coffee 0.4.1

An opinionated 2D game engine focused on simplicity, explicitness, and type-safety
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97

use std::hash::Hasher;
use stretch::result;

use crate::graphics::{Frame, Point};
use crate::ui::core::{self, Element, Event, Layout, MouseCursor};

pub struct Interface<'a, Message, Renderer> {
    hash: u64,
    root: Element<'a, Message, Renderer>,
    layout: result::Layout,
}

pub struct Cache {
    hash: u64,
    layout: result::Layout,
}

impl<'a, Message, Renderer> Interface<'a, Message, Renderer>
where
    Renderer: core::Renderer,
{
    pub fn compute(
        root: Element<'a, Message, Renderer>,
        renderer: &Renderer,
    ) -> Interface<'a, Message, Renderer> {
        let hasher = &mut twox_hash::XxHash::default();
        root.hash(hasher);

        let hash = hasher.finish();
        let layout = root.compute_layout(renderer);

        Interface { hash, root, layout }
    }

    pub fn compute_with_cache(
        root: Element<'a, Message, Renderer>,
        renderer: &Renderer,
        cache: Cache,
    ) -> Interface<'a, Message, Renderer> {
        let hasher = &mut twox_hash::XxHash::default();
        root.hash(hasher);

        let hash = hasher.finish();

        let layout = if hash == cache.hash {
            cache.layout
        } else {
            root.compute_layout(renderer)
        };

        Interface { hash, root, layout }
    }

    pub fn on_event(
        &mut self,
        event: Event,
        cursor_position: Point,
        messages: &mut Vec<Message>,
    ) {
        let Interface { root, layout, .. } = self;

        root.widget.on_event(
            event,
            Self::layout(layout),
            cursor_position,
            messages,
        );
    }

    pub fn draw(
        &self,
        renderer: &mut Renderer,
        frame: &mut Frame<'_>,
        cursor_position: Point,
    ) -> MouseCursor {
        let Interface { root, layout, .. } = self;

        let cursor =
            root.widget
                .draw(renderer, Self::layout(layout), cursor_position);

        renderer.flush(frame);

        cursor
    }

    pub fn cache(self) -> Cache {
        Cache {
            hash: self.hash,
            layout: self.layout,
        }
    }

    fn layout(layout: &result::Layout) -> Layout<'_> {
        Layout::new(layout, Point::new(0.0, 0.0))
    }
}