UI improvment

[jo-mueller]

🚀 Pitch: Add more info to the treeview elements

Motivation

We are having a number of issues (#73, #76, #67) which I think have the same common root cause, as pointed out by @psobolewskiPhD: The QTreeView is not the single source of truth when loading images into the viewer. The other problem is that clicking on some elements of the TreeView (i.e., the ">" icons), triggers unintended multiple loading operations and ultimately even segfaults (not sure where exactly those even come from, tbh).

Improving the UI

While I love the current UI and especially the ThumbGrid, I feel like the UI lacks a few information that are relevant to me when I browse data:

• Image ID
• Image dimensions - when I browse a large dataset and visualize a sample, I may want to not pick the largest one, if it can be avoided
• Channel names

That being said, I'd also want to have a look at the thumbnail, obviously before loading the data, as that's probably the whole point of a thumbnail in the first place. Thus, I suggest to integrate the thumbnail and additional information directly into the QTreeView, which could, in practice, look something like this (just meddled a bit with pyqt):

The additional space now taken up by the QThumbGrid would then be freed to either make more space for the QTreeView or a possible Preview area, which could show the Thumbnail in a larger space, along with a Load button, which would get rid of the implict image loading upon selecting an entry in the TreeView, and, I suppose, the segfaults. It would also considerably remove complexity because the widget wouldn't have to check what data was already in the viewer.

Implementation

Implementation-wise, it should be possible to populate the TreeView with QStandardItems as it is already done right now. By adding these without text, the tree structure in its current form would be maintained. Instead of setting text data in QStandardItem, a CustomWidget could be created and set at the item's index using setIndexWidget(index, widget).

Another option would be to use QStyledItemDelegates for QTreeViewItems, but with that I'm not so familiar myself.

LMKWYT about it. Looking forward to feedback!

[psobolewskiPhD]

I like this idea.
If thumbnails are in the tree view, then the bottom half of the widget could provide some metadata info.

That said, when I browse using the tree to folder with a lot of images, it certainly takes a bit of time to load the thumbnails in the bottom panel, while the text names are instant.
Also I worry a bit about space: in the vertical space of 8 thumbnails, I can see 24 file names in the current tree view.

But 100% getting more metadata before loading the image would be super nice.
If there is an explicit load button, it would be easier to implement extra metadata for selected image (whether using the current style browsing or new style)

[jo-mueller]

Thanks for the feedback!

That said, when I browse using the tree to folder with a lot of images, it certainly takes a bit of time to load the thumbnails in the bottom panel, while the text names are instant.

That's true. Loading of the thumbnails should happen in a threaded manner so that it doesn't block the widget while the thumbnails are fetched. Maybe it can also be implemented so that thumbnails are also only gathered if the scroll area arrives at the respective entry 🤔

Also I worry a bit about space: in the vertical space of 8 thumbnails, I can see 24 file names in the current tree view.

Good point...I would alter the thumbnail size above and make it smaller, but the point remains that you'll have considerable fewer items on screen than before.