aboutsummaryrefslogtreecommitdiff
path: root/helix-term/src/compositor.rs
blob: 3cf6bf03f0ea3c905bfa164ffe29913ebc44a6fd (plain) (blame)
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
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
// Features:
// Tracks currently focused component which receives all input
// Event loop is external as opposed to cursive-rs
// Calls render on the component and translates screen coords to local component coords
//
// TODO:
// Q: where is the Application state stored? do we store it into an external static var?
// A: probably makes sense to initialize the editor into a `static Lazy<>` global var.
//
// Q: how do we composit nested structures? There should be sub-components/views
//
// Each component declares it's own size constraints and gets fitted based on it's parent.
// Q: how does this work with popups?
// cursive does compositor.screen_mut().add_layer_at(pos::absolute(x, y), <component>)

use crate::application::Renderer;
use crossterm::event::Event;
use smol::Executor;
use tui::buffer::Buffer as Surface;

pub type Callback = Box<dyn Fn(&mut Compositor)>;

// --> EventResult should have a callback that takes a context with methods like .popup(),
// .prompt() etc. That way we can abstract it from the renderer.
// Q: How does this interact with popups where we need to be able to specify the rendering of the
// popup?
// A: It could just take a textarea.
//
// If Compositor was specified in the callback that's then problematic because of

// Cursive-inspired
pub enum EventResult {
    Ignored,
    Consumed(Option<Callback>),
}

use helix_view::{Editor, View};
// shared with commands.rs
pub struct Context<'a, 'b> {
    pub editor: &'a mut Editor,
    pub executor: &'a smol::Executor<'b>,
}

pub trait Component {
    /// Process input events, return true if handled.
    fn handle_event(&mut self, event: Event, ctx: &mut Context) -> EventResult;
    // , args: ()

    /// Should redraw? Useful for saving redraw cycles if we know component didn't change.
    fn should_update(&self) -> bool {
        true
    }

    fn render(&mut self, renderer: &mut Renderer, ctx: &mut Context);
}

// struct Editor { };

// For v1:
// Child views are something each view needs to handle on it's own for now, positioning and sizing
// options, focus tracking. In practice this is simple: we only will need special solving for
// splits etc

// impl Editor {
//     fn render(&mut self, surface: &mut Surface, args: ()) {
//         // compute x, y, w, h rects for sub-views!
//         // get surface area
//         // get constraints for textarea, statusbar
//         // -> cassowary-rs

//         // first render textarea
//         // then render statusbar
//     }
// }

// usecases to consider:
// - a single view with subviews (textarea + statusbar)
// - a popup panel / dialog with it's own interactions
// - an autocomplete popup that doesn't change focus

//fn main() {
//    let root = Editor::new();
//    let compositor = Compositor::new();

//    compositor.push(root);

//    // pos: clip to bottom of screen
//    compositor.push_at(pos, Prompt::new(
//        ":",
//        (),
//        |input: &str| match input {}
//    )); // TODO: this Prompt needs to somehow call compositor.pop() on close, but it can't refer to parent
//    // Cursive solves this by allowing to return a special result on process_event
//    // that's either Ignore | Consumed(Opt<C>) where C: fn (Compositor) -> ()

//    // TODO: solve popup focus: we want to push autocomplete popups on top of the current layer
//    // but retain the focus where it was. The popup will also need to update as we type into the
//    // textarea. It should also capture certain input, such as tab presses etc
//    //
//    // 1) This could be faked by the top layer pushing down edits into the previous layer.
//    // 2) Alternatively,
//}

pub struct Compositor {
    layers: Vec<Box<dyn Component>>,
}

impl Compositor {
    pub fn new() -> Self {
        Self { layers: Vec::new() }
    }

    pub fn push(&mut self, layer: Box<dyn Component>) {
        self.layers.push(layer);
    }

    pub fn pop(&mut self) {
        self.layers.pop();
    }

    pub fn handle_event(&mut self, event: Event, cx: &mut Context) -> bool {
        // TODO: custom focus
        if let Some(layer) = self.layers.last_mut() {
            return match layer.handle_event(event, cx) {
                EventResult::Consumed(Some(callback)) => {
                    callback(self);
                    true
                }
                EventResult::Consumed(None) => true,
                EventResult::Ignored => false,
            };
        }
        false
    }

    pub fn render(&mut self, renderer: &mut Renderer, cx: &mut Context) {
        for layer in &mut self.layers {
            layer.render(renderer, cx)
        }
    }
}