As the original author of the Quantum toolkit and the renderer, this
sort of addition goes against what I had in mind when designing the
PaintCollector and the renderer. As the renderer is built around a
ThreadPoolExecutor, stopping system functionality for an edge case is
putting the cart before the horse.
When a Window is miniaturized or set to zero size, or moved offscreen,
there should be no pulses fired at the Window.
This seems more like an issue of ensuring that if the window is 0x0 that
it is not considered dirty, and if there is no dirty scene that
nextPulseRequested() is never called.
There does need to be work done on Quantum to ensure that it cycles down
to no CPU usage when windows are hidden and/or miniaturized on battery
operated devices. That needs to be done cleanly, but even then pausing
the ThreadPoolExecutor seems to be the wrong way of going about it. The
TPE model is more startup, work, then shutdown, and the QuantumToolkit
intermediates JavaFX application state with that model.
Best regards,
--morris meyer
On 11/22/15 6:24 AM, Johan Vos wrote:
I implemented this in the javafxports clone of the OpenJFX 8u-dev repo, and
the diff is here:
https://bitbucket.org/javafxports/8u-dev-rt/commits/67a0fded8208095bd04efda6045aa257e245d6bc
I am more than happy to create an issue in the openjdk bug system
(enhancement?) and provide a patch there as well, but I think it needs a
bit more discussion first?
- Johan
On Sat, Nov 21, 2015 at 9:23 PM, Johan Vos <johan....@gluonhq.com> wrote:
I have a working implementation that needs more stress-testing on
different platforms, but it seems a good and easy solution so far.
I have this on QuantumToolkit:
@Override
public void pauseRenderer(){
Application.invokeAndWait(() -> this.pause = true);
PaintCollector.getInstance().waitForRenderingToComplete();
};
public void resumeRenderer(){
Application.invokeAndWait(() -> this.pause = false);
};
pause is a boolean that is checked for in
void pulse(boolean collect) { ... }
The difficulty I mentioned in my previous mail (how do we know there are
no renderJobs pending/running) was solved easily as there exists this
PaintCollector.waitForRenderingToComplete method.
This might make the pauseRenderer a bit slower, and maybe this is not
needed in all usecases. In that case, we can remove it from the
pauseRenderer() and we can add it either in the Monocle implementation that
will call pauseRenderer, or in a Android/iOS specific code.
However, it seems to me that if you want to pause the renderer, you most
often want to make sure no one is still writing to the glSurface after the
pauseRenderer method is called, so I think it makes sense to keep it there?
- Johan
On Fri, Nov 20, 2015 at 8:14 AM, Johan Vos <johan....@gluonhq.com> wrote:
I didn't plan to intercept or cancel pending/submitted jobs, but I have
to wait until they are done before the android callback method returns.
When Android is about to destroy the context, it will call the
surfaceTextureDestroyed method on the Activity (the FXActivity in our
case). As long as that method doesn't return, the context won't be
destroyed. But once that method returns, the context might become invalid
any moment. So if there are still jobs that want to do a swapBuffer after
we return, those can crash or (even worse) corrupt the egl system.
So it seems to me inside the implementation of surfaceTextureDestroyed,
we need to achieve 2 things:
1. make sure no new pulses are generated.
2. don't return while the QuantumRenderer is still executing jobs.
Those 2 things can be combined in a single Toolkit.pauseRenderer() but it
might be better to only achieve the first task in Toolkit.pauseRenderer().
The contract for this method is than that no new pulses will be
generated, but existing renderJobs might still be running when this method
returns.
The second thing, waiting for the renderJobs to be finished, can be done
in the Android specific implementation.
- Johan
On Thu, Nov 19, 2015 at 10:20 PM, Kevin Rushforth <
kevin.rushfo...@oracle.com> wrote:
This might be a tricky semantic to achieve, and great care will be
needed to ensure no deadlocks or race conditions. Not running any more
pulses after this method returns seems fine, but it might be better to let
any existing renderJobs run (possibly discarding the results). This way you
could send the pause message to the renderer as a special renderJob and not
have to worry about jobs that are scheduled but not yet run.
-- Kevin
Johan Vos wrote:
After some experiments, here is my current thinking:
Toolkit can have 2 new methods:
pauseRenderer()
resumeRenderer()
When pauseRenderer is called, it should be guaranteed that after this
call,
no new pulses are fired until resumeRenderer is called.
That is not hard, but it is not enough. Before we pause the pulses, the
previous pulse probably submitted a renderJob to Prism, executed on the
QuantumRenderer ThreadPoolExecutor. That job should run fine, as the
next
pulse (when we're back) will call
GlassScene.waitForRenderingToComplete().
So we have to wait until there are no running or pending tasks in the
QuantumRenderer as well.
- Johan
On Wed, Nov 18, 2015 at 9:58 PM, David Hill <david.h...@oracle.com>
wrote:
On 11/18/15, 3:45 PM, Johan Vos wrote:
Johan,
I think that it would be reasonable to put in something to Quantum
that causes the render loop to "pause", and then resume later. I
envision
this toggle as causing the render loop to skip, rather than tinkering
with
the pulses.
When resume is called, it might be best to treat the world as dirty.
Added to Toolkit, this would allow someone like Monocle to make the
toggles as is appropriate.
If this works for you, perhaps you could prototype it ?
regards,
Dave
On Android, a JavaFX Application might transfer control to another app
(and
become invisible) and enter the foreground later. In that case, the
GLSurface we are rendering on becomes invalid. In order to avoid
problems
and save battery, we want to pause the renderer thread, but this
turns out
to be more difficult than I expected.
When our app transfers control, we get a callback from Android. We
intercept this in javafxports, and we set the Screen width/height to
0/0
as
we don't want to render on the (invalid) surface while we lost
control.
When we regain control, we resize the Screen and the app renders
again.
The reason we set the width/height to 0/0 is because the
PresentingPainter
will call SceneState.isValid() and this returns false in case
getWidth()
or
getHeight() are 0.
However, SceneState extends PresentableState and it overrides the
update
method. It will call PresentatbleState.update() which will set the
viewWidth to the width of the new Screen (hence, 0) , but after that
it
overwrites the viewWidth with camera.getViewWidth(). The latter still
contains the old value. A quick inspection shows that
camera.setViewWidth()
is called when validate(...) is called on NGDefaultCamera, which is
called
by ES2Context.updateRenderTarget() which happens during rendering,
hence
*after* the PresentingPainter checks if the width is 0.
So immediately after we set the width of the Screen to 0 (on the FX
App
Thread), a Pulse happens, and this one still things the screen is the
original size. While the pulse is happening, the android system
destroys
our context, and the rendering fails. Moreover, the EGL system is in a
unpredictable state (recreating the surface fails).
A very dirty workaround for this is to wait for 1 pulse (with the new
pulselistener API this should be possible) before we return from the
callback method called by Android when the surface is about to be
destroyed. That way, we will have 1 bogus rendering on an existing
(but
about-to-be-destroyed) surface.
But it would be better if there is some way to tell the quantum
renderer
to
immediately stop rendering. Existing pulses are no problem, as the
renderLock guarantuees that we set the size to 0 only when no other
thread
(quantum renderer) has a lock on the renderLock.
- Johan
--
David Hill<david.h...@oracle.com>
Java Embedded Development
"A man's feet should be planted in his country, but his eyes should
survey
the world."
-- George Santayana (1863 - 1952)
