/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
//! Layout for elements with a CSS `display` property of `flex`.
#![deny(unsafe_code)]
use app_units::{Au, MAX_AU};
use block::{AbsoluteAssignBSizesTraversal, BlockFlow, MarginsMayCollapseFlag};
use context::LayoutContext;
use display_list::{DisplayListBuildState, FlexFlowDisplayListBuilding};
use display_list::StackingContextCollectionState;
use euclid::Point2D;
use floats::FloatKind;
use flow::{Flow, FlowClass, GetBaseFlow, ImmutableFlowUtils, OpaqueFlow, FlowFlags};
use fragment::{Fragment, FragmentBorderBoxIterator, Overflow};
use layout_debug;
use model::{AdjoiningMargins, CollapsibleMargins};
use model::{IntrinsicISizes, MaybeAuto, SizeConstraint};
use std::cmp::{max, min};
use std::ops::Range;
use style::computed_values::align_content::T as AlignContent;
use style::computed_values::align_self::T as AlignSelf;
use style::computed_values::flex_direction::T as FlexDirection;
use style::computed_values::flex_wrap::T as FlexWrap;
use style::computed_values::justify_content::T as JustifyContent;
use style::logical_geometry::{Direction, LogicalSize};
use style::properties::ComputedValues;
use style::servo::restyle_damage::ServoRestyleDamage;
use style::values::computed::{LengthOrPercentage, LengthOrPercentageOrAuto, LengthOrPercentageOrNone};
use style::values::computed::flex::FlexBasis;
use style::values::generics::flex::FlexBasis as GenericFlexBasis;
use traversal::PreorderFlowTraversal;
/// The size of an axis. May be a specified size, a min/max
/// constraint, or an unlimited size
#[derive(Debug, Serialize)]
enum AxisSize {
Definite(Au),
MinMax(SizeConstraint),
Infinite,
}
impl AxisSize {
/// Generate a new available cross or main axis size from the specified size of the container,
/// containing block size, min constraint, and max constraint
pub fn new(size: LengthOrPercentageOrAuto, content_size: Option<Au>, min: LengthOrPercentage,
max: LengthOrPercentageOrNone) -> AxisSize {
match size {
LengthOrPercentageOrAuto::Length(length) => AxisSize::Definite(Au::from(length)),
LengthOrPercentageOrAuto::Percentage(percent) => {
match content_size {
Some(size) => AxisSize::Definite(size.scale_by(percent.0)),
None => AxisSize::Infinite
}
}
LengthOrPercentageOrAuto::Calc(calc) => {
match calc.to_used_value(content_size) {
Some(length) => AxisSize::Definite(length),
None => AxisSize::Infinite,
}
}
LengthOrPercentageOrAuto::Auto => {
AxisSize::MinMax(SizeConstraint::new(content_size, min, max, None))
}
}
}
}
/// This function accepts the flex-basis and the size property in main direction from style,
/// and the container size, then return the used value of flex basis. it can be used to help
/// determining the flex base size and to indicate whether the main size of the item
/// is definite after flex size resolving.
fn from_flex_basis(
flex_basis: FlexBasis,
main_length: LengthOrPercentageOrAuto,
containing_length: Option<Au>
) -> MaybeAuto {
match (flex_basis, containing_length) {
(GenericFlexBasis::Length(LengthOrPercentage::Length(length)), _) =>
MaybeAuto::Specified(Au::from(length)),
(GenericFlexBasis::Length(LengthOrPercentage::Percentage(percent)), Some(size)) =>
MaybeAuto::Specified(size.scale_by(percent.0)),
(GenericFlexBasis::Length(LengthOrPercentage::Percentage(_)), None) =>
MaybeAuto::Auto,
(GenericFlexBasis::Length(LengthOrPercentage::Calc(calc)), _) =>
MaybeAuto::from_option(calc.to_used_value(containing_length)),
(GenericFlexBasis::Content, _) =>
MaybeAuto::Auto,
(GenericFlexBasis::Auto, Some(size)) =>
MaybeAuto::from_style(main_length, size),
(GenericFlexBasis::Auto, None) => {
if let LengthOrPercentageOrAuto::Length(length) = main_length {
MaybeAuto::Specified(Au::from(length))
} else {
MaybeAuto::Auto
}
}
}
}
/// Represents a child in a flex container. Most fields here are used in
/// flex size resolving, and items are sorted by the 'order' property.
#[derive(Debug, Serialize)]
struct FlexItem {
/// Main size of a flex item, used to store results of flexible length calcuation.
pub main_size: Au,
/// Used flex base size.
pub base_size: Au,
/// The minimal size in main direction.
pub min_size: Au,
/// The maximal main size. If this property is not actually set by style
/// It will be the largest size available for code reuse.
pub max_size: Au,
/// The index of the actual flow in our child list.
pub index: usize,
/// The 'flex-grow' property of this item.
pub flex_grow: f32,
/// The 'flex-shrink' property of this item.
pub flex_shrink: f32,
/// The 'order' property of this item.
pub order: i32,
/// Whether the main size has met its constraint.
pub is_frozen: bool,
/// True if this flow has property 'visibility::collapse'.
pub is_strut: bool
}
impl FlexItem {
pub fn new(index: usize, flow: &Flow) -> FlexItem {
let style = &flow.as_block().fragment.style;
let flex_grow = style.get_position().flex_grow;
let flex_shrink = style.get_position().flex_shrink;
let order = style.get_position().order;
// TODO(stshine): for item with 'visibility:collapse', set is_strut to true.
FlexItem {
main_size: Au(0),
base_size: Au(0),
min_size: Au(0),
max_size: MAX_AU,
index: index,
flex_grow: flex_grow.into(),
flex_shrink: flex_shrink.into(),
order: order,
is_frozen: false,
is_strut: false
}
}
/// Initialize the used flex base size, minimal main size and maximal main size.
/// For block mode container this method should be called in assign_block_size()
/// pass so that the item has already been layouted.
pub fn init_sizes(&mut self, flow: &mut Flow, containing_length: Au, direction: Direction) {
let block = flow.as_mut_block();
match direction {
// TODO(stshine): the definition of min-{width, height} in style component
// should change to LengthOrPercentageOrAuto for automatic implied minimal size.
// https://drafts.csswg.org/css-flexbox-1/#min-size-auto
Direction::Inline => {
let basis = from_flex_basis(block.fragment.style.get_position().flex_basis,
block.fragment.style.content_inline_size(),
Some(containing_length));
// These methods compute auto margins to zero length, which is exactly what we want.
block.fragment.compute_border_and_padding(containing_length);
block.fragment.compute_inline_direction_margins(containing_length);
block.fragment.compute_block_direction_margins(containing_length);
let (border_padding, margin) = block.fragment.surrounding_intrinsic_inline_size();
let content_size = block.base.intrinsic_inline_sizes.preferred_inline_size
- border_padding
- margin
+ block.fragment.box_sizing_boundary(direction);
self.base_size = basis.specified_or_default(content_size);
self.max_size =
block.fragment.style.max_inline_size()
.to_used_value(containing_length)
.unwrap_or(MAX_AU);
self.min_size = block.fragment.style.min_inline_size().to_used_value(containing_length);
}
Direction::Block => {
let basis = from_flex_basis(block.fragment.style.get_position().flex_basis,
block.fragment.style.content_block_size(),
Some(containing_length));
let content_size = block.fragment.border_box.size.block
- block.fragment.border_padding.block_start_end()
+ block.fragment.box_sizing_boundary(direction);
self.base_size = basis.specified_or_default(content_size);
self.max_size =
block.fragment.style.max_block_size()
.to_used_value(containing_length)
.unwrap_or(MAX_AU);
self.min_size = block.fragment.style.min_block_size().to_used_value(containing_length);
}
}
}
/// Returns the outer main size of the item, including paddings and margins,
/// clamped by max and min size.
pub fn outer_main_size(&self, flow: &Flow, direction: Direction) -> Au {
let ref fragment = flow.as_block().fragment;
let outer_width = match direction {
Direction::Inline => {
fragment.border_padding.inline_start_end() + fragment.margin.inline_start_end()
}
Direction::Block => {
fragment.border_padding.block_start_end() + fragment.margin.block_start_end()
}
};
max(self.min_size, min(self.base_size, self.max_size))
- fragment.box_sizing_boundary(direction) + outer_width
}
/// Returns the number of auto margins in given direction.
pub fn auto_margin_count(&self, flow: &Flow, direction: Direction) -> i32 {
let margin = flow.as_block().fragment.style.logical_margin();
let mut margin_count = 0;
match direction {
Direction::Inline => {
if margin.inline_start == LengthOrPercentageOrAuto::Auto {
margin_count += 1;
}
if margin.inline_end == LengthOrPercentageOrAuto::Auto {
margin_count += 1;
}
}
Direction::Block => {
if margin.block_start == LengthOrPercentageOrAuto::Auto {
margin_count += 1;
}
if margin.block_end == LengthOrPercentageOrAuto::Auto {
margin_count += 1;
}
}
}
margin_count
}
}
/// A line in a flex container.
// TODO(stshine): More fields are required to handle collapsed items and baseline alignment.
#[derive(Debug, Serialize)]
struct FlexLine {
/// Range of items belong to this line in 'self.items'.
pub range: Range<usize>,
/// Remaining free space of this line, items will grow or shrink based on it being positive or negative.
pub free_space: Au,
/// The number of auto margins of items.
pub auto_margin_count: i32,
/// Line size in the block direction.
pub cross_size: Au,
}
impl FlexLine {
pub fn new(range: Range<usize>, free_space: Au, auto_margin_count: i32) -> FlexLine {
FlexLine {
range: range,
auto_margin_count: auto_margin_count,
free_space: free_space,
cross_size: Au(0)
}
}
/// This method implements the flexible lengths resolving algorithm.
/// The 'collapse' parameter is used to indicate whether items with 'visibility: collapse'
/// is included in length resolving. The result main size is stored in 'item.main_size'.
/// <https://drafts.csswg.org/css-flexbox/#resolve-flexible-lengths>
pub fn flex_resolve(&mut self, items: &mut [FlexItem], collapse: bool) {
let mut total_grow = 0.0;
let mut total_shrink = 0.0;
let mut total_scaled = 0.0;
let mut active_count = 0;
// Iterate through items, collect total factors and freeze those that have already met
// their constraints or won't grow/shrink in corresponding scenario.
// https://drafts.csswg.org/css-flexbox/#resolve-flexible-lengths
for item in items.iter_mut().filter(|i| !(i.is_strut && collapse)) {
item.main_size = max(item.min_size, min(item.base_size, item.max_size));
if (self.free_space > Au(0) && (item.flex_grow == 0.0 || item.base_size >= item.max_size)) ||
(self.free_space < Au(0) && (item.flex_shrink == 0.0 || item.base_size <= item.min_size)) {
item.is_frozen = true;
} else {
item.is_frozen = false;
total_grow += item.flex_grow;
total_shrink += item.flex_shrink;
// The scaled factor is used to calculate flex shrink
total_scaled += item.flex_shrink * item.base_size.0 as f32;
active_count += 1;
}
}
let initial_free_space = self.free_space;
let mut total_variation = Au(1);
// If there is no remaining free space or all items are frozen, stop loop.
while total_variation != Au(0) && self.free_space != Au(0) && active_count > 0 {
self.free_space =
// https://drafts.csswg.org/css-flexbox/#remaining-free-space
if self.free_space > Au(0) {
min(initial_free_space.scale_by(total_grow), self.free_space)
} else {
max(initial_free_space.scale_by(total_shrink), self.free_space)
};
total_variation = Au(0);
for item in items.iter_mut().filter(|i| !i.is_frozen).filter(|i| !(i.is_strut && collapse)) {
// Use this and the 'abs()' below to make the code work in both grow and shrink scenarios.
let (factor, end_size) = if self.free_space > Au(0) {
(item.flex_grow / total_grow, item.max_size)
} else {
(item.flex_shrink * item.base_size.0 as f32 / total_scaled, item.min_size)
};
let variation = self.free_space.scale_by(factor);
if variation.0.abs() >= (end_size - item.main_size).0.abs() {
// Use constraint as the target main size, and freeze item.
total_variation += end_size - item.main_size;
item.main_size = end_size;
item.is_frozen = true;
active_count -= 1;
total_shrink -= item.flex_shrink;
total_grow -= item.flex_grow;
total_scaled -= item.flex_shrink * item.base_size.0 as f32;
} else {
total_variation += variation;
item.main_size += variation;
}
}
self.free_space -= total_variation;
}
}
}
#[allow(unsafe_code)]
unsafe impl ::flow::HasBaseFlow for FlexFlow {}
/// A block with the CSS `display` property equal to `flex`.
#[derive(Debug, Serialize)]
#[repr(C)]
pub struct FlexFlow {
/// Data common to all block flows.
block_flow: BlockFlow,
/// The logical axis which the main axis will be parallel with.
/// The cross axis will be parallel with the opposite logical axis.
main_mode: Direction,
/// The available main axis size
available_main_size: AxisSize,
/// The available cross axis size
available_cross_size: AxisSize,
/// List of flex lines in the container.
lines: Vec<FlexLine>,
/// List of flex-items that belong to this flex-container
items: Vec<FlexItem>,
/// True if the flex-direction is *-reversed
main_reverse: bool,
/// True if this flex container can be multiline.
is_wrappable: bool,
/// True if the cross direction is reversed.
cross_reverse: bool
}
impl FlexFlow {
pub fn from_fragment(fragment: Fragment,
flotation: Option<FloatKind>)
-> FlexFlow {
let main_mode;
let main_reverse;
let is_wrappable;
let cross_reverse;
{
let style = fragment.style();
let (mode, reverse) = match style.get_position().flex_direction {
FlexDirection::Row => (Direction::Inline, false),
FlexDirection::RowReverse => (Direction::Inline, true),
FlexDirection::Column => (Direction::Block, false),
FlexDirection::ColumnReverse => (Direction::Block, true),
};
main_mode = mode;
main_reverse =
reverse == style.writing_mode.is_bidi_ltr();
let (wrappable, reverse) = match fragment.style.get_position().flex_wrap {
FlexWrap::Nowrap => (false, false),
FlexWrap::Wrap => (true, false),
FlexWrap::WrapReverse => (true, true),
};
is_wrappable = wrappable;
// TODO(stshine): Handle vertical writing mode.
cross_reverse = reverse;
}
FlexFlow {
block_flow: BlockFlow::from_fragment_and_float_kind(fragment, flotation),
main_mode: main_mode,
available_main_size: AxisSize::Infinite,
available_cross_size: AxisSize::Infinite,
lines: Vec::new(),
items: Vec::new(),
main_reverse: main_reverse,
is_wrappable: is_wrappable,
cross_reverse: cross_reverse
}
}
pub fn main_mode(&self) -> Direction {
self.main_mode
}
/// Returns a line start after the last item that is already in a line.
/// Note that when the container main size is infinite(i.e. A column flexbox with auto height),
/// we do not need to do flex resolving and this can be considered as a fast-path, so the
/// 'container_size' param does not need to be 'None'. A line has to contain at least one item;
/// (except this) if the container can be multi-line the sum of outer main size of items should
/// be less than the container size; a line should be filled by items as much as possible.
/// After been collected in a line a item should have its main sizes initialized.
fn get_flex_line(&mut self, container_size: Au) -> Option<FlexLine> {
let start = self.lines.last().map(|line| line.range.end).unwrap_or(0);
if start == self.items.len() {
return None;
}
let mut end = start;
let mut total_line_size = Au(0);
let mut margin_count = 0;
let items = &mut self.items[start..];
let mut children = self.block_flow.base.children.random_access_mut();
for item in items {
let kid = children.get(item.index);
item.init_sizes(kid, container_size, self.main_mode);
let outer_main_size = item.outer_main_size(kid, self.main_mode);
if total_line_size + outer_main_size > container_size && end != start && self.is_wrappable {
break;
}
margin_count += item.auto_margin_count(kid, self.main_mode);
total_line_size += outer_main_size;
end += 1;
}
let line = FlexLine::new(start..end, container_size - total_line_size, margin_count);
Some(line)
}
// TODO(zentner): This function should use flex-basis.
// Currently, this is the core of BlockFlow::bubble_inline_sizes() with all float logic
// stripped out, and max replaced with union_nonbreaking_inline.
fn inline_mode_bubble_inline_sizes(&mut self) {
let fixed_width = match self.block_flow.fragment.style().get_position().width {
LengthOrPercentageOrAuto::Length(_) => true,
_ => false,
};
let mut computation = self.block_flow.fragment.compute_intrinsic_inline_sizes();
if !fixed_width {
for kid in self.block_flow.base.children.iter_mut() {
let base = kid.mut_base();
let is_absolutely_positioned = base.flags.contains(FlowFlags::IS_ABSOLUTELY_POSITIONED);
if !is_absolutely_positioned {
let flex_item_inline_sizes = IntrinsicISizes {
minimum_inline_size: base.intrinsic_inline_sizes.minimum_inline_size,
preferred_inline_size: base.intrinsic_inline_sizes.preferred_inline_size,
};
computation.union_nonbreaking_inline(&flex_item_inline_sizes);
}
}
}
self.block_flow.base.intrinsic_inline_sizes = computation.finish();
}
// TODO(zentner): This function should use flex-basis.
// Currently, this is the core of BlockFlow::bubble_inline_sizes() with all float logic
// stripped out.
fn block_mode_bubble_inline_sizes(&mut self) {
let fixed_width = match self.block_flow.fragment.style().get_position().width {
LengthOrPercentageOrAuto::Length(_) => true,
_ => false,
};
let mut computation = self.block_flow.fragment.compute_intrinsic_inline_sizes();
if !fixed_width {
for kid in self.block_flow.base.children.iter_mut() {
let base = kid.mut_base();
let is_absolutely_positioned = base.flags.contains(FlowFlags::IS_ABSOLUTELY_POSITIONED);
if !is_absolutely_positioned {
computation.content_intrinsic_sizes.minimum_inline_size =
max(computation.content_intrinsic_sizes.minimum_inline_size,
base.intrinsic_inline_sizes.minimum_inline_size);
computation.content_intrinsic_sizes.preferred_inline_size =
max(computation.content_intrinsic_sizes.preferred_inline_size,
base.intrinsic_inline_sizes.preferred_inline_size);
}
}
}
self.block_flow.base.intrinsic_inline_sizes = computation.finish();
}
// TODO(zentner): This function needs to be radically different for multi-line flexbox.
// Currently, this is the core of BlockFlow::propagate_assigned_inline_size_to_children() with
// all float and table logic stripped out.
fn block_mode_assign_inline_sizes(&mut self,
_layout_context: &LayoutContext,
inline_start_content_edge: Au,
inline_end_content_edge: Au,
content_inline_size: Au) {
let _scope = layout_debug_scope!("flex::block_mode_assign_inline_sizes");
debug!("flex::block_mode_assign_inline_sizes");
// FIXME (mbrubeck): Get correct mode for absolute containing block
let containing_block_mode = self.block_flow.base.writing_mode;
let container_block_size = match self.available_main_size {
AxisSize::Definite(length) => Some(length),
_ => None
};
let container_inline_size = match self.available_cross_size {
AxisSize::Definite(length) => length,
AxisSize::MinMax(ref constraint) => constraint.clamp(content_inline_size),
AxisSize::Infinite => content_inline_size
};
let mut children = self.block_flow.base.children.random_access_mut();
for kid in &mut self.items {
let kid_base = children.get(kid.index).mut_base();
kid_base.block_container_explicit_block_size = container_block_size;
if kid_base.flags.contains(FlowFlags::INLINE_POSITION_IS_STATIC) {
// The inline-start margin edge of the child flow is at our inline-start content
// edge, and its inline-size is our content inline-size.
kid_base.position.start.i =
if kid_base.writing_mode.is_bidi_ltr() == containing_block_mode.is_bidi_ltr() {
inline_start_content_edge
} else {
// The kid's inline 'start' is at the parent's 'end'
inline_end_content_edge
};
}
kid_base.block_container_inline_size = container_inline_size;
kid_base.block_container_writing_mode = containing_block_mode;
kid_base.position.start.i = inline_start_content_edge;
}
}
fn inline_mode_assign_inline_sizes(&mut self,
layout_context: &LayoutContext,
inline_start_content_edge: Au,
_inline_end_content_edge: Au,
content_inline_size: Au) {
let _scope = layout_debug_scope!("flex::inline_mode_assign_inline_sizes");
debug!("inline_mode_assign_inline_sizes");
debug!("content_inline_size = {:?}", content_inline_size);
let child_count = ImmutableFlowUtils::child_count(self as &Flow) as i32;
debug!("child_count = {:?}", child_count);
if child_count == 0 {
return;
}
let inline_size = match self.available_main_size {
AxisSize::Definite(length) => length,
AxisSize::MinMax(ref constraint) => constraint.clamp(content_inline_size),
AxisSize::Infinite => content_inline_size,
};
let container_mode = self.block_flow.base.block_container_writing_mode;
self.block_flow.base.position.size.inline = inline_size;
// Calculate non-auto block size to pass to children.
let box_border = self.block_flow.fragment.box_sizing_boundary(Direction::Block);
let parent_container_size =
self.block_flow.explicit_block_containing_size(layout_context.shared_context());
// https://drafts.csswg.org/css-ui-3/#box-sizing
let explicit_content_size = self
.block_flow
.explicit_block_size(parent_container_size)
.map(|x| max(x - box_border, Au(0)));
let containing_block_text_align =
self.block_flow.fragment.style().get_inheritedtext().text_align;
while let Some(mut line) = self.get_flex_line(inline_size) {
let items = &mut self.items[line.range.clone()];
line.flex_resolve(items, false);
// TODO(stshine): if this flex line contain children that have
// property visibility:collapse, exclude them and resolve again.
let item_count = items.len() as i32;
let mut cur_i = inline_start_content_edge;
let item_interval = if line.free_space >= Au(0) && line.auto_margin_count == 0 {
match self.block_flow.fragment.style().get_position().justify_content {
JustifyContent::SpaceBetween => {
if item_count == 1 {
Au(0)
} else {
line.free_space / (item_count - 1)
}
}
JustifyContent::SpaceAround => {
line.free_space / item_count
}
_ => Au(0),
}
} else {
Au(0)
};
match self.block_flow.fragment.style().get_position().justify_content {
// Overflow equally in both ends of line.
JustifyContent::Center | JustifyContent::SpaceAround => {
cur_i += (line.free_space - item_interval * (item_count - 1)) / 2;
}
JustifyContent::FlexEnd => {
cur_i += line.free_space;
}
_ => {}
}
let mut children = self.block_flow.base.children.random_access_mut();
for item in items.iter_mut() {
let block = children.get(item.index).as_mut_block();
block.base.block_container_writing_mode = container_mode;
block.base.block_container_inline_size = inline_size;
block.base.block_container_explicit_block_size = explicit_content_size;
// Per CSS 2.1 ยง 16.3.1, text alignment propagates to all children in flow.
//
// TODO(#2265, pcwalton): Do this in the cascade instead.
block.base.flags.set_text_align(containing_block_text_align);
let margin = block.fragment.style().logical_margin();
let auto_len =
if line.auto_margin_count == 0 || line.free_space <= Au(0) {
Au(0)
} else {
line.free_space / line.auto_margin_count
};
let margin_inline_start = MaybeAuto::from_style(margin.inline_start, inline_size)
.specified_or_default(auto_len);
let margin_inline_end = MaybeAuto::from_style(margin.inline_end, inline_size)
.specified_or_default(auto_len);
let item_inline_size = item.main_size
- block.fragment.box_sizing_boundary(self.main_mode)
+ block.fragment.border_padding.inline_start_end();
let item_outer_size = item_inline_size + block.fragment.margin.inline_start_end();
block.fragment.margin.inline_start = margin_inline_start;
block.fragment.margin.inline_end = margin_inline_end;
block.fragment.border_box.start.i = margin_inline_start;
block.fragment.border_box.size.inline = item_inline_size;
block.base.position.start.i = if !self.main_reverse {
cur_i
} else {
inline_start_content_edge * 2 + content_inline_size - cur_i - item_outer_size
};
block.base.position.size.inline = item_outer_size;
cur_i += item_outer_size + item_interval;
}
self.lines.push(line);
}
}
// TODO(zentner): This function should actually flex elements!
fn block_mode_assign_block_size(&mut self) {
let mut cur_b = if !self.main_reverse {
self.block_flow.fragment.border_padding.block_start
} else {
self.block_flow.fragment.border_box.size.block
};
let mut children = self.block_flow.base.children.random_access_mut();
for item in &mut self.items {
let base = children.get(item.index).mut_base();
if !self.main_reverse {
base.position.start.b = cur_b;
cur_b = cur_b + base.position.size.block;
} else {
cur_b = cur_b - base.position.size.block;
base.position.start.b = cur_b;
}
}
}
fn inline_mode_assign_block_size(&mut self, layout_context: &LayoutContext) {
let _scope = layout_debug_scope!("flex::inline_mode_assign_block_size");
let line_count = self.lines.len() as i32;
let line_align = self.block_flow.fragment.style().get_position().align_content;
let mut cur_b = self.block_flow.fragment.border_padding.block_start;
let mut total_cross_size = Au(0);
let mut line_interval = Au(0);
{
let mut children = self.block_flow.base.children.random_access_mut();
for line in self.lines.iter_mut() {
for item in &self.items[line.range.clone()] {
let fragment = &children.get(item.index).as_block().fragment;
line.cross_size = max(line.cross_size,
fragment.border_box.size.block +
fragment.margin.block_start_end());
}
total_cross_size += line.cross_size;
}
}
let box_border = self.block_flow.fragment.box_sizing_boundary(Direction::Block);
let parent_container_size =
self.block_flow.explicit_block_containing_size(layout_context.shared_context());
// https://drafts.csswg.org/css-ui-3/#box-sizing
let explicit_content_size = self
.block_flow
.explicit_block_size(parent_container_size)
.map(|x| max(x - box_border, Au(0)));
if let Some(container_block_size) = explicit_content_size {
let free_space = container_block_size - total_cross_size;
total_cross_size = container_block_size;
if line_align == AlignContent::Stretch && free_space > Au(0) {
for line in self.lines.iter_mut() {
line.cross_size += free_space / line_count;
}
}
line_interval = match line_align {
AlignContent::SpaceBetween => {
if line_count <= 1 {
Au(0)
} else {
free_space / (line_count - 1)
}
}
AlignContent::SpaceAround => {
if line_count == 0 {
Au(0)
} else {
free_space / line_count
}
}
_ => Au(0),
};
match line_align {
AlignContent::Center | AlignContent::SpaceAround => {
cur_b += (free_space - line_interval * (line_count - 1)) / 2;
}
AlignContent::FlexEnd => {
cur_b += free_space;
}
_ => {}
}
}
let mut children = self.block_flow.base.children.random_access_mut();
for line in &self.lines {
for item in self.items[line.range.clone()].iter_mut() {
let block = children.get(item.index).as_mut_block();
let auto_margin_count = item.auto_margin_count(block, Direction::Block);
let margin = block.fragment.style().logical_margin();
let mut margin_block_start = block.fragment.margin.block_start;
let mut margin_block_end = block.fragment.margin.block_end;
let mut free_space = line.cross_size - block.base.position.size.block
- block.fragment.margin.block_start_end();
// The spec is a little vague here, but if I understand it correctly, the outer
// cross size of item should equal to the line size if any auto margin exists.
// https://drafts.csswg.org/css-flexbox/#algo-cross-margins
if auto_margin_count > 0 {
if margin.block_start == LengthOrPercentageOrAuto::Auto {
margin_block_start = if free_space < Au(0) {
Au(0)
} else {
free_space / auto_margin_count
};
}
margin_block_end = line.cross_size - margin_block_start - block.base.position.size.block;
free_space = Au(0);
}
let self_align = block.fragment.style().get_position().align_self;
if self_align == AlignSelf::Stretch &&
block.fragment.style().content_block_size() == LengthOrPercentageOrAuto::Auto {
free_space = Au(0);
block.base.block_container_explicit_block_size = Some(line.cross_size);
block.base.position.size.block =
line.cross_size - margin_block_start - margin_block_end;
block.fragment.border_box.size.block = block.base.position.size.block;
// FIXME(stshine): item with 'align-self: stretch' and auto cross size should act
// as if it has a fixed cross size, all child blocks should resolve against it.
// block.assign_block_size(layout_context);
}
block.base.position.start.b = margin_block_start +
if !self.cross_reverse {
cur_b
} else {
self.block_flow.fragment.border_padding.block_start * 2
+ total_cross_size - cur_b - line.cross_size
};
// TODO(stshine): support baseline alignment.
if free_space != Au(0) {
let flex_cross = match self_align {
AlignSelf::FlexEnd => free_space,
AlignSelf::Center => free_space / 2,
_ => Au(0),
};
block.base.position.start.b +=
if !self.cross_reverse {
flex_cross
} else {
free_space - flex_cross
};
}
}
cur_b += line_interval + line.cross_size;
}
let total_block_size = total_cross_size + self.block_flow.fragment.border_padding.block_start_end();
self.block_flow.fragment.border_box.size.block = total_block_size;
self.block_flow.base.position.size.block = total_block_size;
}
}
impl Flow for FlexFlow {
fn class(&self) -> FlowClass {
FlowClass::Flex
}
fn as_mut_flex(&mut self) -> &mut FlexFlow {
self
}
fn as_flex(&self) -> &FlexFlow {
self
}
fn as_block(&self) -> &BlockFlow {
&self.block_flow
}
fn as_mut_block(&mut self) -> &mut BlockFlow {
&mut self.block_flow
}
fn mark_as_root(&mut self) {
self.block_flow.mark_as_root();
}
fn bubble_inline_sizes(&mut self) {
let _scope = layout_debug_scope!("flex::bubble_inline_sizes {:x}",
self.block_flow.base.debug_id());
// Flexbox Section 9.0: Generate anonymous flex items:
// This part was handled in the flow constructor.
// Flexbox Section 9.1: Re-order flex items according to their order.
// FIXME(stshine): This should be done during flow construction.
let mut items: Vec<FlexItem> =
self.block_flow
.base
.children
.iter()
.enumerate()
.filter(|&(_, flow)| {
!flow.as_block().base.flags.contains(FlowFlags::IS_ABSOLUTELY_POSITIONED)
})
.map(|(index, flow)| FlexItem::new(index, flow))
.collect();
items.sort_by_key(|item| item.order);
self.items = items;
match self.main_mode {
Direction::Inline => self.inline_mode_bubble_inline_sizes(),
Direction::Block => self.block_mode_bubble_inline_sizes()
}
}
fn assign_inline_sizes(&mut self, layout_context: &LayoutContext) {
let _scope = layout_debug_scope!("flex::assign_inline_sizes {:x}", self.block_flow.base.debug_id());
debug!("assign_inline_sizes");
if !self.block_flow.base.restyle_damage.intersects(ServoRestyleDamage::REFLOW_OUT_OF_FLOW |
ServoRestyleDamage::REFLOW) {
return
}
self.block_flow.initialize_container_size_for_root(layout_context.shared_context());
// Our inline-size was set to the inline-size of the containing block by the flow's parent.
// Now compute the real value.
let containing_block_inline_size = self.block_flow.base.block_container_inline_size;
self.block_flow.compute_used_inline_size(layout_context.shared_context(),
containing_block_inline_size);
if self.block_flow.base.flags.is_float() {
self.block_flow.float.as_mut().unwrap().containing_inline_size = containing_block_inline_size
}
let (available_block_size, available_inline_size) = {
let style = &self.block_flow.fragment.style;
let (specified_block_size, specified_inline_size) = if style.writing_mode.is_vertical() {
(style.get_position().width, style.get_position().height)
} else {
(style.get_position().height, style.get_position().width)
};
let available_inline_size = AxisSize::new(specified_inline_size,
Some(self.block_flow.base.block_container_inline_size),
style.min_inline_size(),
style.max_inline_size());
let available_block_size = AxisSize::new(specified_block_size,
self.block_flow.base.block_container_explicit_block_size,
style.min_block_size(),
style.max_block_size());
(available_block_size, available_inline_size)
};
// Move in from the inline-start border edge.
let inline_start_content_edge = self.block_flow.fragment.border_box.start.i +
self.block_flow.fragment.border_padding.inline_start;
debug!("inline_start_content_edge = {:?}", inline_start_content_edge);
let padding_and_borders = self.block_flow.fragment.border_padding.inline_start_end();
// Distance from the inline-end margin edge to the inline-end content edge.
let inline_end_content_edge =
self.block_flow.fragment.margin.inline_end +
self.block_flow.fragment.border_padding.inline_end;
debug!("padding_and_borders = {:?}", padding_and_borders);
debug!("self.block_flow.fragment.border_box.size.inline = {:?}",
self.block_flow.fragment.border_box.size.inline);
let content_inline_size = self.block_flow.fragment.border_box.size.inline - padding_and_borders;
match self.main_mode {
Direction::Inline => {
self.available_main_size = available_inline_size;
self.available_cross_size = available_block_size;
self.inline_mode_assign_inline_sizes(layout_context,
inline_start_content_edge,
inline_end_content_edge,
content_inline_size)
}
Direction::Block => {
self.available_main_size = available_block_size;
self.available_cross_size = available_inline_size;
self.block_mode_assign_inline_sizes(layout_context,
inline_start_content_edge,
inline_end_content_edge,
content_inline_size)
}
}
}
fn assign_block_size(&mut self, layout_context: &LayoutContext) {
match self.main_mode {
Direction::Inline => {
self.inline_mode_assign_block_size(layout_context);
let block_start = AdjoiningMargins::from_margin(self.block_flow.fragment.margin.block_start);
let block_end = AdjoiningMargins::from_margin(self.block_flow.fragment.margin.block_end);
self.block_flow.base.collapsible_margins = CollapsibleMargins::Collapse(block_start, block_end);
// TODO(stshine): assign proper static position for absolute descendants.
if (&*self as &Flow).contains_roots_of_absolute_flow_tree() {
// Assign block-sizes for all flows in this absolute flow tree.
// This is preorder because the block-size of an absolute flow may depend on
// the block-size of its containing block, which may also be an absolute flow.
let assign_abs_b_sizes = AbsoluteAssignBSizesTraversal(layout_context.shared_context());
assign_abs_b_sizes.traverse_absolute_flows(&mut *self);
}
}
Direction::Block =>{
self.block_flow
.assign_block_size_block_base(layout_context,
None,
MarginsMayCollapseFlag::MarginsMayNotCollapse);
self.block_mode_assign_block_size();
}
}
}
fn compute_stacking_relative_position(&mut self, layout_context: &LayoutContext) {
self.block_flow.compute_stacking_relative_position(layout_context)
}
fn place_float_if_applicable<'a>(&mut self) {
self.block_flow.place_float_if_applicable()
}
fn update_late_computed_inline_position_if_necessary(&mut self, inline_position: Au) {
self.block_flow.update_late_computed_inline_position_if_necessary(inline_position)
}
fn update_late_computed_block_position_if_necessary(&mut self, block_position: Au) {
self.block_flow.update_late_computed_block_position_if_necessary(block_position)
}
fn build_display_list(&mut self, state: &mut DisplayListBuildState) {
self.build_display_list_for_flex(state);
}
fn collect_stacking_contexts(&mut self, state: &mut StackingContextCollectionState) {
self.block_flow.collect_stacking_contexts(state);
}
fn repair_style(&mut self, new_style: &::ServoArc<ComputedValues>) {
self.block_flow.repair_style(new_style)
}
fn compute_overflow(&self) -> Overflow {
self.block_flow.compute_overflow()
}
fn contains_roots_of_absolute_flow_tree(&self) -> bool {
self.block_flow.contains_roots_of_absolute_flow_tree()
}
fn is_absolute_containing_block(&self) -> bool {
self.block_flow.is_absolute_containing_block()
}
fn generated_containing_block_size(&self, flow: OpaqueFlow) -> LogicalSize<Au> {
self.block_flow.generated_containing_block_size(flow)
}
fn iterate_through_fragment_border_boxes(&self,
iterator: &mut FragmentBorderBoxIterator,
level: i32,
stacking_context_position: &Point2D<Au>) {
self.block_flow.iterate_through_fragment_border_boxes(iterator, level, stacking_context_position);
}
fn mutate_fragments(&mut self, mutator: &mut FnMut(&mut Fragment)) {
self.block_flow.mutate_fragments(mutator);
}
}