[Bug]: Double-tap zoom and image panning not working at the image viewer screen

[rohit9625]

Summary

At the image viewer screen, double-tap zoom does not trigger, and the user cannot pan the image after zooming.
The zoom behavior exists in the codebase, but it seems to be interrupted by other gesture listeners (e.g., swipe to change image).

Steps to reproduce

1. Go to the Custom Selector
2. View any image by long pressing
3. Double-tap on the image or
4. Pinch to zoom the image
5. Then, try panning the zoomed image to explore other areas

Expected behaviour

At step 3, the image should zoom in/out when double-tapped.
At step 5, the image should be pannable to explore different areas.

Actual behaviour

At step 3, double-tapping the image does nothing.
At step 5, the image cannot be dragged or panned. Moving the finger does not shift the image.

Device name

Google Pixe 9 Pro (Emulator)

Android version

Android 15

Commons app version

main

Device logs

No response

Screenshots

Actual Behavior:

Screen_recording_20251126_235705.webm

Expected Behavior:

Screen_recording_20251126_235933.webm

Would you like to work on the issue?

Yes

[nicolas-raoul]

I have always used two fingers to perform zoom and pan in the custom selector, it works well. But I agree double-tap-zoom and one-finger-panning would be nice if easily doable, especially double-tap. I am a bit afraid single-finger-panning might interfere with the already flimsy gestures though.

[nicolas-raoul]

Looking at the screencast, I fear that this change would make swiping difficult.

The merit of this activity is that you can very quickly select picture for upload or not upload by swiping up/down and left/right to skip.

[rohit9625]

Let me create a draft PR so that you can test if it doesn't break swiping. I found a solution yesterday and tested that as well. There was no different in swiping behavior before and after that fix.

I wanted to ask something, is there any other place we use zoomable activity for viewing pictures other than custom selector?

[nicolas-raoul]

no other place. 🙂