Resolve "(ui): sight_calibrator crashes when opening captured images"

Description

This restores the display and saving of calibration images in Sight Calibrator.

How to test it?

First problem

• Launch sight_calibrator and the calibration activity
• Pick a recorded video of calibration like https://cloud.ircad.fr/f/4939039
• Change the checkerboard properties accordingly (8x6 with the above sample video)
• Capture an image with the '+' on the left panel
• Double-click on the image in the tree view
• Observe a modal window is displayed, showing the image

Second problem

• Launch sight_calibrator and the calibration activity
• Pick a recorded video of calibration like https://cloud.ircad.fr/f/4939039
• Change the checkerboard properties accordingly (8x6 with the above sample video)
• Capture several images with the '+' on the left panel
• Click on the button to save the images
• Select a folder
• Open the folder in a file explorer
• Observe the images are well saved in the folder

Data

https://cloud.ircad.fr/f/4939039

Related issue(s)

Closes #1240 (closed)