I am working on a gesture recognition project. There is a C program that captures the gestures from video input and write them to the file. Now, I have an image viewer written in Python - GTK. It switches to the next or previous window according to gestures. This continuous file read and application update is defined as follows:
def ai(self):
if self.mtime!=os.stat("input.txt").st_mtime:
self.mtime=os.stat("input.txt").st_mtime
inp=open("input.txt", "r");
line=inp.read()
if len(line)!=0:
line=line[0:len(line)-1]
for x in line.split(' '):
y=x.split('-')
if(y[1]=="R"):
self.next()
print "Move Right"
elif(y[1]=="L"):
self.prev()
print "Move Left"
time.sleep(1)
print "WakeUp"
self.ai()
Now if I comment out the recursive call here, then application works after reading present file and updating images. Of course, then it doesn't update afterwards.
But if I uncomment the recursive call, then the console keeps on working but image-viewer application stops responding.
Is there any way to perform this function? Any event where i could bind this ai() function that could check for file updates every time that event is fired...
Any help would be appreciated.
Not sure if I understand you correctly, but I would expect what you want to do is to schedule a call to ai() in your main GTK loop, so that your program checks if there is input on a regular base.
If this is what you want you have two choices: scheduling the call periodically or schedule the call for when the program is idle (it is not doing anything else).
Your code should look something like:
gobject.idle_add(callback, ...) #execute callback when idle
gobject.timeout_add(interval, callback, ...) #execute callback every interval millisecs
The documentation should be here but presently there is a server error. Here are the relevant passages:
The gobject.idle_add() function adds a function (specified by callback) to be called whenever there are no higher priority events pending to the default main loop. The function is given the default idle priority, gobject.PRIORITY_DEFAULT_IDLE. Additional arguments to pass to callback can be specified after callback. The idle priority can be specified as a keyword-value pair with the keyword "priority". If callback returns FALSE it is automatically removed from the list of event sources and will not be called again.
The gobject.timeout_add() function sets a function (specified by callback) to be called at regular intervals (specified by interval, with the default priority, gobject.PRIORITY_DEFAULT. Additional arguments to pass to callback can be specified after callback. The idle priority may be specified as a keyword-value pair with the keyword "priority".
A catch: you have your callbacks to return True if you want to keep them in the scheduler, failing to do so will make them execute only once.
HTH!
Disclaimer: I have no experience whatsoever using pygtk.
I guess to make this work, you have to let the GTK event loop call your code (your recursive call makes it so that control never returns to the event loop).
You probably have two options:
Either set up a timer event to call your method every nnn milliseconds (tutorial)
Or use some sort of idle event to call your method whenever the GTK program is otherwise idle (tutorial)
Since you're using gtk, you could use gio module to do the monitoring for you, instead of your own custom solution to periodically poll the file state:
monitor = gio.File(filename).monitor()
monitor.connect('changed', file_changed_cb)
Note that you can connect the changed signal to your callback to perform any update that you need.
Related
I have a main process that does some stuff (e.g. analyzing data) and it runs alone just fine. I also want to make a simple GUI that displays the result of the main task using PyQT5. The idea is that the GUI should not interfere in the main process, that is, if I remove the GUI it shouldn't cause any issue to the main process.
The code of the main process is quite simple:
if __name__ == '__main__':
# initialize the object that performs the main task
tasker = Task()
# the graphical interface to visualize the result of tasker
gui = GUI(task) # GUI is a separate class that keeps a reference to tasker
# read the input data and do stuff on each new data instance
for f in listdir(inrepo):
data = read_new_data(f) # an utility function that reads new data from file
result = tasker.process(data) # tasker processes the new data and return some results
gui.update(data, result) # pass the data and result in the GUI to update it
The code of the GUI class is quite long so I only paste a few lines here, but the lines I skip are just to create widgets, nothing fancy (I didn't connect any event yet)
class GUI(QApplication):
def __init__(self, tasker):
"""Initialize the application"""
super().__init__([])
self.tasker = tasker
# define the main window
self.window = QWidget()
self.window.setWindowTitle('GUI')
... # layout and components etc.
# show stuff
self.window.show()
self.exec()
So I want the GUI to be completely independent from my main process. For example, if I don't need the GUI anymore, I can just comment out the 2 lines gui = GUI(task) and gui.update(data, result).
However, the problem is that starting the GUI blocks the entire process (I assume it's because of self.exec() in GUI.__init__, so my main process cannot proceed to loop over the data. Could you please show me how to make PyQT non-blocking? Is it even feasible?
Some options I have considered:
Threading: it seems more complicated than necessary for my use case and it may make referencing to the task instance difficult from a thread. All new updates to task should be reflected in the GUI. If I'm not mistaken, PyQT's application already runs on a thread. So multi-level threading may be troublesome.
Run the GUI from another Python process, communicated via shared folders: may incur high latency. Any new data and result from task should be immediately reflected in the GUI. Writing to file then reading from file then updating the GUI will cause some delay.
Perform the task in GUI: I could use some timeout event to read new data periodically and run task on them, but then everything depends heavily on the GUI, and I can't just comment it out if I don't need the GUI anymore.
Any suggestion is very much appreciated! Thank you very much!
Switching your program between GUI mode/console mode is often not as simple as commenting out some lines. PyQt in particular does not allow you to run a GUI loop from anything other than a main thread. Not all hope is lost, though - this simply means that you should decide as early as possible whether your program is going to run as a console application or as a GUI.
Instead of relying in commenting out code, you can create a "switch" of sorts inside your code that tells your code how to execute. One way to do this is to check the command-line arguments when you execute the code, e.g.:
import sys
if "--headless" in sys.argv[1:]: # checking the command-line arguments
run_code_without_gui()
else:
run_code_with_gui()
This way, executing your code as python mycode.py --headless will execute it without the GUI (through the run_code_without_gui function), while executing python mycode.py will run it as a GUI (through the run_code_with_gui function). (Although if you're actually going to parse command-line arguments, I recommend using the argparse library).
You can even keep the analysis code completely decoupled from the GUI code, so that you simply run a function from, say, analysis.py when executing without the GUI, and have the GUI call that exact same function when e.g. the user clicks on the "Analyze" button.
Another thing to note is that if your analysis code takes long to execute, it may inadvertently block the GUI. In this case, you should run the analysis code in a separate "worker" thread that spawns upon clicking the "Analyze" button, keeping the GUI responsive while it executes. This might be the way to go if you want the analysis to keep running alongside the GUI indefinitely - create the worker thread for the analysis at the same time that you display the GUI to the user.
I want a Maya camera orbiting a mesh while user chooses what to do with that mesh on my own script interface.
So i have a while orbiting the camera, but no way to interact with user interface while this happens.
There is anyway to "share", or part the focus in second's decims to be able to interact with user interface?
I tried with cmds.evaldeferred(), but no luck...
Technically, Maya widgets interface is immediately available when script finishes the job...
I'm trying to finish the job with one single camera little orbit, and relaunch it with mouse movement event... Time changing event... But no way how to do that... Would be like a daemon running in the background... No idea how I could reach something like that....
Some code:
import maya.cmds as cmds
#declares global variable
global orbitCam
#just something to see in the scene
cmds.polyCube()
#function to stop camera orbit
def stopOrbiting():
global orbitCam
orbitCam = False
#simplest ui
cmds.window("testWindow")
cmds.formlayout("flo", parent="testWindow")
#button that calls stopOrbit function
cmds.button("pushMeIfYouCan", parent="flo", label="pushMeIfYouCan", c="stopOrbiting()")
cmds.showWindow("testWindow")
#condition for the while
orbitCam=True
#while itself
while orbitCam:
cmds.orbit("persp", ra=(0.2,0.1))
Any way to be able to push the button -and interact with widgets- while camera orbits?
Well, based on solution provided by mhlester in the link I posted under the question (and considering a great answer too by theodox, as a wonderful alternative, thank you both, guys), I'm gonna aswer my own question and provide another new detailed explanation perhaps can help somebody in the future.
First of all, Maya's "scriptjob" command utility puts in memory a script (or a function), haves a trigger to start executing that function, and the condition to Maya to execute that function once registered and triggered, is that Maya must to be doing exactly nothing, so, Maya must be idle.
Being that way, Maya never collapses or crashes or hangs by a scriptJob. ScriptJob is basically a... kind of "daemon" working in the background.
The good thing, is that is possible to limit the maximum number of times per second, so you can even maintain your system fresh and working if you want to care it about.
Once a scriptJob is launched (or registered in Maya memory), it can be killed to never runs again, and obviously, can be registered again if we want to start working again.
Exists an internal scriptJobs list inside of Maya, where you can find the scriptjob if you have forgotten to store that scriptJob in a variable, where you can find the "scriptJob ID", just an integer number you can use to kill the job.
After the first theory, let's see some code now:
This line will register a new daemon (maya scriptjob), its reference will be stored in "activeDaemon" variable, it will call a function called "camDaemon" with some arguments:
activeDaemon = registerDaemon(0.04, BackgroundFunction, ArgumentsForBackgroundFunction)
The point here is not just launch the daemon with conditions, besides, to store the daemon id to be able to kill it with:
cmds.scriptJob(kill=activeDaemon)
If we forgotten to store the daemon (scriptjob) id, we can use this command to watch a list with all scriptJobs of Maya:
cmds.scriptJob(listJobs=True)
We would need to find the last ids in the list with the event "idle", and probably we could hit and finished stopping our daemon killing it.
Now let's see "registerDaemon" function (all the absolute credit for MhLester):
def registerDaemon(seconds, backgroundFunction, *args, **kwargs):
def updateNow():
now = time.time()
if now - updateNow.then > seconds:
updateNow.then = now
backgroundFunction(*args, **kwargs)
updateNow.then = time.time()
return cmds.scriptJob(event=("idle", updateNow))
registerDaemon defines an internal function (updateNow) that calls "automatically" at the backgroundFunction we pass as argument, including this "backgroundFunction" arguments. Just that. A function A that defines a function B that calls a function C. And it calls it every quantity of seconds we specify at register the daemon with the first argument, so if we want it executed 25 times per second, 1seg/25fps = 0.04 would be the right value.
To have this function working, we must import the module time in our script with:
import time
Finally it returns the scriptJob id at the same time it registers it in Maya memory, registering with the event "idle" and with the function (B) that calls the function (C) we really want executed in the background. This way we can control the temperatures of the machine not overwhelming the cpu unnecessary. Very complete last line, brilliant, at least, for me.
At this point no other thing left than just register the function we want to have running the background in the Maya memory (take the code you want in the background, put inside a function and execute it one time in Script Editor)
def backgroundFunction():
print "this message shows in idle time by a daemon (Maya scriptjob)"
Of course there are much more in the documentation (Maya scriptJob documentation), as a list of events or conditions, but the base is this.
I am building an app that, when the user hits a 'run' button, generates a table of buttons.
Because this process takes a while, I want to add a popup or progress bar to alert the user that the function is running and not frozen. To do this I decided to create a popup and call my function using threading so that the screen will be updated when the function starts (as opposed to once it is done).
mythread = threading.Thread(target=run_function)
mythread.start()
The trouble is that when I call my function from the above code it works very strangely: the columns of my table are the wrong width, some of my buttons are arbitrarily empty, and others have the wrong fill color. To fix this, all I need to do is to remove the threading operation and simply call run_function()
Any idea why this is happening?
I am new to Python, so it is likely some dumb mistake, but I have no idea. What is different between a process running as a thread and its default operation?
Disclaimer: I haven't worked with Kivy.
Not every framework works well with multithreading.
But most of the GUI frameworks have an event loop which is responsible for managing user events (mouse clicks, keyboard) and queued drawing operations (widgets).
In your case if don't want the UI to be freezed, you should regularly give control to your framework's event loop.
I guess kivy.base.EventLoopBase.dispatch_input is what you need to call to show an added widget or to handle user events.
Here is my dilemma: I have a log parser with a pygtk window. After the user opens a file via the dialog, I have a progress bar showing them approximately when the open will be complete (as it can be a lengthy process). I recently added an option to allow the user to specify a file via the command line.
My problem is, since I have to load the file before calling gtk.main(). Thus, the window and, more importantly, the progress bar are not displayed until after this lengthy load completes, giving the user no indication.
So, I am hoping there is a way to execute a function after calling gtk.main(), or somebody has an alternative approach. Thanks
Rather than beginning the process from the command line as soon as you parse the command line arguments, simply pass the command line argument to your application class (or store in a variable) and process it AFTER you've entered gtk.main. That way you can setup your GUI first. Before beginning the process, and every time you increment the progress bar, make sure you let Gtk catch up using something like:
while Gtk.events_pending():
Gtk.main_iteration()
OK, I'm trying to explain what I want to achieve in another way. Here's an example:
Say if it's an anti virus program, and user can choose between two ways to run the program, choice one, automatically start to scan disks for virus when the program starts up, choice two, hit the start button to make the program scan disks for virus after the program starts up any time the user wants. So, as a wxpython beginner, I know how to bind wx.EVT_BUTTON to let scanning start after the user hit the start button, but I don't know how to make the scanning start once the program starts up. I wonder if there's a program_start event I can bind? Hope you guys can help me out. Thanks!
In wxPython you can override the OnInit method of your Application class to run code when the program launches. For example:
def OnInit(self):
# Check for a running instance for this user. Do not instantiate if found.
if self.checkInstance():
dbcon.cursor().callproc('post_mutex', (self.mutexname,))
dbcon.commit()
self.Cleanup()
return False
# Register for database events.
DataCache['dbListener'] = dbListener()
return True
There is of course another method on my Application class called checkInstance. Depending on it's return value, my application either launches, or triggers the other running instance to launch.
In wxPython you don't have to do anything special with your App class to get the binding to take place for your OnInit method. It'll happen automatically if you override it.
Why don't you run it just in module code? This way it will be run only once, because code in module is run only once per program instance.
In your init or OnInit method, do some kind of check to see if the program should run the startup process on startup (i.e. check a config file or some such). If yes, call the "scan" method using wx.CallAfter or wx.CallLater or call it after you Show() the frame.