oxivgl 0.1.0

Safe no_std Rust bindings for LVGL — embedded GUI on ESP32 and host SDL2
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
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215

#![cfg_attr(target_arch = "xtensa", no_std, no_main)]
#![cfg_attr(
    target_arch = "xtensa",
    feature(impl_trait_in_assoc_type, type_alias_impl_trait)
)]
// SPDX-License-Identifier: MIT OR Apache-2.0
//! Observer 6 — Light / dark theme switching via `bind_style`
//!
//! A panel containing 10 buttons is displayed at 90 % × 90 % of the screen,
//! centered.  Clicking any button toggles the theme subject between 0 (light)
//! and 1 (dark).
//!
//! **Approach**: base (light) styles are applied unconditionally with
//! `add_style`; dark-overlay styles are conditionally applied with
//! `bind_style` whenever the theme subject equals 1.  No runtime style
//! mutation is required — LVGL's observer mechanism handles the switch.

use core::ffi::c_void;
use core::ptr::null_mut;

use oxivgl::{
    enums::EventCode,
    event::Event,
    layout::{FlexAlign, FlexFlow},
    style::{GradDir, Selector, StyleBuilder, color_make, lv_pct},
    view::{NavAction, View},
    widgets::{
        Obj, Align, AsLvHandle, Button, Child, Label, Part, Subject, WidgetError,
        RADIUS_MAX,
    },
};

#[derive(Default)]
struct Observer6 {
    // Panel stored as a top-level widget — owns children in LVGL.
    _panel: Option<Obj<'static>>,
    // Raw handles for event matching (10 buttons).
    btn_handles: [*mut c_void; 10],

    // Styles kept alive via Rc refcount inside Style.
    _panel_base: Option<oxivgl::style::Style>,
    _panel_dark: Option<oxivgl::style::Style>,
    _scrollbar_base: Option<oxivgl::style::Style>,
    _scrollbar_dark: Option<oxivgl::style::Style>,
    _btn_base: Option<oxivgl::style::Style>,
    _btn_dark: Option<oxivgl::style::Style>,
    _btn_pressed_light: Option<oxivgl::style::Style>,
    _btn_pressed_dark: Option<oxivgl::style::Style>,

    // Subject dropped last so observer linkage outlives all widgets.
    theme_subject: Option<Subject>,
}

impl View for Observer6 {
    fn create(&mut self, container: &Obj<'static>) -> Result<(), WidgetError> {

        // ── Theme subject (initial: 1 = dark) ──────────────────────────────
        let theme_subject = Subject::new_int(1);

        // ── Panel base style (light) ───────────────────────────────────────
        let mut b = StyleBuilder::new();
        b.radius(12)
            .bg_opa(255)
            .bg_color_hex(0xffffff)
            .shadow_width(24)
            .shadow_offset_x(4)
            .shadow_offset_y(6)
            .shadow_color(color_make(0x88, 0x88, 0x88))
            .text_color_hex(0x222222)
            .pad_all(12)
            .pad_gap(16);
        let panel_base = b.build();

        // ── Panel dark overlay ─────────────────────────────────────────────
        let mut b = StyleBuilder::new();
        b.bg_color_hex(0x040038)
            .shadow_color(color_make(0xaa, 0xaa, 0xaa))
            .text_color_hex(0xeeeeee);
        let panel_dark = b.build();

        // ── Scrollbar base style (light) ───────────────────────────────────
        let mut b = StyleBuilder::new();
        b.width(4)
            .radius(2)
            .pad_right(8)
            .pad_ver(8)
            .bg_opa(127) // ~50% of 255
            .bg_color_hex(0x888888);
        let scrollbar_base = b.build();

        // ── Scrollbar dark overlay ─────────────────────────────────────────
        let mut b = StyleBuilder::new();
        b.bg_color_hex(0xaaaaaa);
        let scrollbar_dark = b.build();

        // ── Button base style (light) ──────────────────────────────────────
        let mut b = StyleBuilder::new();
        b.radius(RADIUS_MAX as i16)
            .bg_opa(255)
            .bg_grad_dir(GradDir::Hor)
            .bg_color_hex(0x3379de)
            .bg_grad_color_hex(0xd249a5)
            .shadow_width(24)
            .shadow_offset_y(6)
            .shadow_color(color_make(0x33, 0x79, 0xde))
            .text_color_hex(0xffffff)
            .pad_left(32)
            .pad_right(32)
            .pad_top(12)
            .pad_ver(12);
        let btn_base = b.build();

        // ── Button dark overlay ────────────────────────────────────────────
        let mut b = StyleBuilder::new();
        b.bg_color_hex(0xde1382)
            .bg_grad_color_hex(0x4b0c72)
            .shadow_color(color_make(0x4b, 0x0c, 0x72));
        let btn_dark = b.build();

        // ── Button pressed style (light) — shade filter opa 70% ────────────
        let mut b = StyleBuilder::new();
        b.color_filter_shade(178); // LV_OPA_70 ≈ 178
        let btn_pressed_light = b.build();

        // ── Button pressed style (dark) — shade filter opa 30% ─────────────
        let mut b = StyleBuilder::new();
        b.color_filter_shade(76); // LV_OPA_30 ≈ 76
        let btn_pressed_dark = b.build();

        // ── Panel ──────────────────────────────────────────────────────────
        let panel = Obj::new(container)?;
        panel
            .remove_style_all()
            .size(lv_pct(90), lv_pct(90))
            .align(Align::Center, 0, 0)
            .set_flex_flow(FlexFlow::Column)
            .set_flex_align(FlexAlign::Start, FlexAlign::Center, FlexAlign::Center);

        // Apply base (light) styles unconditionally.
        panel.add_style(&panel_base, Selector::DEFAULT);
        panel.add_style(&scrollbar_base, Part::Scrollbar);

        // Bind dark overlays when theme == 1.
        panel.bind_style(&panel_dark, Selector::DEFAULT, &theme_subject, 1);
        panel.bind_style(&scrollbar_dark, Part::Scrollbar, &theme_subject, 1);

        // ── Buttons ────────────────────────────────────────────────────────
        let mut btn_handles: [*mut c_void; 10] = [null_mut(); 10];

        for i in 0..10_usize {
            let btn = Child::new(Button::new(&panel)?);
            btn.remove_style_all();
            btn.add_style(&btn_base, Selector::DEFAULT);
            btn.add_style(&btn_pressed_light, oxivgl::enums::ObjState::PRESSED);
            btn.bind_style(&btn_dark, Selector::DEFAULT, &theme_subject, 1);
            btn.bind_style(
                &btn_pressed_dark,
                oxivgl::enums::ObjState::PRESSED,
                &theme_subject,
                1,
            );

            // Label inside the button.
            let mut lbl_text = heapless::String::<16>::new();
            core::fmt::write(&mut lbl_text, format_args!("Button {}", i + 1))?;
            let lbl = Child::new(Label::new(&*btn)?);
            lbl.text(lbl_text.as_str()).center();

            btn_handles[i] = btn.lv_handle() as *mut c_void;
        }

        // Force initial theme application (subject starts at 1 = dark).
        theme_subject.notify();

                self._panel = Some(panel);
        self.btn_handles = btn_handles;
        self._panel_base = Some(panel_base);
        self._panel_dark = Some(panel_dark);
        self._scrollbar_base = Some(scrollbar_base);
        self._scrollbar_dark = Some(scrollbar_dark);
        self._btn_base = Some(btn_base);
        self._btn_dark = Some(btn_dark);
        self._btn_pressed_light = Some(btn_pressed_light);
        self._btn_pressed_dark = Some(btn_pressed_dark);
        self.theme_subject = Some(theme_subject);
        Ok(())
    }

    fn on_event(&mut self, event: &Event) -> NavAction {
        if event.code() != EventCode::CLICKED {
            return NavAction::None;
        }
        let target = event.target_handle() as *mut c_void;
        for &handle in self.btn_handles.iter() {
            if !handle.is_null() && target == handle {
                // Toggle between light (0) and dark (1).
                if let Some(ref theme_subject) = self.theme_subject {
                    if theme_subject.get_int() == 0 {
                        theme_subject.set_int(1);
                    } else {
                        theme_subject.set_int(0);
                    }
                }
                return NavAction::None;
            }
        }
        NavAction::None
    }

    fn update(&mut self) -> Result<NavAction, WidgetError> {
        Ok(NavAction::None)
    }
}

oxivgl_examples_common::example_main!(Observer6::default());