1use crate::Editor;
 2use serde::Deserialize;
 3
 4#[derive(Clone, PartialEq, Deserialize)]
 5pub enum ScrollAmount {
 6    // Scroll N lines (positive is towards the end of the document)
 7    Line(f32),
 8    // Scroll N pages (positive is towards the end of the document)
 9    Page(f32),
10}
11
12impl ScrollAmount {
13    pub fn lines(&self, editor: &mut Editor) -> f32 {
14        match self {
15            Self::Line(count) => *count,
16            Self::Page(count) => editor
17                .visible_line_count()
18                // subtract one to leave an anchor line
19                // round towards zero (so page-up and page-down are symmetric)
20                .map(|l| (l * count).trunc() - count.signum())
21                .unwrap_or(0.),
22        }
23    }
24}