Delay in Canvas loading for Wasm LocalView

[abhinavsns]

When launching a trame app with vtklocal view, I see a significant delay before the main render window appears. In the meantime the UI already loads but the local view takes a while. The issue is worse when the server is not running locally.
Any tips to either have a progress bar for the render window or to keep waiting on the trame app loader until wasm has fully loaded?

[jourdain]

We could indeed do that as we know how much objects we need to download and what is remaining.

[jourdain]

Would you be interested to implement/contribute that piece with some guidance from us?

[abhinavsns]

Yes!

[jourdain]

Awesome! I'll give you some pointers once I found some time.

[jourdain]

Ok I just looked at the code and it is going to be a little bit more complicated that I was thinking as you will have the code spread across 2 repos. ;-)

So the first thing you need to track is the number of state/hash and how many you already have...

Here is the various relevant lines:

• pendingStates will give you the total number of states you need in order to be fully completed
• pendingHashes will give you the total number of blobs you need in order to be fully completed
• Inside the fetchState and fetchHash you can count how many you truly completed after the await.

Then, you will need to pass something to the wasmManager before that line so you can track the progress. It could be a callback function or something. Then on the vue side, you will create a reactive object with the current/max of state+blob.
And on the template side, you could create an overlay with some kind of progress using those 2 current/max to have 2 progress monitoring.

Let me know if you need more guidance or if you think you are good for now?

[abhinavsns]

@jourdain PRs live.