Virtualization

[Marc-Andre-Rivet]

This is a placeholder issue for virtualization work. It may evolve into an epic or just become an enhancement.

Assumptions

• column width is predictable, the same for all columns for any subset of the table
• row height is predictable, the same across the whole table
• later implementations may be able to accept more flexibility for column/row width/height

[chriddyp]

Early proof of concept:

[Marc-Andre-Rivet]

Update on virtualization progress, there's still a lot to do but the basic use cases are working with and without fixed rows/columns. Existing tests are passing.

Advance testing possible through https://github.com/plotly/dash-table/tree/3.1-issue234-virtualization

Run npm run build.watch and connect to either of:

http://localhost:8080/index.html?mode=virtualized
http://localhost:8080/index.html?mode=fixed,virtualized

for no fixed and fixed rows scenarios

There's still a lot to do for this to be final, here's a summary of what remains

• stability testing / fixes (under certain conditions the table can hang)
• visual testing
• improving styling integration
• sanity testing for various functionalities
• cross browser support
• virtualization-specific tests

Focusing on testing against existing functionalities and stability for now.

[cldougl]

1st pass qa

• vertical scroll too fast: freezes
• scroll too slow: gets sticky (rescrolls over same cells)

[Marc-Andre-Rivet]

Update on virtualization progress,

Completed

• Fixed table hanging
• Modified existing tests to execute in both virtualized and not virtualized scenarios
• Added scrolling and selection tests specific to the virtualized table
• Cross browser seems fine (if testing IE11, Edge) you will need to modify https://github.com/plotly/dash-table/blob/3.1-issue234-virtualization/demo/AppMode.ts manually as the Environment params are not functional in IE (only made sure the code executed, haven't polyfilled the search params)

Still to do

• manual testing to see if all is good, what else to automate
• improve the internal styling & the user facing styling requirements
• slow scrolling stickiness / depending on how hard it is to pin down, could make this a bug for later

See #234 (comment) above for testing / running this locally.

Will create a WIP PR most probably tomorrow to start discussing the finer points.