Access device storage and returning values

[melbayoumy]

Hi,

I need your assistance to know:

• From a python script, how I can access the device storage (e.g. downloads folder) to read a file from it.
• If my python script will print something. How I can pass it to the UI (may be as a toast).

Thanks

[mhsmith]

From a python script, how I can access the device storage (e.g. downloads folder) to read a file from it.

[Answer moved to the FAQ]

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If my python script will print something. How I can pass it to the UI (may be as a toast).

There are several options:

• To display a toast, follow the example in the demo app.
• If your script is text-based, then it might be easiest to base it on the console app. Note that this currently targets Chaquopy 2.0.0, so you might need to edit build.gradle if you need features from newer versions.
• Or for a fully native Android UI, see the examples for writing the UI either in Java or in Python.

[SameerChaudhari30]

Hi @mhsmith, I am facing issue while reading a file using cv2.imread

directory = str(Environment.getExternalStorageDirectory())
directory += "/Pictures/image,jpg"
img = cv2.imread(directory)
gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)

Error : (-215:Assertion failed) !_src.empty() in function 'cvtColor'

[mhsmith]

Have you requested the READ_EXTERNAL_STORAGE permission, as described here?

If your app targets API level 29 or later, then "scoped storage" adds more complications. Once I've had a chance to learn about this, I'll edit my comment above with some recommendations.

Meanwhile, you can probably work around it by reducing your target API level to 28 or lower, or using the requestLegacyExternalStorage option as described here.

[mhsmith]

A solution which works with scoped storage is now given in the FAQ.