buoyant 0.5.2

SwiftUI-like UIs in Rust for embedded devices
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
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
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354

use crate::{
    environment::LayoutEnvironment,
    layout::{Layout, ResolvedLayout},
    primitives::{ProposedDimension, ProposedDimensions},
    render::Renderable,
};

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ContentMode {
    /// Scales the child view to fit within the available space while maintaining its aspect ratio.
    Fit,
    /// Scales the child view to fill the available space while maintaining its aspect ratio.
    Fill,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Ratio {
    /// A fixed aspect ratio defined by width and height
    Fixed(u32, u32),
    /// Maintains the ideal aspect ratio of the child view.
    ///
    /// For most views this will be a square.
    Ideal,
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct AspectRatio<T> {
    #[allow(clippy::struct_field_names)]
    aspect_ratio: Ratio,
    content_mode: ContentMode,
    child: T,
}

impl<T> AspectRatio<T> {
    #[must_use]
    pub const fn new(child: T, aspect_ratio: Ratio, content_mode: ContentMode) -> Self {
        Self {
            aspect_ratio,
            content_mode,
            child,
        }
    }
}

impl<T: Layout> Layout for AspectRatio<T> {
    type Sublayout = T::Sublayout;

    fn layout(
        &self,
        offer: &ProposedDimensions,
        env: &impl LayoutEnvironment,
    ) -> ResolvedLayout<Self::Sublayout> {
        let (ratio_width, ratio_height) = match self.aspect_ratio {
            Ratio::Fixed(width, height) => (width, height),
            Ratio::Ideal => {
                // Use child's ideal size to determine aspect ratio
                let child_ideal_size = self
                    .child
                    .layout(&ProposedDimensions::compact(), env)
                    .resolved_size;
                (
                    child_ideal_size.width.into(),
                    child_ideal_size.height.into(),
                )
            }
        };

        // Avoid division by zero
        if ratio_width == 0 || ratio_height == 0 {
            return self.child.layout(offer, env);
        }

        match (offer.width, offer.height) {
            (ProposedDimension::Exact(w), ProposedDimension::Exact(h)) => {
                let aspect_height = w * ratio_height / ratio_width;
                let aspect_width = h * ratio_width / ratio_height;
                let (final_width, final_height) = match self.content_mode {
                    ContentMode::Fit => {
                        // Choose the smaller scale to fit within bounds
                        if aspect_height <= h {
                            (w, aspect_height)
                        } else {
                            (aspect_width, h)
                        }
                    }
                    ContentMode::Fill => {
                        // Choose the larger scale to fill the space
                        if aspect_height >= h {
                            (w, aspect_height)
                        } else {
                            (aspect_width, h)
                        }
                    }
                };
                let new_offer = ProposedDimensions::new(final_width, final_height);
                self.child.layout(&new_offer, env)
            }

            // One exact dimension, one infinite - Fill returns infinite, Fit calculates
            (ProposedDimension::Exact(w), ProposedDimension::Infinite) => match self.content_mode {
                ContentMode::Fit => {
                    let height = w * ratio_height / ratio_width;
                    let new_offer = ProposedDimensions::new(w, height);
                    self.child.layout(&new_offer, env)
                }
                ContentMode::Fill => self.child.layout(&ProposedDimensions::infinite(), env),
            },
            (ProposedDimension::Infinite, ProposedDimension::Exact(h)) => match self.content_mode {
                ContentMode::Fit => {
                    let width = h * ratio_width / ratio_height;
                    let new_offer = ProposedDimensions::new(width, h);
                    self.child.layout(&new_offer, env)
                }
                ContentMode::Fill => self.child.layout(&ProposedDimensions::infinite(), env),
            },

            // One exact dimension, one compact - always calculate the missing dimension
            (ProposedDimension::Exact(w), ProposedDimension::Compact) => {
                let height = w * ratio_height / ratio_width;
                let new_offer = ProposedDimensions::new(w, height);
                self.child.layout(&new_offer, env)
            }
            (ProposedDimension::Compact, ProposedDimension::Exact(h)) => {
                let width = h * ratio_width / ratio_height;
                let new_offer = ProposedDimensions::new(width, h);
                self.child.layout(&new_offer, env)
            }

            // All other cases delegate to child
            _ => self.child.layout(offer, env),
        }
    }

    fn priority(&self) -> i8 {
        self.child.priority()
    }

    fn is_empty(&self) -> bool {
        self.child.is_empty()
    }
}

impl<T: Renderable> Renderable for AspectRatio<T> {
    type Renderables = T::Renderables;

    fn render_tree(
        &self,
        layout: &ResolvedLayout<Self::Sublayout>,
        origin: crate::primitives::Point,
        env: &impl LayoutEnvironment,
    ) -> Self::Renderables {
        // delegate all rendering to the child
        self.child.render_tree(layout, origin, env)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::environment::DefaultEnvironment;
    use crate::layout::Layout;
    use crate::primitives::{Dimensions, ProposedDimensions};
    use crate::view::prelude::*;

    #[test]
    fn ideal_aspect_ratio_fit() {
        let env = DefaultEnvironment::default();
        let child = Rectangle.flex_frame().with_ideal_size(5, 10);
        let aspect_ratio = AspectRatio::new(child, Ratio::Ideal, ContentMode::Fit);

        let offer = ProposedDimensions::new(100, 100);
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::new(50, 100));

        let offer = ProposedDimensions::new(100, 1000);
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::new(100, 200));

        let offer = ProposedDimensions::new(ProposedDimension::Infinite, 100);
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::new(50, 100));

        let offer = ProposedDimensions::new(ProposedDimension::Compact, 100);
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::new(50, 100));

        let offer = ProposedDimensions::new(100, ProposedDimension::Infinite);
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::new(100, 200));

        let offer = ProposedDimensions::new(100, ProposedDimension::Compact);
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::new(100, 200));

        let offer = ProposedDimensions::compact();
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::new(5, 10));
    }

    #[test]
    fn ideal_aspect_ratio_fill() {
        let env = DefaultEnvironment::default();
        let child = Rectangle.flex_frame().with_ideal_size(5, 10);
        let aspect_ratio = AspectRatio::new(child, Ratio::Ideal, ContentMode::Fill);

        let offer = ProposedDimensions::new(100, 100);
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::new(100, 200));

        let offer = ProposedDimensions::new(100, 1000);
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::new(500, 1000));

        let offer = ProposedDimensions::new(ProposedDimension::Infinite, 100);
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::infinite());

        let offer = ProposedDimensions::new(ProposedDimension::Compact, 100);
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::new(50, 100));

        let offer = ProposedDimensions::new(100, ProposedDimension::Infinite);
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::infinite());

        let offer = ProposedDimensions::new(100, ProposedDimension::Compact);
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::new(100, 200));

        let offer = ProposedDimensions::compact();
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::new(5, 10));
    }

    #[test]
    fn fixed_aspect_ratio_fit() {
        let env = DefaultEnvironment::default();
        let child = Rectangle.flex_frame().with_ideal_size(10, 10);
        let aspect_ratio = AspectRatio::new(child, Ratio::Fixed(1, 2), ContentMode::Fit);

        let offer = ProposedDimensions::new(100, 100);
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::new(50, 100));

        let offer = ProposedDimensions::new(100, 1000);
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::new(100, 200));

        let offer = ProposedDimensions::new(ProposedDimension::Infinite, 100);
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::new(50, 100));

        let offer = ProposedDimensions::new(ProposedDimension::Compact, 100);
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::new(50, 100));

        let offer = ProposedDimensions::new(100, ProposedDimension::Infinite);
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::new(100, 200));

        let offer = ProposedDimensions::new(100, ProposedDimension::Compact);
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::new(100, 200));

        let offer = ProposedDimensions::compact();
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::new(10, 10));
    }

    #[test]
    fn fixed_aspect_ratio_fill() {
        let env = DefaultEnvironment::default();
        let child = Rectangle.flex_frame().with_ideal_size(10, 10);
        let aspect_ratio = AspectRatio::new(child, Ratio::Fixed(1, 2), ContentMode::Fill);

        let offer = ProposedDimensions::new(100, 100);
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::new(100, 200));

        let offer = ProposedDimensions::new(100, 1000);
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::new(500, 1000));

        let offer = ProposedDimensions::new(ProposedDimension::Infinite, 100);
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::infinite());

        let offer = ProposedDimensions::new(ProposedDimension::Compact, 100);
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::new(50, 100));

        let offer = ProposedDimensions::new(100, ProposedDimension::Infinite);
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::infinite());

        let offer = ProposedDimensions::new(100, ProposedDimension::Compact);
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::new(100, 200));

        let offer = ProposedDimensions::compact();
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::new(10, 10));
    }

    /// Should inherit the size of its child, even if that means it isn't the requested
    /// aspect ratio.
    #[test]
    fn aspect_ratio_fit_inherits_fixed_child_size() {
        let env = DefaultEnvironment::default();
        let aspect_ratio = AspectRatio::new(Circle, Ratio::Fixed(1, 2), ContentMode::Fit);

        let offer = ProposedDimensions::new(100, 100);
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::new(50, 50));
    }

    #[test]
    fn aspect_ratio_fill_inherits_fixed_child_size() {
        let env = DefaultEnvironment::default();
        let aspect_ratio = AspectRatio::new(Circle, Ratio::Fixed(1, 2), ContentMode::Fill);

        let offer = ProposedDimensions::new(100, 100);
        let layout = aspect_ratio.layout(&offer, &env);
        assert_eq!(layout.resolved_size, Dimensions::new(100, 100));
    }

    #[test]
    fn zeros_should_not_panic() {
        let env = DefaultEnvironment::default();
        let layout = AspectRatio::new(Circle, Ratio::Fixed(0, 2), ContentMode::Fill)
            .layout(&ProposedDimensions::new(1, 1), &env);
        assert_eq!(layout.resolved_size, Dimensions::new(1, 1));

        let layout = AspectRatio::new(Circle, Ratio::Fixed(2, 0), ContentMode::Fill)
            .layout(&ProposedDimensions::new(1, 1), &env);
        assert_eq!(layout.resolved_size, Dimensions::new(1, 1));

        let layout = AspectRatio::new(Circle, Ratio::Fixed(0, 0), ContentMode::Fill)
            .layout(&ProposedDimensions::new(1, 1), &env);
        assert_eq!(layout.resolved_size, Dimensions::new(1, 1));

        let layout = AspectRatio::new(Circle, Ratio::Ideal, ContentMode::Fit)
            .layout(&ProposedDimensions::new(1, 0), &env);
        assert_eq!(layout.resolved_size, Dimensions::new(0, 0));

        let layout = AspectRatio::new(Circle, Ratio::Ideal, ContentMode::Fit)
            .layout(&ProposedDimensions::new(0, 1), &env);
        assert_eq!(layout.resolved_size, Dimensions::new(0, 0));

        let layout = AspectRatio::new(Circle, Ratio::Ideal, ContentMode::Fill)
            .layout(&ProposedDimensions::new(0, 0), &env);
        assert_eq!(layout.resolved_size, Dimensions::new(0, 0));
    }
}