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e7019f2721
Instead of producing a tree of stacking contexts, display list
generation now produces a flat list of display items and a tree of
stacking contexts. This will eventually allow display list construction
to produce and modify WebRender vertex buffers directly, removing the
overhead of display list conversion. This change also moves
layerization of the display list to the paint thread, since it isn't
currently useful for WebRender.
To accomplish this, display list generation now takes three passes of
the flow tree:
1. Calculation of absolute positions.
2. Collection of a tree of stacking contexts.
3. Creation of a list of display items.
After collection of display items, they are sorted based upon the index
of their parent stacking contexts and their position in CSS 2.1
Appendeix E stacking order.
This is a big change, but it actually simplifies display list generation.
317 lines
12 KiB
Rust
317 lines
12 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 http://mozilla.org/MPL/2.0/. */
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//! CSS Multi-column layout http://dev.w3.org/csswg/css-multicol/
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#![deny(unsafe_code)]
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use app_units::Au;
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use block::BlockFlow;
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use context::LayoutContext;
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use display_list_builder::DisplayListBuildState;
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use euclid::Point2D;
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use floats::FloatKind;
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use flow::{Flow, FlowClass, OpaqueFlow, mut_base, FragmentationContext};
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use flow_ref::{self, FlowRef};
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use fragment::{Fragment, FragmentBorderBoxIterator, Overflow};
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use gfx::display_list::{StackingContext, StackingContextId};
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use std::cmp::{min, max};
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use std::fmt;
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use std::sync::Arc;
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use style::context::StyleContext;
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use style::logical_geometry::LogicalSize;
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use style::properties::ComputedValues;
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use style::values::computed::{LengthOrPercentageOrAuto, LengthOrPercentageOrNone};
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use util::print_tree::PrintTree;
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pub struct MulticolFlow {
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pub block_flow: BlockFlow,
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/// Length between the inline-start edge of a column and that of the next.
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/// That is, the used column-width + used column-gap.
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pub column_pitch: Au,
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}
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pub struct MulticolColumnFlow {
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pub block_flow: BlockFlow,
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}
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impl MulticolFlow {
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pub fn from_fragment(fragment: Fragment, float_kind: Option<FloatKind>) -> MulticolFlow {
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MulticolFlow {
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block_flow: BlockFlow::from_fragment(fragment, float_kind),
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column_pitch: Au(0),
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}
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}
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}
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impl MulticolColumnFlow {
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pub fn from_fragment(fragment: Fragment) -> MulticolColumnFlow {
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MulticolColumnFlow {
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block_flow: BlockFlow::from_fragment(fragment, None),
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}
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}
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}
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impl Flow for MulticolFlow {
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fn class(&self) -> FlowClass {
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FlowClass::Multicol
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}
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fn as_mut_block(&mut self) -> &mut BlockFlow {
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&mut self.block_flow
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}
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fn as_block(&self) -> &BlockFlow {
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&self.block_flow
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}
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fn as_mut_multicol(&mut self) -> &mut MulticolFlow {
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self
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}
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fn bubble_inline_sizes(&mut self) {
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// FIXME(SimonSapin) http://dev.w3.org/csswg/css-sizing/#multicol-intrinsic
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self.block_flow.bubble_inline_sizes();
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}
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fn assign_inline_sizes(&mut self, layout_context: &LayoutContext) {
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debug!("assign_inline_sizes({}): assigning inline_size for flow", "multicol");
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self.block_flow.compute_inline_sizes(layout_context);
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// Move in from the inline-start border edge.
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let inline_start_content_edge = self.block_flow.fragment.border_box.start.i +
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self.block_flow.fragment.border_padding.inline_start;
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// Distance from the inline-end margin edge to the inline-end content edge.
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let inline_end_content_edge =
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self.block_flow.fragment.margin.inline_end +
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self.block_flow.fragment.border_padding.inline_end;
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self.block_flow.assign_inline_sizes(layout_context);
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let padding_and_borders = self.block_flow.fragment.border_padding.inline_start_end();
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let content_inline_size =
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self.block_flow.fragment.border_box.size.inline - padding_and_borders;
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let column_width;
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{
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let column_style = self.block_flow.fragment.style.get_column();
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// `None` is 'normal': "UA-specified length. A value of 1em is suggested."
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let column_gap = column_style.column_gap.0.unwrap_or_else(||
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self.block_flow.fragment.style.get_font().font_size);
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let mut column_count;
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if let Some(column_width) = column_style.column_width.0 {
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column_count =
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max(1, (content_inline_size + column_gap).0 / (column_width + column_gap).0);
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if let Some(specified_column_count) = column_style.column_count.0 {
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column_count = min(column_count, specified_column_count as i32);
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}
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} else {
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column_count = column_style.column_count.0.unwrap() as i32;
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}
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column_width =
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max(Au(0), (content_inline_size + column_gap) / column_count - column_gap);
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self.column_pitch = column_width + column_gap;
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}
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self.block_flow.fragment.border_box.size.inline = content_inline_size + padding_and_borders;
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self.block_flow.propagate_assigned_inline_size_to_children(
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layout_context, inline_start_content_edge, inline_end_content_edge, column_width,
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|_, _, _, _, _, _| {});
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}
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fn assign_block_size<'a>(&mut self, ctx: &'a LayoutContext<'a>) {
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debug!("assign_block_size: assigning block_size for multicol");
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let fragmentation_context = Some(FragmentationContext {
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this_fragment_is_empty: true,
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available_block_size: {
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let style = &self.block_flow.fragment.style;
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if let LengthOrPercentageOrAuto::Length(length) = style.content_block_size() {
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length
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} else if let LengthOrPercentageOrNone::Length(length) = style.max_block_size() {
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length
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} else {
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// FIXME: do column balancing instead
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// FIXME: (until column balancing) substract margins/borders/padding
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LogicalSize::from_physical(
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self.block_flow.base.writing_mode,
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ctx.shared_context().viewport_size,
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).block
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}
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}
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});
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// Before layout, everything is in a single "column"
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assert!(self.block_flow.base.children.len() == 1);
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let mut column = self.block_flow.base.children.pop_front().unwrap();
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// Pretend there is no children for this:
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self.block_flow.assign_block_size(ctx);
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loop {
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let remaining = flow_ref::deref_mut(&mut column).fragment(ctx, fragmentation_context);
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self.block_flow.base.children.push_back(column);
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column = match remaining {
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Some(remaining) => remaining,
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None => break
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};
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}
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}
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fn compute_absolute_position(&mut self, layout_context: &LayoutContext) {
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self.block_flow.compute_absolute_position(layout_context);
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let pitch = LogicalSize::new(self.block_flow.base.writing_mode, self.column_pitch, Au(0));
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let pitch = pitch.to_physical(self.block_flow.base.writing_mode);
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for (i, child) in self.block_flow.base.children.iter_mut().enumerate() {
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let point = &mut mut_base(child).stacking_relative_position;
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*point = *point + pitch * i as i32;
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}
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}
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fn update_late_computed_inline_position_if_necessary(&mut self, inline_position: Au) {
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self.block_flow.update_late_computed_inline_position_if_necessary(inline_position)
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}
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fn update_late_computed_block_position_if_necessary(&mut self, block_position: Au) {
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self.block_flow.update_late_computed_block_position_if_necessary(block_position)
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}
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fn build_display_list(&mut self, state: &mut DisplayListBuildState) {
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debug!("build_display_list_multicol");
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self.block_flow.build_display_list(state);
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}
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fn collect_stacking_contexts(&mut self,
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parent_id: StackingContextId,
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contexts: &mut Vec<StackingContext>)
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-> StackingContextId {
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self.block_flow.collect_stacking_contexts(parent_id, contexts)
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}
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fn repair_style(&mut self, new_style: &Arc<ComputedValues>) {
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self.block_flow.repair_style(new_style)
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}
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fn compute_overflow(&self) -> Overflow {
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self.block_flow.compute_overflow()
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}
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fn generated_containing_block_size(&self, flow: OpaqueFlow) -> LogicalSize<Au> {
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self.block_flow.generated_containing_block_size(flow)
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}
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fn iterate_through_fragment_border_boxes(&self,
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iterator: &mut FragmentBorderBoxIterator,
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level: i32,
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stacking_context_position: &Point2D<Au>) {
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self.block_flow.iterate_through_fragment_border_boxes(iterator, level, stacking_context_position);
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}
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fn mutate_fragments(&mut self, mutator: &mut FnMut(&mut Fragment)) {
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self.block_flow.mutate_fragments(mutator);
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}
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fn print_extra_flow_children(&self, print_tree: &mut PrintTree) {
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self.block_flow.print_extra_flow_children(print_tree);
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}
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}
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impl Flow for MulticolColumnFlow {
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fn class(&self) -> FlowClass {
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FlowClass::MulticolColumn
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}
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fn as_mut_block(&mut self) -> &mut BlockFlow {
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&mut self.block_flow
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}
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fn as_block(&self) -> &BlockFlow {
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&self.block_flow
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}
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fn bubble_inline_sizes(&mut self) {
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self.block_flow.bubble_inline_sizes();
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}
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fn assign_inline_sizes(&mut self, layout_context: &LayoutContext) {
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debug!("assign_inline_sizes({}): assigning inline_size for flow", "multicol column");
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self.block_flow.assign_inline_sizes(layout_context);
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}
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fn assign_block_size<'a>(&mut self, ctx: &'a LayoutContext<'a>) {
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debug!("assign_block_size: assigning block_size for multicol column");
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self.block_flow.assign_block_size(ctx);
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}
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fn fragment(&mut self, layout_context: &LayoutContext,
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fragmentation_context: Option<FragmentationContext>)
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-> Option<FlowRef> {
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Flow::fragment(&mut self.block_flow, layout_context, fragmentation_context)
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}
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fn compute_absolute_position(&mut self, layout_context: &LayoutContext) {
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self.block_flow.compute_absolute_position(layout_context)
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}
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fn update_late_computed_inline_position_if_necessary(&mut self, inline_position: Au) {
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self.block_flow.update_late_computed_inline_position_if_necessary(inline_position)
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}
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fn update_late_computed_block_position_if_necessary(&mut self, block_position: Au) {
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self.block_flow.update_late_computed_block_position_if_necessary(block_position)
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}
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fn build_display_list(&mut self, state: &mut DisplayListBuildState) {
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debug!("build_display_list_multicol column");
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self.block_flow.build_display_list(state);
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}
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fn collect_stacking_contexts(&mut self,
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parent_id: StackingContextId,
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contexts: &mut Vec<StackingContext>)
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-> StackingContextId {
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self.block_flow.collect_stacking_contexts(parent_id, contexts)
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}
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fn repair_style(&mut self, new_style: &Arc<ComputedValues>) {
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self.block_flow.repair_style(new_style)
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}
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fn compute_overflow(&self) -> Overflow {
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self.block_flow.compute_overflow()
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}
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fn generated_containing_block_size(&self, flow: OpaqueFlow) -> LogicalSize<Au> {
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self.block_flow.generated_containing_block_size(flow)
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}
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fn iterate_through_fragment_border_boxes(&self,
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iterator: &mut FragmentBorderBoxIterator,
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level: i32,
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stacking_context_position: &Point2D<Au>) {
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self.block_flow.iterate_through_fragment_border_boxes(iterator, level, stacking_context_position);
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}
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fn mutate_fragments(&mut self, mutator: &mut FnMut(&mut Fragment)) {
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self.block_flow.mutate_fragments(mutator);
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}
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fn print_extra_flow_children(&self, print_tree: &mut PrintTree) {
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self.block_flow.print_extra_flow_children(print_tree);
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}
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}
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impl fmt::Debug for MulticolFlow {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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write!(f, "MulticolFlow: {:?}", self.block_flow)
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}
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}
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impl fmt::Debug for MulticolColumnFlow {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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write!(f, "MulticolColumnFlow: {:?}", self.block_flow)
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}
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}
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