void for hidding the GlassPane
best code for GlassPane by #camickr, or my question about based on this code
You are blocking the EDT (Event Dispatching Thread, the single thread where all UI events are handled) with your time consuming job.
2 solutions:
Wrap the calls to:someTimeConsumingMethod();glassPane.setVisible(false); in SwingUtilities.invokeLater(), this will allow the frame to repaint itself once more. However this will still freeze your GUI.
Move your someTimeConsumingMethod() into a SwingWorker (this is the recommended option). This will prevent your GUI from ever freezing.
Read the javadoc of SwingWorker to understand better what is going on and how to use it.
You may also learn a lot in this tutorial about Swing and multi-threading
JButton startB = new JButton("Start the big operation!");
startB.addActionListener(new ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent A) {
// manually control the 1.2/1.3 bug work-around
glass.setNeedToRedispatch(false);
glass.setVisible(true);
startTimer();
}
});
glasspane here used here is FixedGlassPane glass;
ref: http://www.java2s.com/Code/Java/Swing-JFC/Showhowaglasspanecanbeusedtoblockmouseandkeyevents.htm
Guillaume is right. When you are on the main thread, each line will finish before the next line. You definitely need another thread.
An easy way to solve your problem is to spin off the display of the glasspane in another thread (normal thread or Swing threads - either will work fine).
if (item.equals(button)) {
new Thread(new Runnable(){
public void run(){
glassPane.setVisible(true);
}
}).start();
someTimeConsumingMethod();
glassPane.setVisible(false);
}
That way, a different thread is blocked by setvisible(true) while someTimeConsumingMethod() runs on the main thread. When it's done, glasspane will disappear. The anonymous thread reaches the end of the run method and stops.
I have a fractal generation component (a subclass of JPanel) inside a JFrame. When the user resizes the window, it takes quite a while to update the fractal to the new size.
I currently have a ComponentListener on the JPanel, but its componentResized event is called every time the user moves the mouse while dragging the window border. This means that the fractal is told to resize many times, and slowly (over the course of a few minutes) grows to the new size.
Is there a way to be notified when the user releases the mouse button, so that I can only change the fractal size when the user has finished resizing?
Others have reported this happening when the listener is attached to the JFrame instead, but this doesn't work for me (and others), for some reason.
Instead of starting the calculation each time you receive a receive-event, you can only start the calculation after you received the last event by using a timer, e.g. in pseudo-code (or at least code which I typed here directly and not in my IDE)
private Timer recalculateTimer = new Timer( 20, myRecalculateActionListener );
constructor(){
recalculateTimer.setRepeats( false );
}
#Override
public void componentResized(ComponentEvent e){
if ( recalculateTimer.isRunning() ){
recalculateTimer.restart();
} else {
recalculateTimer.start();
}
}
And you can still combine this with Andrews suggestion to use an image which you stretch until the calculation has actually finished.
you have look at HierarchyListener, where you can listening for HierarchyEvent with interface to HierarchyBoundsListener
basically nothing wrong with ComponentListener, but you have to wrapping expected events to the Swing Timer, in the case that events repeated, only to call Timer#restart(), output from Swing Timer should be Swing Action
It's a bit late, but it looks like no one found the correct answer. I found that when you call child.updateUI() inside a ComponentListener (componentResized block) of a window, this child resizes it self and updates its content. Using timers is unsafe.