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
pub use euclid::Rect;
use rustc_hash::FxHashMap;

use crate::{
    custom_measurer::LayoutMeasurer,
    dom_adapter::{
        DOMAdapter,
        LayoutNode,
        NodeKey,
    },
    geometry::{
        Area,
        Size2D,
    },
    measure_mode::MeasureMode,
    node::Node,
    prelude::{
        AlignmentDirection,
        AreaModel,
        LayoutMetadata,
        Torin,
    },
};

/// Some layout strategies require two-phase measurements
/// Example: Alignments or content-fit.
#[derive(Clone, Copy, PartialEq)]
pub enum Phase {
    Initial,
    Final,
}

/// Measure a Node layout
#[allow(clippy::too_many_arguments)]
#[inline(always)]
pub fn measure_node<Key: NodeKey>(
    node_id: Key,
    node: &Node,
    layout: &mut Torin<Key>,
    // Area occupied by it's parent
    parent_area: &Area,
    // Area that is available to use by the children of the parent
    available_parent_area: &Area,
    measurer: &mut Option<impl LayoutMeasurer<Key>>,
    // Whether to cache the measurements of this Node's children
    must_cache_inner_nodes: bool,
    // Adapter for the provided DOM
    dom_adapter: &mut impl DOMAdapter<Key>,

    layout_metadata: &LayoutMetadata,

    invalidated_tree: bool,

    phase: Phase,
) -> (bool, LayoutNode) {
    let must_revalidate = invalidated_tree
        || layout.dirty.contains(&node_id)
        || !layout.results.contains_key(&node_id);
    if must_revalidate {
        // Create the initial Node area size
        let mut area_size = Size2D::new(node.padding.horizontal(), node.padding.vertical());

        // Compute the width and height given the size, the minimum size, the maximum size and margins
        area_size.width = node.width.min_max(
            area_size.width,
            parent_area.size.width,
            available_parent_area.size.width,
            node.margin.left(),
            node.margin.horizontal(),
            &node.minimum_width,
            &node.maximum_width,
            layout_metadata.root_area.width(),
            phase,
        );
        area_size.height = node.height.min_max(
            area_size.height,
            parent_area.size.height,
            available_parent_area.size.height,
            node.margin.top(),
            node.margin.vertical(),
            &node.minimum_height,
            &node.maximum_height,
            layout_metadata.root_area.height(),
            phase,
        );

        // If available, run a custom layout measure function
        // This is useful when you use third-party libraries (e.g. rust-skia, cosmic-text) to measure text layouts
        // When a Node is measured by a custom measurer function the inner children will be skipped
        let (measure_inner_children, node_data) = if let Some(measurer) = measurer {
            let most_fitting_width = *node
                .width
                .most_fitting_size(&area_size.width, &available_parent_area.size.width);
            let most_fitting_height = *node
                .height
                .most_fitting_size(&area_size.height, &available_parent_area.size.height);

            let most_fitting_area_size = Size2D::new(most_fitting_width, most_fitting_height);
            let res = measurer.measure(node_id, node, &most_fitting_area_size);

            // Compute the width and height again using the new custom area sizes
            if let Some((custom_size, node_data)) = res {
                if node.width.inner_sized() {
                    area_size.width = node.width.min_max(
                        custom_size.width,
                        parent_area.size.width,
                        available_parent_area.size.width,
                        node.margin.left(),
                        node.margin.horizontal(),
                        &node.minimum_width,
                        &node.maximum_width,
                        layout_metadata.root_area.width(),
                        phase,
                    );
                }
                if node.height.inner_sized() {
                    area_size.height = node.height.min_max(
                        custom_size.height,
                        parent_area.size.height,
                        available_parent_area.size.height,
                        node.margin.top(),
                        node.margin.vertical(),
                        &node.minimum_height,
                        &node.maximum_height,
                        layout_metadata.root_area.height(),
                        phase,
                    );
                }

                // Do not measure inner children
                (false, Some(node_data))
            } else {
                (true, None)
            }
        } else {
            (true, None)
        };

        // There is no need to measure inner children in the initial phase if this Node size
        // isn't decided by his children
        let phase_measure_inner_children = if phase == Phase::Initial {
            node.width.inner_sized() || node.height.inner_sized()
        } else {
            true
        };

        // Compute the inner size of the Node, which is basically the size inside the margins and paddings
        let inner_size = {
            let mut inner_size = area_size;

            // When having an unsized bound we set it to whatever is still available in the parent's area
            if node.width.inner_sized() {
                inner_size.width = node.width.min_max(
                    available_parent_area.width(),
                    parent_area.size.width,
                    available_parent_area.width(),
                    node.margin.left(),
                    node.margin.horizontal(),
                    &node.minimum_width,
                    &node.maximum_width,
                    layout_metadata.root_area.width(),
                    phase,
                );
            }
            if node.height.inner_sized() {
                inner_size.height = node.height.min_max(
                    available_parent_area.height(),
                    parent_area.size.height,
                    available_parent_area.height(),
                    node.margin.top(),
                    node.margin.vertical(),
                    &node.minimum_height,
                    &node.maximum_height,
                    layout_metadata.root_area.height(),
                    phase,
                );
            }
            inner_size
        };

        // Create the areas
        let area_origin = node
            .position
            .get_origin(available_parent_area, parent_area, &area_size);
        let mut area = Rect::new(area_origin, area_size);
        let mut inner_area = Rect::new(area_origin, inner_size)
            .after_gaps(&node.padding)
            .after_gaps(&node.margin);

        let mut inner_sizes = Size2D::default();

        if measure_inner_children && phase_measure_inner_children {
            // Create an area containing the available space inside the inner area
            let mut available_area = inner_area;

            available_area.move_with_offsets(&node.offset_x, &node.offset_y);

            let mut measurement_mode = MeasureMode::ParentIsNotCached {
                area: &mut area,
                inner_area: &mut inner_area,
            };

            // Measure the layout of this Node's children
            measure_inner_nodes(
                &node_id,
                node,
                layout,
                &mut available_area,
                &mut inner_sizes,
                measurer,
                must_cache_inner_nodes,
                &mut measurement_mode,
                dom_adapter,
                layout_metadata,
                true,
            );
        }

        (
            must_cache_inner_nodes,
            LayoutNode {
                area,
                margin: node.margin,
                inner_area,
                inner_sizes,
                data: node_data,
            },
        )
    } else {
        let layout_node = layout.get(node_id).unwrap().clone();

        let mut inner_sizes = layout_node.inner_sizes;
        let mut available_area = layout_node.inner_area;

        available_area.move_with_offsets(&node.offset_x, &node.offset_y);

        let mut measurement_mode = MeasureMode::ParentIsCached {
            inner_area: &layout_node.inner_area,
        };

        let measure_inner_children = if let Some(measurer) = measurer {
            measurer.should_measure_inner_children(node_id)
        } else {
            true
        };

        if measure_inner_children {
            measure_inner_nodes(
                &node_id,
                node,
                layout,
                &mut available_area,
                &mut inner_sizes,
                measurer,
                must_cache_inner_nodes,
                &mut measurement_mode,
                dom_adapter,
                layout_metadata,
                false,
            );
        }

        (false, layout_node)
    }
}

/// Measure the children layouts of a Node
#[allow(clippy::too_many_arguments)]
#[inline(always)]
pub fn measure_inner_nodes<Key: NodeKey>(
    parent_node_id: &Key,
    parent_node: &Node,
    layout: &mut Torin<Key>,
    // Area available inside the Node
    available_area: &mut Area,
    // Accumulated sizes in both axis in the Node
    inner_sizes: &mut Size2D,
    measurer: &mut Option<impl LayoutMeasurer<Key>>,
    // Whether to cache the measurements of this Node's children
    must_cache_inner_nodes: bool,
    mode: &mut MeasureMode,
    // Adapter for the provided DOM
    dom_adapter: &mut impl DOMAdapter<Key>,

    layout_metadata: &LayoutMetadata,

    invalidated_tree: bool,
) {
    let children = dom_adapter.children_of(parent_node_id);

    let mut initial_phase_sizes = FxHashMap::default();
    let mut initial_phase_inner_sizes = *inner_sizes;

    // Initial phase: Measure the size and position of the children if the parent has a
    // non-start cross alignment, non-start main aligment of a fit-content.
    if parent_node.cross_alignment.is_not_start()
        || parent_node.main_alignment.is_not_start()
        || parent_node.content.is_fit()
    {
        let mut initial_phase_mode = mode.to_owned();
        let mut initial_phase_mode = initial_phase_mode.to_mut();
        let mut initial_phase_available_area = *available_area;

        // 1. Measure the children
        for child_id in &children {
            let Some(child_data) = dom_adapter.get_node(child_id) else {
                continue;
            };

            if child_data.position.is_absolute() {
                continue;
            }

            let inner_area = *initial_phase_mode.inner_area();

            let (_, child_areas) = measure_node(
                *child_id,
                &child_data,
                layout,
                &inner_area,
                &initial_phase_available_area,
                measurer,
                false,
                dom_adapter,
                layout_metadata,
                invalidated_tree,
                Phase::Initial,
            );

            initial_phase_mode.stack_into_node(
                parent_node,
                &mut initial_phase_available_area,
                &child_areas.area,
                &mut initial_phase_inner_sizes,
                &child_data,
            );

            if parent_node.cross_alignment.is_not_start() || parent_node.main_alignment.is_spaced()
            {
                initial_phase_sizes.insert(*child_id, child_areas.area.size);
            }
        }

        if parent_node.main_alignment.is_not_start() {
            // 2. Adjust the available and inner areas of the Main axis
            initial_phase_mode.fit_bounds_when_unspecified(
                parent_node,
                AlignmentDirection::Main,
                available_area,
            );

            // 3. Align the Main axis
            available_area.align_content(
                initial_phase_mode.inner_area(),
                &initial_phase_inner_sizes,
                &parent_node.main_alignment,
                &parent_node.direction,
                AlignmentDirection::Main,
            );
        }

        if parent_node.cross_alignment.is_not_start() || parent_node.content.is_fit() {
            // 4. Adjust the available and inner areas of the Cross axis
            initial_phase_mode.fit_bounds_when_unspecified(
                parent_node,
                AlignmentDirection::Cross,
                available_area,
            );
        }
    }

    let initial_available_area = *available_area;

    // Final phase: measure the children with all the axis and sizes adjusted
    for (child_n, child_id) in children.into_iter().enumerate() {
        let Some(child_data) = dom_adapter.get_node(&child_id) else {
            continue;
        };

        let mut adapted_available_area = *available_area;

        if parent_node.main_alignment.is_spaced() {
            // Align the Main axis if necessary
            adapted_available_area.align_position(
                &initial_available_area,
                &initial_phase_inner_sizes,
                &parent_node.main_alignment,
                &parent_node.direction,
                AlignmentDirection::Main,
                initial_phase_sizes.len(),
                child_n,
            );
        }

        if parent_node.cross_alignment.is_not_start() {
            let initial_phase_size = initial_phase_sizes.get(&child_id);

            if let Some(initial_phase_size) = initial_phase_size {
                // Align the Cross axis if necessary
                adapted_available_area.align_content(
                    available_area,
                    initial_phase_size,
                    &parent_node.cross_alignment,
                    &parent_node.direction,
                    AlignmentDirection::Cross,
                );
            }
        }

        let inner_area = *mode.inner_area();

        // Final measurement
        let (child_revalidated, child_areas) = measure_node(
            child_id,
            &child_data,
            layout,
            &inner_area,
            &adapted_available_area,
            measurer,
            must_cache_inner_nodes,
            dom_adapter,
            layout_metadata,
            invalidated_tree,
            Phase::Final,
        );

        // Stack the child into its parent
        mode.stack_into_node(
            parent_node,
            available_area,
            &child_areas.area,
            inner_sizes,
            &child_data,
        );

        // Cache the child layout if it was mutated and inner nodes must be cache
        if child_revalidated && must_cache_inner_nodes {
            if let Some(measurer) = measurer {
                if child_data.has_layout_references {
                    measurer.notify_layout_references(child_id, &child_areas);
                }
            }
            layout.cache_node(child_id, child_areas);
        }
    }
}