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f0b4162328
This is the first part of constructing the box tree for table layout. No layout is actually done and the construction of tables is now hidden behind a flag (in order to not regress WPT). Notably, this does not handle anonymous table part construction, when the DOM does not reflect a fully-formed table. That's part two. Progress toward #27459. Co-authored-by: Oriol Brufau <obrufau@igalia.com> Co-authored-by: Manish Goregaokar <manishsmail@gmail.com>
439 lines
18 KiB
Rust
439 lines
18 KiB
Rust
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
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use std::borrow::Cow;
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use std::convert::{TryFrom, TryInto};
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use log::warn;
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use script_layout_interface::wrapper_traits::ThreadSafeLayoutNode;
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use style::values::specified::TextDecorationLine;
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use super::{Table, TableSlot, TableSlotCell, TableSlotCoordinates, TableSlotOffset};
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use crate::context::LayoutContext;
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use crate::dom::{BoxSlot, NodeExt};
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use crate::dom_traversal::{Contents, NodeAndStyleInfo, NonReplacedContents, TraversalHandler};
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use crate::flow::BlockFormattingContext;
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use crate::style_ext::{DisplayGeneratingBox, DisplayLayoutInternal};
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/// A reference to a slot and its coordinates in the table
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#[derive(Clone, Copy, Debug)]
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struct ResolvedSlotAndLocation<'a> {
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cell: &'a TableSlotCell,
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coords: TableSlotCoordinates,
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}
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impl<'a> ResolvedSlotAndLocation<'a> {
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fn covers_cell_at(&self, coords: TableSlotCoordinates) -> bool {
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let covered_in_x =
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coords.x >= self.coords.x && coords.x < self.coords.x + self.cell.colspan;
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let covered_in_y = coords.y >= self.coords.y &&
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(self.cell.rowspan == 0 || coords.y < self.coords.y + self.cell.rowspan);
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covered_in_x && covered_in_y
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}
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}
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impl Table {
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pub(crate) fn construct<'dom>(
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context: &LayoutContext,
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info: &NodeAndStyleInfo<impl NodeExt<'dom>>,
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contents: NonReplacedContents,
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propagated_text_decoration_line: TextDecorationLine,
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) -> Self {
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let mut traversal = TableBuilderTraversal {
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context,
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_info: info,
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propagated_text_decoration_line,
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builder: Default::default(),
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};
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contents.traverse(context, info, &mut traversal);
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traversal.builder.finish()
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}
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/// Push a new slot into the last row of this table.
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fn push_new_slot_to_last_row(&mut self, slot: TableSlot) {
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self.slots.last_mut().expect("Should have rows").push(slot)
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}
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/// Convenience method for get() that returns a SlotAndLocation
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fn get_slot<'a>(&'a self, coords: TableSlotCoordinates) -> Option<&'a TableSlot> {
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self.slots.get(coords.y)?.get(coords.x)
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}
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/// Find [`ResolvedSlotAndLocation`] of all the slots that cover the slot at the given
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/// coordinates. This recursively resolves all of the [`TableSlotCell`]s that cover
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/// the target and returns a [`ResolvedSlotAndLocation`] for each of them. If there is
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/// no slot at the given coordinates or that slot is an empty space, an empty vector
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/// is returned.
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fn resolve_slot_at<'a>(
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&'a self,
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coords: TableSlotCoordinates,
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) -> Vec<ResolvedSlotAndLocation<'a>> {
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let slot = self.get_slot(coords);
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match slot {
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Some(TableSlot::Cell(cell)) => vec![ResolvedSlotAndLocation {
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cell: &cell,
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coords,
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}],
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Some(TableSlot::Spanned(ref offsets)) => offsets
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.iter()
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.map(|offset| self.resolve_slot_at(coords - *offset))
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.flatten()
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.collect(),
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Some(TableSlot::Empty) | None => {
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warn!("Tried to resolve an empty or nonexistant slot!");
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vec![]
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},
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}
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}
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/// Create a [`TableSlot::Spanned`] for the target cell at the given coordinates. If
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/// no slots cover the target, then this returns [`None`]. Note: This does not handle
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/// slots that cover the target using `colspan`, but instead only considers slots that
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/// cover this slot via `rowspan`. `colspan` should be handled by appending to the
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/// return value of this function.
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fn create_spanned_slot_based_on_cell_above(
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&self,
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target_coords: TableSlotCoordinates,
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) -> Option<TableSlot> {
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let coords_for_slot_above =
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TableSlotCoordinates::new(target_coords.x, self.slots.len() - 2);
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let slots_covering_slot_above = self.resolve_slot_at(coords_for_slot_above);
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let coords_of_slots_that_cover_target: Vec<_> = slots_covering_slot_above
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.into_iter()
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.filter(|ref slot| slot.covers_cell_at(target_coords))
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.map(|slot| target_coords - slot.coords)
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.collect();
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if coords_of_slots_that_cover_target.is_empty() {
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return None;
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} else {
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Some(TableSlot::Spanned(coords_of_slots_that_cover_target))
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}
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}
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}
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impl TableSlot {
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/// Merge a TableSlot::Spanned(x, y) with this (only for model errors)
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pub fn push_spanned(&mut self, new_offset: TableSlotOffset) {
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match *self {
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TableSlot::Cell { .. } => {
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panic!("Should never have a table model error with an originating cell slot overlapping a spanned slot")
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},
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TableSlot::Spanned(ref mut vec) => vec.insert(0, new_offset),
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TableSlot::Empty => {
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panic!("Should never have a table model error with an empty slot");
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},
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}
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}
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}
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#[derive(Default)]
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pub struct TableBuilder {
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/// The table that we are building.
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table: Table,
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/// An incoming rowspan is a value indicating that a cell in a row above the current row,
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/// had a rowspan value other than 1. The values in this array indicate how many more
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/// rows the cell should span. For example, a value of 0 at an index before `current_x()`
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/// indicates that the cell on that column will not span into the next row, and at an index
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/// after `current_x()` it indicates that the cell will not span into the current row.
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/// A negative value means that the cell will span all remaining rows in the row group.
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///
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/// As each column in a row is processed, the values in this vector are updated for the
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/// next row.
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pub incoming_rowspans: Vec<isize>,
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}
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impl TableBuilder {
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pub fn finish(self) -> Table {
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self.table
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}
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fn current_y(&self) -> usize {
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self.table.slots.len() - 1
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}
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fn current_x(&self) -> usize {
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self.table.slots[self.current_y()].len()
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}
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fn current_coords(&self) -> TableSlotCoordinates {
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TableSlotCoordinates::new(self.current_x(), self.current_y())
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}
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pub fn start_row<'builder>(&'builder mut self) {
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self.table.slots.push(Vec::new());
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self.create_slots_for_cells_above_with_rowspan(true);
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}
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pub fn end_row(&mut self) {
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// TODO: We need to insert a cell for any leftover non-table-like
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// content in the TableRowBuilder.
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// Truncate entries that are zero at the end of [`Self::incoming_rowspans`]. This
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// prevents padding the table with empty cells when it isn't necessary.
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let current_x = self.current_x();
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for i in (current_x..self.incoming_rowspans.len()).rev() {
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if self.incoming_rowspans[i] == 0 {
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self.incoming_rowspans.pop();
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} else {
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break;
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}
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}
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self.create_slots_for_cells_above_with_rowspan(false);
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}
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/// When not in the process of filling a cell, make sure any incoming rowspans are
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/// filled so that the next specified cell comes after them. Should have been called before
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/// [`Self::handle_cell`].
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///
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/// if `stop_at_cell_opportunity` is set, this will stop at the first slot with
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/// `incoming_rowspans` equal to zero. If not, it will insert [`TableSlot::Empty`] and
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/// continue to look for more incoming rowspans (which should only be done once we're
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/// finished processing the cells in a row, and after calling truncating cells with
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/// remaining rowspan from the end of `incoming_rowspans`.
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fn create_slots_for_cells_above_with_rowspan(&mut self, stop_at_cell_opportunity: bool) {
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let mut current_x = self.current_x();
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while let Some(span) = self.incoming_rowspans.get_mut(current_x) {
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// This column has no incoming rowspanned cells and `stop_at_zero` is true, so
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// we should stop to process new cells defined in the current row.
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if *span == 0 && stop_at_cell_opportunity {
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break;
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}
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let new_cell = if *span != 0 {
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*span -= 1;
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self.table
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.create_spanned_slot_based_on_cell_above(self.current_coords())
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.expect(
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"Nonzero incoming rowspan cannot occur without a cell spanning this slot",
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)
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} else {
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TableSlot::Empty
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};
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self.table.push_new_slot_to_last_row(new_cell);
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current_x = self.current_x();
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}
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}
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/// https://html.spec.whatwg.org/multipage/#algorithm-for-processing-rows
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/// Push a single cell onto the slot map, handling any colspans it may have, and
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/// setting up the outgoing rowspans.
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pub fn add_cell(&mut self, cell: TableSlotCell) {
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// Make sure the incoming_rowspans table is large enough
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// because we will be writing to it.
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let current_x = self.current_x();
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let colspan = cell.colspan;
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let rowspan = cell.rowspan;
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if self.incoming_rowspans.len() < current_x + colspan {
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self.incoming_rowspans.resize(current_x + colspan, 0isize);
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}
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debug_assert_eq!(
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self.incoming_rowspans[current_x], 0,
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"Added a cell in a position that also had an incoming rowspan!"
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);
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// If `rowspan` is zero, this is automatically negative and will stay negative.
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let outgoing_rowspan = rowspan as isize - 1;
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self.table.push_new_slot_to_last_row(TableSlot::Cell(cell));
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self.incoming_rowspans[current_x] = outgoing_rowspan;
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// Draw colspanned cells
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for colspan_offset in 1..colspan {
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let current_x_plus_colspan_offset = current_x + colspan_offset;
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let new_offset = TableSlotOffset::new(colspan_offset, 0);
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let incoming_rowspan = &mut self.incoming_rowspans[current_x_plus_colspan_offset];
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let new_slot = if *incoming_rowspan == 0 {
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*incoming_rowspan = outgoing_rowspan;
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TableSlot::new_spanned(new_offset)
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} else {
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// This means we have a table model error.
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// if `incoming_rowspan` is greater than zero, a cell from above is spanning
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// into our row, colliding with the cells we are creating via colspan. In
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// that case, set the incoming rowspan to the highest of two possible
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// outgoing rowspan values (the incoming rowspan minus one, OR this cell's
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// outgoing rowspan). `spanned_slot()`` will handle filtering out
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// inapplicable spans when it needs to.
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//
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// If the `incoming_rowspan` is negative we are in `rowspan=0` mode, (i.e.
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// rowspan=infinity), so we don't have to worry about the current cell
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// making it larger. In that case, don't change the rowspan.
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if *incoming_rowspan > 0 {
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*incoming_rowspan = std::cmp::max(*incoming_rowspan - 1, outgoing_rowspan);
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}
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// This code creates a new slot in the case that there is a table model error.
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let coords_of_spanned_cell =
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TableSlotCoordinates::new(current_x_plus_colspan_offset, self.current_y());
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match self
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.table
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.create_spanned_slot_based_on_cell_above(coords_of_spanned_cell)
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{
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Some(mut incoming_slot) => {
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incoming_slot.push_spanned(new_offset);
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incoming_slot
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},
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None => TableSlot::new_spanned(new_offset),
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}
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};
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self.table.push_new_slot_to_last_row(new_slot);
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}
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debug_assert_eq!(
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current_x + colspan,
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self.current_x(),
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"Must have produced `colspan` slot entries!"
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);
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self.create_slots_for_cells_above_with_rowspan(true);
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}
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}
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struct TableBuilderTraversal<'a, Node> {
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context: &'a LayoutContext<'a>,
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_info: &'a NodeAndStyleInfo<Node>,
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/// Propagated value for text-decoration-line, used to construct the block
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/// contents of table cells.
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propagated_text_decoration_line: TextDecorationLine,
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/// The [`TableBuilder`] for this [`TableBuilderTraversal`]. This is separated
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/// into another struct so that we can write unit tests against the builder.
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builder: TableBuilder,
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}
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impl<'a, 'dom, Node: 'dom> TraversalHandler<'dom, Node> for TableBuilderTraversal<'a, Node>
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where
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Node: NodeExt<'dom>,
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{
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fn handle_text(&mut self, _info: &NodeAndStyleInfo<Node>, _text: Cow<'dom, str>) {
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// TODO: We should collect these contents into a new table cell.
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}
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/// https://html.spec.whatwg.org/multipage/#forming-a-table
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fn handle_element(
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&mut self,
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info: &NodeAndStyleInfo<Node>,
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display: DisplayGeneratingBox,
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contents: Contents,
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box_slot: BoxSlot<'dom>,
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) {
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match display {
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DisplayGeneratingBox::LayoutInternal(internal) => match internal {
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DisplayLayoutInternal::TableRowGroup => {
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// TODO: Should we fixup `rowspan=0` to the actual resolved value and
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// any other rowspans that have been cut short?
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self.builder.incoming_rowspans.clear();
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NonReplacedContents::try_from(contents).unwrap().traverse(
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self.context,
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info,
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self,
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);
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// TODO: Handle style for row groups here.
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},
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DisplayLayoutInternal::TableRow => {
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self.builder.start_row();
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NonReplacedContents::try_from(contents).unwrap().traverse(
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self.context,
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info,
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&mut TableRowBuilder::new(self),
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);
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self.builder.end_row();
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},
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_ => {
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// TODO: Handle other types of unparented table content, colgroups, and captions.
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},
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},
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_ => {
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// TODO: Create an anonymous row and cell for other unwrapped content.
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},
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}
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// We are doing this until we have actually set a Box for this `BoxSlot`.
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::std::mem::forget(box_slot)
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}
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}
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struct TableRowBuilder<'a, 'builder, Node> {
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table_traversal: &'builder mut TableBuilderTraversal<'a, Node>,
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}
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impl<'a, 'builder, Node> TableRowBuilder<'a, 'builder, Node> {
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fn new(table_traversal: &'builder mut TableBuilderTraversal<'a, Node>) -> Self {
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TableRowBuilder { table_traversal }
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}
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}
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impl<'a, 'builder, 'dom, Node: 'dom> TraversalHandler<'dom, Node>
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for TableRowBuilder<'a, 'builder, Node>
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where
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Node: NodeExt<'dom>,
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{
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fn handle_text(&mut self, _info: &NodeAndStyleInfo<Node>, _text: Cow<'dom, str>) {
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// TODO: We should collect these contents into a new table cell.
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}
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/// https://html.spec.whatwg.org/multipage/#algorithm-for-processing-rows
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fn handle_element(
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&mut self,
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info: &NodeAndStyleInfo<Node>,
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display: DisplayGeneratingBox,
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contents: Contents,
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box_slot: BoxSlot<'dom>,
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) {
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match display {
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DisplayGeneratingBox::LayoutInternal(internal) => match internal {
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DisplayLayoutInternal::TableCell => {
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// This value will already have filtered out rowspan=0
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// in quirks mode, so we don't have to worry about that.
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//
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// The HTML specification limits the parsed value of `rowspan` to
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// 65534 and `colspan` to 1000, so we also enforce the same limits
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// when dealing with arbitrary DOM elements (perhaps created via
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// script).
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let node = info.node.to_threadsafe();
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let rowspan = std::cmp::min(node.get_rowspan() as usize, 65534);
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let colspan = std::cmp::min(node.get_colspan() as usize, 1000);
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let contents = match contents.try_into() {
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Ok(non_replaced_contents) => {
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BlockFormattingContext::construct(
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self.table_traversal.context,
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info,
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non_replaced_contents,
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self.table_traversal.propagated_text_decoration_line,
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false, /* is_list_item */
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)
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},
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Err(_replaced) => {
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panic!("We don't handle this yet.");
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},
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};
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self.table_traversal.builder.add_cell(TableSlotCell {
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contents,
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colspan,
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rowspan,
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id: 0, // This is just an id used for testing purposes.
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});
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},
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_ => {
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// TODO: Properly handle other table-like elements in the middle of a row.
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},
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},
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_ => {
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// TODO: We should collect these contents into a new table cell.
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},
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}
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// We are doing this until we have actually set a Box for this `BoxSlot`.
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::std::mem::forget(box_slot)
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}
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}
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