BlockFormattingContext.cpp 61 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. void BlockFormattingContext::compute_width(Box const& box, AvailableSpace const& available_space, LayoutMode)
  104. {
  105. if (box.is_absolutely_positioned()) {
  106. compute_width_for_absolutely_positioned_element(box, available_space);
  107. return;
  108. }
  109. auto remaining_available_space = available_space;
  110. if (available_space.width.is_definite() && creates_block_formatting_context(box)) {
  111. // 9.5 Floats
  112. // The border box of a table, a block-level replaced element, or an element in the normal flow that establishes a
  113. // new block formatting context (such as an element with 'overflow' other than 'visible') must not overlap the margin
  114. // box of any floats in the same block formatting context as the element itself. If necessary, implementations should
  115. // clear the said element by placing it below any preceding floats, but may place it adjacent to such floats if there is
  116. // sufficient space. They may even make the border box of said element narrower than defined by section 10.3.3.
  117. // CSS2 does not define when a UA may put said element next to the float or by how much said element may
  118. // become narrower.
  119. auto intrusion = intrusion_by_floats_into_box(box, 0);
  120. auto remaining_width = available_space.width.to_px_or_zero() - intrusion.left - intrusion.right;
  121. remaining_available_space.width = AvailableSize::make_definite(remaining_width);
  122. }
  123. if (box_is_sized_as_replaced_element(box)) {
  124. // FIXME: This should not be done *by* ReplacedBox
  125. if (is<ReplacedBox>(box)) {
  126. auto& replaced = verify_cast<ReplacedBox>(box);
  127. // FIXME: This const_cast is gross.
  128. const_cast<ReplacedBox&>(replaced).prepare_for_replaced_layout();
  129. }
  130. compute_width_for_block_level_replaced_element_in_normal_flow(box, remaining_available_space);
  131. if (box.is_floating()) {
  132. // 10.3.6 Floating, replaced elements:
  133. // https://www.w3.org/TR/CSS22/visudet.html#float-replaced-width
  134. return;
  135. }
  136. }
  137. if (box.is_floating()) {
  138. // 10.3.5 Floating, non-replaced elements:
  139. // https://www.w3.org/TR/CSS22/visudet.html#float-width
  140. compute_width_for_floating_box(box, available_space);
  141. return;
  142. }
  143. auto const& computed_values = box.computed_values();
  144. auto width_of_containing_block = remaining_available_space.width.to_px_or_zero();
  145. auto width_of_containing_block_as_length_for_resolve = remaining_available_space.width.is_definite() ? CSS::Length::make_px(width_of_containing_block) : CSS::Length::make_px(0);
  146. auto zero_value = CSS::Length::make_px(0);
  147. auto margin_left = CSS::Length::make_auto();
  148. auto margin_right = CSS::Length::make_auto();
  149. auto const padding_left = computed_values.padding().left().resolved(box, width_of_containing_block_as_length_for_resolve).to_px(box);
  150. auto const padding_right = computed_values.padding().right().resolved(box, width_of_containing_block_as_length_for_resolve).to_px(box);
  151. auto& box_state = m_state.get_mutable(box);
  152. box_state.border_left = computed_values.border_left().width;
  153. box_state.border_right = computed_values.border_right().width;
  154. box_state.padding_left = padding_left;
  155. box_state.padding_right = padding_right;
  156. // NOTE: If we are calculating the min-content or max-content width of this box,
  157. // and the width should be treated as auto, then we can simply return here,
  158. // as the preferred width and min/max constraints are irrelevant for intrinsic sizing.
  159. if (box_state.width_constraint != SizeConstraint::None)
  160. return;
  161. auto try_compute_width = [&](auto const& a_width) {
  162. CSS::Length width = a_width;
  163. margin_left = computed_values.margin().left().resolved(box, width_of_containing_block_as_length_for_resolve);
  164. margin_right = computed_values.margin().right().resolved(box, width_of_containing_block_as_length_for_resolve);
  165. CSSPixels total_px = computed_values.border_left().width + computed_values.border_right().width;
  166. for (auto& value : { margin_left, CSS::Length::make_px(padding_left), width, CSS::Length::make_px(padding_right), margin_right }) {
  167. total_px += value.to_px(box);
  168. }
  169. if (!box.is_inline()) {
  170. // 10.3.3 Block-level, non-replaced elements in normal flow
  171. // 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.
  172. if (!width.is_auto() && total_px > width_of_containing_block) {
  173. if (margin_left.is_auto())
  174. margin_left = zero_value;
  175. if (margin_right.is_auto())
  176. margin_right = zero_value;
  177. }
  178. // 10.3.3 cont'd.
  179. auto underflow_px = width_of_containing_block - total_px;
  180. if (available_space.width.is_intrinsic_sizing_constraint())
  181. underflow_px = 0;
  182. if (width.is_auto()) {
  183. if (margin_left.is_auto())
  184. margin_left = zero_value;
  185. if (margin_right.is_auto())
  186. margin_right = zero_value;
  187. if (available_space.width.is_definite()) {
  188. if (underflow_px >= 0) {
  189. width = CSS::Length::make_px(underflow_px);
  190. } else {
  191. width = zero_value;
  192. margin_right = CSS::Length::make_px(margin_right.to_px(box) + underflow_px);
  193. }
  194. }
  195. } else {
  196. if (!margin_left.is_auto() && !margin_right.is_auto()) {
  197. margin_right = CSS::Length::make_px(margin_right.to_px(box) + underflow_px);
  198. } else if (!margin_left.is_auto() && margin_right.is_auto()) {
  199. margin_right = CSS::Length::make_px(underflow_px);
  200. } else if (margin_left.is_auto() && !margin_right.is_auto()) {
  201. margin_left = CSS::Length::make_px(underflow_px);
  202. } else { // margin_left.is_auto() && margin_right.is_auto()
  203. auto half_of_the_underflow = CSS::Length::make_px(underflow_px / 2);
  204. margin_left = half_of_the_underflow;
  205. margin_right = half_of_the_underflow;
  206. }
  207. }
  208. }
  209. return width;
  210. };
  211. auto input_width = [&] {
  212. if (box_is_sized_as_replaced_element(box)) {
  213. // NOTE: Replaced elements had their width calculated independently above.
  214. // We use that width as the input here to ensure that margins get resolved.
  215. return CSS::Length::make_px(box_state.content_width());
  216. }
  217. if (is<TableWrapper>(box))
  218. return CSS::Length::make_px(compute_table_box_width_inside_table_wrapper(box, remaining_available_space));
  219. if (should_treat_width_as_auto(box, remaining_available_space))
  220. return CSS::Length::make_auto();
  221. return calculate_inner_width(box, remaining_available_space.width, computed_values.width());
  222. }();
  223. // 1. The tentative used width is calculated (without 'min-width' and 'max-width')
  224. auto used_width = try_compute_width(input_width);
  225. // 2. The tentative used width is greater than 'max-width', the rules above are applied again,
  226. // but this time using the computed value of 'max-width' as the computed value for 'width'.
  227. if (!should_treat_max_width_as_none(box, available_space.width)) {
  228. auto max_width = calculate_inner_width(box, remaining_available_space.width, computed_values.max_width());
  229. auto used_width_px = used_width.is_auto() ? CSSPixels { 0 } : used_width.to_px(box);
  230. if (used_width_px > max_width.to_px(box)) {
  231. used_width = try_compute_width(max_width);
  232. }
  233. }
  234. // 3. If the resulting width is smaller than 'min-width', the rules above are applied again,
  235. // but this time using the value of 'min-width' as the computed value for 'width'.
  236. if (!computed_values.min_width().is_auto()) {
  237. auto min_width = calculate_inner_width(box, remaining_available_space.width, computed_values.min_width());
  238. auto used_width_px = used_width.is_auto() ? remaining_available_space.width : AvailableSize::make_definite(used_width.to_px(box));
  239. if (used_width_px < min_width.to_px(box)) {
  240. used_width = try_compute_width(min_width);
  241. }
  242. }
  243. if (!box_is_sized_as_replaced_element(box) && !used_width.is_auto())
  244. box_state.set_content_width(used_width.to_px(box));
  245. box_state.margin_left = margin_left.to_px(box);
  246. box_state.margin_right = margin_right.to_px(box);
  247. }
  248. void BlockFormattingContext::compute_width_for_floating_box(Box const& box, AvailableSpace const& available_space)
  249. {
  250. // 10.3.5 Floating, non-replaced elements
  251. auto& computed_values = box.computed_values();
  252. auto zero_value = CSS::Length::make_px(0);
  253. auto width_of_containing_block = available_space.width.to_px_or_zero();
  254. auto width_of_containing_block_as_length_for_resolve = CSS::Length::make_px(width_of_containing_block);
  255. if (!available_space.width.is_definite())
  256. width_of_containing_block_as_length_for_resolve = CSS::Length::make_px(0);
  257. auto margin_left = computed_values.margin().left().resolved(box, width_of_containing_block_as_length_for_resolve);
  258. auto margin_right = computed_values.margin().right().resolved(box, width_of_containing_block_as_length_for_resolve);
  259. auto const padding_left = computed_values.padding().left().resolved(box, width_of_containing_block_as_length_for_resolve).to_px(box);
  260. auto const padding_right = computed_values.padding().right().resolved(box, width_of_containing_block_as_length_for_resolve).to_px(box);
  261. // If 'margin-left', or 'margin-right' are computed as 'auto', their used value is '0'.
  262. if (margin_left.is_auto())
  263. margin_left = zero_value;
  264. if (margin_right.is_auto())
  265. margin_right = zero_value;
  266. auto compute_width = [&](auto width) {
  267. // If 'width' is computed as 'auto', the used value is the "shrink-to-fit" width.
  268. if (width.is_auto()) {
  269. // Find the available width: in this case, this is the width of the containing
  270. // block minus the used values of 'margin-left', 'border-left-width', 'padding-left',
  271. // 'padding-right', 'border-right-width', 'margin-right', and the widths of any relevant scroll bars.
  272. auto available_width = width_of_containing_block
  273. - margin_left.to_px(box) - computed_values.border_left().width - padding_left
  274. - padding_right - computed_values.border_right().width - margin_right.to_px(box);
  275. auto result = calculate_shrink_to_fit_widths(box);
  276. // Then the shrink-to-fit width is: min(max(preferred minimum width, available width), preferred width).
  277. width = CSS::Length::make_px(min(max(result.preferred_minimum_width, available_width), result.preferred_width));
  278. }
  279. return width;
  280. };
  281. auto input_width = [&] {
  282. if (should_treat_width_as_auto(box, available_space))
  283. return CSS::Length::make_auto();
  284. return calculate_inner_width(box, available_space.width, computed_values.width());
  285. }();
  286. // 1. The tentative used width is calculated (without 'min-width' and 'max-width')
  287. auto width = compute_width(input_width);
  288. // 2. The tentative used width is greater than 'max-width', the rules above are applied again,
  289. // but this time using the computed value of 'max-width' as the computed value for 'width'.
  290. if (!should_treat_max_width_as_none(box, available_space.width)) {
  291. auto max_width = calculate_inner_width(box, available_space.width, computed_values.max_width());
  292. if (width.to_px(box) > max_width.to_px(box))
  293. width = compute_width(max_width);
  294. }
  295. // 3. If the resulting width is smaller than 'min-width', the rules above are applied again,
  296. // but this time using the value of 'min-width' as the computed value for 'width'.
  297. if (!computed_values.min_width().is_auto()) {
  298. auto min_width = calculate_inner_width(box, available_space.width, computed_values.min_width());
  299. if (width.to_px(box) < min_width.to_px(box))
  300. width = compute_width(min_width);
  301. }
  302. auto& box_state = m_state.get_mutable(box);
  303. box_state.set_content_width(width.to_px(box));
  304. box_state.margin_left = margin_left.to_px(box);
  305. box_state.margin_right = margin_right.to_px(box);
  306. box_state.border_left = computed_values.border_left().width;
  307. box_state.border_right = computed_values.border_right().width;
  308. box_state.padding_left = padding_left;
  309. box_state.padding_right = padding_right;
  310. }
  311. void BlockFormattingContext::compute_width_for_block_level_replaced_element_in_normal_flow(Box const& box, AvailableSpace const& available_space)
  312. {
  313. // 10.3.6 Floating, replaced elements
  314. auto& computed_values = box.computed_values();
  315. auto zero_value = CSS::Length::make_px(0);
  316. auto width_of_containing_block = available_space.width.to_px_or_zero();
  317. auto width_of_containing_block_as_length_for_resolve = CSS::Length::make_px(width_of_containing_block);
  318. if (!available_space.width.is_definite())
  319. width_of_containing_block_as_length_for_resolve = CSS::Length::make_px(0);
  320. // 10.3.4 Block-level, replaced elements in normal flow
  321. // The used value of 'width' is determined as for inline replaced elements. Then the rules for
  322. // non-replaced block-level elements are applied to determine the margins.
  323. auto margin_left = computed_values.margin().left().resolved(box, width_of_containing_block_as_length_for_resolve);
  324. auto margin_right = computed_values.margin().right().resolved(box, width_of_containing_block_as_length_for_resolve);
  325. auto const padding_left = computed_values.padding().left().resolved(box, width_of_containing_block_as_length_for_resolve).to_px(box);
  326. auto const padding_right = computed_values.padding().right().resolved(box, width_of_containing_block_as_length_for_resolve).to_px(box);
  327. // If 'margin-left', or 'margin-right' are computed as 'auto', their used value is '0'.
  328. if (margin_left.is_auto())
  329. margin_left = zero_value;
  330. if (margin_right.is_auto())
  331. margin_right = zero_value;
  332. auto& box_state = m_state.get_mutable(box);
  333. box_state.set_content_width(compute_width_for_replaced_element(box, available_space));
  334. box_state.margin_left = margin_left.to_px(box);
  335. box_state.margin_right = margin_right.to_px(box);
  336. box_state.border_left = computed_values.border_left().width;
  337. box_state.border_right = computed_values.border_right().width;
  338. box_state.padding_left = padding_left;
  339. box_state.padding_right = padding_right;
  340. }
  341. CSSPixels BlockFormattingContext::compute_table_box_width_inside_table_wrapper(Box const& box, AvailableSpace const& available_space)
  342. {
  343. // 17.5.2
  344. // Table wrapper width should be equal to width of table box it contains
  345. auto const& computed_values = box.computed_values();
  346. auto width_of_containing_block = available_space.width.to_px_or_zero();
  347. auto width_of_containing_block_as_length_for_resolve = available_space.width.is_definite() ? CSS::Length::make_px(width_of_containing_block) : CSS::Length::make_px(0);
  348. auto zero_value = CSS::Length::make_px(0);
  349. auto margin_left = computed_values.margin().left().resolved(box, width_of_containing_block_as_length_for_resolve);
  350. auto margin_right = computed_values.margin().right().resolved(box, width_of_containing_block_as_length_for_resolve);
  351. // If 'margin-left', or 'margin-right' are computed as 'auto', their used value is '0'.
  352. if (margin_left.is_auto())
  353. margin_left = zero_value;
  354. if (margin_right.is_auto())
  355. margin_right = zero_value;
  356. // table-wrapper can't have borders or paddings but it might have margin taken from table-root.
  357. auto available_width = width_of_containing_block - margin_left.to_px(box) - margin_right.to_px(box);
  358. LayoutState throwaway_state(&m_state);
  359. auto context = create_independent_formatting_context_if_needed(throwaway_state, box);
  360. VERIFY(context);
  361. context->run(box, LayoutMode::IntrinsicSizing, m_state.get(box).available_inner_space_or_constraints_from(available_space));
  362. Optional<Box const&> table_box;
  363. box.for_each_in_subtree_of_type<Box>([&](Box const& child_box) {
  364. if (child_box.display().is_table_inside()) {
  365. table_box = child_box;
  366. return IterationDecision::Break;
  367. }
  368. return IterationDecision::Continue;
  369. });
  370. VERIFY(table_box.has_value());
  371. auto table_used_width = throwaway_state.get(*table_box).border_box_width();
  372. return available_space.width.is_definite() ? min(table_used_width, available_width) : table_used_width;
  373. }
  374. void BlockFormattingContext::compute_height(Box const& box, AvailableSpace const& available_space)
  375. {
  376. auto const& computed_values = box.computed_values();
  377. auto containing_block_height = CSS::Length::make_px(available_space.height.to_px_or_zero());
  378. // Then work out what the height is, based on box type and CSS properties.
  379. CSSPixels height = 0;
  380. if (box_is_sized_as_replaced_element(box)) {
  381. height = compute_height_for_replaced_element(box, available_space);
  382. } else {
  383. if (should_treat_height_as_auto(box, available_space)) {
  384. height = compute_auto_height_for_block_level_element(box, m_state.get(box).available_inner_space_or_constraints_from(available_space));
  385. } else {
  386. height = calculate_inner_height(box, available_space.height, computed_values.height()).to_px(box);
  387. }
  388. }
  389. if (!should_treat_max_height_as_none(box, available_space.height)) {
  390. auto max_height = calculate_inner_height(box, available_space.height, computed_values.max_height());
  391. if (!max_height.is_auto())
  392. height = min(height, max_height.to_px(box));
  393. }
  394. if (!computed_values.min_height().is_auto()) {
  395. height = max(height, calculate_inner_height(box, available_space.height, computed_values.min_height()).to_px(box));
  396. }
  397. if (box.document().in_quirks_mode()
  398. && box.dom_node()
  399. && box.dom_node()->is_html_html_element()
  400. && box.computed_values().height().is_auto()) {
  401. // 3.6. The html element fills the viewport quirk
  402. // https://quirks.spec.whatwg.org/#the-html-element-fills-the-viewport-quirk
  403. // FIXME: Handle vertical writing mode.
  404. auto& box_state = m_state.get_mutable(box);
  405. // 1. Let margins be sum of the used values of the margin-left and margin-right properties of element
  406. // if element has a vertical writing mode, otherwise let margins be the sum of the used values of
  407. // the margin-top and margin-bottom properties of element.
  408. auto margins = box_state.margin_top + box_state.margin_bottom;
  409. // 2. Let size be the size of the initial containing block in the block flow direction minus margins.
  410. auto size = box_state.content_height() - margins;
  411. // 3. Return the bigger value of size and the normal border box size the element would have
  412. // according to the CSS specification.
  413. height = max(size, height);
  414. }
  415. m_state.get_mutable(box).set_content_height(height);
  416. }
  417. void BlockFormattingContext::layout_inline_children(BlockContainer const& block_container, LayoutMode layout_mode, AvailableSpace const& available_space)
  418. {
  419. VERIFY(block_container.children_are_inline());
  420. auto& block_container_state = m_state.get_mutable(block_container);
  421. InlineFormattingContext context(m_state, block_container, *this);
  422. context.run(
  423. block_container,
  424. layout_mode,
  425. available_space);
  426. if (!block_container_state.has_definite_width()) {
  427. // NOTE: min-width or max-width for boxes with inline children can only be applied after inside layout
  428. // is done and width of box content is known
  429. auto used_width_px = context.automatic_content_width();
  430. auto available_width = AvailableSize::make_definite(used_width_px);
  431. if (!should_treat_max_width_as_none(block_container, available_space.width)) {
  432. auto max_width_px = calculate_inner_width(block_container, available_width, block_container.computed_values().max_width()).to_px(block_container);
  433. if (used_width_px > max_width_px)
  434. used_width_px = max_width_px;
  435. }
  436. auto should_treat_min_width_as_auto = [&] {
  437. auto const& available_width = available_space.width;
  438. auto const& min_width = block_container.computed_values().min_width();
  439. if (min_width.is_auto())
  440. return true;
  441. if (min_width.is_fit_content() && available_width.is_intrinsic_sizing_constraint())
  442. return true;
  443. if (min_width.is_max_content() && available_width.is_max_content())
  444. return true;
  445. if (min_width.is_min_content() && available_width.is_min_content())
  446. return true;
  447. return false;
  448. }();
  449. if (!should_treat_min_width_as_auto) {
  450. auto min_width_px = calculate_inner_width(block_container, available_width, block_container.computed_values().min_width()).to_px(block_container);
  451. if (used_width_px < min_width_px)
  452. used_width_px = min_width_px;
  453. }
  454. block_container_state.set_content_width(used_width_px);
  455. }
  456. if (!block_container_state.has_definite_height())
  457. block_container_state.set_content_height(context.automatic_content_height());
  458. }
  459. CSSPixels BlockFormattingContext::compute_auto_height_for_block_level_element(Box const& box, AvailableSpace const& available_space)
  460. {
  461. if (creates_block_formatting_context(box)) {
  462. return compute_auto_height_for_block_formatting_context_root(box);
  463. }
  464. auto const& box_state = m_state.get(box);
  465. auto display = box.display();
  466. if (display.is_flex_inside()) {
  467. // https://drafts.csswg.org/css-flexbox-1/#algo-main-container
  468. // NOTE: The automatic block size of a block-level flex container is its max-content size.
  469. return calculate_max_content_height(box, available_space.width.to_px_or_zero());
  470. }
  471. if (display.is_grid_inside()) {
  472. // https://www.w3.org/TR/css-grid-2/#intrinsic-sizes
  473. // In both inline and block formatting contexts, the grid container’s auto block size is its
  474. // max-content size.
  475. return calculate_max_content_height(box, available_space.width.to_px_or_zero());
  476. }
  477. if (display.is_table_inside()) {
  478. return calculate_max_content_height(box, available_space.width.to_px_or_zero());
  479. }
  480. // https://www.w3.org/TR/CSS22/visudet.html#normal-block
  481. // 10.6.3 Block-level non-replaced elements in normal flow when 'overflow' computes to 'visible'
  482. // The element's height is the distance from its top content edge to the first applicable of the following:
  483. // 1. the bottom edge of the last line box, if the box establishes a inline formatting context with one or more lines
  484. if (box.children_are_inline() && !box_state.line_boxes.is_empty())
  485. return box_state.line_boxes.last().bottom();
  486. // 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
  487. // 3. the bottom border edge of the last in-flow child whose top margin doesn't collapse with the element's bottom margin
  488. if (!box.children_are_inline()) {
  489. for (auto* child_box = box.last_child_of_type<Box>(); child_box; child_box = child_box->previous_sibling_of_type<Box>()) {
  490. if (child_box->is_absolutely_positioned() || child_box->is_floating())
  491. continue;
  492. // FIXME: This is hack. If the last child is a list-item marker box, we ignore it for purposes of height calculation.
  493. // Perhaps markers should not be considered in-flow(?) Perhaps they should always be the first child of the list-item
  494. // box instead of the last child.
  495. if (child_box->is_list_item_marker_box())
  496. continue;
  497. auto const& child_box_state = m_state.get(*child_box);
  498. if (margins_collapse_through(*child_box, m_state))
  499. continue;
  500. auto margin_bottom = m_margin_state.current_collapsed_margin();
  501. if (box_state.padding_bottom == 0 && box_state.border_bottom == 0) {
  502. m_margin_state.box_last_in_flow_child_margin_bottom_collapsed = true;
  503. margin_bottom = 0;
  504. }
  505. return max(CSSPixels(0), child_box_state.offset.y() + child_box_state.content_height() + child_box_state.border_box_bottom() + margin_bottom);
  506. }
  507. }
  508. // 4. zero, otherwise
  509. return 0;
  510. }
  511. 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)
  512. {
  513. auto& box_state = m_state.get_mutable(box);
  514. if (box.is_absolutely_positioned()) {
  515. m_absolutely_positioned_boxes.append(box);
  516. return;
  517. }
  518. // NOTE: ListItemMarkerBoxes are placed by their corresponding ListItemBox.
  519. if (is<ListItemMarkerBox>(box))
  520. return;
  521. resolve_vertical_box_model_metrics(box);
  522. if (box.is_floating()) {
  523. auto const y = m_y_offset_of_current_block_container.value();
  524. auto margin_top = !m_margin_state.has_block_container_waiting_for_final_y_position() ? m_margin_state.current_collapsed_margin() : 0;
  525. layout_floating_box(box, block_container, layout_mode, available_space, margin_top + y);
  526. bottom_of_lowest_margin_box = max(bottom_of_lowest_margin_box, box_state.offset.y() + box_state.content_height() + box_state.margin_box_bottom());
  527. return;
  528. }
  529. m_margin_state.add_margin(box_state.margin_top);
  530. auto introduce_clearance = clear_floating_boxes(box, {});
  531. if (introduce_clearance == DidIntroduceClearance::Yes)
  532. m_margin_state.reset();
  533. auto const y = m_y_offset_of_current_block_container.value();
  534. if (box_state.has_definite_height()) {
  535. compute_height(box, available_space);
  536. }
  537. auto independent_formatting_context = create_independent_formatting_context_if_needed(m_state, box);
  538. m_margin_state.update_block_waiting_for_final_y_position();
  539. CSSPixels margin_top = m_margin_state.current_collapsed_margin();
  540. if (m_margin_state.has_block_container_waiting_for_final_y_position()) {
  541. // If first child margin top will collapse with margin-top of containing block then margin-top of child is 0
  542. margin_top = 0;
  543. }
  544. if (independent_formatting_context) {
  545. // Margins of elements that establish new formatting contexts do not collapse with their in-flow children
  546. m_margin_state.reset();
  547. }
  548. place_block_level_element_in_normal_flow_vertically(box, y + margin_top);
  549. compute_width(box, available_space, layout_mode);
  550. place_block_level_element_in_normal_flow_horizontally(box, available_space);
  551. if (box.is_replaced_box())
  552. compute_height(box, available_space);
  553. if (independent_formatting_context) {
  554. // This box establishes a new formatting context. Pass control to it.
  555. independent_formatting_context->run(box, layout_mode, box_state.available_inner_space_or_constraints_from(available_space));
  556. } else {
  557. // This box participates in the current block container's flow.
  558. if (box.children_are_inline()) {
  559. layout_inline_children(verify_cast<BlockContainer>(box), layout_mode, box_state.available_inner_space_or_constraints_from(available_space));
  560. } else {
  561. if (box_state.border_top > 0 || box_state.padding_top > 0) {
  562. // margin-top of block container can't collapse with it's children if it has non zero border or padding
  563. m_margin_state.reset();
  564. } else if (!m_margin_state.has_block_container_waiting_for_final_y_position()) {
  565. // margin-top of block container can be updated during children layout hence it's final y position yet to be determined
  566. m_margin_state.register_block_container_y_position_update_callback([&](CSSPixels margin_top) {
  567. if (introduce_clearance == DidIntroduceClearance::No) {
  568. place_block_level_element_in_normal_flow_vertically(box, margin_top + y);
  569. }
  570. });
  571. }
  572. layout_block_level_children(verify_cast<BlockContainer>(box), layout_mode, box_state.available_inner_space_or_constraints_from(available_space));
  573. }
  574. }
  575. // Tables already set their height during the independent formatting context run. When multi-line text cells are involved, using different
  576. // available space here than during the independent formatting context run can result in different line breaks and thus a different height.
  577. if (!box.display().is_table_inside()) {
  578. compute_height(box, available_space);
  579. }
  580. if (independent_formatting_context || !margins_collapse_through(box, m_state)) {
  581. if (!m_margin_state.box_last_in_flow_child_margin_bottom_collapsed) {
  582. m_margin_state.reset();
  583. }
  584. m_y_offset_of_current_block_container = box_state.offset.y() + box_state.content_height() + box_state.border_box_bottom();
  585. }
  586. m_margin_state.box_last_in_flow_child_margin_bottom_collapsed = false;
  587. m_margin_state.add_margin(box_state.margin_bottom);
  588. m_margin_state.update_block_waiting_for_final_y_position();
  589. compute_inset(box);
  590. if (is<ListItemBox>(box)) {
  591. layout_list_item_marker(static_cast<ListItemBox const&>(box));
  592. }
  593. bottom_of_lowest_margin_box = max(bottom_of_lowest_margin_box, box_state.offset.y() + box_state.content_height() + box_state.margin_box_bottom());
  594. if (independent_formatting_context)
  595. independent_formatting_context->parent_context_did_dimension_child_root_box();
  596. }
  597. void BlockFormattingContext::layout_block_level_children(BlockContainer const& block_container, LayoutMode layout_mode, AvailableSpace const& available_space)
  598. {
  599. VERIFY(!block_container.children_are_inline());
  600. CSSPixels bottom_of_lowest_margin_box = 0;
  601. TemporaryChange<Optional<CSSPixels>> change { m_y_offset_of_current_block_container, CSSPixels(0) };
  602. block_container.for_each_child_of_type<Box>([&](Box& box) {
  603. layout_block_level_box(box, block_container, layout_mode, bottom_of_lowest_margin_box, available_space);
  604. return IterationDecision::Continue;
  605. });
  606. m_margin_state.block_container_y_position_update_callback = {};
  607. if (layout_mode == LayoutMode::IntrinsicSizing) {
  608. auto& block_container_state = m_state.get_mutable(block_container);
  609. if (!block_container_state.has_definite_width())
  610. block_container_state.set_content_width(greatest_child_width(block_container));
  611. if (!block_container_state.has_definite_height())
  612. block_container_state.set_content_height(bottom_of_lowest_margin_box);
  613. }
  614. }
  615. void BlockFormattingContext::resolve_vertical_box_model_metrics(Box const& box)
  616. {
  617. auto& box_state = m_state.get_mutable(box);
  618. auto const& computed_values = box.computed_values();
  619. auto width_of_containing_block = containing_block_width_for(box);
  620. box_state.margin_top = computed_values.margin().top().to_px(box, width_of_containing_block);
  621. box_state.margin_bottom = computed_values.margin().bottom().to_px(box, width_of_containing_block);
  622. box_state.border_top = computed_values.border_top().width;
  623. box_state.border_bottom = computed_values.border_bottom().width;
  624. box_state.padding_top = computed_values.padding().top().to_px(box, width_of_containing_block);
  625. box_state.padding_bottom = computed_values.padding().bottom().to_px(box, width_of_containing_block);
  626. }
  627. CSSPixels BlockFormattingContext::BlockMarginState::current_collapsed_margin() const
  628. {
  629. CSSPixels smallest_margin = 0;
  630. CSSPixels largest_margin = 0;
  631. size_t negative_margin_count = 0;
  632. for (auto margin : current_collapsible_margins) {
  633. if (margin < 0)
  634. ++negative_margin_count;
  635. largest_margin = max(largest_margin, margin);
  636. smallest_margin = min(smallest_margin, margin);
  637. }
  638. CSSPixels collapsed_margin = 0;
  639. if (negative_margin_count == current_collapsible_margins.size()) {
  640. // When all margins are negative, the size of the collapsed margin is the smallest (most negative) margin.
  641. collapsed_margin = smallest_margin;
  642. } else if (negative_margin_count > 0) {
  643. // 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.
  644. collapsed_margin = largest_margin + smallest_margin;
  645. } else {
  646. // Otherwise, collapse all the adjacent margins by using only the largest one.
  647. collapsed_margin = largest_margin;
  648. }
  649. return collapsed_margin;
  650. }
  651. BlockFormattingContext::DidIntroduceClearance BlockFormattingContext::clear_floating_boxes(Node const& child_box, Optional<InlineFormattingContext&> inline_formatting_context)
  652. {
  653. auto const& computed_values = child_box.computed_values();
  654. auto result = DidIntroduceClearance::No;
  655. auto clear_floating_boxes = [&](FloatSideData& float_side) {
  656. if (!float_side.current_boxes.is_empty()) {
  657. // NOTE: Floating boxes are globally relevant within this BFC, *but* their offset coordinates
  658. // are relative to their containing block.
  659. // This means that we have to first convert to a root-space Y coordinate before clearing,
  660. // and then convert back to a local Y coordinate when assigning the cleared offset to
  661. // the `child_box` layout state.
  662. // First, find the lowest margin box edge on this float side and calculate the Y offset just below it.
  663. CSSPixels clearance_y_in_root = 0;
  664. for (auto const& floating_box : float_side.current_boxes) {
  665. auto floating_box_rect_in_root = margin_box_rect_in_ancestor_coordinate_space(floating_box.box, root());
  666. clearance_y_in_root = max(clearance_y_in_root, floating_box_rect_in_root.bottom());
  667. }
  668. // Then, convert the clearance Y to a coordinate relative to the containing block of `child_box`.
  669. CSSPixels clearance_y_in_containing_block = clearance_y_in_root;
  670. for (auto* containing_block = child_box.containing_block(); containing_block && containing_block != &root(); containing_block = containing_block->containing_block())
  671. clearance_y_in_containing_block -= m_state.get(*containing_block).offset.y();
  672. if (inline_formatting_context.has_value()) {
  673. if (clearance_y_in_containing_block > inline_formatting_context->vertical_float_clearance()) {
  674. result = DidIntroduceClearance::Yes;
  675. inline_formatting_context->set_vertical_float_clearance(clearance_y_in_containing_block);
  676. }
  677. } else if (clearance_y_in_containing_block > m_y_offset_of_current_block_container.value()) {
  678. result = DidIntroduceClearance::Yes;
  679. m_y_offset_of_current_block_container = clearance_y_in_containing_block;
  680. }
  681. float_side.clear();
  682. }
  683. };
  684. // Flex-items don't float and also don't clear.
  685. if ((computed_values.clear() == CSS::Clear::Left || computed_values.clear() == CSS::Clear::Both) && !child_box.is_flex_item())
  686. clear_floating_boxes(m_left_floats);
  687. if ((computed_values.clear() == CSS::Clear::Right || computed_values.clear() == CSS::Clear::Both) && !child_box.is_flex_item())
  688. clear_floating_boxes(m_right_floats);
  689. return result;
  690. }
  691. void BlockFormattingContext::place_block_level_element_in_normal_flow_vertically(Box const& child_box, CSSPixels y)
  692. {
  693. auto& box_state = m_state.get_mutable(child_box);
  694. y += box_state.border_box_top();
  695. box_state.set_content_offset(CSSPixelPoint { box_state.offset.x(), y });
  696. }
  697. // Returns whether the given box has the given ancestor on the path to root, ignoring the anonymous blocks.
  698. static bool box_has_ancestor_in_non_anonymous_containing_block_chain(Box const* box, Box const& ancestor, Box const& root)
  699. {
  700. Box const* current_ancestor = box ? box->non_anonymous_containing_block() : &root;
  701. while (current_ancestor != &root) {
  702. if (current_ancestor == &ancestor)
  703. return true;
  704. current_ancestor = current_ancestor->non_anonymous_containing_block();
  705. }
  706. return false;
  707. }
  708. void BlockFormattingContext::place_block_level_element_in_normal_flow_horizontally(Box const& child_box, AvailableSpace const& available_space)
  709. {
  710. auto& box_state = m_state.get_mutable(child_box);
  711. CSSPixels x = 0;
  712. CSSPixels available_width_within_containing_block = available_space.width.to_px_or_zero();
  713. if ((!m_left_floats.current_boxes.is_empty() || !m_right_floats.current_boxes.is_empty())
  714. && creates_block_formatting_context(child_box)) {
  715. auto box_in_root_rect = content_box_rect_in_ancestor_coordinate_space(child_box, root());
  716. auto space_and_containing_margin = space_used_and_containing_margin_for_floats(box_in_root_rect.y());
  717. available_width_within_containing_block -= space_and_containing_margin.left_used_space + space_and_containing_margin.right_used_space;
  718. auto const& containing_box_state = m_state.get(*child_box.containing_block());
  719. 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()))
  720. x = space_and_containing_margin.left_used_space;
  721. else
  722. // 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.
  723. x = max(space_and_containing_margin.left_used_space - containing_box_state.margin_left, 0);
  724. }
  725. if (child_box.containing_block()->computed_values().text_align() == CSS::TextAlign::LibwebCenter) {
  726. x += (available_width_within_containing_block / 2) - box_state.content_width() / 2;
  727. } else if (child_box.containing_block()->computed_values().text_align() == CSS::TextAlign::LibwebRight) {
  728. // Subtracting the left margin here because left and right margins need to be swapped when aligning to the right
  729. x += available_width_within_containing_block - box_state.content_width() - box_state.margin_box_left();
  730. } else {
  731. x += box_state.margin_box_left();
  732. }
  733. box_state.set_content_offset({ x, box_state.offset.y() });
  734. }
  735. void BlockFormattingContext::layout_viewport(LayoutMode layout_mode, AvailableSpace const& available_space)
  736. {
  737. // NOTE: If we are laying out a standalone SVG document, we give it some special treatment:
  738. // The root <svg> container gets the same size as the viewport,
  739. // and we call directly into the SVG layout code from here.
  740. if (root().first_child() && root().first_child()->is_svg_svg_box()) {
  741. auto const& svg_root = verify_cast<SVGSVGBox>(*root().first_child());
  742. auto svg_formatting_context = create_independent_formatting_context_if_needed(m_state, svg_root);
  743. svg_formatting_context->run(svg_root, layout_mode, available_space);
  744. } else {
  745. if (root().children_are_inline())
  746. layout_inline_children(root(), layout_mode, available_space);
  747. else
  748. layout_block_level_children(root(), layout_mode, available_space);
  749. }
  750. }
  751. void BlockFormattingContext::layout_floating_box(Box const& box, BlockContainer const&, LayoutMode layout_mode, AvailableSpace const& available_space, CSSPixels y, LineBuilder* line_builder)
  752. {
  753. VERIFY(box.is_floating());
  754. auto& box_state = m_state.get_mutable(box);
  755. CSSPixels width_of_containing_block = available_space.width.to_px_or_zero();
  756. resolve_vertical_box_model_metrics(box);
  757. compute_width(box, available_space, layout_mode);
  758. auto independent_formatting_context = layout_inside(box, layout_mode, box_state.available_inner_space_or_constraints_from(available_space));
  759. compute_height(box, available_space);
  760. // First we place the box normally (to get the right y coordinate.)
  761. // If we have a LineBuilder, we're in the middle of inline layout, otherwise this is block layout.
  762. if (line_builder) {
  763. auto y = max(line_builder->y_for_float_to_be_inserted_here(box), line_builder->inline_formatting_context().vertical_float_clearance());
  764. box_state.set_content_y(y + box_state.margin_box_top());
  765. } else {
  766. place_block_level_element_in_normal_flow_vertically(box, y + box_state.margin_top);
  767. place_block_level_element_in_normal_flow_horizontally(box, available_space);
  768. }
  769. // Then we float it to the left or right.
  770. auto float_box = [&](FloatSide side, FloatSideData& side_data, FloatSideData& other_side_data) {
  771. CSSPixels offset_from_edge = 0;
  772. auto float_to_edge = [&] {
  773. if (side == FloatSide::Left)
  774. offset_from_edge = box_state.margin_box_left();
  775. else
  776. offset_from_edge = box_state.content_width() + box_state.margin_box_right();
  777. };
  778. auto box_in_root_rect = content_box_rect_in_ancestor_coordinate_space(box, root());
  779. CSSPixels y_in_root = box_in_root_rect.y();
  780. CSSPixels y = box_state.offset.y();
  781. if (side_data.current_boxes.is_empty()) {
  782. // This is the first floating box on this side. Go all the way to the edge.
  783. float_to_edge();
  784. side_data.y_offset = 0;
  785. } else {
  786. // NOTE: If we're in inline layout, the LineBuilder has already provided the right Y offset.
  787. // In block layout, we adjust by the side's current Y offset here.
  788. if (!line_builder)
  789. y_in_root += side_data.y_offset;
  790. bool did_touch_preceding_float = false;
  791. bool did_place_next_to_preceding_float = false;
  792. // Walk all currently tracked floats on the side we're floating towards.
  793. // We're looking for the innermost preceding float that intersects vertically with `box`.
  794. for (auto& preceding_float : side_data.current_boxes.in_reverse()) {
  795. auto const preceding_float_rect = margin_box_rect_in_ancestor_coordinate_space(preceding_float.box, root());
  796. if (!preceding_float_rect.contains_vertically(y_in_root))
  797. continue;
  798. // We found a preceding float that intersects vertically with the current float.
  799. // Now we need to find out if there's enough inline-axis space to stack them next to each other.
  800. auto const& preceding_float_state = m_state.get(preceding_float.box);
  801. CSSPixels tentative_offset_from_edge = 0;
  802. bool fits_next_to_preceding_float = false;
  803. if (side == FloatSide::Left) {
  804. tentative_offset_from_edge = preceding_float.offset_from_edge + preceding_float_state.content_width() + preceding_float_state.margin_box_right() + box_state.margin_box_left();
  805. fits_next_to_preceding_float = (tentative_offset_from_edge + box_state.content_width() + box_state.margin_box_right()) <= width_of_containing_block;
  806. } else {
  807. tentative_offset_from_edge = preceding_float.offset_from_edge + preceding_float_state.margin_box_left() + box_state.margin_box_right() + box_state.content_width();
  808. fits_next_to_preceding_float = tentative_offset_from_edge >= 0;
  809. }
  810. did_touch_preceding_float = true;
  811. if (!fits_next_to_preceding_float)
  812. break;
  813. offset_from_edge = tentative_offset_from_edge;
  814. did_place_next_to_preceding_float = true;
  815. break;
  816. }
  817. if (!did_touch_preceding_float || !did_place_next_to_preceding_float) {
  818. // One of two things happened:
  819. // - This box does not touch another floating box.
  820. // - We ran out of horizontal space on this "float line", and need to break.
  821. // Either way, we float this box all the way to the edge.
  822. float_to_edge();
  823. CSSPixels lowest_margin_edge = 0;
  824. for (auto const& box : side_data.current_boxes) {
  825. auto const& box_state = m_state.get(box.box);
  826. lowest_margin_edge = max(lowest_margin_edge, box_state.margin_box_height());
  827. }
  828. side_data.y_offset += lowest_margin_edge;
  829. // Also, forget all previous boxes floated to this side while since they're no longer relevant.
  830. side_data.clear();
  831. }
  832. }
  833. // NOTE: If we're in inline layout, the LineBuilder has already provided the right Y offset.
  834. // In block layout, we adjust by the side's current Y offset here.
  835. // FIXME: It's annoying that we have different behavior for inline vs block here.
  836. // Find a way to unify the behavior so we don't need to branch here.
  837. if (!line_builder)
  838. y += side_data.y_offset;
  839. auto top_margin_edge = y - box_state.margin_box_top();
  840. side_data.all_boxes.append(adopt_own(*new FloatingBox {
  841. .box = box,
  842. .offset_from_edge = offset_from_edge,
  843. .top_margin_edge = top_margin_edge,
  844. .bottom_margin_edge = y + box_state.content_height() + box_state.margin_box_bottom(),
  845. }));
  846. side_data.current_boxes.append(*side_data.all_boxes.last());
  847. if (side == FloatSide::Left) {
  848. side_data.current_width = offset_from_edge + box_state.content_width() + box_state.margin_box_right();
  849. } else {
  850. side_data.current_width = offset_from_edge + box_state.margin_box_left();
  851. }
  852. side_data.max_width = max(side_data.current_width, side_data.max_width);
  853. // NOTE: We don't set the X position here, that happens later, once we know the root block width.
  854. // See parent_context_did_dimension_child_root_box() for that logic.
  855. box_state.set_content_y(y);
  856. // If the new box was inserted below the bottom of the opposite side,
  857. // we reset the other side back to its edge.
  858. if (top_margin_edge > other_side_data.y_offset)
  859. other_side_data.clear();
  860. };
  861. // Next, float to the left and/or right
  862. if (box.computed_values().float_() == CSS::Float::Left) {
  863. float_box(FloatSide::Left, m_left_floats, m_right_floats);
  864. } else if (box.computed_values().float_() == CSS::Float::Right) {
  865. float_box(FloatSide::Right, m_right_floats, m_left_floats);
  866. }
  867. m_state.get_mutable(root()).add_floating_descendant(box);
  868. if (line_builder)
  869. line_builder->recalculate_available_space();
  870. compute_inset(box);
  871. if (independent_formatting_context)
  872. independent_formatting_context->parent_context_did_dimension_child_root_box();
  873. }
  874. void BlockFormattingContext::layout_list_item_marker(ListItemBox const& list_item_box)
  875. {
  876. if (!list_item_box.marker())
  877. return;
  878. auto& marker = *list_item_box.marker();
  879. auto& marker_state = m_state.get_mutable(marker);
  880. auto& list_item_state = m_state.get_mutable(list_item_box);
  881. CSSPixels image_width = 0;
  882. CSSPixels image_height = 0;
  883. if (auto const* list_style_image = marker.list_style_image()) {
  884. image_width = list_style_image->natural_width().value_or(0);
  885. image_height = list_style_image->natural_height().value_or(0);
  886. }
  887. CSSPixels default_marker_width = max(4, marker.font().pixel_size_rounded_up() - 4);
  888. if (marker.text().is_empty()) {
  889. marker_state.set_content_width(image_width + default_marker_width);
  890. } else {
  891. auto text_width = marker.font().width(marker.text());
  892. marker_state.set_content_width(image_width + text_width);
  893. }
  894. marker_state.set_content_height(max(image_height, marker.font().pixel_size_rounded_up() + 1));
  895. if (marker.list_style_type() == CSS::ListStyleType::DisclosureClosed || marker.list_style_type() == CSS::ListStyleType::DisclosureOpen)
  896. marker_state.set_content_width(marker_state.content_height());
  897. auto final_marker_width = marker_state.content_width() + default_marker_width;
  898. if (marker.list_style_position() == CSS::ListStylePosition::Inside) {
  899. list_item_state.set_content_offset({ final_marker_width, list_item_state.offset.y() });
  900. list_item_state.set_content_width(list_item_state.content_width() - final_marker_width);
  901. }
  902. marker_state.set_content_offset({ -final_marker_width, max(CSSPixels(0), (CSSPixels(marker.line_height()) - marker_state.content_height()) / 2) });
  903. if (marker_state.content_height() > list_item_state.content_height())
  904. list_item_state.set_content_height(marker_state.content_height());
  905. }
  906. BlockFormattingContext::SpaceUsedAndContainingMarginForFloats BlockFormattingContext::space_used_and_containing_margin_for_floats(CSSPixels y) const
  907. {
  908. SpaceUsedAndContainingMarginForFloats space_and_containing_margin;
  909. for (auto const& floating_box_ptr : m_left_floats.all_boxes.in_reverse()) {
  910. auto const& floating_box = *floating_box_ptr;
  911. auto const& floating_box_state = m_state.get(floating_box.box);
  912. // NOTE: The floating box is *not* in the final horizontal position yet, but the size and vertical position is valid.
  913. auto rect = margin_box_rect_in_ancestor_coordinate_space(floating_box.box, root());
  914. if (rect.contains_vertically(y)) {
  915. CSSPixels offset_from_containing_block_chain_margins_between_here_and_root = 0;
  916. for (auto const* containing_block = floating_box.box->containing_block(); containing_block && containing_block != &root(); containing_block = containing_block->containing_block()) {
  917. auto const& containing_block_state = m_state.get(*containing_block);
  918. offset_from_containing_block_chain_margins_between_here_and_root += containing_block_state.margin_box_left();
  919. }
  920. space_and_containing_margin.left_used_space = floating_box.offset_from_edge
  921. + floating_box_state.content_width()
  922. + floating_box_state.margin_box_right();
  923. space_and_containing_margin.left_total_containing_margin = offset_from_containing_block_chain_margins_between_here_and_root;
  924. space_and_containing_margin.matching_left_float_box = floating_box.box.ptr();
  925. break;
  926. }
  927. }
  928. for (auto const& floating_box_ptr : m_right_floats.all_boxes.in_reverse()) {
  929. auto const& floating_box = *floating_box_ptr;
  930. auto const& floating_box_state = m_state.get(floating_box.box);
  931. // NOTE: The floating box is *not* in the final horizontal position yet, but the size and vertical position is valid.
  932. auto rect = margin_box_rect_in_ancestor_coordinate_space(floating_box.box, root());
  933. if (rect.contains_vertically(y)) {
  934. CSSPixels offset_from_containing_block_chain_margins_between_here_and_root = 0;
  935. for (auto const* containing_block = floating_box.box->containing_block(); containing_block && containing_block != &root(); containing_block = containing_block->containing_block()) {
  936. auto const& containing_block_state = m_state.get(*containing_block);
  937. offset_from_containing_block_chain_margins_between_here_and_root += containing_block_state.margin_box_right();
  938. }
  939. space_and_containing_margin.right_used_space = floating_box.offset_from_edge
  940. + floating_box_state.margin_box_left();
  941. space_and_containing_margin.right_total_containing_margin = offset_from_containing_block_chain_margins_between_here_and_root;
  942. break;
  943. }
  944. }
  945. return space_and_containing_margin;
  946. }
  947. FormattingContext::SpaceUsedByFloats BlockFormattingContext::intrusion_by_floats_into_box(Box const& box, CSSPixels y_in_box) const
  948. {
  949. // NOTE: Floats are relative to the BFC root box, not necessarily the containing block of this IFC.
  950. auto box_in_root_rect = content_box_rect_in_ancestor_coordinate_space(box, root());
  951. CSSPixels y_in_root = box_in_root_rect.y() + y_in_box;
  952. auto space_and_containing_margin = space_used_and_containing_margin_for_floats(y_in_root);
  953. auto left_side_floats_limit_to_right = space_and_containing_margin.left_total_containing_margin + space_and_containing_margin.left_used_space;
  954. auto right_side_floats_limit_to_right = space_and_containing_margin.right_used_space + space_and_containing_margin.right_total_containing_margin;
  955. auto left_intrusion = max(CSSPixels(0), left_side_floats_limit_to_right - max(CSSPixels(0), box_in_root_rect.x()));
  956. CSSPixels offset_from_containing_block_chain_margins_between_here_and_root = 0;
  957. for (auto const* containing_block = static_cast<Box const*>(&box); containing_block && containing_block != &root(); containing_block = containing_block->containing_block()) {
  958. auto const& containing_block_state = m_state.get(*containing_block);
  959. offset_from_containing_block_chain_margins_between_here_and_root = max(offset_from_containing_block_chain_margins_between_here_and_root, containing_block_state.margin_box_right());
  960. }
  961. auto right_intrusion = max(CSSPixels(0), right_side_floats_limit_to_right - offset_from_containing_block_chain_margins_between_here_and_root);
  962. return { left_intrusion, right_intrusion };
  963. }
  964. CSSPixels BlockFormattingContext::greatest_child_width(Box const& box) const
  965. {
  966. // Similar to FormattingContext::greatest_child_width()
  967. // but this one takes floats into account!
  968. CSSPixels max_width = m_left_floats.max_width + m_right_floats.max_width;
  969. if (box.children_are_inline()) {
  970. for (auto const& line_box : m_state.get(verify_cast<BlockContainer>(box)).line_boxes) {
  971. CSSPixels width_here = line_box.width();
  972. CSSPixels extra_width_from_left_floats = 0;
  973. for (auto& left_float : m_left_floats.all_boxes) {
  974. // NOTE: Floats directly affect the automatic size of their containing block, but only indirectly anything above in the tree.
  975. if (left_float->box->containing_block() != &box)
  976. continue;
  977. if (line_box.baseline() >= left_float->top_margin_edge || line_box.baseline() <= left_float->bottom_margin_edge) {
  978. auto const& left_float_state = m_state.get(left_float->box);
  979. extra_width_from_left_floats = max(extra_width_from_left_floats, left_float->offset_from_edge + left_float_state.content_width() + left_float_state.margin_box_right());
  980. }
  981. }
  982. CSSPixels extra_width_from_right_floats = 0;
  983. for (auto& right_float : m_right_floats.all_boxes) {
  984. // NOTE: Floats directly affect the automatic size of their containing block, but only indirectly anything above in the tree.
  985. if (right_float->box->containing_block() != &box)
  986. continue;
  987. if (line_box.baseline() >= right_float->top_margin_edge || line_box.baseline() <= right_float->bottom_margin_edge) {
  988. auto const& right_float_state = m_state.get(right_float->box);
  989. extra_width_from_right_floats = max(extra_width_from_right_floats, right_float->offset_from_edge + right_float_state.margin_box_left());
  990. }
  991. }
  992. width_here += extra_width_from_left_floats + extra_width_from_right_floats;
  993. max_width = max(max_width, width_here);
  994. }
  995. } else {
  996. box.for_each_child_of_type<Box>([&](Box const& child) {
  997. if (!child.is_absolutely_positioned())
  998. max_width = max(max_width, m_state.get(child).margin_box_width());
  999. });
  1000. }
  1001. return max_width;
  1002. }
  1003. void BlockFormattingContext::determine_width_of_child(Box const&, AvailableSpace const&)
  1004. {
  1005. // NOTE: We don't do anything here, since we'll have already determined the width of the child
  1006. // before recursing into nested layout within the child.
  1007. }
  1008. void BlockFormattingContext::determine_height_of_child(Box const& box, AvailableSpace const& available_space)
  1009. {
  1010. compute_height(box, available_space);
  1011. }
  1012. }