1use serde::Deserialize;
 2use ui::{Pixels, px};
 3
 4#[derive(Debug)]
 5pub enum ScrollDirection {
 6    Upwards,
 7    Downwards,
 8}
 9
10impl ScrollDirection {
11    pub fn is_upwards(&self) -> bool {
12        matches!(self, ScrollDirection::Upwards)
13    }
14}
15
16#[derive(Debug, Clone, PartialEq, Deserialize)]
17pub enum ScrollAmount {
18    // Scroll N lines (positive is towards the end of the document)
19    Line(f32),
20    // Scroll N pages (positive is towards the end of the document)
21    Page(f32),
22}
23
24impl ScrollAmount {
25    pub fn lines(&self, mut visible_line_count: f32) -> f32 {
26        match self {
27            Self::Line(count) => *count,
28            Self::Page(count) => {
29                // for full pages subtract one to leave an anchor line
30                if self.is_full_page() {
31                    visible_line_count -= 1.0
32                }
33                (visible_line_count * count).trunc()
34            }
35        }
36    }
37
38    pub fn pixels(&self, line_height: Pixels, height: Pixels) -> Pixels {
39        match self {
40            ScrollAmount::Line(x) => px(line_height.0 * x),
41            ScrollAmount::Page(x) => px(height.0 * x),
42        }
43    }
44
45    pub fn is_full_page(&self) -> bool {
46        match self {
47            ScrollAmount::Page(count) if count.abs() == 1.0 => true,
48            _ => false,
49        }
50    }
51
52    pub fn direction(&self) -> ScrollDirection {
53        match self {
54            Self::Line(amount) if amount.is_sign_positive() => ScrollDirection::Downwards,
55            Self::Page(amount) if amount.is_sign_positive() => ScrollDirection::Downwards,
56            _ => ScrollDirection::Upwards,
57        }
58    }
59}