wrap.dart 29.2 KB
Newer Older
Ian Hickson's avatar
Ian Hickson committed
1
// Copyright 2014 The Flutter Authors. All rights reserved.
Adam Barth's avatar
Adam Barth committed
2 3 4 5 6 7
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'dart:math' as math;

import 'box.dart';
8
import 'layer.dart';
9
import 'layout_helper.dart';
Adam Barth's avatar
Adam Barth committed
10 11 12 13 14 15 16 17
import 'object.dart';

/// How [Wrap] should align objects.
///
/// Used both to align children within a run in the main axis as well as to
/// align the runs themselves in the cross axis.
enum WrapAlignment {
  /// Place the objects as close to the start of the axis as possible.
18 19 20 21 22 23
  ///
  /// If this value is used in a horizontal direction, a [TextDirection] must be
  /// available to determine if the start is the left or the right.
  ///
  /// If this value is used in a vertical direction, a [VerticalDirection] must be
  /// available to determine if the start is the top or the bottom.
Adam Barth's avatar
Adam Barth committed
24 25 26
  start,

  /// Place the objects as close to the end of the axis as possible.
27 28 29 30 31 32
  ///
  /// If this value is used in a horizontal direction, a [TextDirection] must be
  /// available to determine if the end is the left or the right.
  ///
  /// If this value is used in a vertical direction, a [VerticalDirection] must be
  /// available to determine if the end is the top or the bottom.
Adam Barth's avatar
Adam Barth committed
33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53
  end,

  /// Place the objects as close to the middle of the axis as possible.
  center,

  /// Place the free space evenly between the objects.
  spaceBetween,

  /// Place the free space evenly between the objects as well as half of that
  /// space before and after the first and last objects.
  spaceAround,

  /// Place the free space evenly between the objects as well as before and
  /// after the first and last objects.
  spaceEvenly,
}

/// Who [Wrap] should align children within a run in the cross axis.
enum WrapCrossAlignment {
  /// Place the children as close to the start of the run in the cross axis as
  /// possible.
54 55 56 57 58 59
  ///
  /// If this value is used in a horizontal direction, a [TextDirection] must be
  /// available to determine if the start is the left or the right.
  ///
  /// If this value is used in a vertical direction, a [VerticalDirection] must be
  /// available to determine if the start is the top or the bottom.
Adam Barth's avatar
Adam Barth committed
60 61 62 63
  start,

  /// Place the children as close to the end of the run in the cross axis as
  /// possible.
64 65 66 67 68 69
  ///
  /// If this value is used in a horizontal direction, a [TextDirection] must be
  /// available to determine if the end is the left or the right.
  ///
  /// If this value is used in a vertical direction, a [VerticalDirection] must be
  /// available to determine if the end is the top or the bottom.
Adam Barth's avatar
Adam Barth committed
70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87
  end,

  /// Place the children as close to the middle of the run in the cross axis as
  /// possible.
  center,

  // TODO(ianh): baseline.
}

class _RunMetrics {
  _RunMetrics(this.mainAxisExtent, this.crossAxisExtent, this.childCount);

  final double mainAxisExtent;
  final double crossAxisExtent;
  final int childCount;
}

/// Parent data for use with [RenderWrap].
88
class WrapParentData extends ContainerBoxParentData<RenderBox> {
Adam Barth's avatar
Adam Barth committed
89 90 91
  int _runIndex = 0;
}

92 93 94 95 96 97 98 99 100 101 102 103 104 105
/// Displays its children in multiple horizontal or vertical runs.
///
/// A [RenderWrap] lays out each child and attempts to place the child adjacent
/// to the previous child in the main axis, given by [direction], leaving
/// [spacing] space in between. If there is not enough space to fit the child,
/// [RenderWrap] creates a new _run_ adjacent to the existing children in the
/// cross axis.
///
/// After all the children have been allocated to runs, the children within the
/// runs are positioned according to the [alignment] in the main axis and
/// according to the [crossAxisAlignment] in the cross axis.
///
/// The runs themselves are then positioned in the cross axis according to the
/// [runSpacing] and [runAlignment].
106 107 108
class RenderWrap extends RenderBox
    with ContainerRenderObjectMixin<RenderBox, WrapParentData>,
         RenderBoxContainerDefaultsMixin<RenderBox, WrapParentData> {
109 110 111 112
  /// Creates a wrap render object.
  ///
  /// By default, the wrap layout is horizontal and both the children and the
  /// runs are aligned to the start.
Adam Barth's avatar
Adam Barth committed
113
  RenderWrap({
114
    List<RenderBox>? children,
115 116 117 118 119 120
    Axis direction = Axis.horizontal,
    WrapAlignment alignment = WrapAlignment.start,
    double spacing = 0.0,
    WrapAlignment runAlignment = WrapAlignment.start,
    double runSpacing = 0.0,
    WrapCrossAlignment crossAxisAlignment = WrapCrossAlignment.start,
121
    TextDirection? textDirection,
122
    VerticalDirection verticalDirection = VerticalDirection.down,
123
    Clip clipBehavior = Clip.none,
124 125 126 127 128 129
  }) : assert(direction != null),
       assert(alignment != null),
       assert(spacing != null),
       assert(runAlignment != null),
       assert(runSpacing != null),
       assert(crossAxisAlignment != null),
130
       assert(clipBehavior != null),
131
       _direction = direction,
Adam Barth's avatar
Adam Barth committed
132 133 134 135
       _alignment = alignment,
       _spacing = spacing,
       _runAlignment = runAlignment,
       _runSpacing = runSpacing,
136 137
       _crossAxisAlignment = crossAxisAlignment,
       _textDirection = textDirection,
138 139
       _verticalDirection = verticalDirection,
       _clipBehavior = clipBehavior {
Adam Barth's avatar
Adam Barth committed
140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158
    addAll(children);
  }

  /// The direction to use as the main axis.
  ///
  /// For example, if [direction] is [Axis.horizontal], the default, the
  /// children are placed adjacent to one another in a horizontal run until the
  /// available horizontal space is consumed, at which point a subsequent
  /// children are placed in a new run vertically adjacent to the previous run.
  Axis get direction => _direction;
  Axis _direction;
  set direction (Axis value) {
    assert(value != null);
    if (_direction == value)
      return;
    _direction = value;
    markNeedsLayout();
  }

159
  /// How the children within a run should be placed in the main axis.
Adam Barth's avatar
Adam Barth committed
160 161
  ///
  /// For example, if [alignment] is [WrapAlignment.center], the children in
162
  /// each run are grouped together in the center of their run in the main axis.
Adam Barth's avatar
Adam Barth committed
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
  ///
  /// Defaults to [WrapAlignment.start].
  ///
  /// See also:
  ///
  ///  * [runAlignment], which controls how the runs are placed relative to each
  ///    other in the cross axis.
  ///  * [crossAxisAlignment], which controls how the children within each run
  ///    are placed relative to each other in the cross axis.
  WrapAlignment get alignment => _alignment;
  WrapAlignment _alignment;
  set alignment (WrapAlignment value) {
    assert(value != null);
    if (_alignment == value)
      return;
    _alignment = value;
    markNeedsLayout();
  }

  /// How much space to place between children in a run in the main axis.
  ///
  /// For example, if [spacing] is 10.0, the children will be spaced at least
  /// 10.0 logical pixels apart in the main axis.
  ///
  /// If there is additional free space in a run (e.g., because the wrap has a
  /// minimum size that is not filled or because some runs are longer than
  /// others), the additional free space will be allocated according to the
  /// [alignment].
  ///
  /// Defaults to 0.0.
  double get spacing => _spacing;
  double _spacing;
  set spacing (double value) {
    assert(value != null);
    if (_spacing == value)
      return;
    _spacing = value;
    markNeedsLayout();
  }

  /// How the runs themselves should be placed in the cross axis.
  ///
  /// For example, if [runAlignment] is [WrapAlignment.center], the runs are
206
  /// grouped together in the center of the overall [RenderWrap] in the cross
Adam Barth's avatar
Adam Barth committed
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
  /// axis.
  ///
  /// Defaults to [WrapAlignment.start].
  ///
  /// See also:
  ///
  ///  * [alignment], which controls how the children within each run are placed
  ///    relative to each other in the main axis.
  ///  * [crossAxisAlignment], which controls how the children within each run
  ///    are placed relative to each other in the cross axis.
  WrapAlignment get runAlignment => _runAlignment;
  WrapAlignment _runAlignment;
  set runAlignment (WrapAlignment value) {
    assert(value != null);
    if (_runAlignment == value)
      return;
    _runAlignment = value;
    markNeedsLayout();
  }

  /// How much space to place between the runs themselves in the cross axis.
  ///
  /// For example, if [runSpacing] is 10.0, the runs will be spaced at least
  /// 10.0 logical pixels apart in the cross axis.
  ///
  /// If there is additional free space in the overall [RenderWrap] (e.g.,
  /// because the wrap has a minimum size that is not filled), the additional
  /// free space will be allocated according to the [runAlignment].
  ///
  /// Defaults to 0.0.
  double get runSpacing => _runSpacing;
  double _runSpacing;
  set runSpacing (double value) {
    assert(value != null);
    if (_runSpacing == value)
      return;
    _runSpacing = value;
    markNeedsLayout();
  }

  /// How the children within a run should be aligned relative to each other in
  /// the cross axis.
  ///
  /// For example, if this is set to [WrapCrossAlignment.end], and the
251
  /// [direction] is [Axis.horizontal], then the children within each
Adam Barth's avatar
Adam Barth committed
252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271
  /// run will have their bottom edges aligned to the bottom edge of the run.
  ///
  /// Defaults to [WrapCrossAlignment.start].
  ///
  /// See also:
  ///
  ///  * [alignment], which controls how the children within each run are placed
  ///    relative to each other in the main axis.
  ///  * [runAlignment], which controls how the runs are placed relative to each
  ///    other in the cross axis.
  WrapCrossAlignment get crossAxisAlignment => _crossAxisAlignment;
  WrapCrossAlignment _crossAxisAlignment;
  set crossAxisAlignment (WrapCrossAlignment value) {
    assert(value != null);
    if (_crossAxisAlignment == value)
      return;
    _crossAxisAlignment = value;
    markNeedsLayout();
  }

272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294
  /// Determines the order to lay children out horizontally and how to interpret
  /// `start` and `end` in the horizontal direction.
  ///
  /// If the [direction] is [Axis.horizontal], this controls the order in which
  /// children are positioned (left-to-right or right-to-left), and the meaning
  /// of the [alignment] property's [WrapAlignment.start] and
  /// [WrapAlignment.end] values.
  ///
  /// If the [direction] is [Axis.horizontal], and either the
  /// [alignment] is either [WrapAlignment.start] or [WrapAlignment.end], or
  /// there's more than one child, then the [textDirection] must not be null.
  ///
  /// If the [direction] is [Axis.vertical], this controls the order in
  /// which runs are positioned, the meaning of the [runAlignment] property's
  /// [WrapAlignment.start] and [WrapAlignment.end] values, as well as the
  /// [crossAxisAlignment] property's [WrapCrossAlignment.start] and
  /// [WrapCrossAlignment.end] values.
  ///
  /// If the [direction] is [Axis.vertical], and either the
  /// [runAlignment] is either [WrapAlignment.start] or [WrapAlignment.end], the
  /// [crossAxisAlignment] is either [WrapCrossAlignment.start] or
  /// [WrapCrossAlignment.end], or there's more than one child, then the
  /// [textDirection] must not be null.
295 296 297
  TextDirection? get textDirection => _textDirection;
  TextDirection? _textDirection;
  set textDirection(TextDirection? value) {
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
    if (_textDirection != value) {
      _textDirection = value;
      markNeedsLayout();
    }
  }

  /// Determines the order to lay children out vertically and how to interpret
  /// `start` and `end` in the vertical direction.
  ///
  /// If the [direction] is [Axis.vertical], this controls which order children
  /// are painted in (down or up), the meaning of the [alignment] property's
  /// [WrapAlignment.start] and [WrapAlignment.end] values.
  ///
  /// If the [direction] is [Axis.vertical], and either the [alignment]
  /// is either [WrapAlignment.start] or [WrapAlignment.end], or there's
  /// more than one child, then the [verticalDirection] must not be null.
  ///
  /// If the [direction] is [Axis.horizontal], this controls the order in which
  /// runs are positioned, the meaning of the [runAlignment] property's
  /// [WrapAlignment.start] and [WrapAlignment.end] values, as well as the
  /// [crossAxisAlignment] property's [WrapCrossAlignment.start] and
  /// [WrapCrossAlignment.end] values.
  ///
  /// If the [direction] is [Axis.horizontal], and either the
  /// [runAlignment] is either [WrapAlignment.start] or [WrapAlignment.end], the
  /// [crossAxisAlignment] is either [WrapCrossAlignment.start] or
  /// [WrapCrossAlignment.end], or there's more than one child, then the
  /// [verticalDirection] must not be null.
  VerticalDirection get verticalDirection => _verticalDirection;
  VerticalDirection _verticalDirection;
  set verticalDirection(VerticalDirection value) {
    if (_verticalDirection != value) {
      _verticalDirection = value;
      markNeedsLayout();
    }
  }

335
  /// {@macro flutter.material.Material.clipBehavior}
336 337 338 339 340 341 342 343 344 345 346 347 348
  ///
  /// Defaults to [Clip.none], and must not be null.
  Clip get clipBehavior => _clipBehavior;
  Clip _clipBehavior = Clip.none;
  set clipBehavior(Clip value) {
    assert(value != null);
    if (value != _clipBehavior) {
      _clipBehavior = value;
      markNeedsPaint();
      markNeedsSemanticsUpdate();
    }
  }

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
  bool get _debugHasNecessaryDirections {
    assert(direction != null);
    assert(alignment != null);
    assert(runAlignment != null);
    assert(crossAxisAlignment != null);
    if (firstChild != null && lastChild != firstChild) {
      // i.e. there's more than one child
      switch (direction) {
        case Axis.horizontal:
          assert(textDirection != null, 'Horizontal $runtimeType with multiple children has a null textDirection, so the layout order is undefined.');
          break;
        case Axis.vertical:
          assert(verticalDirection != null, 'Vertical $runtimeType with multiple children has a null verticalDirection, so the layout order is undefined.');
          break;
      }
    }
    if (alignment == WrapAlignment.start || alignment == WrapAlignment.end) {
      switch (direction) {
        case Axis.horizontal:
          assert(textDirection != null, 'Horizontal $runtimeType with alignment $alignment has a null textDirection, so the alignment cannot be resolved.');
          break;
        case Axis.vertical:
          assert(verticalDirection != null, 'Vertical $runtimeType with alignment $alignment has a null verticalDirection, so the alignment cannot be resolved.');
          break;
      }
    }
    if (runAlignment == WrapAlignment.start || runAlignment == WrapAlignment.end) {
      switch (direction) {
        case Axis.horizontal:
          assert(verticalDirection != null, 'Horizontal $runtimeType with runAlignment $runAlignment has a null verticalDirection, so the alignment cannot be resolved.');
          break;
        case Axis.vertical:
          assert(textDirection != null, 'Vertical $runtimeType with runAlignment $runAlignment has a null textDirection, so the alignment cannot be resolved.');
          break;
      }
    }
    if (crossAxisAlignment == WrapCrossAlignment.start || crossAxisAlignment == WrapCrossAlignment.end) {
      switch (direction) {
        case Axis.horizontal:
          assert(verticalDirection != null, 'Horizontal $runtimeType with crossAxisAlignment $crossAxisAlignment has a null verticalDirection, so the alignment cannot be resolved.');
          break;
        case Axis.vertical:
          assert(textDirection != null, 'Vertical $runtimeType with crossAxisAlignment $crossAxisAlignment has a null textDirection, so the alignment cannot be resolved.');
          break;
      }
    }
    return true;
  }

Adam Barth's avatar
Adam Barth committed
398 399 400
  @override
  void setupParentData(RenderBox child) {
    if (child.parentData is! WrapParentData)
401
      child.parentData = WrapParentData();
Adam Barth's avatar
Adam Barth committed
402 403 404 405 406 407 408
  }

  @override
  double computeMinIntrinsicWidth(double height) {
    switch (direction) {
      case Axis.horizontal:
        double width = 0.0;
409
        RenderBox? child = firstChild;
Adam Barth's avatar
Adam Barth committed
410
        while (child != null) {
411
          width = math.max(width, child.getMinIntrinsicWidth(double.infinity));
Adam Barth's avatar
Adam Barth committed
412 413 414 415
          child = childAfter(child);
        }
        return width;
      case Axis.vertical:
416
        return computeDryLayout(BoxConstraints(maxHeight: height)).width;
Adam Barth's avatar
Adam Barth committed
417 418 419 420 421 422 423
    }
  }

  @override
  double computeMaxIntrinsicWidth(double height) {
    switch (direction) {
      case Axis.horizontal:
424
        double width = 0.0;
425
        RenderBox? child = firstChild;
Adam Barth's avatar
Adam Barth committed
426
        while (child != null) {
427
          width += child.getMaxIntrinsicWidth(double.infinity);
Adam Barth's avatar
Adam Barth committed
428 429 430 431
          child = childAfter(child);
        }
        return width;
      case Axis.vertical:
432
        return computeDryLayout(BoxConstraints(maxHeight: height)).width;
Adam Barth's avatar
Adam Barth committed
433 434 435 436 437 438 439
    }
  }

  @override
  double computeMinIntrinsicHeight(double width) {
    switch (direction) {
      case Axis.horizontal:
440
        return computeDryLayout(BoxConstraints(maxWidth: width)).height;
Adam Barth's avatar
Adam Barth committed
441 442
      case Axis.vertical:
        double height = 0.0;
443
        RenderBox? child = firstChild;
Adam Barth's avatar
Adam Barth committed
444
        while (child != null) {
445
          height = math.max(height, child.getMinIntrinsicHeight(double.infinity));
Adam Barth's avatar
Adam Barth committed
446 447 448 449 450 451 452 453 454 455
          child = childAfter(child);
        }
        return height;
    }
  }

  @override
  double computeMaxIntrinsicHeight(double width) {
    switch (direction) {
      case Axis.horizontal:
456
        return computeDryLayout(BoxConstraints(maxWidth: width)).height;
Adam Barth's avatar
Adam Barth committed
457
      case Axis.vertical:
458
        double height = 0.0;
459
        RenderBox? child = firstChild;
Adam Barth's avatar
Adam Barth committed
460
        while (child != null) {
461
          height += child.getMaxIntrinsicHeight(double.infinity);
Adam Barth's avatar
Adam Barth committed
462 463 464 465 466 467 468
          child = childAfter(child);
        }
        return height;
    }
  }

  @override
469
  double? computeDistanceToActualBaseline(TextBaseline baseline) {
Adam Barth's avatar
Adam Barth committed
470 471 472
    return defaultComputeDistanceToHighestActualBaseline(baseline);
  }

473
  double _getMainAxisExtent(Size childSize) {
Adam Barth's avatar
Adam Barth committed
474 475
    switch (direction) {
      case Axis.horizontal:
476
        return childSize.width;
Adam Barth's avatar
Adam Barth committed
477
      case Axis.vertical:
478
        return childSize.height;
Adam Barth's avatar
Adam Barth committed
479 480 481
    }
  }

482
  double _getCrossAxisExtent(Size childSize) {
Adam Barth's avatar
Adam Barth committed
483 484
    switch (direction) {
      case Axis.horizontal:
485
        return childSize.height;
Adam Barth's avatar
Adam Barth committed
486
      case Axis.vertical:
487
        return childSize.width;
Adam Barth's avatar
Adam Barth committed
488 489 490 491 492 493
    }
  }

  Offset _getOffset(double mainAxisOffset, double crossAxisOffset) {
    switch (direction) {
      case Axis.horizontal:
494
        return Offset(mainAxisOffset, crossAxisOffset);
Adam Barth's avatar
Adam Barth committed
495
      case Axis.vertical:
496
        return Offset(crossAxisOffset, mainAxisOffset);
Adam Barth's avatar
Adam Barth committed
497 498 499
    }
  }

500 501
  double _getChildCrossAxisOffset(bool flipCrossAxis, double runCrossAxisExtent, double childCrossAxisExtent) {
    final double freeSpace = runCrossAxisExtent - childCrossAxisExtent;
Adam Barth's avatar
Adam Barth committed
502 503
    switch (crossAxisAlignment) {
      case WrapCrossAlignment.start:
504
        return flipCrossAxis ? freeSpace : 0.0;
Adam Barth's avatar
Adam Barth committed
505
      case WrapCrossAlignment.end:
506 507 508
        return flipCrossAxis ? 0.0 : freeSpace;
      case WrapCrossAlignment.center:
        return freeSpace / 2.0;
Adam Barth's avatar
Adam Barth committed
509 510 511 512 513
    }
  }

  bool _hasVisualOverflow = false;

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
  @override
  Size computeDryLayout(BoxConstraints constraints) {
    return _computeDryLayout(constraints);
  }

  Size _computeDryLayout(BoxConstraints constraints, [ChildLayouter layoutChild = ChildLayoutHelper.dryLayoutChild]) {
    final BoxConstraints childConstraints;
    double mainAxisLimit = 0.0;
    switch (direction) {
      case Axis.horizontal:
        childConstraints = BoxConstraints(maxWidth: constraints.maxWidth);
        mainAxisLimit = constraints.maxWidth;
        break;
      case Axis.vertical:
        childConstraints = BoxConstraints(maxHeight: constraints.maxHeight);
        mainAxisLimit = constraints.maxHeight;
        break;
    }

    double mainAxisExtent = 0.0;
    double crossAxisExtent = 0.0;
    double runMainAxisExtent = 0.0;
    double runCrossAxisExtent = 0.0;
    int childCount = 0;
    RenderBox? child = firstChild;
    while (child != null) {
      final Size childSize = layoutChild(child, childConstraints);
      final double childMainAxisExtent = _getMainAxisExtent(childSize);
      final double childCrossAxisExtent = _getCrossAxisExtent(childSize);
      // There must be at least one child before we move on to the next run.
      if (childCount > 0 && runMainAxisExtent + childMainAxisExtent + spacing > mainAxisLimit) {
        mainAxisExtent = math.max(mainAxisExtent, runMainAxisExtent);
        crossAxisExtent += runCrossAxisExtent + runSpacing;
        runMainAxisExtent = 0.0;
        runCrossAxisExtent = 0.0;
        childCount = 0;
      }
      runMainAxisExtent += childMainAxisExtent;
      runCrossAxisExtent = math.max(runCrossAxisExtent, childCrossAxisExtent);
      if (childCount > 0)
        runMainAxisExtent += spacing;
      childCount += 1;
      child = childAfter(child);
    }
    crossAxisExtent += runCrossAxisExtent;
    mainAxisExtent = math.max(mainAxisExtent, runMainAxisExtent);

    switch (direction) {
      case Axis.horizontal:
        return constraints.constrain(Size(mainAxisExtent, crossAxisExtent));
      case Axis.vertical:
        return constraints.constrain(Size(crossAxisExtent, mainAxisExtent));
    }
  }

Adam Barth's avatar
Adam Barth committed
569 570
  @override
  void performLayout() {
571
    final BoxConstraints constraints = this.constraints;
572
    assert(_debugHasNecessaryDirections);
Adam Barth's avatar
Adam Barth committed
573
    _hasVisualOverflow = false;
574
    RenderBox? child = firstChild;
Adam Barth's avatar
Adam Barth committed
575 576 577 578
    if (child == null) {
      size = constraints.smallest;
      return;
    }
579
    final BoxConstraints childConstraints;
Adam Barth's avatar
Adam Barth committed
580
    double mainAxisLimit = 0.0;
581 582
    bool flipMainAxis = false;
    bool flipCrossAxis = false;
Adam Barth's avatar
Adam Barth committed
583 584
    switch (direction) {
      case Axis.horizontal:
585
        childConstraints = BoxConstraints(maxWidth: constraints.maxWidth);
Adam Barth's avatar
Adam Barth committed
586
        mainAxisLimit = constraints.maxWidth;
587 588 589 590
        if (textDirection == TextDirection.rtl)
          flipMainAxis = true;
        if (verticalDirection == VerticalDirection.up)
          flipCrossAxis = true;
Adam Barth's avatar
Adam Barth committed
591 592
        break;
      case Axis.vertical:
593
        childConstraints = BoxConstraints(maxHeight: constraints.maxHeight);
Adam Barth's avatar
Adam Barth committed
594
        mainAxisLimit = constraints.maxHeight;
595 596 597 598
        if (verticalDirection == VerticalDirection.up)
          flipMainAxis = true;
        if (textDirection == TextDirection.rtl)
          flipCrossAxis = true;
Adam Barth's avatar
Adam Barth committed
599 600 601 602
        break;
    }
    assert(childConstraints != null);
    assert(mainAxisLimit != null);
603 604
    final double spacing = this.spacing;
    final double runSpacing = this.runSpacing;
Adam Barth's avatar
Adam Barth committed
605 606 607 608 609 610 611 612
    final List<_RunMetrics> runMetrics = <_RunMetrics>[];
    double mainAxisExtent = 0.0;
    double crossAxisExtent = 0.0;
    double runMainAxisExtent = 0.0;
    double runCrossAxisExtent = 0.0;
    int childCount = 0;
    while (child != null) {
      child.layout(childConstraints, parentUsesSize: true);
613 614
      final double childMainAxisExtent = _getMainAxisExtent(child.size);
      final double childCrossAxisExtent = _getCrossAxisExtent(child.size);
615
      if (childCount > 0 && runMainAxisExtent + spacing + childMainAxisExtent > mainAxisLimit) {
Adam Barth's avatar
Adam Barth committed
616 617 618 619
        mainAxisExtent = math.max(mainAxisExtent, runMainAxisExtent);
        crossAxisExtent += runCrossAxisExtent;
        if (runMetrics.isNotEmpty)
          crossAxisExtent += runSpacing;
620
        runMetrics.add(_RunMetrics(runMainAxisExtent, runCrossAxisExtent, childCount));
Adam Barth's avatar
Adam Barth committed
621 622 623 624 625 626 627 628 629
        runMainAxisExtent = 0.0;
        runCrossAxisExtent = 0.0;
        childCount = 0;
      }
      runMainAxisExtent += childMainAxisExtent;
      if (childCount > 0)
        runMainAxisExtent += spacing;
      runCrossAxisExtent = math.max(runCrossAxisExtent, childCrossAxisExtent);
      childCount += 1;
630
      final WrapParentData childParentData = child.parentData! as WrapParentData;
Adam Barth's avatar
Adam Barth committed
631 632 633 634 635
      childParentData._runIndex = runMetrics.length;
      child = childParentData.nextSibling;
    }
    if (childCount > 0) {
      mainAxisExtent = math.max(mainAxisExtent, runMainAxisExtent);
636 637 638
      crossAxisExtent += runCrossAxisExtent;
      if (runMetrics.isNotEmpty)
        crossAxisExtent += runSpacing;
639
      runMetrics.add(_RunMetrics(runMainAxisExtent, runCrossAxisExtent, childCount));
Adam Barth's avatar
Adam Barth committed
640 641 642 643 644 645 646 647 648 649
    }

    final int runCount = runMetrics.length;
    assert(runCount > 0);

    double containerMainAxisExtent = 0.0;
    double containerCrossAxisExtent = 0.0;

    switch (direction) {
      case Axis.horizontal:
650
        size = constraints.constrain(Size(mainAxisExtent, crossAxisExtent));
Adam Barth's avatar
Adam Barth committed
651 652 653 654
        containerMainAxisExtent = size.width;
        containerCrossAxisExtent = size.height;
        break;
      case Axis.vertical:
655
        size = constraints.constrain(Size(crossAxisExtent, mainAxisExtent));
Adam Barth's avatar
Adam Barth committed
656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687
        containerMainAxisExtent = size.height;
        containerCrossAxisExtent = size.width;
        break;
    }

    _hasVisualOverflow = containerMainAxisExtent < mainAxisExtent || containerCrossAxisExtent < crossAxisExtent;

    final double crossAxisFreeSpace = math.max(0.0, containerCrossAxisExtent - crossAxisExtent);
    double runLeadingSpace = 0.0;
    double runBetweenSpace = 0.0;
    switch (runAlignment) {
      case WrapAlignment.start:
        break;
      case WrapAlignment.end:
        runLeadingSpace = crossAxisFreeSpace;
        break;
      case WrapAlignment.center:
        runLeadingSpace = crossAxisFreeSpace / 2.0;
        break;
      case WrapAlignment.spaceBetween:
        runBetweenSpace = runCount > 1 ? crossAxisFreeSpace / (runCount - 1) : 0.0;
        break;
      case WrapAlignment.spaceAround:
        runBetweenSpace = crossAxisFreeSpace / runCount;
        runLeadingSpace = runBetweenSpace / 2.0;
        break;
      case WrapAlignment.spaceEvenly:
        runBetweenSpace = crossAxisFreeSpace / (runCount + 1);
        runLeadingSpace = runBetweenSpace;
        break;
    }

688 689 690
    runBetweenSpace += runSpacing;
    double crossAxisOffset = flipCrossAxis ? containerCrossAxisExtent - runLeadingSpace : runLeadingSpace;

Adam Barth's avatar
Adam Barth committed
691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723
    child = firstChild;
    for (int i = 0; i < runCount; ++i) {
      final _RunMetrics metrics = runMetrics[i];
      final double runMainAxisExtent = metrics.mainAxisExtent;
      final double runCrossAxisExtent = metrics.crossAxisExtent;
      final int childCount = metrics.childCount;

      final double mainAxisFreeSpace = math.max(0.0, containerMainAxisExtent - runMainAxisExtent);
      double childLeadingSpace = 0.0;
      double childBetweenSpace = 0.0;

      switch (alignment) {
        case WrapAlignment.start:
          break;
        case WrapAlignment.end:
          childLeadingSpace = mainAxisFreeSpace;
          break;
        case WrapAlignment.center:
          childLeadingSpace = mainAxisFreeSpace / 2.0;
          break;
        case WrapAlignment.spaceBetween:
          childBetweenSpace = childCount > 1 ? mainAxisFreeSpace / (childCount - 1) : 0.0;
          break;
        case WrapAlignment.spaceAround:
          childBetweenSpace = mainAxisFreeSpace / childCount;
          childLeadingSpace = childBetweenSpace / 2.0;
          break;
        case WrapAlignment.spaceEvenly:
          childBetweenSpace = mainAxisFreeSpace / (childCount + 1);
          childLeadingSpace = childBetweenSpace;
          break;
      }

724 725 726 727 728 729
      childBetweenSpace += spacing;
      double childMainPosition = flipMainAxis ? containerMainAxisExtent - childLeadingSpace : childLeadingSpace;

      if (flipCrossAxis)
        crossAxisOffset -= runCrossAxisExtent;

Adam Barth's avatar
Adam Barth committed
730
      while (child != null) {
731
        final WrapParentData childParentData = child.parentData! as WrapParentData;
Adam Barth's avatar
Adam Barth committed
732 733
        if (childParentData._runIndex != i)
          break;
734 735
        final double childMainAxisExtent = _getMainAxisExtent(child.size);
        final double childCrossAxisExtent = _getCrossAxisExtent(child.size);
736 737 738 739 740 741 742 743
        final double childCrossAxisOffset = _getChildCrossAxisOffset(flipCrossAxis, runCrossAxisExtent, childCrossAxisExtent);
        if (flipMainAxis)
          childMainPosition -= childMainAxisExtent;
        childParentData.offset = _getOffset(childMainPosition, crossAxisOffset + childCrossAxisOffset);
        if (flipMainAxis)
          childMainPosition -= childBetweenSpace;
        else
          childMainPosition += childMainAxisExtent + childBetweenSpace;
Adam Barth's avatar
Adam Barth committed
744 745 746
        child = childParentData.nextSibling;
      }

747 748 749 750
      if (flipCrossAxis)
        crossAxisOffset -= runBetweenSpace;
      else
        crossAxisOffset += runCrossAxisExtent + runBetweenSpace;
Adam Barth's avatar
Adam Barth committed
751 752 753 754
    }
  }

  @override
755
  bool hitTestChildren(BoxHitTestResult result, { required Offset position }) {
Adam Barth's avatar
Adam Barth committed
756 757 758 759 760 761 762
    return defaultHitTestChildren(result, position: position);
  }

  @override
  void paint(PaintingContext context, Offset offset) {
    // TODO(ianh): move the debug flex overflow paint logic somewhere common so
    // it can be reused here
763
    if (_hasVisualOverflow && clipBehavior != Clip.none) {
764
      _clipRectLayer.layer = context.pushClipRect(
765 766 767 768 769
        needsCompositing,
        offset,
        Offset.zero & size,
        defaultPaint,
        clipBehavior: clipBehavior,
770
        oldLayer: _clipRectLayer.layer,
771
      );
772
    } else {
773
      _clipRectLayer.layer = null;
Adam Barth's avatar
Adam Barth committed
774
      defaultPaint(context, offset);
775
    }
Adam Barth's avatar
Adam Barth committed
776 777
  }

778 779 780 781 782 783 784
  final LayerHandle<ClipRectLayer> _clipRectLayer = LayerHandle<ClipRectLayer>();

  @override
  void dispose() {
    _clipRectLayer.layer = null;
    super.dispose();
  }
785

Adam Barth's avatar
Adam Barth committed
786
  @override
787 788
  void debugFillProperties(DiagnosticPropertiesBuilder properties) {
    super.debugFillProperties(properties);
789 790 791 792 793 794 795 796
    properties.add(EnumProperty<Axis>('direction', direction));
    properties.add(EnumProperty<WrapAlignment>('alignment', alignment));
    properties.add(DoubleProperty('spacing', spacing));
    properties.add(EnumProperty<WrapAlignment>('runAlignment', runAlignment));
    properties.add(DoubleProperty('runSpacing', runSpacing));
    properties.add(DoubleProperty('crossAxisAlignment', runSpacing));
    properties.add(EnumProperty<TextDirection>('textDirection', textDirection, defaultValue: null));
    properties.add(EnumProperty<VerticalDirection>('verticalDirection', verticalDirection, defaultValue: VerticalDirection.down));
Adam Barth's avatar
Adam Barth committed
797 798
  }
}