Two Touch Line Graph Feature

Is it possible to add the ability for a user to touch a line graph in 2 spots and have 2 points on the graph that map to the touch points? Kind of like how its done with stock market apps?

Start by locating the line-graph touch-interaction entry point in the Flutter chart library. Clarify how two touch positions should map to two graph points, including the expected stock-market-style presentation, then verify the behavior with an appropriate example or test.

Written by the indexing model from the issue text.