viewport(v2): Unexpected scrolling behavior with `SoftWrap`

[kamiheku]

Describe the bug

Scrolling a Viewport up or down with SoftWrap enabled feels broken.

As an example, when a single line has been wrapped to span six logical / visual lines, the user must press j/↓ five times in order to achieve any scrolling of the viewport.

Setup

macOS, WezTerm, v2 dependencies:

github.com/charmbracelet/bubbles/v2 v2.0.0-beta.1
github.com/charmbracelet/bubbletea/v2 v2.0.0-beta1

To Reproduce

Steps to reproduce the behavior:

1. Create a Viewport with content that has lines exceeding the width of the viewport
2. Turn SoftWrap on
3. Scroll vertically past soft linebreaks -- multiple key presses are required for a view update

Source Code

See this gist for a quick repro.

Pressing w toggles SoftWrap on and off.

Expected behavior

I would expect the viewport scrolling to happen by logical lines. That is, pressing j once should immediately scroll the topmost (wrapped) line of content out of view.

Screenshots

viewport.mp4