ae1a83f095
The motivation behind this PR is to make it so a `HistoryCell` is more like a `WidgetRef` that knows how to render itself into a `Rect` so that it can be backed by something other than a `Vec<Line>`. Because a `HistoryCell` is intended to appear in a scrollable list, we want to ensure the stack of cells can be scrolled one `Line` at a time even if the `HistoryCell` is not backed by a `Vec<Line>` itself. To this end, we introduce the `CellWidget` trait whose key method is: ``` fn render_window(&self, first_visible_line: usize, area: Rect, buf: &mut Buffer); ``` The `first_visible_line` param is what differs from `WidgetRef::render_ref()`, as a `CellWidget` needs to know the offset into its "full view" at which it should start rendering. The bookkeeping in `ConversationHistoryWidget` has been updated accordingly to ensure each `CellWidget` in the history is rendered appropriately.
21 lines
1.0 KiB
Rust
21 lines
1.0 KiB
Rust
use ratatui::prelude::*;
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/// Trait implemented by every type that can live inside the conversation
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/// history list. It provides two primitives that the parent scroll-view
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/// needs: how *tall* the widget is at a given width and how to render an
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/// arbitrary contiguous *window* of that widget.
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///
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/// The `first_visible_line` argument to [`render_window`] allows partial
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/// rendering when the top of the widget is scrolled off-screen. The caller
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/// guarantees that `first_visible_line + area.height as usize` never exceeds
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/// the total height previously returned by [`height`].
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pub(crate) trait CellWidget {
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/// Total height measured in wrapped terminal lines when drawn with the
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/// given *content* width (no scrollbar column included).
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fn height(&self, width: u16) -> usize;
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/// Render a *window* that starts `first_visible_line` lines below the top
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/// of the widget. The window’s size is given by `area`.
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fn render_window(&self, first_visible_line: usize, area: Rect, buf: &mut Buffer);
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}
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