1use serde::Deserialize;
 2use ui::{Pixels, px};
 3
 4#[derive(Debug)]
 5pub enum ScrollDirection {
 6    Upwards,
 7    Downwards,
 8    Rightwards,
 9    Leftwards,
10}
11
12impl ScrollDirection {
13    pub fn is_upwards(&self) -> bool {
14        matches!(self, ScrollDirection::Upwards)
15    }
16}
17
18#[derive(Debug, Clone, PartialEq, Deserialize)]
19pub enum ScrollAmount {
20    // Scroll N lines (positive is towards the end of the document)
21    Line(f32),
22    // Scroll N pages (positive is towards the end of the document)
23    Page(f32),
24    // Scroll N columns (positive is towards the right of the document)
25    Column(f32),
26}
27
28impl ScrollAmount {
29    pub fn lines(&self, mut visible_line_count: f32) -> f32 {
30        match self {
31            Self::Line(count) => *count,
32            Self::Page(count) => {
33                // for full pages subtract one to leave an anchor line
34                if self.is_full_page() {
35                    visible_line_count -= 1.0
36                }
37                (visible_line_count * count).trunc()
38            }
39            Self::Column(_count) => 0.0,
40        }
41    }
42
43    pub fn columns(&self) -> f32 {
44        match self {
45            Self::Line(_count) => 0.0,
46            Self::Page(_count) => 0.0,
47            Self::Column(count) => *count,
48        }
49    }
50
51    pub fn pixels(&self, line_height: Pixels, height: Pixels) -> Pixels {
52        match self {
53            ScrollAmount::Line(x) => px(line_height.0 * x),
54            ScrollAmount::Page(x) => px(height.0 * x),
55            // This function seems to only be leveraged by the popover that is
56            // displayed by the editor when, for example, viewing a function's
57            // documentation. Right now that only supports vertical scrolling,
58            // so I'm leaving this at 0.0 for now to try and make it clear that
59            // this should not have an impact on that?
60            ScrollAmount::Column(_) => px(0.0),
61        }
62    }
63
64    pub fn is_full_page(&self) -> bool {
65        match self {
66            ScrollAmount::Page(count) if count.abs() == 1.0 => true,
67            _ => false,
68        }
69    }
70
71    pub fn direction(&self) -> ScrollDirection {
72        match self {
73            Self::Line(amount) if amount.is_sign_positive() => ScrollDirection::Downwards,
74            Self::Page(amount) if amount.is_sign_positive() => ScrollDirection::Downwards,
75            Self::Column(amount) if amount.is_sign_positive() => ScrollDirection::Rightwards,
76            Self::Column(amount) if amount.is_sign_negative() => ScrollDirection::Leftwards,
77            _ => ScrollDirection::Upwards,
78        }
79    }
80}