druid 0.6.0

Data-oriented Rust UI design toolkit.
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
98
99
100
101
102
103
104
105

// Copyright 2019 The xi-editor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//! An example of a blocking function running in another thread.

use std::{thread, time};

use druid::{
    AppDelegate, AppLauncher, Command, Data, DelegateCtx, Env, ExtEventSink, Lens, LocalizedString,
    Selector, Target, Widget, WidgetExt, WindowDesc,
};

use druid::widget::{Button, Either, Flex, Label, Spinner};

const START_SLOW_FUNCTION: Selector<u32> = Selector::new("start_slow_function");

const FINISH_SLOW_FUNCTION: Selector<u32> = Selector::new("finish_slow_function");

struct Delegate {
    eventsink: ExtEventSink,
}

#[derive(Clone, Default, Data, Lens)]
struct AppState {
    processing: bool,
    value: u32,
}

// Pretend this is downloading a file, or doing heavy calculations...
fn slow_function(number: u32) -> u32 {
    let a_while = time::Duration::from_millis(2000);
    thread::sleep(a_while);
    number + 1
}

fn wrapped_slow_function(sink: ExtEventSink, number: u32) {
    thread::spawn(move || {
        let number = slow_function(number);
        sink.submit_command(FINISH_SLOW_FUNCTION, number, None)
            .expect("command failed to submit");
    });
}

impl AppDelegate<AppState> for Delegate {
    fn command(
        &mut self,
        _ctx: &mut DelegateCtx,
        _target: Target,
        cmd: &Command,
        data: &mut AppState,
        _env: &Env,
    ) -> bool {
        if cmd.is(START_SLOW_FUNCTION) {
            data.processing = true;
            wrapped_slow_function(self.eventsink.clone(), data.value);
        }
        if let Some(number) = cmd.get(FINISH_SLOW_FUNCTION) {
            data.processing = false;
            data.value = *number;
        }
        true
    }
}

fn ui_builder() -> impl Widget<AppState> {
    let button = Button::new("Start slow increment")
        .on_click(|ctx, _data: &mut AppState, _env| {
            let cmd = Command::new(START_SLOW_FUNCTION, 0);
            ctx.submit_command(cmd, None);
        })
        .padding(5.0);
    let button_placeholder = Flex::column()
        .with_child(Label::new(LocalizedString::new("Processing...")).padding(5.0))
        .with_child(Spinner::new());

    let text = LocalizedString::new("hello-counter")
        .with_arg("count", |data: &AppState, _env| (data.value).into());
    let label = Label::new(text).padding(5.0).center();

    let either = Either::new(|data, _env| data.processing, button_placeholder, button);

    Flex::column().with_child(label).with_child(either)
}
fn main() {
    let main_window = WindowDesc::new(ui_builder).title(LocalizedString::new("Blocking functions"));
    let app = AppLauncher::with_window(main_window);
    let delegate = Delegate {
        eventsink: app.get_external_handle(),
    };
    app.delegate(delegate)
        .use_simple_logger()
        .launch(AppState::default())
        .expect("launch failed");
}