BlockFormattingContext.cpp 62 KB

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  1. /*
  2. * Copyright (c) 2020-2022, Andreas Kling <kling@serenityos.org>
  3. *
  4. * SPDX-License-Identifier: BSD-2-Clause
  5. */
  6. #include <AK/TemporaryChange.h>
  7. #include <LibWeb/CSS/Length.h>
  8. #include <LibWeb/DOM/Node.h>
  9. #include <LibWeb/Dump.h>
  10. #include <LibWeb/HTML/BrowsingContext.h>
  11. #include <LibWeb/Layout/BlockContainer.h>
  12. #include <LibWeb/Layout/BlockFormattingContext.h>
  13. #include <LibWeb/Layout/Box.h>
  14. #include <LibWeb/Layout/InlineFormattingContext.h>
  15. #include <LibWeb/Layout/LineBuilder.h>
  16. #include <LibWeb/Layout/ListItemBox.h>
  17. #include <LibWeb/Layout/ListItemMarkerBox.h>
  18. #include <LibWeb/Layout/ReplacedBox.h>
  19. #include <LibWeb/Layout/SVGSVGBox.h>
  20. #include <LibWeb/Layout/TableWrapper.h>
  21. #include <LibWeb/Layout/Viewport.h>
  22. namespace Web::Layout {
  23. BlockFormattingContext::BlockFormattingContext(LayoutState& state, BlockContainer const& root, FormattingContext* parent)
  24. : FormattingContext(Type::Block, state, root, parent)
  25. {
  26. }
  27. BlockFormattingContext::~BlockFormattingContext()
  28. {
  29. if (!m_was_notified_after_parent_dimensioned_my_root_box) {
  30. // HACK: The parent formatting context never notified us after assigning dimensions to our root box.
  31. // Pretend that it did anyway, to make sure absolutely positioned children get laid out.
  32. // FIXME: Get rid of this hack once parent contexts behave properly.
  33. parent_context_did_dimension_child_root_box();
  34. }
  35. }
  36. CSSPixels BlockFormattingContext::automatic_content_width() const
  37. {
  38. if (root().children_are_inline())
  39. return m_state.get(root()).content_width();
  40. return greatest_child_width(root());
  41. }
  42. CSSPixels BlockFormattingContext::automatic_content_height() const
  43. {
  44. return compute_auto_height_for_block_formatting_context_root(root());
  45. }
  46. static bool margins_collapse_through(Box const& box, LayoutState& state)
  47. {
  48. // FIXME: A box's own margins collapse if the 'min-height' property is zero, and it has neither top or bottom borders
  49. // nor top or bottom padding, and it has a 'height' of either 0 or 'auto', and it does not contain a line box, and
  50. // all of its in-flow children's margins (if any) collapse.
  51. // https://www.w3.org/TR/CSS22/box.html#collapsing-margins
  52. // FIXME: For the purpose of margin collapsing (CSS 2 §8.3.1 Collapsing margins), if the block axis is the
  53. // ratio-dependent axis, it is not considered to have a computed block-size of auto.
  54. // https://www.w3.org/TR/css-sizing-4/#aspect-ratio-margin-collapse
  55. if (box.computed_values().clear() != CSS::Clear::None)
  56. return false;
  57. return state.get(box).border_box_height() == 0;
  58. }
  59. void BlockFormattingContext::run(Box const&, LayoutMode layout_mode, AvailableSpace const& available_space)
  60. {
  61. if (is<Viewport>(root())) {
  62. layout_viewport(layout_mode, available_space);
  63. return;
  64. }
  65. if (root().children_are_inline())
  66. layout_inline_children(root(), layout_mode, available_space);
  67. else
  68. layout_block_level_children(root(), layout_mode, available_space);
  69. // Assign collapsed margin left after children layout of formatting context to the last child box
  70. if (m_margin_state.current_collapsed_margin() != 0) {
  71. for (auto* child_box = root().last_child_of_type<Box>(); child_box; child_box = child_box->previous_sibling_of_type<Box>()) {
  72. if (child_box->is_absolutely_positioned() || child_box->is_floating())
  73. continue;
  74. if (margins_collapse_through(*child_box, m_state))
  75. continue;
  76. m_state.get_mutable(*child_box).margin_bottom = m_margin_state.current_collapsed_margin();
  77. break;
  78. }
  79. }
  80. }
  81. void BlockFormattingContext::parent_context_did_dimension_child_root_box()
  82. {
  83. m_was_notified_after_parent_dimensioned_my_root_box = true;
  84. // Left-side floats: offset_from_edge is from left edge (0) to left content edge of floating_box.
  85. for (auto& floating_box : m_left_floats.all_boxes) {
  86. auto& box_state = m_state.get_mutable(floating_box->box);
  87. box_state.set_content_x(floating_box->offset_from_edge);
  88. }
  89. // Right-side floats: offset_from_edge is from right edge (float_containing_block_width) to the left content edge of floating_box.
  90. for (auto& floating_box : m_right_floats.all_boxes) {
  91. auto float_containing_block_width = containing_block_width_for(floating_box->box);
  92. auto& box_state = m_state.get_mutable(floating_box->box);
  93. box_state.set_content_x(float_containing_block_width - floating_box->offset_from_edge);
  94. }
  95. // We can also layout absolutely positioned boxes within this BFC.
  96. for (auto& box : m_absolutely_positioned_boxes) {
  97. auto& cb_state = m_state.get(*box->containing_block());
  98. auto available_width = AvailableSize::make_definite(cb_state.content_width() + cb_state.padding_left + cb_state.padding_right);
  99. auto available_height = AvailableSize::make_definite(cb_state.content_height() + cb_state.padding_top + cb_state.padding_bottom);
  100. layout_absolutely_positioned_element(box, AvailableSpace(available_width, available_height));
  101. }
  102. }
  103. bool BlockFormattingContext::box_should_avoid_floats_because_it_establishes_fc(Box const& box)
  104. {
  105. if (auto formatting_context_type = formatting_context_type_created_by_box(box); formatting_context_type.has_value()) {
  106. if (formatting_context_type.value() == Type::Block)
  107. return true;
  108. if (formatting_context_type.value() == Type::Flex)
  109. return true;
  110. if (formatting_context_type.value() == Type::Grid)
  111. return true;
  112. }
  113. return false;
  114. }
  115. void BlockFormattingContext::compute_width(Box const& box, AvailableSpace const& available_space, LayoutMode)
  116. {
  117. if (box.is_absolutely_positioned()) {
  118. compute_width_for_absolutely_positioned_element(box, available_space);
  119. return;
  120. }
  121. auto remaining_available_space = available_space;
  122. if (available_space.width.is_definite() && box_should_avoid_floats_because_it_establishes_fc(box)) {
  123. // NOTE: Although CSS 2.2 specification says that only block formatting contexts should avoid floats,
  124. // we also do this for flex and grid formatting contexts, because that how other engines behave.
  125. // 9.5 Floats
  126. // The border box of a table, a block-level replaced element, or an element in the normal flow that establishes a
  127. // new block formatting context (such as an element with 'overflow' other than 'visible') must not overlap the margin
  128. // box of any floats in the same block formatting context as the element itself. If necessary, implementations should
  129. // clear the said element by placing it below any preceding floats, but may place it adjacent to such floats if there is
  130. // sufficient space. They may even make the border box of said element narrower than defined by section 10.3.3.
  131. // CSS2 does not define when a UA may put said element next to the float or by how much said element may
  132. // become narrower.
  133. auto intrusion = intrusion_by_floats_into_box(box, 0);
  134. auto remaining_width = available_space.width.to_px_or_zero() - intrusion.left - intrusion.right;
  135. remaining_available_space.width = AvailableSize::make_definite(remaining_width);
  136. }
  137. if (box_is_sized_as_replaced_element(box)) {
  138. // FIXME: This should not be done *by* ReplacedBox
  139. if (is<ReplacedBox>(box)) {
  140. auto& replaced = verify_cast<ReplacedBox>(box);
  141. // FIXME: This const_cast is gross.
  142. const_cast<ReplacedBox&>(replaced).prepare_for_replaced_layout();
  143. }
  144. compute_width_for_block_level_replaced_element_in_normal_flow(box, remaining_available_space);
  145. if (box.is_floating()) {
  146. // 10.3.6 Floating, replaced elements:
  147. // https://www.w3.org/TR/CSS22/visudet.html#float-replaced-width
  148. return;
  149. }
  150. }
  151. if (box.is_floating()) {
  152. // 10.3.5 Floating, non-replaced elements:
  153. // https://www.w3.org/TR/CSS22/visudet.html#float-width
  154. compute_width_for_floating_box(box, available_space);
  155. return;
  156. }
  157. auto const& computed_values = box.computed_values();
  158. auto width_of_containing_block = remaining_available_space.width.to_px_or_zero();
  159. auto zero_value = CSS::Length::make_px(0);
  160. auto margin_left = CSS::Length::make_auto();
  161. auto margin_right = CSS::Length::make_auto();
  162. auto const padding_left = computed_values.padding().left().resolved(box, width_of_containing_block).to_px(box);
  163. auto const padding_right = computed_values.padding().right().resolved(box, width_of_containing_block).to_px(box);
  164. auto& box_state = m_state.get_mutable(box);
  165. box_state.border_left = computed_values.border_left().width;
  166. box_state.border_right = computed_values.border_right().width;
  167. box_state.padding_left = padding_left;
  168. box_state.padding_right = padding_right;
  169. // NOTE: If we are calculating the min-content or max-content width of this box,
  170. // and the width should be treated as auto, then we can simply return here,
  171. // as the preferred width and min/max constraints are irrelevant for intrinsic sizing.
  172. if (box_state.width_constraint != SizeConstraint::None)
  173. return;
  174. auto try_compute_width = [&](CSS::Length const& a_width) {
  175. CSS::Length width = a_width;
  176. margin_left = computed_values.margin().left().resolved(box, width_of_containing_block);
  177. margin_right = computed_values.margin().right().resolved(box, width_of_containing_block);
  178. CSSPixels total_px = computed_values.border_left().width + computed_values.border_right().width;
  179. for (auto& value : { margin_left, CSS::Length::make_px(padding_left), width, CSS::Length::make_px(padding_right), margin_right }) {
  180. total_px += value.to_px(box);
  181. }
  182. if (!box.is_inline()) {
  183. // 10.3.3 Block-level, non-replaced elements in normal flow
  184. // If 'width' is not 'auto' and 'border-left-width' + 'padding-left' + 'width' + 'padding-right' + 'border-right-width' (plus any of 'margin-left' or 'margin-right' that are not 'auto') is larger than the width of the containing block, then any 'auto' values for 'margin-left' or 'margin-right' are, for the following rules, treated as zero.
  185. if (!width.is_auto() && total_px > width_of_containing_block) {
  186. if (margin_left.is_auto())
  187. margin_left = zero_value;
  188. if (margin_right.is_auto())
  189. margin_right = zero_value;
  190. }
  191. // 10.3.3 cont'd.
  192. auto underflow_px = width_of_containing_block - total_px;
  193. if (available_space.width.is_intrinsic_sizing_constraint())
  194. underflow_px = 0;
  195. if (width.is_auto()) {
  196. if (margin_left.is_auto())
  197. margin_left = zero_value;
  198. if (margin_right.is_auto())
  199. margin_right = zero_value;
  200. if (available_space.width.is_definite()) {
  201. if (underflow_px >= 0) {
  202. width = CSS::Length::make_px(underflow_px);
  203. } else {
  204. width = zero_value;
  205. margin_right = CSS::Length::make_px(margin_right.to_px(box) + underflow_px);
  206. }
  207. }
  208. } else {
  209. if (!margin_left.is_auto() && !margin_right.is_auto()) {
  210. margin_right = CSS::Length::make_px(margin_right.to_px(box) + underflow_px);
  211. } else if (!margin_left.is_auto() && margin_right.is_auto()) {
  212. margin_right = CSS::Length::make_px(underflow_px);
  213. } else if (margin_left.is_auto() && !margin_right.is_auto()) {
  214. margin_left = CSS::Length::make_px(underflow_px);
  215. } else { // margin_left.is_auto() && margin_right.is_auto()
  216. auto half_of_the_underflow = CSS::Length::make_px(underflow_px / 2);
  217. margin_left = half_of_the_underflow;
  218. margin_right = half_of_the_underflow;
  219. }
  220. }
  221. }
  222. return width;
  223. };
  224. auto input_width = [&] {
  225. if (box_is_sized_as_replaced_element(box)) {
  226. // NOTE: Replaced elements had their width calculated independently above.
  227. // We use that width as the input here to ensure that margins get resolved.
  228. return CSS::Length::make_px(box_state.content_width());
  229. }
  230. if (is<TableWrapper>(box))
  231. return CSS::Length::make_px(compute_table_box_width_inside_table_wrapper(box, remaining_available_space));
  232. if (should_treat_width_as_auto(box, remaining_available_space))
  233. return CSS::Length::make_auto();
  234. return CSS::Length::make_px(calculate_inner_width(box, remaining_available_space.width, computed_values.width()));
  235. }();
  236. // 1. The tentative used width is calculated (without 'min-width' and 'max-width')
  237. auto used_width = try_compute_width(input_width);
  238. // 2. The tentative used width is greater than 'max-width', the rules above are applied again,
  239. // but this time using the computed value of 'max-width' as the computed value for 'width'.
  240. if (!should_treat_max_width_as_none(box, available_space.width)) {
  241. auto max_width = calculate_inner_width(box, remaining_available_space.width, computed_values.max_width());
  242. auto used_width_px = used_width.is_auto() ? CSSPixels { 0 } : used_width.to_px(box);
  243. if (used_width_px > max_width) {
  244. used_width = try_compute_width(CSS::Length::make_px(max_width));
  245. }
  246. }
  247. // 3. If the resulting width is smaller than 'min-width', the rules above are applied again,
  248. // but this time using the value of 'min-width' as the computed value for 'width'.
  249. if (!computed_values.min_width().is_auto()) {
  250. auto min_width = calculate_inner_width(box, remaining_available_space.width, computed_values.min_width());
  251. auto used_width_px = used_width.is_auto() ? remaining_available_space.width : AvailableSize::make_definite(used_width.to_px(box));
  252. if (used_width_px < min_width) {
  253. used_width = try_compute_width(CSS::Length::make_px(min_width));
  254. }
  255. }
  256. if (!box_is_sized_as_replaced_element(box) && !used_width.is_auto())
  257. box_state.set_content_width(used_width.to_px(box));
  258. box_state.margin_left = margin_left.to_px(box);
  259. box_state.margin_right = margin_right.to_px(box);
  260. }
  261. void BlockFormattingContext::compute_width_for_floating_box(Box const& box, AvailableSpace const& available_space)
  262. {
  263. // 10.3.5 Floating, non-replaced elements
  264. auto& computed_values = box.computed_values();
  265. auto zero_value = CSS::Length::make_px(0);
  266. auto width_of_containing_block = available_space.width.to_px_or_zero();
  267. auto margin_left = computed_values.margin().left().resolved(box, width_of_containing_block);
  268. auto margin_right = computed_values.margin().right().resolved(box, width_of_containing_block);
  269. auto const padding_left = computed_values.padding().left().resolved(box, width_of_containing_block).to_px(box);
  270. auto const padding_right = computed_values.padding().right().resolved(box, width_of_containing_block).to_px(box);
  271. // If 'margin-left', or 'margin-right' are computed as 'auto', their used value is '0'.
  272. if (margin_left.is_auto())
  273. margin_left = zero_value;
  274. if (margin_right.is_auto())
  275. margin_right = zero_value;
  276. auto compute_width = [&](auto width) {
  277. // If 'width' is computed as 'auto', the used value is the "shrink-to-fit" width.
  278. if (width.is_auto()) {
  279. auto result = calculate_shrink_to_fit_widths(box);
  280. if (available_space.width.is_definite()) {
  281. // Find the available width: in this case, this is the width of the containing
  282. // block minus the used values of 'margin-left', 'border-left-width', 'padding-left',
  283. // 'padding-right', 'border-right-width', 'margin-right', and the widths of any relevant scroll bars.
  284. auto available_width = available_space.width.to_px_or_zero()
  285. - margin_left.to_px(box) - computed_values.border_left().width - padding_left
  286. - padding_right - computed_values.border_right().width - margin_right.to_px(box);
  287. // Then the shrink-to-fit width is: min(max(preferred minimum width, available width), preferred width).
  288. width = CSS::Length::make_px(min(max(result.preferred_minimum_width, available_width), result.preferred_width));
  289. } else if (available_space.width.is_indefinite() || available_space.width.is_max_content()) {
  290. // Fold the formula for shrink-to-fit width for indefinite and max-content available width.
  291. width = CSS::Length::make_px(result.preferred_width);
  292. } else {
  293. // Fold the formula for shrink-to-fit width for min-content available width.
  294. width = CSS::Length::make_px(min(result.preferred_minimum_width, result.preferred_width));
  295. }
  296. }
  297. return width;
  298. };
  299. auto input_width = [&] {
  300. if (should_treat_width_as_auto(box, available_space))
  301. return CSS::Length::make_auto();
  302. return CSS::Length::make_px(calculate_inner_width(box, available_space.width, computed_values.width()));
  303. }();
  304. // 1. The tentative used width is calculated (without 'min-width' and 'max-width')
  305. auto width = compute_width(input_width);
  306. // 2. The tentative used width is greater than 'max-width', the rules above are applied again,
  307. // but this time using the computed value of 'max-width' as the computed value for 'width'.
  308. if (!should_treat_max_width_as_none(box, available_space.width)) {
  309. auto max_width = calculate_inner_width(box, available_space.width, computed_values.max_width());
  310. if (width.to_px(box) > max_width)
  311. width = compute_width(CSS::Length::make_px(max_width));
  312. }
  313. // 3. If the resulting width is smaller than 'min-width', the rules above are applied again,
  314. // but this time using the value of 'min-width' as the computed value for 'width'.
  315. if (!computed_values.min_width().is_auto()) {
  316. auto min_width = calculate_inner_width(box, available_space.width, computed_values.min_width());
  317. if (width.to_px(box) < min_width)
  318. width = compute_width(CSS::Length::make_px(min_width));
  319. }
  320. auto& box_state = m_state.get_mutable(box);
  321. box_state.set_content_width(width.to_px(box));
  322. box_state.margin_left = margin_left.to_px(box);
  323. box_state.margin_right = margin_right.to_px(box);
  324. box_state.border_left = computed_values.border_left().width;
  325. box_state.border_right = computed_values.border_right().width;
  326. box_state.padding_left = padding_left;
  327. box_state.padding_right = padding_right;
  328. }
  329. void BlockFormattingContext::compute_width_for_block_level_replaced_element_in_normal_flow(Box const& box, AvailableSpace const& available_space)
  330. {
  331. // 10.3.6 Floating, replaced elements
  332. auto& computed_values = box.computed_values();
  333. auto zero_value = CSS::Length::make_px(0);
  334. auto width_of_containing_block = available_space.width.to_px_or_zero();
  335. // 10.3.4 Block-level, replaced elements in normal flow
  336. // The used value of 'width' is determined as for inline replaced elements. Then the rules for
  337. // non-replaced block-level elements are applied to determine the margins.
  338. auto margin_left = computed_values.margin().left().resolved(box, width_of_containing_block);
  339. auto margin_right = computed_values.margin().right().resolved(box, width_of_containing_block);
  340. auto const padding_left = computed_values.padding().left().resolved(box, width_of_containing_block).to_px(box);
  341. auto const padding_right = computed_values.padding().right().resolved(box, width_of_containing_block).to_px(box);
  342. // If 'margin-left', or 'margin-right' are computed as 'auto', their used value is '0'.
  343. if (margin_left.is_auto())
  344. margin_left = zero_value;
  345. if (margin_right.is_auto())
  346. margin_right = zero_value;
  347. auto& box_state = m_state.get_mutable(box);
  348. box_state.set_content_width(compute_width_for_replaced_element(box, available_space));
  349. box_state.margin_left = margin_left.to_px(box);
  350. box_state.margin_right = margin_right.to_px(box);
  351. box_state.border_left = computed_values.border_left().width;
  352. box_state.border_right = computed_values.border_right().width;
  353. box_state.padding_left = padding_left;
  354. box_state.padding_right = padding_right;
  355. }
  356. void BlockFormattingContext::compute_height(Box const& box, AvailableSpace const& available_space)
  357. {
  358. auto const& computed_values = box.computed_values();
  359. auto& box_used_values = m_state.get_mutable(box);
  360. // Then work out what the height is, based on box type and CSS properties.
  361. CSSPixels height = 0;
  362. if (box_is_sized_as_replaced_element(box)) {
  363. height = compute_height_for_replaced_element(box, available_space);
  364. } else {
  365. if (should_treat_height_as_auto(box, available_space)) {
  366. height = compute_auto_height_for_block_level_element(box, m_state.get(box).available_inner_space_or_constraints_from(available_space));
  367. } else {
  368. height = calculate_inner_height(box, available_space.height, computed_values.height());
  369. }
  370. }
  371. if (!should_treat_max_height_as_none(box, available_space.height)) {
  372. if (!computed_values.max_height().is_auto()) {
  373. auto max_height = calculate_inner_height(box, available_space.height, computed_values.max_height());
  374. height = min(height, max_height);
  375. }
  376. }
  377. if (!computed_values.min_height().is_auto()) {
  378. height = max(height, calculate_inner_height(box, available_space.height, computed_values.min_height()));
  379. }
  380. if (box.document().in_quirks_mode()
  381. && box.dom_node()
  382. && box.dom_node()->is_html_html_element()
  383. && box.computed_values().height().is_auto()) {
  384. // 3.6. The html element fills the viewport quirk
  385. // https://quirks.spec.whatwg.org/#the-html-element-fills-the-viewport-quirk
  386. // FIXME: Handle vertical writing mode.
  387. auto& box_state = m_state.get_mutable(box);
  388. // 1. Let margins be sum of the used values of the margin-left and margin-right properties of element
  389. // if element has a vertical writing mode, otherwise let margins be the sum of the used values of
  390. // the margin-top and margin-bottom properties of element.
  391. auto margins = box_state.margin_top + box_state.margin_bottom;
  392. // 2. Let size be the size of the initial containing block in the block flow direction minus margins.
  393. auto size = m_state.get(*box.containing_block()).content_height() - margins;
  394. // 3. Return the bigger value of size and the normal border box size the element would have
  395. // according to the CSS specification.
  396. height = max(size, height);
  397. // NOTE: The height of the root element when affected by this quirk is considered to be definite.
  398. box_used_values.set_has_definite_height(true);
  399. }
  400. box_used_values.set_content_height(height);
  401. }
  402. void BlockFormattingContext::layout_inline_children(BlockContainer const& block_container, LayoutMode layout_mode, AvailableSpace const& available_space)
  403. {
  404. VERIFY(block_container.children_are_inline());
  405. auto& block_container_state = m_state.get_mutable(block_container);
  406. InlineFormattingContext context(m_state, block_container, block_container_state, *this);
  407. context.run(
  408. block_container,
  409. layout_mode,
  410. available_space);
  411. if (!block_container_state.has_definite_width()) {
  412. // NOTE: min-width or max-width for boxes with inline children can only be applied after inside layout
  413. // is done and width of box content is known
  414. auto used_width_px = context.automatic_content_width();
  415. // https://www.w3.org/TR/css-sizing-3/#sizing-values
  416. // Percentages are resolved against the width/height, as appropriate, of the box’s containing block.
  417. auto containing_block_width = m_state.get(*block_container.containing_block()).content_width();
  418. auto available_width = AvailableSize::make_definite(containing_block_width);
  419. if (!should_treat_max_width_as_none(block_container, available_space.width)) {
  420. auto max_width_px = calculate_inner_width(block_container, available_width, block_container.computed_values().max_width());
  421. if (used_width_px > max_width_px)
  422. used_width_px = max_width_px;
  423. }
  424. auto should_treat_min_width_as_auto = [&] {
  425. auto const& available_width = available_space.width;
  426. auto const& min_width = block_container.computed_values().min_width();
  427. if (min_width.is_auto())
  428. return true;
  429. if (min_width.is_fit_content() && available_width.is_intrinsic_sizing_constraint())
  430. return true;
  431. if (min_width.is_max_content() && available_width.is_max_content())
  432. return true;
  433. if (min_width.is_min_content() && available_width.is_min_content())
  434. return true;
  435. return false;
  436. }();
  437. if (!should_treat_min_width_as_auto) {
  438. auto min_width_px = calculate_inner_width(block_container, available_width, block_container.computed_values().min_width());
  439. if (used_width_px < min_width_px)
  440. used_width_px = min_width_px;
  441. }
  442. block_container_state.set_content_width(used_width_px);
  443. block_container_state.set_content_height(context.automatic_content_height());
  444. }
  445. }
  446. CSSPixels BlockFormattingContext::compute_auto_height_for_block_level_element(Box const& box, AvailableSpace const& available_space)
  447. {
  448. if (creates_block_formatting_context(box)) {
  449. return compute_auto_height_for_block_formatting_context_root(box);
  450. }
  451. auto const& box_state = m_state.get(box);
  452. auto display = box.display();
  453. if (display.is_flex_inside()) {
  454. // https://drafts.csswg.org/css-flexbox-1/#algo-main-container
  455. // NOTE: The automatic block size of a block-level flex container is its max-content size.
  456. return calculate_max_content_height(box, available_space.width.to_px_or_zero());
  457. }
  458. if (display.is_grid_inside()) {
  459. // https://www.w3.org/TR/css-grid-2/#intrinsic-sizes
  460. // In both inline and block formatting contexts, the grid container’s auto block size is its
  461. // max-content size.
  462. return calculate_max_content_height(box, available_space.width.to_px_or_zero());
  463. }
  464. if (display.is_table_inside()) {
  465. return calculate_max_content_height(box, available_space.width.to_px_or_zero());
  466. }
  467. // https://www.w3.org/TR/CSS22/visudet.html#normal-block
  468. // 10.6.3 Block-level non-replaced elements in normal flow when 'overflow' computes to 'visible'
  469. // The element's height is the distance from its top content edge to the first applicable of the following:
  470. // 1. the bottom edge of the last line box, if the box establishes a inline formatting context with one or more lines
  471. if (box.children_are_inline() && !box_state.line_boxes.is_empty())
  472. return box_state.line_boxes.last().bottom();
  473. // 2. the bottom edge of the bottom (possibly collapsed) margin of its last in-flow child, if the child's bottom margin does not collapse with the element's bottom margin
  474. // 3. the bottom border edge of the last in-flow child whose top margin doesn't collapse with the element's bottom margin
  475. if (!box.children_are_inline()) {
  476. for (auto* child_box = box.last_child_of_type<Box>(); child_box; child_box = child_box->previous_sibling_of_type<Box>()) {
  477. if (child_box->is_absolutely_positioned() || child_box->is_floating())
  478. continue;
  479. // FIXME: This is hack. If the last child is a list-item marker box, we ignore it for purposes of height calculation.
  480. // Perhaps markers should not be considered in-flow(?) Perhaps they should always be the first child of the list-item
  481. // box instead of the last child.
  482. if (child_box->is_list_item_marker_box())
  483. continue;
  484. auto const& child_box_state = m_state.get(*child_box);
  485. if (margins_collapse_through(*child_box, m_state))
  486. continue;
  487. auto margin_bottom = m_margin_state.current_collapsed_margin();
  488. if (box_state.padding_bottom == 0 && box_state.border_bottom == 0) {
  489. m_margin_state.box_last_in_flow_child_margin_bottom_collapsed = true;
  490. margin_bottom = 0;
  491. }
  492. return max(CSSPixels(0), child_box_state.offset.y() + child_box_state.content_height() + child_box_state.border_box_bottom() + margin_bottom);
  493. }
  494. }
  495. // 4. zero, otherwise
  496. return 0;
  497. }
  498. void BlockFormattingContext::layout_block_level_box(Box const& box, BlockContainer const& block_container, LayoutMode layout_mode, CSSPixels& bottom_of_lowest_margin_box, AvailableSpace const& available_space)
  499. {
  500. auto& box_state = m_state.get_mutable(box);
  501. if (box.is_absolutely_positioned()) {
  502. box_state.vertical_offset_of_parent_block_container = m_y_offset_of_current_block_container.value();
  503. m_absolutely_positioned_boxes.append(box);
  504. return;
  505. }
  506. // NOTE: ListItemMarkerBoxes are placed by their corresponding ListItemBox.
  507. if (is<ListItemMarkerBox>(box))
  508. return;
  509. resolve_vertical_box_model_metrics(box);
  510. if (box.is_floating()) {
  511. auto const y = m_y_offset_of_current_block_container.value();
  512. auto margin_top = !m_margin_state.has_block_container_waiting_for_final_y_position() ? m_margin_state.current_collapsed_margin() : 0;
  513. layout_floating_box(box, block_container, layout_mode, available_space, margin_top + y);
  514. bottom_of_lowest_margin_box = max(bottom_of_lowest_margin_box, box_state.offset.y() + box_state.content_height() + box_state.margin_box_bottom());
  515. return;
  516. }
  517. m_margin_state.add_margin(box_state.margin_top);
  518. auto introduce_clearance = clear_floating_boxes(box, {});
  519. if (introduce_clearance == DidIntroduceClearance::Yes)
  520. m_margin_state.reset();
  521. auto const y = m_y_offset_of_current_block_container.value();
  522. auto box_is_html_element_in_quirks_mode = box.document().in_quirks_mode()
  523. && box.dom_node()
  524. && box.dom_node()->is_html_html_element()
  525. && box.computed_values().height().is_auto();
  526. // NOTE: In quirks mode, the html element's height matches the viewport so it can be treated as definite
  527. if (box_state.has_definite_height() || box_is_html_element_in_quirks_mode) {
  528. compute_height(box, available_space);
  529. }
  530. auto independent_formatting_context = create_independent_formatting_context_if_needed(m_state, box);
  531. if (!independent_formatting_context && !is<BlockContainer>(box)) {
  532. dbgln("FIXME: Block-level box is not BlockContainer but does not create formatting context: {}", box.debug_description());
  533. return;
  534. }
  535. m_margin_state.update_block_waiting_for_final_y_position();
  536. CSSPixels margin_top = m_margin_state.current_collapsed_margin();
  537. if (m_margin_state.has_block_container_waiting_for_final_y_position()) {
  538. // If first child margin top will collapse with margin-top of containing block then margin-top of child is 0
  539. margin_top = 0;
  540. }
  541. if (independent_formatting_context) {
  542. // Margins of elements that establish new formatting contexts do not collapse with their in-flow children
  543. m_margin_state.reset();
  544. }
  545. place_block_level_element_in_normal_flow_vertically(box, y + margin_top);
  546. compute_width(box, available_space, layout_mode);
  547. place_block_level_element_in_normal_flow_horizontally(box, available_space);
  548. // NOTE: Flex containers with `auto` height are treated as `max-content`, so we can compute their height early.
  549. if (box.is_replaced_box() || box.display().is_flex_inside())
  550. compute_height(box, available_space);
  551. if (independent_formatting_context) {
  552. // This box establishes a new formatting context. Pass control to it.
  553. independent_formatting_context->run(box, layout_mode, box_state.available_inner_space_or_constraints_from(available_space));
  554. } else {
  555. // This box participates in the current block container's flow.
  556. if (box.children_are_inline()) {
  557. layout_inline_children(verify_cast<BlockContainer>(box), layout_mode, box_state.available_inner_space_or_constraints_from(available_space));
  558. } else {
  559. if (box_state.border_top > 0 || box_state.padding_top > 0) {
  560. // margin-top of block container can't collapse with it's children if it has non zero border or padding
  561. m_margin_state.reset();
  562. } else if (!m_margin_state.has_block_container_waiting_for_final_y_position()) {
  563. // margin-top of block container can be updated during children layout hence it's final y position yet to be determined
  564. m_margin_state.register_block_container_y_position_update_callback([&](CSSPixels margin_top) {
  565. if (introduce_clearance == DidIntroduceClearance::No) {
  566. place_block_level_element_in_normal_flow_vertically(box, margin_top + y);
  567. }
  568. });
  569. }
  570. layout_block_level_children(verify_cast<BlockContainer>(box), layout_mode, box_state.available_inner_space_or_constraints_from(available_space));
  571. }
  572. }
  573. // Tables already set their height during the independent formatting context run. When multi-line text cells are involved, using different
  574. // available space here than during the independent formatting context run can result in different line breaks and thus a different height.
  575. if (!box.display().is_table_inside()) {
  576. compute_height(box, available_space);
  577. }
  578. if (independent_formatting_context || !margins_collapse_through(box, m_state)) {
  579. if (!m_margin_state.box_last_in_flow_child_margin_bottom_collapsed) {
  580. m_margin_state.reset();
  581. }
  582. m_y_offset_of_current_block_container = box_state.offset.y() + box_state.content_height() + box_state.border_box_bottom();
  583. }
  584. m_margin_state.box_last_in_flow_child_margin_bottom_collapsed = false;
  585. m_margin_state.add_margin(box_state.margin_bottom);
  586. m_margin_state.update_block_waiting_for_final_y_position();
  587. compute_inset(box);
  588. if (is<ListItemBox>(box)) {
  589. layout_list_item_marker(static_cast<ListItemBox const&>(box));
  590. }
  591. bottom_of_lowest_margin_box = max(bottom_of_lowest_margin_box, box_state.offset.y() + box_state.content_height() + box_state.margin_box_bottom());
  592. if (independent_formatting_context)
  593. independent_formatting_context->parent_context_did_dimension_child_root_box();
  594. }
  595. void BlockFormattingContext::layout_block_level_children(BlockContainer const& block_container, LayoutMode layout_mode, AvailableSpace const& available_space)
  596. {
  597. VERIFY(!block_container.children_are_inline());
  598. CSSPixels bottom_of_lowest_margin_box = 0;
  599. TemporaryChange<Optional<CSSPixels>> change { m_y_offset_of_current_block_container, CSSPixels(0) };
  600. block_container.for_each_child_of_type<Box>([&](Box& box) {
  601. layout_block_level_box(box, block_container, layout_mode, bottom_of_lowest_margin_box, available_space);
  602. return IterationDecision::Continue;
  603. });
  604. m_margin_state.block_container_y_position_update_callback = {};
  605. if (layout_mode == LayoutMode::IntrinsicSizing) {
  606. auto& block_container_state = m_state.get_mutable(block_container);
  607. if (!block_container_state.has_definite_width()) {
  608. auto width = greatest_child_width(block_container);
  609. auto const& computed_values = block_container.computed_values();
  610. // NOTE: Min and max constraints are not applied to a box that is being sized as intrinsic because
  611. // according to css-sizing-3 spec:
  612. // The min-content size of a box in each axis is the size it would have if it was a float given an
  613. // auto size in that axis (and no minimum or maximum size in that axis) and if its containing block
  614. // was zero-sized in that axis.
  615. if (block_container_state.width_constraint == SizeConstraint::None) {
  616. if (!should_treat_max_width_as_none(block_container, available_space.width)) {
  617. auto max_width = calculate_inner_width(block_container, available_space.width,
  618. computed_values.max_width());
  619. width = min(width, max_width);
  620. }
  621. if (!computed_values.min_width().is_auto()) {
  622. auto min_width = calculate_inner_width(block_container, available_space.width,
  623. computed_values.min_width());
  624. width = max(width, min_width);
  625. }
  626. }
  627. block_container_state.set_content_width(width);
  628. block_container_state.set_content_height(bottom_of_lowest_margin_box);
  629. }
  630. }
  631. }
  632. void BlockFormattingContext::resolve_vertical_box_model_metrics(Box const& box)
  633. {
  634. auto& box_state = m_state.get_mutable(box);
  635. auto const& computed_values = box.computed_values();
  636. auto width_of_containing_block = containing_block_width_for(box);
  637. box_state.margin_top = computed_values.margin().top().to_px(box, width_of_containing_block);
  638. box_state.margin_bottom = computed_values.margin().bottom().to_px(box, width_of_containing_block);
  639. box_state.border_top = computed_values.border_top().width;
  640. box_state.border_bottom = computed_values.border_bottom().width;
  641. box_state.padding_top = computed_values.padding().top().to_px(box, width_of_containing_block);
  642. box_state.padding_bottom = computed_values.padding().bottom().to_px(box, width_of_containing_block);
  643. }
  644. CSSPixels BlockFormattingContext::BlockMarginState::current_collapsed_margin() const
  645. {
  646. CSSPixels smallest_margin = 0;
  647. CSSPixels largest_margin = 0;
  648. size_t negative_margin_count = 0;
  649. for (auto margin : current_collapsible_margins) {
  650. if (margin < 0)
  651. ++negative_margin_count;
  652. largest_margin = max(largest_margin, margin);
  653. smallest_margin = min(smallest_margin, margin);
  654. }
  655. CSSPixels collapsed_margin = 0;
  656. if (negative_margin_count == current_collapsible_margins.size()) {
  657. // When all margins are negative, the size of the collapsed margin is the smallest (most negative) margin.
  658. collapsed_margin = smallest_margin;
  659. } else if (negative_margin_count > 0) {
  660. // When negative margins are involved, the size of the collapsed margin is the sum of the largest positive margin and the smallest (most negative) negative margin.
  661. collapsed_margin = largest_margin + smallest_margin;
  662. } else {
  663. // Otherwise, collapse all the adjacent margins by using only the largest one.
  664. collapsed_margin = largest_margin;
  665. }
  666. return collapsed_margin;
  667. }
  668. BlockFormattingContext::DidIntroduceClearance BlockFormattingContext::clear_floating_boxes(Node const& child_box, Optional<InlineFormattingContext&> inline_formatting_context)
  669. {
  670. auto const& computed_values = child_box.computed_values();
  671. auto result = DidIntroduceClearance::No;
  672. auto clear_floating_boxes = [&](FloatSideData& float_side) {
  673. if (!float_side.current_boxes.is_empty()) {
  674. // NOTE: Floating boxes are globally relevant within this BFC, *but* their offset coordinates
  675. // are relative to their containing block.
  676. // This means that we have to first convert to a root-space Y coordinate before clearing,
  677. // and then convert back to a local Y coordinate when assigning the cleared offset to
  678. // the `child_box` layout state.
  679. // First, find the lowest margin box edge on this float side and calculate the Y offset just below it.
  680. CSSPixels clearance_y_in_root = 0;
  681. for (auto const& floating_box : float_side.current_boxes) {
  682. auto floating_box_rect_in_root = margin_box_rect_in_ancestor_coordinate_space(floating_box.used_values, root());
  683. clearance_y_in_root = max(clearance_y_in_root, floating_box_rect_in_root.bottom());
  684. }
  685. // Then, convert the clearance Y to a coordinate relative to the containing block of `child_box`.
  686. CSSPixels clearance_y_in_containing_block = clearance_y_in_root;
  687. for (auto* containing_block = child_box.containing_block(); containing_block && containing_block != &root(); containing_block = containing_block->containing_block())
  688. clearance_y_in_containing_block -= m_state.get(*containing_block).offset.y();
  689. if (inline_formatting_context.has_value()) {
  690. if (clearance_y_in_containing_block > inline_formatting_context->vertical_float_clearance()) {
  691. result = DidIntroduceClearance::Yes;
  692. inline_formatting_context->set_vertical_float_clearance(clearance_y_in_containing_block);
  693. }
  694. } else if (clearance_y_in_containing_block > m_y_offset_of_current_block_container.value()) {
  695. result = DidIntroduceClearance::Yes;
  696. m_y_offset_of_current_block_container = clearance_y_in_containing_block;
  697. }
  698. float_side.clear();
  699. }
  700. };
  701. if (computed_values.clear() == CSS::Clear::Left || computed_values.clear() == CSS::Clear::Both)
  702. clear_floating_boxes(m_left_floats);
  703. if (computed_values.clear() == CSS::Clear::Right || computed_values.clear() == CSS::Clear::Both)
  704. clear_floating_boxes(m_right_floats);
  705. return result;
  706. }
  707. void BlockFormattingContext::place_block_level_element_in_normal_flow_vertically(Box const& child_box, CSSPixels y)
  708. {
  709. auto& box_state = m_state.get_mutable(child_box);
  710. y += box_state.border_box_top();
  711. box_state.set_content_offset(CSSPixelPoint { box_state.offset.x(), y });
  712. }
  713. // Returns whether the given box has the given ancestor on the path to root, ignoring the anonymous blocks.
  714. static bool box_has_ancestor_in_non_anonymous_containing_block_chain(Box const* box, Box const& ancestor, Box const& root)
  715. {
  716. Box const* current_ancestor = box ? box->non_anonymous_containing_block() : &root;
  717. while (current_ancestor != &root) {
  718. if (current_ancestor == &ancestor)
  719. return true;
  720. current_ancestor = current_ancestor->non_anonymous_containing_block();
  721. }
  722. return false;
  723. }
  724. void BlockFormattingContext::place_block_level_element_in_normal_flow_horizontally(Box const& child_box, AvailableSpace const& available_space)
  725. {
  726. auto& box_state = m_state.get_mutable(child_box);
  727. CSSPixels x = 0;
  728. CSSPixels available_width_within_containing_block = available_space.width.to_px_or_zero();
  729. if ((!m_left_floats.current_boxes.is_empty() || !m_right_floats.current_boxes.is_empty())
  730. && creates_block_formatting_context(child_box)) {
  731. auto box_in_root_rect = content_box_rect_in_ancestor_coordinate_space(box_state, root());
  732. auto space_and_containing_margin = space_used_and_containing_margin_for_floats(box_in_root_rect.y());
  733. available_width_within_containing_block -= space_and_containing_margin.left_used_space + space_and_containing_margin.right_used_space;
  734. auto const& containing_box_state = m_state.get(*child_box.containing_block());
  735. if (box_has_ancestor_in_non_anonymous_containing_block_chain(space_and_containing_margin.matching_left_float_box, *child_box.non_anonymous_containing_block(), root()))
  736. x = space_and_containing_margin.left_used_space;
  737. else
  738. // If the floating box doesn't share a containing block with the child box, the child box margin should overlap with the width of the floating box.
  739. x = max(space_and_containing_margin.left_used_space - containing_box_state.margin_left, 0);
  740. }
  741. if (child_box.containing_block()->computed_values().text_align() == CSS::TextAlign::LibwebCenter) {
  742. x += (available_width_within_containing_block / 2) - box_state.content_width() / 2;
  743. } else if (child_box.containing_block()->computed_values().text_align() == CSS::TextAlign::LibwebRight) {
  744. // Subtracting the left margin here because left and right margins need to be swapped when aligning to the right
  745. x += available_width_within_containing_block - box_state.content_width() - box_state.margin_box_left();
  746. } else {
  747. x += box_state.margin_box_left();
  748. }
  749. box_state.set_content_offset({ x, box_state.offset.y() });
  750. }
  751. void BlockFormattingContext::layout_viewport(LayoutMode layout_mode, AvailableSpace const& available_space)
  752. {
  753. // NOTE: If we are laying out a standalone SVG document, we give it some special treatment:
  754. // The root <svg> container gets the same size as the viewport,
  755. // and we call directly into the SVG layout code from here.
  756. if (root().first_child() && root().first_child()->is_svg_svg_box()) {
  757. auto const& svg_root = verify_cast<SVGSVGBox>(*root().first_child());
  758. auto content_height = m_state.get(*svg_root.containing_block()).content_height();
  759. m_state.get_mutable(svg_root).set_content_height(content_height);
  760. auto svg_formatting_context = create_independent_formatting_context_if_needed(m_state, svg_root);
  761. svg_formatting_context->run(svg_root, layout_mode, available_space);
  762. } else {
  763. if (root().children_are_inline())
  764. layout_inline_children(root(), layout_mode, available_space);
  765. else
  766. layout_block_level_children(root(), layout_mode, available_space);
  767. }
  768. }
  769. void BlockFormattingContext::layout_floating_box(Box const& box, BlockContainer const&, LayoutMode layout_mode, AvailableSpace const& available_space, CSSPixels y, LineBuilder* line_builder)
  770. {
  771. VERIFY(box.is_floating());
  772. auto& box_state = m_state.get_mutable(box);
  773. auto const& computed_values = box.computed_values();
  774. resolve_vertical_box_model_metrics(box);
  775. compute_width(box, available_space, layout_mode);
  776. // NOTE: Flex containers with `auto` height are treated as `max-content`, so we can compute their height early.
  777. if (box.is_replaced_box() || box.display().is_flex_inside())
  778. compute_height(box, available_space);
  779. auto independent_formatting_context = layout_inside(box, layout_mode, box_state.available_inner_space_or_constraints_from(available_space));
  780. compute_height(box, available_space);
  781. // First we place the box normally (to get the right y coordinate.)
  782. // If we have a LineBuilder, we're in the middle of inline layout, otherwise this is block layout.
  783. if (line_builder) {
  784. auto y = max(line_builder->y_for_float_to_be_inserted_here(box), line_builder->inline_formatting_context().vertical_float_clearance());
  785. box_state.set_content_y(y + box_state.margin_box_top());
  786. } else {
  787. place_block_level_element_in_normal_flow_vertically(box, y + box_state.margin_top);
  788. place_block_level_element_in_normal_flow_horizontally(box, available_space);
  789. }
  790. // Then we float it to the left or right.
  791. auto float_box = [&](FloatSide side, FloatSideData& side_data, FloatSideData& other_side_data) {
  792. CSSPixels offset_from_edge = 0;
  793. auto float_to_edge = [&] {
  794. if (side == FloatSide::Left)
  795. offset_from_edge = box_state.margin_box_left();
  796. else
  797. offset_from_edge = box_state.content_width() + box_state.margin_box_right();
  798. };
  799. auto box_in_root_rect = content_box_rect_in_ancestor_coordinate_space(box_state, root());
  800. CSSPixels y_in_root = box_in_root_rect.y();
  801. CSSPixels y = box_state.offset.y();
  802. if (side_data.current_boxes.is_empty()) {
  803. // This is the first floating box on this side. Go all the way to the edge.
  804. float_to_edge();
  805. side_data.y_offset = 0;
  806. } else {
  807. // NOTE: If we're in inline layout, the LineBuilder has already provided the right Y offset.
  808. // In block layout, we adjust by the side's current Y offset here.
  809. if (!line_builder)
  810. y_in_root += side_data.y_offset;
  811. bool did_touch_preceding_float = false;
  812. bool did_place_next_to_preceding_float = false;
  813. // Walk all currently tracked floats on the side we're floating towards.
  814. // We're looking for the innermost preceding float that intersects vertically with `box`.
  815. for (auto& preceding_float : side_data.current_boxes.in_reverse()) {
  816. auto const preceding_float_rect = margin_box_rect_in_ancestor_coordinate_space(preceding_float.used_values, root());
  817. if (!preceding_float_rect.contains_vertically(y_in_root))
  818. continue;
  819. // We found a preceding float that intersects vertically with the current float.
  820. // Now we need to find out if there's enough inline-axis space to stack them next to each other.
  821. CSSPixels tentative_offset_from_edge = 0;
  822. bool fits_next_to_preceding_float = false;
  823. if (side == FloatSide::Left) {
  824. tentative_offset_from_edge = max(preceding_float.offset_from_edge + preceding_float.used_values.content_width() + preceding_float.used_values.margin_box_right(), 0) + box_state.margin_box_left();
  825. if (available_space.width.is_definite()) {
  826. fits_next_to_preceding_float = (tentative_offset_from_edge + box_state.content_width() + box_state.margin_box_right()) <= available_space.width.to_px_or_zero();
  827. } else if (available_space.width.is_max_content() || available_space.width.is_indefinite()) {
  828. fits_next_to_preceding_float = true;
  829. }
  830. } else {
  831. tentative_offset_from_edge = preceding_float.offset_from_edge + preceding_float.used_values.margin_box_left() + box_state.margin_box_right() + box_state.content_width();
  832. fits_next_to_preceding_float = tentative_offset_from_edge >= 0;
  833. }
  834. did_touch_preceding_float = true;
  835. if (!fits_next_to_preceding_float)
  836. break;
  837. offset_from_edge = tentative_offset_from_edge;
  838. did_place_next_to_preceding_float = true;
  839. break;
  840. }
  841. auto has_clearance = false;
  842. if (side == FloatSide::Left) {
  843. has_clearance = computed_values.clear() == CSS::Clear::Left || computed_values.clear() == CSS::Clear::Both;
  844. } else if (side == FloatSide::Right) {
  845. has_clearance = computed_values.clear() == CSS::Clear::Right || computed_values.clear() == CSS::Clear::Both;
  846. }
  847. if (!did_touch_preceding_float || !did_place_next_to_preceding_float || has_clearance) {
  848. // One of three things happened:
  849. // - This box does not touch another floating box.
  850. // - We ran out of horizontal space on this "float line", and need to break.
  851. // - This box has clearance.
  852. // Either way, we float this box all the way to the edge.
  853. float_to_edge();
  854. CSSPixels lowest_margin_edge = 0;
  855. for (auto const& current : side_data.current_boxes) {
  856. lowest_margin_edge = max(lowest_margin_edge, current.used_values.margin_box_height());
  857. }
  858. side_data.y_offset += lowest_margin_edge;
  859. // Also, forget all previous boxes floated to this side while since they're no longer relevant.
  860. side_data.clear();
  861. }
  862. }
  863. // NOTE: If we're in inline layout, the LineBuilder has already provided the right Y offset.
  864. // In block layout, we adjust by the side's current Y offset here.
  865. // FIXME: It's annoying that we have different behavior for inline vs block here.
  866. // Find a way to unify the behavior so we don't need to branch here.
  867. if (!line_builder)
  868. y += side_data.y_offset;
  869. auto top_margin_edge = y - box_state.margin_box_top();
  870. side_data.all_boxes.append(adopt_own(*new FloatingBox {
  871. .box = box,
  872. .used_values = box_state,
  873. .offset_from_edge = offset_from_edge,
  874. .top_margin_edge = top_margin_edge,
  875. .bottom_margin_edge = y + box_state.content_height() + box_state.margin_box_bottom(),
  876. }));
  877. side_data.current_boxes.append(*side_data.all_boxes.last());
  878. if (side == FloatSide::Left) {
  879. side_data.current_width = offset_from_edge + box_state.content_width() + box_state.margin_box_right();
  880. } else {
  881. side_data.current_width = offset_from_edge + box_state.margin_box_left();
  882. }
  883. side_data.max_width = max(side_data.current_width, side_data.max_width);
  884. // NOTE: We don't set the X position here, that happens later, once we know the root block width.
  885. // See parent_context_did_dimension_child_root_box() for that logic.
  886. box_state.set_content_y(y);
  887. // If the new box was inserted below the bottom of the opposite side,
  888. // we reset the other side back to its edge.
  889. if (top_margin_edge > other_side_data.y_offset)
  890. other_side_data.clear();
  891. };
  892. // Next, float to the left and/or right
  893. if (box.computed_values().float_() == CSS::Float::Left) {
  894. float_box(FloatSide::Left, m_left_floats, m_right_floats);
  895. } else if (box.computed_values().float_() == CSS::Float::Right) {
  896. float_box(FloatSide::Right, m_right_floats, m_left_floats);
  897. }
  898. m_state.get_mutable(root()).add_floating_descendant(box);
  899. if (line_builder)
  900. line_builder->recalculate_available_space();
  901. compute_inset(box);
  902. if (independent_formatting_context)
  903. independent_formatting_context->parent_context_did_dimension_child_root_box();
  904. }
  905. void BlockFormattingContext::layout_list_item_marker(ListItemBox const& list_item_box)
  906. {
  907. if (!list_item_box.marker())
  908. return;
  909. auto& marker = *list_item_box.marker();
  910. auto& marker_state = m_state.get_mutable(marker);
  911. auto& list_item_state = m_state.get_mutable(list_item_box);
  912. CSSPixels image_width = 0;
  913. CSSPixels image_height = 0;
  914. if (auto const* list_style_image = marker.list_style_image()) {
  915. image_width = list_style_image->natural_width().value_or(0);
  916. image_height = list_style_image->natural_height().value_or(0);
  917. }
  918. CSSPixels default_marker_width = max(4, marker.first_available_font().pixel_size_rounded_up() - 4);
  919. auto marker_text = marker.text().value_or("");
  920. if (marker_text.is_empty()) {
  921. marker_state.set_content_width(image_width + default_marker_width);
  922. } else {
  923. auto text_width = marker.first_available_font().width(marker_text);
  924. marker_state.set_content_width(image_width + CSSPixels::nearest_value_for(text_width));
  925. }
  926. marker_state.set_content_height(max(image_height, marker.first_available_font().pixel_size_rounded_up() + 1));
  927. auto final_marker_width = marker_state.content_width() + default_marker_width;
  928. if (marker.list_style_position() == CSS::ListStylePosition::Inside) {
  929. list_item_state.set_content_offset({ final_marker_width, list_item_state.offset.y() });
  930. list_item_state.set_content_width(list_item_state.content_width() - final_marker_width);
  931. }
  932. auto offset_y = max(CSSPixels(0), (marker.computed_values().line_height() - marker_state.content_height()) / 2);
  933. auto space_and_containing_margin = intrusion_by_floats_into_box(list_item_state, offset_y);
  934. marker_state.set_content_offset({ space_and_containing_margin.left - final_marker_width, offset_y });
  935. if (marker_state.content_height() > list_item_state.content_height())
  936. list_item_state.set_content_height(marker_state.content_height());
  937. }
  938. BlockFormattingContext::SpaceUsedAndContainingMarginForFloats BlockFormattingContext::space_used_and_containing_margin_for_floats(CSSPixels y) const
  939. {
  940. SpaceUsedAndContainingMarginForFloats space_and_containing_margin;
  941. for (auto const& floating_box_ptr : m_left_floats.all_boxes.in_reverse()) {
  942. auto const& floating_box = *floating_box_ptr;
  943. // NOTE: The floating box is *not* in the final horizontal position yet, but the size and vertical position is valid.
  944. auto rect = margin_box_rect_in_ancestor_coordinate_space(floating_box.used_values, root());
  945. if (rect.contains_vertically(y)) {
  946. CSSPixels offset_from_containing_block_chain_margins_between_here_and_root = 0;
  947. for (auto const* containing_block = floating_box.used_values.containing_block_used_values(); containing_block && &containing_block->node() != &root(); containing_block = containing_block->containing_block_used_values()) {
  948. offset_from_containing_block_chain_margins_between_here_and_root += containing_block->margin_box_left();
  949. }
  950. space_and_containing_margin.left_used_space = floating_box.offset_from_edge
  951. + floating_box.used_values.content_width()
  952. + floating_box.used_values.margin_box_right();
  953. space_and_containing_margin.left_total_containing_margin = offset_from_containing_block_chain_margins_between_here_and_root;
  954. space_and_containing_margin.matching_left_float_box = floating_box.box.ptr();
  955. break;
  956. }
  957. }
  958. for (auto const& floating_box_ptr : m_right_floats.all_boxes.in_reverse()) {
  959. auto const& floating_box = *floating_box_ptr;
  960. // NOTE: The floating box is *not* in the final horizontal position yet, but the size and vertical position is valid.
  961. auto rect = margin_box_rect_in_ancestor_coordinate_space(floating_box.used_values, root());
  962. if (rect.contains_vertically(y)) {
  963. CSSPixels offset_from_containing_block_chain_margins_between_here_and_root = 0;
  964. for (auto const* containing_block = floating_box.used_values.containing_block_used_values(); containing_block && &containing_block->node() != &root(); containing_block = containing_block->containing_block_used_values()) {
  965. offset_from_containing_block_chain_margins_between_here_and_root += containing_block->margin_box_right();
  966. }
  967. space_and_containing_margin.right_used_space = floating_box.offset_from_edge
  968. + floating_box.used_values.margin_box_left();
  969. space_and_containing_margin.right_total_containing_margin = offset_from_containing_block_chain_margins_between_here_and_root;
  970. break;
  971. }
  972. }
  973. return space_and_containing_margin;
  974. }
  975. FormattingContext::SpaceUsedByFloats BlockFormattingContext::intrusion_by_floats_into_box(Box const& box, CSSPixels y_in_box) const
  976. {
  977. return intrusion_by_floats_into_box(m_state.get(box), y_in_box);
  978. }
  979. FormattingContext::SpaceUsedByFloats BlockFormattingContext::intrusion_by_floats_into_box(LayoutState::UsedValues const& box_used_values, CSSPixels y_in_box) const
  980. {
  981. // NOTE: Floats are relative to the BFC root box, not necessarily the containing block of this IFC.
  982. auto box_in_root_rect = content_box_rect_in_ancestor_coordinate_space(box_used_values, root());
  983. CSSPixels y_in_root = box_in_root_rect.y() + y_in_box;
  984. auto space_and_containing_margin = space_used_and_containing_margin_for_floats(y_in_root);
  985. auto left_side_floats_limit_to_right = space_and_containing_margin.left_total_containing_margin + space_and_containing_margin.left_used_space;
  986. auto right_side_floats_limit_to_right = space_and_containing_margin.right_used_space + space_and_containing_margin.right_total_containing_margin;
  987. auto left_intrusion = max(CSSPixels(0), left_side_floats_limit_to_right - max(CSSPixels(0), box_in_root_rect.x()));
  988. CSSPixels offset_from_containing_block_chain_margins_between_here_and_root = 0;
  989. for (auto const* containing_block = &box_used_values; containing_block && &containing_block->node() != &root(); containing_block = containing_block->containing_block_used_values()) {
  990. offset_from_containing_block_chain_margins_between_here_and_root = max(offset_from_containing_block_chain_margins_between_here_and_root, containing_block->margin_box_right());
  991. }
  992. auto right_intrusion = max(CSSPixels(0), right_side_floats_limit_to_right - offset_from_containing_block_chain_margins_between_here_and_root);
  993. return { left_intrusion, right_intrusion };
  994. }
  995. CSSPixels BlockFormattingContext::greatest_child_width(Box const& box) const
  996. {
  997. // Similar to FormattingContext::greatest_child_width()
  998. // but this one takes floats into account!
  999. CSSPixels max_width = m_left_floats.max_width + m_right_floats.max_width;
  1000. if (box.children_are_inline()) {
  1001. for (auto const& line_box : m_state.get(verify_cast<BlockContainer>(box)).line_boxes) {
  1002. CSSPixels width_here = line_box.width();
  1003. CSSPixels extra_width_from_left_floats = 0;
  1004. for (auto& left_float : m_left_floats.all_boxes) {
  1005. // NOTE: Floats directly affect the automatic size of their containing block, but only indirectly anything above in the tree.
  1006. if (left_float->box->containing_block() != &box)
  1007. continue;
  1008. if (line_box.baseline() >= left_float->top_margin_edge || line_box.baseline() <= left_float->bottom_margin_edge) {
  1009. extra_width_from_left_floats = max(extra_width_from_left_floats, left_float->offset_from_edge + left_float->used_values.content_width() + left_float->used_values.margin_box_right());
  1010. }
  1011. }
  1012. CSSPixels extra_width_from_right_floats = 0;
  1013. for (auto& right_float : m_right_floats.all_boxes) {
  1014. // NOTE: Floats directly affect the automatic size of their containing block, but only indirectly anything above in the tree.
  1015. if (right_float->box->containing_block() != &box)
  1016. continue;
  1017. if (line_box.baseline() >= right_float->top_margin_edge || line_box.baseline() <= right_float->bottom_margin_edge) {
  1018. extra_width_from_right_floats = max(extra_width_from_right_floats, right_float->offset_from_edge + right_float->used_values.margin_box_left());
  1019. }
  1020. }
  1021. width_here += extra_width_from_left_floats + extra_width_from_right_floats;
  1022. max_width = max(max_width, width_here);
  1023. }
  1024. } else {
  1025. box.for_each_child_of_type<Box>([&](Box const& child) {
  1026. if (!child.is_absolutely_positioned())
  1027. max_width = max(max_width, m_state.get(child).margin_box_width());
  1028. });
  1029. }
  1030. return max_width;
  1031. }
  1032. }