/* 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/. */
//! Borders, padding, and margins.
#![deny(unsafe_code)]
use fragment::Fragment;
use euclid::{Matrix4, SideOffsets2D};
use std::cmp::{max, min};
use std::fmt;
use style::computed_values::transform::ComputedMatrix;
use style::properties::ComputedValues;
use style::values::computed::{LengthAndPercentage, LengthOrPercentageOrAuto};
use style::values::computed::{LengthOrPercentageOrNone, LengthOrPercentage};
use util::geometry::Au;
use util::logical_geometry::LogicalMargin;
/// A collapsible margin. See CSS 2.1 § 8.3.1.
#[derive(Copy, Clone)]
pub struct AdjoiningMargins {
/// The value of the greatest positive margin.
pub most_positive: Au,
/// The actual value (not the absolute value) of the negative margin with the largest absolute
/// value. Since this is not the absolute value, this is always zero or negative.
pub most_negative: Au,
}
impl AdjoiningMargins {
pub fn new() -> AdjoiningMargins {
AdjoiningMargins {
most_positive: Au(0),
most_negative: Au(0),
}
}
pub fn from_margin(margin_value: Au) -> AdjoiningMargins {
if margin_value >= Au(0) {
AdjoiningMargins {
most_positive: margin_value,
most_negative: Au(0),
}
} else {
AdjoiningMargins {
most_positive: Au(0),
most_negative: margin_value,
}
}
}
pub fn union(&mut self, other: AdjoiningMargins) {
self.most_positive = max(self.most_positive, other.most_positive);
self.most_negative = min(self.most_negative, other.most_negative)
}
pub fn collapse(&self) -> Au {
self.most_positive + self.most_negative
}
}
/// Represents the block-start and block-end margins of a flow with collapsible margins. See CSS 2.1 § 8.3.1.
#[derive(Copy, Clone)]
pub enum CollapsibleMargins {
/// Margins may not collapse with this flow.
None(Au, Au),
/// Both the block-start and block-end margins (specified here in that order) may collapse, but the
/// margins do not collapse through this flow.
Collapse(AdjoiningMargins, AdjoiningMargins),
/// Margins collapse *through* this flow. This means, essentially, that the flow doesn’t
/// have any border, padding, or out-of-flow (floating or positioned) content
CollapseThrough(AdjoiningMargins),
}
impl CollapsibleMargins {
pub fn new() -> CollapsibleMargins {
CollapsibleMargins::None(Au(0), Au(0))
}
/// Returns the amount of margin that should be applied in a noncollapsible context. This is
/// currently used to apply block-start margin for hypothetical boxes, since we do not collapse
/// margins of hypothetical boxes.
pub fn block_start_margin_for_noncollapsible_context(&self) -> Au {
match *self {
CollapsibleMargins::None(block_start, _) => block_start,
CollapsibleMargins::Collapse(ref block_start, _) |
CollapsibleMargins::CollapseThrough(ref block_start) => block_start.collapse(),
}
}
}
enum FinalMarginState {
MarginsCollapseThrough,
BottomMarginCollapses,
}
pub struct MarginCollapseInfo {
pub state: MarginCollapseState,
pub block_start_margin: AdjoiningMargins,
pub margin_in: AdjoiningMargins,
}
impl MarginCollapseInfo {
/// TODO(#2012, pcwalton): Remove this method once `fragment` is not an `Option`.
pub fn new() -> MarginCollapseInfo {
MarginCollapseInfo {
state: MarginCollapseState::AccumulatingCollapsibleTopMargin,
block_start_margin: AdjoiningMargins::new(),
margin_in: AdjoiningMargins::new(),
}
}
pub fn initialize_block_start_margin(&mut self,
fragment: &Fragment,
can_collapse_block_start_margin_with_kids: bool) {
if !can_collapse_block_start_margin_with_kids {
self.state = MarginCollapseState::AccumulatingMarginIn
}
self.block_start_margin = AdjoiningMargins::from_margin(fragment.margin.block_start)
}
pub fn finish_and_compute_collapsible_margins(mut self,
fragment: &Fragment,
can_collapse_block_end_margin_with_kids: bool)
-> (CollapsibleMargins, Au) {
let state = match self.state {
MarginCollapseState::AccumulatingCollapsibleTopMargin => {
match fragment.style().content_block_size() {
LengthOrPercentageOrAuto::Auto | LengthOrPercentageOrAuto::Length(Au(0)) |
LengthOrPercentageOrAuto::Percentage(0.) => {
match fragment.style().min_block_size() {
LengthOrPercentage::Length(Au(0)) | LengthOrPercentage::Percentage(0.) => {
FinalMarginState::MarginsCollapseThrough
},
_ => {
// If the fragment has non-zero min-block-size, margins may not
// collapse through it.
FinalMarginState::BottomMarginCollapses
}
}
},
_ => {
// If the fragment has an explicitly specified block-size, margins may not
// collapse through it.
FinalMarginState::BottomMarginCollapses
}
}
}
MarginCollapseState::AccumulatingMarginIn => FinalMarginState::BottomMarginCollapses,
};
// Different logic is needed here depending on whether this flow can collapse its block-end
// margin with its children.
let block_end_margin = fragment.margin.block_end;
if !can_collapse_block_end_margin_with_kids {
match state {
FinalMarginState::MarginsCollapseThrough => {
let advance = self.block_start_margin.collapse();
self.margin_in.union(AdjoiningMargins::from_margin(block_end_margin));
(CollapsibleMargins::Collapse(self.block_start_margin, self.margin_in), advance)
}
FinalMarginState::BottomMarginCollapses => {
let advance = self.margin_in.collapse();
self.margin_in.union(AdjoiningMargins::from_margin(block_end_margin));
(CollapsibleMargins::Collapse(self.block_start_margin, self.margin_in), advance)
}
}
} else {
match state {
FinalMarginState::MarginsCollapseThrough => {
self.block_start_margin.union(AdjoiningMargins::from_margin(block_end_margin));
(CollapsibleMargins::CollapseThrough(self.block_start_margin), Au(0))
}
FinalMarginState::BottomMarginCollapses => {
self.margin_in.union(AdjoiningMargins::from_margin(block_end_margin));
(CollapsibleMargins::Collapse(self.block_start_margin, self.margin_in), Au(0))
}
}
}
}
pub fn current_float_ceiling(&mut self) -> Au {
match self.state {
MarginCollapseState::AccumulatingCollapsibleTopMargin => {
// We do not include the top margin in the float ceiling, because the float flow
// needs to be positioned relative to our *border box*, not our margin box. See
// `tests/ref/float_under_top_margin_a.html`.
Au(0)
}
MarginCollapseState::AccumulatingMarginIn => self.margin_in.collapse(),
}
}
/// Adds the child's potentially collapsible block-start margin to the current margin state and
/// advances the Y offset by the appropriate amount to handle that margin. Returns the amount
/// that should be added to the Y offset during block layout.
pub fn advance_block_start_margin(&mut self, child_collapsible_margins: &CollapsibleMargins)
-> Au {
match (self.state, *child_collapsible_margins) {
(MarginCollapseState::AccumulatingCollapsibleTopMargin,
CollapsibleMargins::None(block_start, _)) => {
self.state = MarginCollapseState::AccumulatingMarginIn;
block_start
}
(MarginCollapseState::AccumulatingCollapsibleTopMargin,
CollapsibleMargins::Collapse(block_start, _)) => {
self.block_start_margin.union(block_start);
self.state = MarginCollapseState::AccumulatingMarginIn;
Au(0)
}
(MarginCollapseState::AccumulatingMarginIn,
CollapsibleMargins::None(block_start, _)) => {
let previous_margin_value = self.margin_in.collapse();
self.margin_in = AdjoiningMargins::new();
previous_margin_value + block_start
}
(MarginCollapseState::AccumulatingMarginIn, CollapsibleMargins::Collapse(block_start, _)) => {
self.margin_in.union(block_start);
let margin_value = self.margin_in.collapse();
self.margin_in = AdjoiningMargins::new();
margin_value
}
(_, CollapsibleMargins::CollapseThrough(_)) => {
// For now, we ignore this; this will be handled by `advance_block-end_margin` below.
Au(0)
}
}
}
/// Adds the child's potentially collapsible block-end margin to the current margin state and
/// advances the Y offset by the appropriate amount to handle that margin. Returns the amount
/// that should be added to the Y offset during block layout.
pub fn advance_block_end_margin(&mut self, child_collapsible_margins: &CollapsibleMargins) -> Au {
match (self.state, *child_collapsible_margins) {
(MarginCollapseState::AccumulatingCollapsibleTopMargin, CollapsibleMargins::None(..)) |
(MarginCollapseState::AccumulatingCollapsibleTopMargin, CollapsibleMargins::Collapse(..)) => {
// Can't happen because the state will have been replaced with
// `MarginCollapseState::AccumulatingMarginIn` above.
panic!("should not be accumulating collapsible block_start margins anymore!")
}
(MarginCollapseState::AccumulatingCollapsibleTopMargin, CollapsibleMargins::CollapseThrough(margin)) => {
self.block_start_margin.union(margin);
Au(0)
}
(MarginCollapseState::AccumulatingMarginIn, CollapsibleMargins::None(_, block_end)) => {
assert_eq!(self.margin_in.most_positive, Au(0));
assert_eq!(self.margin_in.most_negative, Au(0));
block_end
}
(MarginCollapseState::AccumulatingMarginIn, CollapsibleMargins::Collapse(_, block_end)) |
(MarginCollapseState::AccumulatingMarginIn, CollapsibleMargins::CollapseThrough(block_end)) => {
self.margin_in.union(block_end);
Au(0)
}
}
}
}
#[derive(Copy, Clone)]
pub enum MarginCollapseState {
AccumulatingCollapsibleTopMargin,
AccumulatingMarginIn,
}
/// Intrinsic inline-sizes, which consist of minimum and preferred.
#[derive(RustcEncodable)]
pub struct IntrinsicISizes {
/// The *minimum inline-size* of the content.
pub minimum_inline_size: Au,
/// The *preferred inline-size* of the content.
pub preferred_inline_size: Au,
}
impl fmt::Debug for IntrinsicISizes {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "min={:?}, pref={:?}", self.minimum_inline_size, self.preferred_inline_size)
}
}
impl IntrinsicISizes {
pub fn new() -> IntrinsicISizes {
IntrinsicISizes {
minimum_inline_size: Au(0),
preferred_inline_size: Au(0),
}
}
}
/// The temporary result of the computation of intrinsic inline-sizes.
pub struct IntrinsicISizesContribution {
/// Intrinsic sizes for the content only (not counting borders, padding, or margins).
pub content_intrinsic_sizes: IntrinsicISizes,
/// The inline size of borders and padding, as well as margins if appropriate.
pub surrounding_size: Au,
}
impl IntrinsicISizesContribution {
/// Creates and initializes an inline size computation with all sizes set to zero.
pub fn new() -> IntrinsicISizesContribution {
IntrinsicISizesContribution {
content_intrinsic_sizes: IntrinsicISizes::new(),
surrounding_size: Au(0),
}
}
/// Adds the content intrinsic sizes and the surrounding size together to yield the final
/// intrinsic size computation.
pub fn finish(self) -> IntrinsicISizes {
IntrinsicISizes {
minimum_inline_size: self.content_intrinsic_sizes.minimum_inline_size +
self.surrounding_size,
preferred_inline_size: self.content_intrinsic_sizes.preferred_inline_size +
self.surrounding_size,
}
}
/// Updates the computation so that the minimum is the maximum of the current minimum and the
/// given minimum and the preferred is the sum of the current preferred and the given
/// preferred. This is used when laying out fragments in the inline direction.
///
/// FIXME(pcwalton): This is incorrect when the inline fragment contains forced line breaks
/// (e.g. `<br>` or `white-space: pre`).
pub fn union_inline(&mut self, sizes: &IntrinsicISizes) {
self.content_intrinsic_sizes.minimum_inline_size =
max(self.content_intrinsic_sizes.minimum_inline_size, sizes.minimum_inline_size);
self.content_intrinsic_sizes.preferred_inline_size =
self.content_intrinsic_sizes.preferred_inline_size + sizes.preferred_inline_size
}
/// Updates the computation so that the minimum is the sum of the current minimum and the
/// given minimum and the preferred is the sum of the current preferred and the given
/// preferred. This is used when laying out fragments in the inline direction when
/// `white-space` is `pre` or `nowrap`.
pub fn union_nonbreaking_inline(&mut self, sizes: &IntrinsicISizes) {
self.content_intrinsic_sizes.minimum_inline_size =
self.content_intrinsic_sizes.minimum_inline_size + sizes.minimum_inline_size;
self.content_intrinsic_sizes.preferred_inline_size =
self.content_intrinsic_sizes.preferred_inline_size + sizes.preferred_inline_size
}
/// Updates the computation so that the minimum is the maximum of the current minimum and the
/// given minimum and the preferred is the maximum of the current preferred and the given
/// preferred. This can be useful when laying out fragments in the block direction (but note
/// that it does not take floats into account, so `BlockFlow` does not use it).
///
/// This is used when contributing the intrinsic sizes for individual fragments.
pub fn union_block(&mut self, sizes: &IntrinsicISizes) {
self.content_intrinsic_sizes.minimum_inline_size =
max(self.content_intrinsic_sizes.minimum_inline_size, sizes.minimum_inline_size);
self.content_intrinsic_sizes.preferred_inline_size =
max(self.content_intrinsic_sizes.preferred_inline_size, sizes.preferred_inline_size)
}
}
/// Useful helper data type when computing values for blocks and positioned elements.
#[derive(Copy, Clone, PartialEq, Debug)]
pub enum MaybeAuto {
Auto,
Specified(Au),
}
impl MaybeAuto {
#[inline]
pub fn from_style(length: LengthOrPercentageOrAuto, containing_length: Au)
-> MaybeAuto {
match length {
LengthOrPercentageOrAuto::Auto => MaybeAuto::Auto,
LengthOrPercentageOrAuto::Percentage(percent) => {
MaybeAuto::Specified(containing_length.scale_by(percent))
}
LengthOrPercentageOrAuto::Length(length) => MaybeAuto::Specified(length)
}
}
#[inline]
pub fn specified_or_default(&self, default: Au) -> Au {
match *self {
MaybeAuto::Auto => default,
MaybeAuto::Specified(value) => value,
}
}
#[inline]
pub fn specified_or_zero(&self) -> Au {
self.specified_or_default(Au::new(0))
}
#[inline]
pub fn map<F>(&self, mapper: F) -> MaybeAuto where F: FnOnce(Au) -> Au {
match *self {
MaybeAuto::Auto => MaybeAuto::Auto,
MaybeAuto::Specified(value) => MaybeAuto::Specified(mapper(value)),
}
}
}
pub fn specified_or_none(length: LengthOrPercentageOrNone, containing_length: Au) -> Option<Au> {
match length {
LengthOrPercentageOrNone::None => None,
LengthOrPercentageOrNone::Percentage(percent) => Some(containing_length.scale_by(percent)),
LengthOrPercentageOrNone::Length(length) => Some(length),
}
}
pub fn specified(length: LengthOrPercentage, containing_length: Au) -> Au {
match length {
LengthOrPercentage::Length(length) => length,
LengthOrPercentage::Percentage(p) => containing_length.scale_by(p)
}
}
#[inline]
pub fn padding_from_style(style: &ComputedValues, containing_block_inline_size: Au)
-> LogicalMargin<Au> {
let padding_style = style.get_padding();
LogicalMargin::from_physical(style.writing_mode, SideOffsets2D::new(
specified(padding_style.padding_top, containing_block_inline_size),
specified(padding_style.padding_right, containing_block_inline_size),
specified(padding_style.padding_bottom, containing_block_inline_size),
specified(padding_style.padding_left, containing_block_inline_size)))
}
pub trait ToGfxMatrix {
fn to_gfx_matrix(&self) -> Matrix4;
}
impl ToGfxMatrix for ComputedMatrix {
fn to_gfx_matrix(&self) -> Matrix4 {
Matrix4 {
m11: self.m11 as f32, m12: self.m12 as f32, m13: self.m13 as f32, m14: self.m14 as f32,
m21: self.m21 as f32, m22: self.m22 as f32, m23: self.m23 as f32, m24: self.m24 as f32,
m31: self.m31 as f32, m32: self.m32 as f32, m33: self.m33 as f32, m34: self.m34 as f32,
m41: self.m41 as f32, m42: self.m42 as f32, m43: self.m43 as f32, m44: self.m44 as f32
}
}
}
pub trait ToAu {
fn to_au(&self, containing_size: Au) -> Au;
}
impl ToAu for LengthAndPercentage {
#[inline]
fn to_au(&self, containing_size: Au) -> Au {
self.length + Au::from_f32_px(self.percentage * containing_size.to_f32_px())
}
}