I'm writing a Tkinter program that loads some .png images.
Since files can be faulty or non-existent, it is good to use a try-except block. I'm first checking the file with generic Python. Then I load the image file into Tkinter if it passes the generic Python try-except block:
ok = True
try:
image_file = open("cat.png")
image_file.close()
except IOError:
ok = False
if ok:
self.image = PhotoImage(file="cat.png")
This has to load the image file twice: once for the Python check, and once for Tkinter. Also, there is no guarantee the Tkinter image load attempt will work. If the file were arriving over a network, it is possible the file was available for the Python try-except call, but was then suddenly not available for the Tkinter call.
When I intentionally crash the program by making a call to an unavailable file, I get:
tkinter.TclError: couldn't open "fakefile.png": no such file or directory
This is exactly the error type (file not found) that I am trying to catch inside of Tkinter. I've hunted around, but I have been unable to find out a way for Tkinter to try-except its own call to: PhotoImage(...).
How can I safely load the PNG?
You don't need to make tkinter try-except its own call; just try-except your call to tkinter:
try:
self.image = PhotoImage(file="cat.png")
except tkinter.TclError:
# do whatever you wanted to do instead
For example:
try:
self.image = PhotoImage(file="cat.png")
except tkinter.TclError:
self.cat = Label(text="Sorry I have no cat pictures")
else:
self.cat = Label(image=self.image)
Related
I would like to play video with python-vlc module. I wrote the following code. My computer is MacOS Catalina.
#!/usr/bin/env python3
import vlc
p = vlc.MediaPlayer("mediafile.mp4")
p.play()
while True:
pass
But the python3 interpreter threw the following errors.
[00007f89b9661950] caopengllayer vout display error: No drawable-nsobject found!
[00007f89b9661950] macosx vout display error: No drawable-nsobject nor vout_window_t found, passing over.
[00007f89b30530f0] main video output error: video output creation failed
[00007f89b9650c00] main decoder error: failed to create video output
[h264 # 0x7f89b407c000] get_buffer() failed
[h264 # 0x7f89b407c000] thread_get_buffer() failed
[h264 # 0x7f89b407c000] decode_slice_header error
[h264 # 0x7f89b407c000] no frame!
I guessed that this code didn't make a frame displaying the video. It'll be a main cause of this error, I think.
However, I can not come up with a solution of this problem.
Please tell me how to play video with python-vlc module!!
I think the possible reason is, it requires an active hwnd where it can show the video.
So you need an GUI and set hwnd to that player.
Here is my code for Tkinter Window.You can also check out different GUI based example From Github
import vlc
from tkinter import *
root=Tk()
instance=vlc.Instance()
p=instance.media_player_new()
p.set_hwnd(root.winfo_id())
p.set_media(instance.media_new(path_to_media))
p.play()
root.mainloop()
And if you r using Mac ,then as per the example
you should use instaed of this line
p.set_hwnd(root.winfo_id())
try:
libtk = 'libtk%s.dylib' % (Tk.TkVersion,)
prefix = getattr(sys, 'base_prefix', sys.prefix)
libtk = joined(prefix, 'lib', libtk)
dylib = cdll.LoadLibrary(libtk)
# getNSView = dylib.TkMacOSXDrawableView is the
# proper function to call, but that is non-public
# (in Tk source file macosx/TkMacOSXSubwindows.c)
# and dylib.TkMacOSXGetRootControl happens to call
# dylib.TkMacOSXDrawableView and return the NSView
_GetNSView = dylib.TkMacOSXGetRootControl
# C signature: void *_GetNSView(void *drawable) to get
# the Cocoa/Obj-C NSWindow.contentView attribute, the
# drawable NSView object of the (drawable) NSWindow
_GetNSView.restype = c_void_p
_GetNSView.argtypes = c_void_p,
del dylib
except (NameError, OSError): # image or symbol not found
def _GetNSView(unused):
return None
libtk = "N/A"
h = root.winfo_id() # .winfo_visualid()?
# XXX 1) using the videopanel.winfo_id() handle
# causes the video to play in the entire panel on
# macOS, covering the buttons, sliders, etc.
# XXX 2) .winfo_id() to return NSView on macOS?
v= _GetNSView(h)
if v:
p.set_nsobject(v)
else:
p.set_xwindow(h)# plays audio, no video
I think this will work:
import vlc
media = vlc.MediaPlayer("1.mp4")
media.play()
It just takes a media filename for you.
Make sure the video is in the same folder as the script.
I have this function and I need to close the file before exiting the function say("some text").
def say(self, text):
tts = gTTS(text, lang='fr')
file="text.mp3"
tts.save(file)
audio = MP3(file)
p = vlc.MediaPlayer(file)
p.play()
time.sleep((audio.info.length)) #to avoid it listening to itself
p.stop()
return file
Because If I don't do this, I have this error
OS Error: [Errno -9993] Illegal combination of I/O device
I think that this error occurs because I'm trying to listen just after the call of the function say and the file is still open.
nb: I'm working with Python 3
Though i am not to experienced with TTS, shouldnt it work if you just do close(os.getcwd()+'/'+file)?
I am having an issue writing to a NamedTemporaryFile in Python and then reading it back. The function downloads a file via tftpy to the temp file, reads it, hashes the contents, and then compares the hash digest to the original file. The function in question is below:
def verify_upload(self, image, destination):
# create a tftp client
client = TftpClient(ip, 69, localip=self.binding_ip)
# generate a temp file to hold the download info
if not os.path.exists("temp"):
os.makedirs("temp")
with NamedTemporaryFile(dir="temp") as tempfile, open(image, 'r') as original:
try:
# attempt to download the target image
client.download(destination, tempfile, timeout=self.download_timeout)
except TftpTimeout:
raise RuntimeError("Could not download {0} from {1} for verification".format(destination, self.target_ip))
# hash the original file and the downloaded version
original_digest = hashlib.sha256(original.read()).hexdigest()
uploaded_digest = hashlib.sha256(tempfile.read()).hexdigest()
if self.verbose:
print "Original SHA-256: {0}\nUploaded SHA-256: {1}".format(original_digest, uploaded_digest)
# return the hash comparison
return original_digest == uploaded_digest
The problem is that every time I try to execute the line uploaded_digest = hashlib.sha256(tempfile.read()).hexdigest() the application errors out with a ValueError - I/O Operation on a closed file. Since the with block is not complete I am struggling to understand why the temp file would be closed. The only possibility I can think of is that tftpy is closing the file after doing the download, but I cannot find any point in the tftpy source where this would be happening. Note, I have also tried inserting the line tempfile.seek(0) in order to put the file back in a proper state for reading, however this also gives me the ValueError.
Is tftpy closing the file possibly? I read that there is possibly a bug in NamedTemporaryFile causing this problem? Why is the file closed before the reference defined by the with block goes out of scope?
TFTPy is closing the file. When you were looking at the source, you missed the following code path:
class TftpClient(TftpSession):
...
def download(self, filename, output, packethook=None, timeout=SOCK_TIMEOUT):
...
self.context = TftpContextClientDownload(self.host,
self.iport,
filename,
output,
self.options,
packethook,
timeout,
localip = self.localip)
self.context.start()
# Download happens here
self.context.end() # <--
TftpClient.download calls TftpContextClientDownload.end:
class TftpContextClientDownload(TftpContext):
...
def end(self):
"""Finish up the context."""
TftpContext.end(self) # <--
self.metrics.end_time = time.time()
log.debug("Set metrics.end_time to %s", self.metrics.end_time)
self.metrics.compute()
TftpContextClientDownload.end calls TftpContext.end:
class TftpContext(object):
...
def end(self):
"""Perform session cleanup, since the end method should always be
called explicitely by the calling code, this works better than the
destructor."""
log.debug("in TftpContext.end")
self.sock.close()
if self.fileobj is not None and not self.fileobj.closed:
log.debug("self.fileobj is open - closing")
self.fileobj.close() # <--
and TftpContext.end closes the file.
I am using a python script to transfer the contents of three files to a different three files. The original files are data from three thermometers I have connected to an RPI running raspian. All the script is supposed to do is take the contents of the files and move them so that I can have another program (ComScript) read and parse them.
My problem is that if one or more of the thermometers is disconnected before the script starts, it freezes. It doesn't freeze if I disconnect a thermometer while the script is running.
Here is the code
import time
a = 1
while a == 1:
try:
tfile = open("/sys/bus/w1/devices/28-000004d2ca5e/w1_slave")
text = tfile.read()
tfile.close()
temperature = text
tfile2 = open("/sys/bus/w1/devices/28-000004d2fb20/w1_slave")
text2 = tfile2.read()
tfile2.close()
temperature2 = text2
tfile3 = open("/sys/bus/w1/devices/28-000004d30568/w1_slave")
text3 = tfile3.read()
tfile3.close()
temperature3 = text3
textfile = open("/home/pi/ComScriptPi/profiles/Temperature_parse/w1_slave1", "w ")
textfile2 = open("/home/pi/ComScriptPi/profiles/Temperature_parse/w1_slave2", "w ")
textfile3 = open("/home/pi/ComScriptPi/profiles/Temperature_parse/w1_slave3", "w ")
temperature = str(temperature)
temperature2 = str(temperature2)
temperature3 = str(temperature3)
textfile.write(temperature)
textfile2.write(temperature2)
textfile3.write(temperature3)
textfile.close()
textfile2.close()
textfile3.close()
print temperature
print temperature2
print temperature3
time.sleep(3)
except:
pass
I added the exception pass because I need it to keep running even if it gets bad values. WHen one of the thermometers is disconnected the file python is trying to read is blank, but still there.
Remove the blanket except.
Your script is not freezing, but any error you get is being ignored in an endless loop. Because you use a blanket except: you catch all exceptions, including the keyboard interrupt exception KeyboardInterrupt.
At the very least log the exception, and catch only Exception:
except Exception:
import logging
logging.exception('Oops: error occurred')
KeyboardInterrupt is a subclass of BaseException, not Exception and won't be caught by this except handler.
Take a look at the shutil module for copying files, you doing way too much work:
import time
import shutil
import os.path
paths = ('28-000004d2ca5e', '28-000004d2fb20', '28-000004d30568')
while True:
for i, name in enumerate(paths, 1):
src = os.path.join('/sys/bus/w1/devices', name, 'w1_slave')
dst = '/home/pi/ComScriptPi/profiles/Temperature_parse/w1_slave{}'.format(i)
try:
shutil.copyfile(src, dst)
except EnvironmentError:
import logging
logging.exception('Oops: error occurred')
time.sleep(3)
Handling files should only ever raise EnvironmentError or it's subclasses, there is no need to catch everything here.
The open of the unplugged device is most likely blocking because the device driver won't open if the device is not present.
You'll need to use os.open which is the equivalent of the Unix system call "open" and specify the flag O_NONBLOCK and check the return code. You can then use os.fdopen to turn the return value of os.open into a normal Python file object.
I am trying to write a python program that will eventually take a command line argument of a file, determine if its a tar or zip etc file and then exctract it accordingly. I am just trying to get the tar part working now and I am getting multiple errors. The file I am checking for resides in my ~/ directory. Any ideas would be great.
#!/usr/bin/python
import tarfile
import os
def open_tar(file):
if tarfile.is_tarfile(file):
try:
tar = tarfile.open("file")
tar.extractall()
tar.close()
except ReadError:
print "File is somehow invalid or can not be handled by tarfile"
except CompressionError:
print "Compression method is not supported or data cannot be decoded"
except StreamError:
print "Is raised for the limitations that are typical for stream-like TarFile objects."
except ExtractError:
print "Is raised for non-fatal errors when using TarFile.extract(), but only if TarFile.errorlevel== 2."
if __name__ == '__main__':
file = "xampp-linux-1.7.3a.tar.gz"
print os.getcwd()
print file
open_tar(file)
Here are the errors. IF I comment out the Read Error, I just get teh same error on the next exception as well.
tux#crosnet:~$ python openall.py
/home/tux
xampp-linux-1.7.3a.tar.gz
Traceback (most recent call last):
File "openall.py", line 25, in <module>
open_tar(file)
File "openall.py", line 12, in open_tar
except ReadError:
NameError: global name 'ReadError' is not defined
tux#crosnet:~$
You can clearly see in your error it states
NameError: global name 'ReadError' is not defined
ReadError is not a global python name. If you look at the tarfile documentation you will see ReadError is part of that modules exceptions. So in this case, you would want to do:
except tarfile.ReadError:
# rest of your code
And you will need to do the same for the rest of those errors. Also, if all those errors will generate the same result (an error message of some sort, or a pass) you can simply do:
except (tarfile.ReadError, tarfile.StreamError) # and so on
Instead of doing them each on a seperate line. That's only if they will give the same exception
You would need to use except tarfile.ReadError or alternatively use from tarfile import is_tarfile, open, ReadError, CompressionError, etc. and put that inside the open_tar function instead of globally.
I think you might need tarfile.ReadError rather than just ReadError?
Okay. All your exceptions (ReadError, CompressionError etc.) are inside the tarfile module and so you'll have to say except tarfile.ReadError instead of just except ReadError.