How to run external QT program from PyQT5 on MacOS

[Benjamin Halko]

When trying to run a QT program from PyQT5 the external program crashes and says that qt.qpa.plugin: Could not load the Qt platform plugin "{a platform}" in "" even though it was found. This is probably because it is trying to load 2 sets of libraries, one from my app and one from the external programs.

On Windows this can be fix by setting QT_QPA_PLATFORM_PLUGIN_PATH to the plugin path in the folder, but on MacOS I can't seem to get it working on MacOS, is there an easier way of running a program in PyQT5 than this?

By the way, the program I am trying to run is the Dolphin Emulator.

Windows Code:

env = os.environ
env["QT_QPA_PLATFORM_PLUGIN_PATH"] = os.path.dirname(programPath)+'/QtPlugins/platforms/'
subprocess.Popen(programPath,env=env)

MacOS Code:

env = os.environ
env["QT_QPA_PLATFORM_PLUGIN_PATH"] = programPath+'/Contents/MacOS/platforms/'
subprocess.Popen(programPath+'/Contents/MacOS/Dolphin',env=env)

[SGaist]

Hi and welcome to devnet,

Why not start the application through the app bundle rather than going inside it to the executable ?

[Benjamin Halko]

When I try doing that it tells me permission denied.

Here's where I got that fix from: https://stackoverflow.com/questions/23353472/permission-denied-opening-application-in-python-shell

[SGaist]

Ok, in that case I would use the open shell command and pass it the path to the bundle.

[Benjamin Halko]

Ok thanks, I will try that out!

[Benjamin Halko]

@SGaist I tried it out, and it gave me LSOpenURLsWithRole() failed with error -10810 for the file /Users/benjamin/Desktop/Dolphin.app.

[SGaist]

@Benjamin-Halko said in How to run external QT program from PyQT5 on MacOS:

LSOpenURLsWithRole() failed with error -10810

Are you hitting the situation described here ?

[Benjamin Halko]

@SGaist Yes that is actually the problem I am running into. Dolphin does not like being a child process of my program. Does QT have a simple solution to this problem?

[SGaist]

Does it only happen with Dolphin ?
By the way, why Dolphin on macOS rather than Finder ?

[Benjamin Halko]

Well Dolphin is the only .app I am trying to open with my program, so I wouldn't know if this happens with other programs.

What do you mean by macOS rather than Finder?

[jsulm]

@Benjamin-Halko said in How to run external QT program from PyQT5 on MacOS:

What do you mean by macOS rather than Finder?

The file manager on MacOS is called Finder. There is no Dolphin unless you install it.

[Benjamin Halko]

@jsulm Yeah finder is installed. By Finder rather than MacOS do you mean telling finder to open Dolphin Emulator rather than just tell MacOS to open it?

Oh and Dolphin works just fine when running it from Finder normally, it is just when I launch it using subprocess.Popen that is the trouble.

[SGaist]

From the looks of it, we are talking about very different software.

"Dolphin" is known to be the KDE file manager. So from the looks of it you are trying to start something very different. Can you give more details about what it is ? And what exactly you are trying to do with your application ?

[Benjamin Halko]

@SGaist I am wanting to open the Dolphin Emulator from my app as well as tell it to load a game using the -e argument that it accepts. However since Dolphin is also a QT program when trying to run it using subprocess, it tries loading both sets of libraries (from my app and Dolphin)

[SGaist]

What if you use the QProcess::startDetached method ?

[Benjamin Halko]

@SGaist Ok so I tried and nothing happened! But then I tried using the executable located in /Contents/MacOS/Dolphin
and it gave me this:

objc[2357]: Class QMacAutoReleasePoolTracker is implemented in both /Users/benjamin/Desktop/Dolphin.app/Contents/Frameworks/QtCore.framework/Versions/5/QtCore (0x10b53a9f8) and /private/var/folders/50/g29zbzlx4fb85zh8kk4g6gm40000gn/T/_MEIYRjNbS/QtCore (0x10efe8198). One of the two will be used. Which one is undefined.
objc[2357]: Class QT_ROOT_LEVEL_POOL__THESE_OBJECTS_WILL_BE_RELEASED_WHEN_QAPP_GOES_OUT_OF_SCOPE is implemented in both /Users/benjamin/Desktop/Dolphin.app/Contents/Frameworks/QtCore.framework/Versions/5/QtCore (0x10b53aa70) and /private/var/folders/50/g29zbzlx4fb85zh8kk4g6gm40000gn/T/_MEIYRjNbS/QtCore (0x10efe8210). One of the two will be used. Which one is undefined.
objc[2357]: Class KeyValueObserver is implemented in both /Users/benjamin/Desktop/Dolphin.app/Contents/Frameworks/QtCore.framework/Versions/5/QtCore (0x10b53aa98) and /private/var/folders/50/g29zbzlx4fb85zh8kk4g6gm40000gn/T/_MEIYRjNbS/QtCore (0x10efe8238). One of the two will be used. Which one is undefined.
objc[2357]: Class RunLoopModeTracker is implemented in both /Users/benjamin/Desktop/Dolphin.app/Contents/Frameworks/QtCore.framework/Versions/5/QtCore (0x10b53aae8) and /private/var/folders/50/g29zbzlx4fb85zh8kk4g6gm40000gn/T/_MEIYRjNbS/QtCore (0x10efe8288). One of the two will be used. Which one is undefined.
QObject::moveToThread: Current thread (0x7faab1e065c0) is not the object's thread (0x7faab1c17ed0).
Cannot move to target thread (0x7faab1e065c0)

You might be loading two sets of Qt binaries into the same process. Check that all plugins are compiled against the right Qt binaries. Export DYLD_PRINT_LIBRARIES=1 and check that only one set of binaries are being loaded.
qt.qpa.plugin: Could not load the Qt platform plugin "cocoa" in "" even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

Available platform plugins are: cocoa, minimal, offscreen, webgl.

This was the code I used:

launch = QProcess()
launch.startDetached(dolphinPath+"/Contents/MacOS/Dolphin")

[Benjamin Halko]

@SGaist Oh by the way, this issue only occurs when the program is packaged with pyinstaller, running it regularly works just fine.

[SGaist]

What exactly are you packaging ?

[Benjamin Halko]

Here is my project folder. Here is the actual run dolphin function. Hope that helps.

[SGaist]

Did you try to use Popen with shell=True ?