crap, that last sentence was all sorts of broken... I meant, do you have a QT call that is writing to a python variable? On Wed, Nov 11, 2009 at 10:41 AM, Chris Colbert <sccolbert@gmail.com> wrote:
right, but the gil ensures that only one piece of python code is executing at a time.
Perhaps I missed it, did have a qt call that right to a python variable?
On Wed, Nov 11, 2009 at 10:39 AM, SirVer <sirver@gmx.de> wrote:
Hi Chris,
DId you find that you needed the mutex even with the GIL? Yes I did. The GIL doesn't prevent deadlocks in all cases since we have no guarantee when python does a context switch. Shared variables (that can be written in both threads) still need protection by something. I am pretty sure it is needed at this point.
Cheers Holger
Chris
On Tue, Nov 10, 2009 at 9:48 PM, SirVer <sir...@gmx.de> wrote:
Chris,
I forget to point you to a working example in my pydc code. Sorry for that:
http://bazaar.launchpad.net/%7Esirver/pydc1394/trunk/annotate/head%3A...
That's pretty much all knowledge I have about real time acquistion & display with PyQt & PyOpenGL.
Cheers, Holger
On 10 Nov., 12:08, Chris Colbert <sccolb...@gmail.com> wrote:
Holger,
#2 looks a lot like what I cooked up over here. (#1 always segaults for me, but i could be doing it wrong.) I tried the Qthread both with a while loop and a QTimer. I think i like the timer better...
At least I know i'm heading in the right direction.
Cheers,
Chris!
On Tue, Nov 10, 2009 at 10:49 AM, SirVer <sir...@gmx.de> wrote:
Hi Chris,
> Are you able to feed your display widget with images from within a > python loop in the interactive shell?
> ie:
> while True: > img = grab_new_image() > display.new_image(img) > The issue I am having with this PyOS_InputHook, is that for me, that > type of loop never lets the interpreter idle (even with a sleep() > call) and thus the PyOS_InputHook never gets called, and the gui never > updates. This can't work as you said. PyOS_InputHook is never called. I doesn't work in ipython -q4thread either because the thread switch doesn't seem to occure. There are two ways to do it 1) either call PyOS_InputHook yourself. 2) acquire your images in another thread.
I always use 2) since my image acquisition always takes place continously in the background. This is also a way were PyQT really shines (It also works with wxWidgets that way, but it hurts a bit).
so your above example would look a bit like that (not tested, just written down like that):
class WorkerThread(QThread): def __init__(self, display): self.connect(self, SIGNAL("newImage"), self.display.newImage) # Keep a copy of display around so that the C object doesn't get deleted self.display = display
def run(self): while True: img = grab_new_image() self.emit(SIGNAL("newImage"), img)
def acquire_images(display): t = WorkerThread(display) t.start()
This example should work from the interactive shell provided you created a QApplication object so that Qt4 has the PyOS_InputHook acquired. Just call acquire_images(display).
Cheers, Holger
> Cheers,
> Chris
> On Fri, Nov 6, 2009 at 11:24 AM, SirVer <sir...@gmx.de> wrote:
> > Hi Chris,
> > thanks for the links! It made for some interesting reading; i wasn't > > aware of the System Hook. But I just investigated and my Widget works > > just fine in a pure python session as long as a QApplication object > > has been created before. So there is no problem here, it will work > > fine now in ipython -qt4thread and will continue to work in future > > ipython and also in vanilla python as long as QApplication(sys.argv) > > has been called before the window is created (which is mandatory for > > all QT4 Applications). So no problem here.
> > I now try to come to a conclusion to this thread. I didn't mean to > > start a lengthy discussion of how things should be done differently, I > > only want to have direction how to implement this. I try to summarize > > my thoughts:
> > * I am often in need to display images from a camera and annotate them > > with some output from algorithms (for example mark detected balls in > > my ping pong roboters images in red). For this I've written the code > > that can be found in my gui branch. > > * I feel that this use case is quite different from the idea of the > > imshow() plugin. I also feel that more people than me could profit > > from this functionality as I use it ATM. > > * I feel that this is hard to pull off with a plugin like > > architecture, because the annotation part will be different for all > > backends and all individual uses. En plus, this is more a Library kind > > of functionality, not a enduser kind like imshow(). > > * My solution works for me and uses PyQt and PyOpenGL. My experiments > > showed me that this is the only combination that offers the drawing > > speed I want. I understand that other approaches could be possible or > > feasible, but I also think that for use cases like mine, this is a > > very common approach; especially since annotating in OpenGL is so easy > > to do with PyQt4. > > * Please let me state again that I do not plan to corrupt or change > > the imshow() plugin architecture which I really like. I am just of the > > opinion that something else is needed for my use case.
> > Now, please note that these are my opinions and thought and not really > > subject to discussion. What I now really need is a design decision by > > the architect of scikit.image; which I assume to be you, stefan:
> > How should I contribute this code? In which module should it go or is > > this not a direction that scikit.image should evolve in (I'd > > understand that and instead bring this code into my pydc1394 library > > were it would also fit).
> > Cheers, > > Holger
> > On 5 Nov., 17:33, Chris Colbert <sccolb...@gmail.com> wrote: > >> Here's a couple links on it Holger.
> >> Hopefully the scipy links work for you (its the Ipython part of the > >> discussion). I cant get to them right now.
> >>http://mail.scipy.org/pipermail/ipython-dev/2009-July/005256.htmlhttp...
> >> On Thu, Nov 5, 2009 at 5:14 PM, SirVer <sir...@gmx.de> wrote:
> >> >> However, i'm afraid that your current gui may rely on ipython > >> >> -q4thread, which is now deprecated (big mailing list discussion on > >> >> this). So that may throw a wrench in the video portion of it, unless > >> >> we can figure out this pyos_input hook thing. > >> > It infact does. Chris, could you please point me at this discussion? > >> > It is most relevant for my work.
> >> > Cheers, > >> > Holger
> >> >> But as my previous example shows, its definately possible to fit it > >> >> within the plugin framework.
> >> >> Cheers!
> >> >> Chris
> >> >> On Thu, Nov 5, 2009 at 4:56 PM, Chris Colbert <sccolb...@gmail.com> wrote: > >> >> > So while i havent yet been able to get the pyos_inputhook thing sorted > >> >> > out, I did time a couple loops.
> >> >> > For a decent sized image, we can easily get 60fps update rates, and > >> >> > thats including the time for the numpy operations:
> >> >> > In [5]: img = io.imread('/home/brucewayne/Pictures/failboat_4.jpg')
> >> >> > In [6]: img.shape > >> >> > Out[6]: (503, 790, 3)
> >> >> > In [7]: win = io.imshow(img, updateable=True)
> >> >> > In [8]: def test(img, win): > >> >> > ...: for i in range(30): > >> >> > ...: img[:] += 1 > >> >> > ...: win.update() > >> >> > ...: > >> >> > ...:
> >> >> > In [9]: %timeit test(img, win) > >> >> > 1 loops, best of 3: 564 ms per loop
> >> >> > one thing to note, I bypassed the prepare_for_display() method that we > >> >> > usually call to make sure an array is contiguous, of the right dtype, > >> >> > etc... > >> >> > I assume if someone wants video, they can prepare the arrays themselves.
> >> >> > This behavior can also be changed by the plugin writer. For this > >> >> > example, i simply took the easy route and subclassed ImageWindow
> >> >> > Cheers,
> >> >> > Chris
> >> >> > On Thu, Nov 5, 2009 at 4:24 PM, Chris Colbert <sccolb...@gmail.com> wrote: > >> >> >> I was just testing out something along these lines, but I run into the > >> >> >> problem of the the python interpreter not considering time.sleep() as > >> >> >> idle time, thus, it never calls PyOS_InputHook inside of for-loops. So > >> >> >> i'm not quite sure how to get video feed to run interactively without > >> >> >> hacking out something like ipython -whatever thread.
> >> >> >> Mind you, this is not a problem with the plugin architecture, its a > >> >> >> problem with the python interpreter...
> >> >> >> but maybe i can ctypes into the os_hook and call it at the end of a > >> >> >> loop.... <evil grin>
> >> >> >> 2009/11/5 Stéfan van der Walt <ste...@sun.ac.za>:
> >> >> >>> 2009/11/5 Chris Colbert <sccolb...@gmail.com>: > >> >> >>>> Further, these imshow() type widgets are primarily meant to be used > >> >> >>>> from the interactive interpreter, an environment not best suited for > >> >> >>>> real time image acquisition and display. that said, the plugin > >> >> >>>> archiceture can most certainly be used in the method you speak of. You > >> >> >>>> just simply have your imshow() function return the window object, and > >> >> >>>> implement an update() or similar method that the consumer can call to > >> >> >>>> update the image.
> >> >> >>> This could even be accomplished using 'imshow' only. The > >> >> >>> WindowManager keeps track of the single window produced, and 'imshow' > >> >> >>> simply grabs that window and updates its current content. I'd be > >> >> >>> surprised if we couldn't pump out a large number of frames-per-second > >> >> >>> that way.
> >> >> >>> Stéfan