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
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
//! Decorate content and apply alignment.
use crate::core::alignment::{self, Alignment};
use crate::core::border::{self, Border};
use crate::core::event::{self, Event};
use crate::core::gradient::{self, Gradient};
use crate::core::layout;
use crate::core::mouse;
use crate::core::overlay;
use crate::core::renderer;
use crate::core::widget::tree::{self, Tree};
use crate::core::widget::{self, Operation};
use crate::core::{
    self, color, Background, Clipboard, Color, Element, Layout, Length,
    Padding, Pixels, Point, Rectangle, Shadow, Shell, Size, Theme, Vector,
    Widget,
};
use crate::runtime::task::{self, Task};

/// An element decorating some content.
///
/// It is normally used for alignment purposes.
#[allow(missing_debug_implementations)]
pub struct Container<
    'a,
    Message,
    Theme = crate::Theme,
    Renderer = crate::Renderer,
> where
    Theme: Catalog,
    Renderer: core::Renderer,
{
    id: Option<Id>,
    padding: Padding,
    width: Length,
    height: Length,
    max_width: f32,
    max_height: f32,
    horizontal_alignment: alignment::Horizontal,
    vertical_alignment: alignment::Vertical,
    clip: bool,
    content: Element<'a, Message, Theme, Renderer>,
    class: Theme::Class<'a>,
}

impl<'a, Message, Theme, Renderer> Container<'a, Message, Theme, Renderer>
where
    Theme: Catalog,
    Renderer: core::Renderer,
{
    /// Creates a [`Container`] with the given content.
    pub fn new(
        content: impl Into<Element<'a, Message, Theme, Renderer>>,
    ) -> Self {
        let content = content.into();
        let size = content.as_widget().size_hint();

        Container {
            id: None,
            padding: Padding::ZERO,
            width: size.width.fluid(),
            height: size.height.fluid(),
            max_width: f32::INFINITY,
            max_height: f32::INFINITY,
            horizontal_alignment: alignment::Horizontal::Left,
            vertical_alignment: alignment::Vertical::Top,
            clip: false,
            class: Theme::default(),
            content,
        }
    }

    /// Sets the [`Id`] of the [`Container`].
    pub fn id(mut self, id: Id) -> Self {
        self.id = Some(id);
        self
    }

    /// Sets the [`Padding`] of the [`Container`].
    pub fn padding<P: Into<Padding>>(mut self, padding: P) -> Self {
        self.padding = padding.into();
        self
    }

    /// Sets the width of the [`Container`].
    pub fn width(mut self, width: impl Into<Length>) -> Self {
        self.width = width.into();
        self
    }

    /// Sets the height of the [`Container`].
    pub fn height(mut self, height: impl Into<Length>) -> Self {
        self.height = height.into();
        self
    }

    /// Sets the maximum width of the [`Container`].
    pub fn max_width(mut self, max_width: impl Into<Pixels>) -> Self {
        self.max_width = max_width.into().0;
        self
    }

    /// Sets the maximum height of the [`Container`].
    pub fn max_height(mut self, max_height: impl Into<Pixels>) -> Self {
        self.max_height = max_height.into().0;
        self
    }

    /// Sets the width of the [`Container`] and centers its contents horizontally.
    pub fn center_x(self, width: impl Into<Length>) -> Self {
        self.width(width).align_x(alignment::Horizontal::Center)
    }

    /// Sets the height of the [`Container`] and centers its contents vertically.
    pub fn center_y(self, height: impl Into<Length>) -> Self {
        self.height(height).align_y(alignment::Vertical::Center)
    }

    /// Centers the contents in both the horizontal and vertical axes of the
    /// [`Container`].
    ///
    /// This is equivalent to chaining [`center_x`] and [`center_y`].
    ///
    /// [`center_x`]: Self::center_x
    /// [`center_y`]: Self::center_y
    pub fn center(self, length: impl Into<Length>) -> Self {
        let length = length.into();

        self.center_x(length).center_y(length)
    }

    /// Aligns the contents of the [`Container`] to the left.
    pub fn align_left(self, width: impl Into<Length>) -> Self {
        self.width(width).align_x(alignment::Horizontal::Left)
    }

    /// Aligns the contents of the [`Container`] to the right.
    pub fn align_right(self, width: impl Into<Length>) -> Self {
        self.width(width).align_x(alignment::Horizontal::Right)
    }

    /// Aligns the contents of the [`Container`] to the top.
    pub fn align_top(self, height: impl Into<Length>) -> Self {
        self.height(height).align_y(alignment::Vertical::Top)
    }

    /// Aligns the contents of the [`Container`] to the bottom.
    pub fn align_bottom(self, height: impl Into<Length>) -> Self {
        self.height(height).align_y(alignment::Vertical::Bottom)
    }

    /// Sets the content alignment for the horizontal axis of the [`Container`].
    pub fn align_x(
        mut self,
        alignment: impl Into<alignment::Horizontal>,
    ) -> Self {
        self.horizontal_alignment = alignment.into();
        self
    }

    /// Sets the content alignment for the vertical axis of the [`Container`].
    pub fn align_y(
        mut self,
        alignment: impl Into<alignment::Vertical>,
    ) -> Self {
        self.vertical_alignment = alignment.into();
        self
    }

    /// Sets whether the contents of the [`Container`] should be clipped on
    /// overflow.
    pub fn clip(mut self, clip: bool) -> Self {
        self.clip = clip;
        self
    }

    /// Sets the style of the [`Container`].
    #[must_use]
    pub fn style(mut self, style: impl Fn(&Theme) -> Style + 'a) -> Self
    where
        Theme::Class<'a>: From<StyleFn<'a, Theme>>,
    {
        self.class = (Box::new(style) as StyleFn<'a, Theme>).into();
        self
    }

    /// Sets the style class of the [`Container`].
    #[cfg(feature = "advanced")]
    #[must_use]
    pub fn class(mut self, class: impl Into<Theme::Class<'a>>) -> Self {
        self.class = class.into();
        self
    }
}

impl<'a, Message, Theme, Renderer> Widget<Message, Theme, Renderer>
    for Container<'a, Message, Theme, Renderer>
where
    Theme: Catalog,
    Renderer: core::Renderer,
{
    fn tag(&self) -> tree::Tag {
        self.content.as_widget().tag()
    }

    fn state(&self) -> tree::State {
        self.content.as_widget().state()
    }

    fn children(&self) -> Vec<Tree> {
        self.content.as_widget().children()
    }

    fn diff(&self, tree: &mut Tree) {
        self.content.as_widget().diff(tree);
    }

    fn size(&self) -> Size<Length> {
        Size {
            width: self.width,
            height: self.height,
        }
    }

    fn layout(
        &self,
        tree: &mut Tree,
        renderer: &Renderer,
        limits: &layout::Limits,
    ) -> layout::Node {
        layout(
            limits,
            self.width,
            self.height,
            self.max_width,
            self.max_height,
            self.padding,
            self.horizontal_alignment,
            self.vertical_alignment,
            |limits| self.content.as_widget().layout(tree, renderer, limits),
        )
    }

    fn operate(
        &self,
        tree: &mut Tree,
        layout: Layout<'_>,
        renderer: &Renderer,
        operation: &mut dyn Operation<()>,
    ) {
        operation.container(
            self.id.as_ref().map(|id| &id.0),
            layout.bounds(),
            &mut |operation| {
                self.content.as_widget().operate(
                    tree,
                    layout.children().next().unwrap(),
                    renderer,
                    operation,
                );
            },
        );
    }

    fn on_event(
        &mut self,
        tree: &mut Tree,
        event: Event,
        layout: Layout<'_>,
        cursor: mouse::Cursor,
        renderer: &Renderer,
        clipboard: &mut dyn Clipboard,
        shell: &mut Shell<'_, Message>,
        viewport: &Rectangle,
    ) -> event::Status {
        self.content.as_widget_mut().on_event(
            tree,
            event,
            layout.children().next().unwrap(),
            cursor,
            renderer,
            clipboard,
            shell,
            viewport,
        )
    }

    fn mouse_interaction(
        &self,
        tree: &Tree,
        layout: Layout<'_>,
        cursor: mouse::Cursor,
        viewport: &Rectangle,
        renderer: &Renderer,
    ) -> mouse::Interaction {
        self.content.as_widget().mouse_interaction(
            tree,
            layout.children().next().unwrap(),
            cursor,
            viewport,
            renderer,
        )
    }

    fn draw(
        &self,
        tree: &Tree,
        renderer: &mut Renderer,
        theme: &Theme,
        renderer_style: &renderer::Style,
        layout: Layout<'_>,
        cursor: mouse::Cursor,
        viewport: &Rectangle,
    ) {
        let bounds = layout.bounds();
        let style = theme.style(&self.class);

        if let Some(clipped_viewport) = bounds.intersection(viewport) {
            draw_background(renderer, &style, bounds);

            self.content.as_widget().draw(
                tree,
                renderer,
                theme,
                &renderer::Style {
                    text_color: style
                        .text_color
                        .unwrap_or(renderer_style.text_color),
                },
                layout.children().next().unwrap(),
                cursor,
                if self.clip {
                    &clipped_viewport
                } else {
                    viewport
                },
            );
        }
    }

    fn overlay<'b>(
        &'b mut self,
        tree: &'b mut Tree,
        layout: Layout<'_>,
        renderer: &Renderer,
        translation: Vector,
    ) -> Option<overlay::Element<'b, Message, Theme, Renderer>> {
        self.content.as_widget_mut().overlay(
            tree,
            layout.children().next().unwrap(),
            renderer,
            translation,
        )
    }
}

impl<'a, Message, Theme, Renderer> From<Container<'a, Message, Theme, Renderer>>
    for Element<'a, Message, Theme, Renderer>
where
    Message: 'a,
    Theme: Catalog + 'a,
    Renderer: core::Renderer + 'a,
{
    fn from(
        column: Container<'a, Message, Theme, Renderer>,
    ) -> Element<'a, Message, Theme, Renderer> {
        Element::new(column)
    }
}

/// Computes the layout of a [`Container`].
pub fn layout(
    limits: &layout::Limits,
    width: Length,
    height: Length,
    max_width: f32,
    max_height: f32,
    padding: Padding,
    horizontal_alignment: alignment::Horizontal,
    vertical_alignment: alignment::Vertical,
    layout_content: impl FnOnce(&layout::Limits) -> layout::Node,
) -> layout::Node {
    layout::positioned(
        &limits.max_width(max_width).max_height(max_height),
        width,
        height,
        padding,
        |limits| layout_content(&limits.loose()),
        |content, size| {
            content.align(
                Alignment::from(horizontal_alignment),
                Alignment::from(vertical_alignment),
                size,
            )
        },
    )
}

/// Draws the background of a [`Container`] given its [`Style`] and its `bounds`.
pub fn draw_background<Renderer>(
    renderer: &mut Renderer,
    style: &Style,
    bounds: Rectangle,
) where
    Renderer: core::Renderer,
{
    if style.background.is_some()
        || style.border.width > 0.0
        || style.shadow.color.a > 0.0
    {
        renderer.fill_quad(
            renderer::Quad {
                bounds,
                border: style.border,
                shadow: style.shadow,
            },
            style
                .background
                .unwrap_or(Background::Color(Color::TRANSPARENT)),
        );
    }
}

/// The identifier of a [`Container`].
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub struct Id(widget::Id);

impl Id {
    /// Creates a custom [`Id`].
    pub fn new(id: impl Into<std::borrow::Cow<'static, str>>) -> Self {
        Self(widget::Id::new(id))
    }

    /// Creates a unique [`Id`].
    ///
    /// This function produces a different [`Id`] every time it is called.
    pub fn unique() -> Self {
        Self(widget::Id::unique())
    }
}

impl From<Id> for widget::Id {
    fn from(id: Id) -> Self {
        id.0
    }
}

/// Produces a [`Task`] that queries the visible screen bounds of the
/// [`Container`] with the given [`Id`].
pub fn visible_bounds(id: Id) -> Task<Option<Rectangle>> {
    struct VisibleBounds {
        target: widget::Id,
        depth: usize,
        scrollables: Vec<(Vector, Rectangle, usize)>,
        bounds: Option<Rectangle>,
    }

    impl Operation<Option<Rectangle>> for VisibleBounds {
        fn scrollable(
            &mut self,
            _state: &mut dyn widget::operation::Scrollable,
            _id: Option<&widget::Id>,
            bounds: Rectangle,
            translation: Vector,
        ) {
            match self.scrollables.last() {
                Some((last_translation, last_viewport, _depth)) => {
                    let viewport = last_viewport
                        .intersection(&(bounds - *last_translation))
                        .unwrap_or(Rectangle::new(Point::ORIGIN, Size::ZERO));

                    self.scrollables.push((
                        translation + *last_translation,
                        viewport,
                        self.depth,
                    ));
                }
                None => {
                    self.scrollables.push((translation, bounds, self.depth));
                }
            }
        }

        fn container(
            &mut self,
            id: Option<&widget::Id>,
            bounds: Rectangle,
            operate_on_children: &mut dyn FnMut(
                &mut dyn Operation<Option<Rectangle>>,
            ),
        ) {
            if self.bounds.is_some() {
                return;
            }

            if id == Some(&self.target) {
                match self.scrollables.last() {
                    Some((translation, viewport, _)) => {
                        self.bounds =
                            viewport.intersection(&(bounds - *translation));
                    }
                    None => {
                        self.bounds = Some(bounds);
                    }
                }

                return;
            }

            self.depth += 1;

            operate_on_children(self);

            self.depth -= 1;

            match self.scrollables.last() {
                Some((_, _, depth)) if self.depth == *depth => {
                    let _ = self.scrollables.pop();
                }
                _ => {}
            }
        }

        fn finish(&self) -> widget::operation::Outcome<Option<Rectangle>> {
            widget::operation::Outcome::Some(self.bounds)
        }
    }

    task::widget(VisibleBounds {
        target: id.into(),
        depth: 0,
        scrollables: Vec::new(),
        bounds: None,
    })
}

/// The appearance of a container.
#[derive(Debug, Clone, Copy, Default)]
pub struct Style {
    /// The text [`Color`] of the container.
    pub text_color: Option<Color>,
    /// The [`Background`] of the container.
    pub background: Option<Background>,
    /// The [`Border`] of the container.
    pub border: Border,
    /// The [`Shadow`] of the container.
    pub shadow: Shadow,
}

impl Style {
    /// Updates the text color of the [`Style`].
    pub fn color(self, color: impl Into<Color>) -> Self {
        Self {
            text_color: Some(color.into()),
            ..self
        }
    }

    /// Updates the border of the [`Style`].
    pub fn border(self, border: impl Into<Border>) -> Self {
        Self {
            border: border.into(),
            ..self
        }
    }

    /// Updates the background of the [`Style`].
    pub fn background(self, background: impl Into<Background>) -> Self {
        Self {
            background: Some(background.into()),
            ..self
        }
    }

    /// Updates the shadow of the [`Style`].
    pub fn shadow(self, shadow: impl Into<Shadow>) -> Self {
        Self {
            shadow: shadow.into(),
            ..self
        }
    }
}

impl From<Color> for Style {
    fn from(color: Color) -> Self {
        Self::default().background(color)
    }
}

impl From<Gradient> for Style {
    fn from(gradient: Gradient) -> Self {
        Self::default().background(gradient)
    }
}

impl From<gradient::Linear> for Style {
    fn from(gradient: gradient::Linear) -> Self {
        Self::default().background(gradient)
    }
}

/// The theme catalog of a [`Container`].
pub trait Catalog {
    /// The item class of the [`Catalog`].
    type Class<'a>;

    /// The default class produced by the [`Catalog`].
    fn default<'a>() -> Self::Class<'a>;

    /// The [`Style`] of a class with the given status.
    fn style(&self, class: &Self::Class<'_>) -> Style;
}

/// A styling function for a [`Container`].
pub type StyleFn<'a, Theme> = Box<dyn Fn(&Theme) -> Style + 'a>;

impl Catalog for Theme {
    type Class<'a> = StyleFn<'a, Self>;

    fn default<'a>() -> Self::Class<'a> {
        Box::new(transparent)
    }

    fn style(&self, class: &Self::Class<'_>) -> Style {
        class(self)
    }
}

/// A transparent [`Container`].
pub fn transparent<Theme>(_theme: &Theme) -> Style {
    Style::default()
}

/// A rounded [`Container`] with a background.
pub fn rounded_box(theme: &Theme) -> Style {
    let palette = theme.extended_palette();

    Style {
        background: Some(palette.background.weak.color.into()),
        border: border::rounded(2),
        ..Style::default()
    }
}

/// A bordered [`Container`] with a background.
pub fn bordered_box(theme: &Theme) -> Style {
    let palette = theme.extended_palette();

    Style {
        background: Some(palette.background.weak.color.into()),
        border: Border {
            width: 1.0,
            radius: 0.0.into(),
            color: palette.background.strong.color,
        },
        ..Style::default()
    }
}

/// A [`Container`] with a dark background and white text.
pub fn dark(_theme: &Theme) -> Style {
    Style {
        background: Some(color!(0x111111).into()),
        text_color: Some(Color::WHITE),
        border: border::rounded(2),
        ..Style::default()
    }
}