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servo/components/layout/fragment.rs
Patrick Walton 6943ddb93e layout: Implement overflow-wrap/word-wrap per CSS-TEXT § 6.2. 
This property is used by approximately 55% of page loads.

To implement the line breaking behavior, the "breaking strategy" has
been cleaned up and abstracted. This should allow us to easily support
other similar properties in the future, such as `text-overflow` and
`word-break`.
2014-12-13 13:05:05 -08:00

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/* 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/. */
//! The `Fragment` type, which represents the leaves of the layout tree.
#![deny(unsafe_blocks)]
use css::node_style::StyledNode;
use construct::FlowConstructor;
use context::LayoutContext;
use floats::{ClearBoth, ClearLeft, ClearRight, ClearType};
use flow;
use flow::Flow;
use flow_ref::FlowRef;
use incremental::RestyleDamage;
use inline::{InlineFragmentContext, InlineMetrics};
use layout_debug;
use model::{Auto, IntrinsicISizes, IntrinsicISizesContribution, MaybeAuto, Specified, specified};
use model;
use text;
use util::OpaqueNodeMethods;
use wrapper::{TLayoutNode, ThreadSafeLayoutNode};
use geom::{Point2D, Rect, Size2D};
use gfx::display_list::OpaqueNode;
use gfx::text::glyph::CharIndex;
use gfx::text::text_run::{TextRun, TextRunSlice};
use script_traits::UntrustedNodeAddress;
use serialize::{Encodable, Encoder};
use servo_msg::constellation_msg::{PipelineId, SubpageId};
use servo_net::image::holder::ImageHolder;
use servo_net::local_image_cache::LocalImageCache;
use servo_util::geometry::Au;
use servo_util::geometry;
use servo_util::logical_geometry::{LogicalRect, LogicalSize, LogicalMargin};
use servo_util::range::*;
use servo_util::smallvec::SmallVec;
use servo_util::str::is_whitespace;
use std::cmp::{max, min};
use std::fmt;
use std::from_str::FromStr;
use string_cache::Atom;
use style::{ComputedValues, TElement, TNode, cascade_anonymous};
use style::computed_values::{LengthOrPercentage, LengthOrPercentageOrAuto};
use style::computed_values::{LengthOrPercentageOrNone};
use style::computed_values::{LPA_Auto, clear, overflow_wrap, position, text_align};
use style::computed_values::{text_decoration, vertical_align, white_space};
use sync::{Arc, Mutex};
use url::Url;
/// Fragments (`struct Fragment`) are the leaves of the layout tree. They cannot position
/// themselves. In general, fragments do not have a simple correspondence with CSS fragments in the
/// specification:
///
/// * Several fragments may correspond to the same CSS box or DOM node. For example, a CSS text box
/// broken across two lines is represented by two fragments.
///
/// * Some CSS fragments are not created at all, such as some anonymous block fragments induced by
/// inline fragments with block-level sibling fragments. In that case, Servo uses an `InlineFlow`
/// with `BlockFlow` siblings; the `InlineFlow` is block-level, but not a block container. It is
/// positioned as if it were a block fragment, but its children are positioned according to
/// inline flow.
///
/// A `GenericFragment` is an empty fragment that contributes only borders, margins, padding, and
/// backgrounds. It is analogous to a CSS nonreplaced content box.
///
/// A fragment's type influences how its styles are interpreted during layout. For example,
/// replaced content such as images are resized differently from tables, text, or other content.
/// Different types of fragments may also contain custom data; for example, text fragments contain
/// text.
///
/// Do not add fields to this structure unless they're really really mega necessary! Fragments get
/// moved around a lot and thus their size impacts performance of layout quite a bit.
///
/// FIXME(#2260, pcwalton): This can be slimmed down some by (at least) moving `inline_context`
/// to be on `InlineFlow` only.
#[deriving(Clone)]
pub struct Fragment {
/// An opaque reference to the DOM node that this `Fragment` originates from.
pub node: OpaqueNode,
/// The CSS style of this fragment.
pub style: Arc<ComputedValues>,
/// The position of this fragment relative to its owning flow.
/// The size includes padding and border, but not margin.
pub border_box: LogicalRect<Au>,
/// The sum of border and padding; i.e. the distance from the edge of the border box to the
/// content edge of the fragment.
pub border_padding: LogicalMargin<Au>,
/// The margin of the content box.
pub margin: LogicalMargin<Au>,
/// Info specific to the kind of fragment. Keep this enum small.
pub specific: SpecificFragmentInfo,
/// Holds the style context information for fragments
/// that are part of an inline formatting context.
pub inline_context: Option<InlineFragmentContext>,
/// A debug ID that is consistent for the life of
/// this fragment (via transform etc).
pub debug_id: u16,
/// How damaged this fragment is since last reflow.
pub restyle_damage: RestyleDamage,
}
impl<E, S: Encoder<E>> Encodable<S, E> for Fragment {
fn encode(&self, e: &mut S) -> Result<(), E> {
e.emit_struct("fragment", 0, |e| {
try!(e.emit_struct_field("id", 0, |e| self.debug_id().encode(e)))
try!(e.emit_struct_field("border_box", 1, |e| self.border_box.encode(e)))
e.emit_struct_field("margin", 2, |e| self.margin.encode(e))
})
}
}
/// Info specific to the kind of fragment.
///
/// Keep this enum small. As in, no more than one word. Or pcwalton will yell at you.
#[deriving(Clone)]
pub enum SpecificFragmentInfo {
GenericFragment,
IframeFragment(Box<IframeFragmentInfo>),
ImageFragment(Box<ImageFragmentInfo>),
/// A hypothetical box (see CSS 2.1 § 10.3.7) for an absolutely-positioned block that was
/// declared with `display: inline;`.
InlineAbsoluteHypotheticalFragment(InlineAbsoluteHypotheticalFragmentInfo),
InlineBlockFragment(InlineBlockFragmentInfo),
ScannedTextFragment(Box<ScannedTextFragmentInfo>),
TableFragment,
TableCellFragment,
TableColumnFragment(TableColumnFragmentInfo),
TableRowFragment,
TableWrapperFragment,
UnscannedTextFragment(UnscannedTextFragmentInfo),
}
impl SpecificFragmentInfo {
fn restyle_damage(&self) -> RestyleDamage {
let flow =
match *self {
IframeFragment(_)
| ImageFragment(_)
| ScannedTextFragment(_)
| TableFragment
| TableCellFragment
| TableColumnFragment(_)
| TableRowFragment
| TableWrapperFragment
| UnscannedTextFragment(_)
| GenericFragment => return RestyleDamage::empty(),
InlineAbsoluteHypotheticalFragment(ref info) => &info.flow_ref,
InlineBlockFragment(ref info) => &info.flow_ref,
};
flow::base(flow.deref()).restyle_damage
}
pub fn get_type(&self) -> &'static str {
match *self {
GenericFragment => "GenericFragment",
IframeFragment(_) => "IframeFragment",
ImageFragment(_) => "ImageFragment",
InlineAbsoluteHypotheticalFragment(_) => "InlineAbsoluteHypotheticalFragment",
InlineBlockFragment(_) => "InlineBlockFragment",
ScannedTextFragment(_) => "ScannedTextFragment",
TableFragment => "TableFragment",
TableCellFragment => "TableCellFragment",
TableColumnFragment(_) => "TableColumnFragment",
TableRowFragment => "TableRowFragment",
TableWrapperFragment => "TableWrapperFragment",
UnscannedTextFragment(_) => "UnscannedTextFragment",
}
}
}
/// A hypothetical box (see CSS 2.1 § 10.3.7) for an absolutely-positioned block that was declared
/// with `display: inline;`.
///
/// FIXME(pcwalton): Stop leaking this `FlowRef` to layout; that is not memory safe because layout
/// can clone it.
#[deriving(Clone)]
pub struct InlineAbsoluteHypotheticalFragmentInfo {
pub flow_ref: FlowRef,
}
impl InlineAbsoluteHypotheticalFragmentInfo {
pub fn new(flow_ref: FlowRef) -> InlineAbsoluteHypotheticalFragmentInfo {
InlineAbsoluteHypotheticalFragmentInfo {
flow_ref: flow_ref,
}
}
}
/// A fragment that represents an inline-block element.
///
/// FIXME(pcwalton): Stop leaking this `FlowRef` to layout; that is not memory safe because layout
/// can clone it.
#[deriving(Clone)]
pub struct InlineBlockFragmentInfo {
pub flow_ref: FlowRef,
}
impl InlineBlockFragmentInfo {
pub fn new(flow_ref: FlowRef) -> InlineBlockFragmentInfo {
InlineBlockFragmentInfo {
flow_ref: flow_ref,
}
}
}
/// A fragment that represents a replaced content image and its accompanying borders, shadows, etc.
#[deriving(Clone)]
pub struct ImageFragmentInfo {
/// The image held within this fragment.
pub image: ImageHolder<UntrustedNodeAddress>,
pub for_node: UntrustedNodeAddress,
pub computed_inline_size: Option<Au>,
pub computed_block_size: Option<Au>,
pub dom_inline_size: Option<Au>,
pub dom_block_size: Option<Au>,
pub writing_mode_is_vertical: bool,
}
impl ImageFragmentInfo {
/// Creates a new image fragment from the given URL and local image cache.
///
/// FIXME(pcwalton): The fact that image fragments store the cache in the fragment makes little
/// sense to me.
pub fn new(node: &ThreadSafeLayoutNode,
image_url: Url,
local_image_cache: Arc<Mutex<LocalImageCache<UntrustedNodeAddress>>>)
-> ImageFragmentInfo {
fn convert_length(node: &ThreadSafeLayoutNode, name: &Atom) -> Option<Au> {
let element = node.as_element();
element.get_attr(&ns!(""), name).and_then(|string| {
let n: Option<int> = FromStr::from_str(string);
n
}).and_then(|pixels| Some(Au::from_px(pixels)))
}
let is_vertical = node.style().writing_mode.is_vertical();
let dom_width = convert_length(node, &atom!("width"));
let dom_height = convert_length(node, &atom!("height"));
let opaque_node: OpaqueNode = OpaqueNodeMethods::from_thread_safe_layout_node(node);
let untrusted_node: UntrustedNodeAddress = opaque_node.to_untrusted_node_address();
ImageFragmentInfo {
image: ImageHolder::new(image_url, local_image_cache),
for_node: untrusted_node,
computed_inline_size: None,
computed_block_size: None,
dom_inline_size: if is_vertical { dom_height } else { dom_width },
dom_block_size: if is_vertical { dom_width } else { dom_height },
writing_mode_is_vertical: is_vertical,
}
}
/// Returns the calculated inline-size of the image, accounting for the inline-size attribute.
pub fn computed_inline_size(&self) -> Au {
self.computed_inline_size.expect("image inline_size is not computed yet!")
}
/// Returns the calculated block-size of the image, accounting for the block-size attribute.
pub fn computed_block_size(&self) -> Au {
self.computed_block_size.expect("image block_size is not computed yet!")
}
/// Returns the original inline-size of the image.
pub fn image_inline_size(&mut self) -> Au {
let size = self.image.get_size(self.for_node).unwrap_or(Size2D::zero());
Au::from_px(if self.writing_mode_is_vertical { size.height } else { size.width })
}
/// Returns the original block-size of the image.
pub fn image_block_size(&mut self) -> Au {
let size = self.image.get_size(self.for_node).unwrap_or(Size2D::zero());
Au::from_px(if self.writing_mode_is_vertical { size.width } else { size.height })
}
// Return used value for inline-size or block-size.
//
// `dom_length`: inline-size or block-size as specified in the `img` tag.
// `style_length`: inline-size as given in the CSS
pub fn style_length(style_length: LengthOrPercentageOrAuto,
dom_length: Option<Au>,
container_inline_size: Au) -> MaybeAuto {
match (MaybeAuto::from_style(style_length,container_inline_size),dom_length) {
(Specified(length),_) => {
Specified(length)
},
(Auto,Some(length)) => {
Specified(length)
},
(Auto,None) => {
Auto
}
}
}
/// Clamp a value obtained from style_length, based on min / max lengths.
pub fn clamp_size(size: Au, min_size: LengthOrPercentage, max_size: LengthOrPercentageOrNone,
container_inline_size: Au) -> Au {
let min_size = model::specified(min_size, container_inline_size);
let max_size = model::specified_or_none(max_size, container_inline_size);
Au::max(min_size, match max_size {
None => size,
Some(max_size) => Au::min(size, max_size),
})
}
/// Tile an image
pub fn tile_image(position: &mut Au, size: &mut Au,
virtual_position: Au, image_size: u32) {
let image_size = image_size as int;
let delta_pixels = geometry::to_px(virtual_position - *position);
let tile_count = (delta_pixels + image_size - 1) / image_size;
let offset = Au::from_px(image_size * tile_count);
let new_position = virtual_position - offset;
*size = *position - new_position + *size;
*position = new_position;
}
}
/// A fragment that represents an inline frame (iframe). This stores the pipeline ID so that the size
/// of this iframe can be communicated via the constellation to the iframe's own layout task.
#[deriving(Clone)]
pub struct IframeFragmentInfo {
/// The pipeline ID of this iframe.
pub pipeline_id: PipelineId,
/// The subpage ID of this iframe.
pub subpage_id: SubpageId,
}
impl IframeFragmentInfo {
/// Creates the information specific to an iframe fragment.
pub fn new(node: &ThreadSafeLayoutNode) -> IframeFragmentInfo {
let (pipeline_id, subpage_id) = node.iframe_pipeline_and_subpage_ids();
IframeFragmentInfo {
pipeline_id: pipeline_id,
subpage_id: subpage_id,
}
}
}
/// A scanned text fragment represents a single run of text with a distinct style. A `TextFragment`
/// may be split into two or more fragments across line breaks. Several `TextFragment`s may
/// correspond to a single DOM text node. Split text fragments are implemented by referring to
/// subsets of a single `TextRun` object.
#[deriving(Clone)]
pub struct ScannedTextFragmentInfo {
/// The text run that this represents.
pub run: Arc<Box<TextRun>>,
/// The range within the above text run that this represents.
pub range: Range<CharIndex>,
/// The positions of newlines within this scanned text fragment.
///
/// FIXME(#2260, pcwalton): Can't this go somewhere else, like in the text run or something?
/// Or can we just remove it?
pub new_line_pos: Vec<CharIndex>,
/// The new_line_pos is eaten during line breaking. If we need to re-merge
/// fragments, it will have to be restored.
pub original_new_line_pos: Option<Vec<CharIndex>>,
/// The intrinsic size of the text fragment.
pub content_size: LogicalSize<Au>,
}
impl ScannedTextFragmentInfo {
/// Creates the information specific to a scanned text fragment from a range and a text run.
pub fn new(run: Arc<Box<TextRun>>,
range: Range<CharIndex>,
new_line_positions: Vec<CharIndex>,
content_size: LogicalSize<Au>)
-> ScannedTextFragmentInfo {
ScannedTextFragmentInfo {
run: run,
range: range,
new_line_pos: new_line_positions,
original_new_line_pos: None,
content_size: content_size,
}
}
}
/// Describes how to split a fragment. This is used during line breaking as part of the return
/// value of `find_split_info_for_inline_size()`.
#[deriving(Show)]
pub struct SplitInfo {
// TODO(bjz): this should only need to be a single character index, but both values are
// currently needed for splitting in the `inline::try_append_*` functions.
pub range: Range<CharIndex>,
pub inline_size: Au,
}
impl SplitInfo {
fn new(range: Range<CharIndex>, info: &ScannedTextFragmentInfo) -> SplitInfo {
SplitInfo {
range: range,
inline_size: info.run.advance_for_range(&range),
}
}
}
/// Describes how to split a fragment into two. This contains up to two `SplitInfo`s.
pub struct SplitResult {
/// The part of the fragment that goes on the first line.
pub inline_start: Option<SplitInfo>,
/// The part of the fragment that goes on the second line.
pub inline_end: Option<SplitInfo>,
/// The text run which is being split.
pub text_run: Arc<Box<TextRun>>,
}
/// Data for an unscanned text fragment. Unscanned text fragments are the results of flow
/// construction that have not yet had their inline-size determined.
#[deriving(Clone)]
pub struct UnscannedTextFragmentInfo {
/// The text inside the fragment.
///
/// FIXME(pcwalton): Is there something more clever we can do here that avoids the double
/// indirection while not penalizing all fragments?
pub text: Box<String>,
}
impl UnscannedTextFragmentInfo {
/// Creates a new instance of `UnscannedTextFragmentInfo` from the given DOM node.
pub fn new(node: &ThreadSafeLayoutNode) -> UnscannedTextFragmentInfo {
// FIXME(pcwalton): Don't copy text; atomically reference count it instead.
UnscannedTextFragmentInfo {
text: box node.text(),
}
}
/// Creates a new instance of `UnscannedTextFragmentInfo` from the given text.
#[inline]
pub fn from_text(text: String) -> UnscannedTextFragmentInfo {
UnscannedTextFragmentInfo {
text: box text,
}
}
}
/// A fragment that represents a table column.
#[deriving(Clone)]
pub struct TableColumnFragmentInfo {
/// the number of columns a <col> element should span
pub span: int,
}
impl TableColumnFragmentInfo {
/// Create the information specific to an table column fragment.
pub fn new(node: &ThreadSafeLayoutNode) -> TableColumnFragmentInfo {
let span = {
let element = node.as_element();
element.get_attr(&ns!(""), &atom!("span")).and_then(|string| {
let n: Option<int> = FromStr::from_str(string);
n
}).unwrap_or(0)
};
TableColumnFragmentInfo {
span: span,
}
}
}
impl Fragment {
/// Constructs a new `Fragment` instance for the given node.
///
/// This does *not* construct the text for generated content. See comments in
/// `FlowConstructor::build_specific_fragment_info_for_node()` for more details.
///
/// Arguments:
///
/// * `constructor`: The flow constructor.
/// * `node`: The node to create a fragment for.
pub fn new(constructor: &mut FlowConstructor, node: &ThreadSafeLayoutNode) -> Fragment {
let style = node.style().clone();
let writing_mode = style.writing_mode;
Fragment {
node: OpaqueNodeMethods::from_thread_safe_layout_node(node),
style: style,
restyle_damage: node.restyle_damage(),
border_box: LogicalRect::zero(writing_mode),
border_padding: LogicalMargin::zero(writing_mode),
margin: LogicalMargin::zero(writing_mode),
specific: constructor.build_specific_fragment_info_for_node(node),
inline_context: None,
debug_id: layout_debug::generate_unique_debug_id(),
}
}
/// Constructs a new `Fragment` instance from a specific info.
pub fn new_from_specific_info(node: &ThreadSafeLayoutNode, specific: SpecificFragmentInfo)
-> Fragment {
let style = node.style().clone();
let writing_mode = style.writing_mode;
Fragment {
node: OpaqueNodeMethods::from_thread_safe_layout_node(node),
style: style,
restyle_damage: node.restyle_damage(),
border_box: LogicalRect::zero(writing_mode),
border_padding: LogicalMargin::zero(writing_mode),
margin: LogicalMargin::zero(writing_mode),
specific: specific,
inline_context: None,
debug_id: layout_debug::generate_unique_debug_id(),
}
}
/// Constructs a new `Fragment` instance for an anonymous table object.
pub fn new_anonymous_table_fragment(node: &ThreadSafeLayoutNode,
specific: SpecificFragmentInfo)
-> Fragment {
// CSS 2.1 § 17.2.1 This is for non-inherited properties on anonymous table fragments
// example:
//
// <div style="display: table">
// Foo
// </div>
//
// Anonymous table fragments, TableRowFragment and TableCellFragment, are generated around
// `Foo`, but they shouldn't inherit the border.
let node_style = cascade_anonymous(&**node.style());
let writing_mode = node_style.writing_mode;
Fragment {
node: OpaqueNodeMethods::from_thread_safe_layout_node(node),
style: Arc::new(node_style),
restyle_damage: node.restyle_damage(),
border_box: LogicalRect::zero(writing_mode),
border_padding: LogicalMargin::zero(writing_mode),
margin: LogicalMargin::zero(writing_mode),
specific: specific,
inline_context: None,
debug_id: layout_debug::generate_unique_debug_id(),
}
}
/// Constructs a new `Fragment` instance from an opaque node.
pub fn from_opaque_node_and_style(node: OpaqueNode,
style: Arc<ComputedValues>,
restyle_damage: RestyleDamage,
specific: SpecificFragmentInfo)
-> Fragment {
let writing_mode = style.writing_mode;
Fragment {
node: node,
style: style,
restyle_damage: restyle_damage,
border_box: LogicalRect::zero(writing_mode),
border_padding: LogicalMargin::zero(writing_mode),
margin: LogicalMargin::zero(writing_mode),
specific: specific,
inline_context: None,
debug_id: layout_debug::generate_unique_debug_id(),
}
}
pub fn reset_inline_sizes(&mut self) {
self.border_padding = LogicalMargin::zero(self.style.writing_mode);
self.margin = LogicalMargin::zero(self.style.writing_mode);
}
/// Saves the new_line_pos vector into a `ScannedTextFragment`. This will fail
/// if called on any other type of fragment.
pub fn save_new_line_pos(&mut self) {
match &mut self.specific {
&ScannedTextFragment(ref mut info) => {
if !info.new_line_pos.is_empty() {
info.original_new_line_pos = Some(info.new_line_pos.clone());
}
}
_ => {}
}
}
pub fn restore_new_line_pos(&mut self) {
match &mut self.specific {
&ScannedTextFragment(ref mut info) => {
match info.original_new_line_pos.take() {
None => {}
Some(new_line_pos) => info.new_line_pos = new_line_pos,
}
return
}
_ => {}
}
}
/// Returns a debug ID of this fragment. This ID should not be considered stable across
/// multiple layouts or fragment manipulations.
pub fn debug_id(&self) -> u16 {
self.debug_id
}
/// Transforms this fragment into another fragment of the given type, with the given size,
/// preserving all the other data.
pub fn transform(&self, size: LogicalSize<Au>, mut info: Box<ScannedTextFragmentInfo>)
-> Fragment {
let new_border_box = LogicalRect::from_point_size(self.style.writing_mode,
self.border_box.start,
size);
info.content_size = size.clone();
Fragment {
node: self.node,
style: self.style.clone(),
restyle_damage: RestyleDamage::all(),
border_box: new_border_box,
border_padding: self.border_padding,
margin: self.margin,
specific: ScannedTextFragment(info),
inline_context: self.inline_context.clone(),
debug_id: self.debug_id,
}
}
pub fn restyle_damage(&self) -> RestyleDamage {
self.restyle_damage | self.specific.restyle_damage()
}
/// Adds a style to the inline context for this fragment. If the inline
/// context doesn't exist yet, it will be created.
pub fn add_inline_context_style(&mut self, style: Arc<ComputedValues>) {
if self.inline_context.is_none() {
self.inline_context = Some(InlineFragmentContext::new());
}
self.inline_context.as_mut().unwrap().styles.push(style.clone());
}
/// Determines which quantities (border/padding/margin/specified) should be included in the
/// intrinsic inline size of this fragment.
fn quantities_included_in_intrinsic_inline_size(&self)
-> QuantitiesIncludedInIntrinsicInlineSizes {
match self.specific {
GenericFragment | IframeFragment(_) | ImageFragment(_) | InlineBlockFragment(_) => {
QuantitiesIncludedInIntrinsicInlineSizes::all()
}
TableFragment | TableCellFragment => {
INTRINSIC_INLINE_SIZE_INCLUDES_PADDING |
INTRINSIC_INLINE_SIZE_INCLUDES_BORDER |
INTRINSIC_INLINE_SIZE_INCLUDES_SPECIFIED
}
TableWrapperFragment => {
INTRINSIC_INLINE_SIZE_INCLUDES_MARGINS |
INTRINSIC_INLINE_SIZE_INCLUDES_BORDER |
INTRINSIC_INLINE_SIZE_INCLUDES_SPECIFIED
}
TableRowFragment => {
INTRINSIC_INLINE_SIZE_INCLUDES_BORDER |
INTRINSIC_INLINE_SIZE_INCLUDES_SPECIFIED
}
ScannedTextFragment(_) | TableColumnFragment(_) | UnscannedTextFragment(_) |
InlineAbsoluteHypotheticalFragment(_) => {
QuantitiesIncludedInIntrinsicInlineSizes::empty()
}
}
}
/// Returns the portion of the intrinsic inline-size that consists of borders, padding, and/or
/// margins.
///
/// FIXME(#2261, pcwalton): This won't work well for inlines: is this OK?
pub fn surrounding_intrinsic_inline_size(&self) -> Au {
let flags = self.quantities_included_in_intrinsic_inline_size();
let style = self.style();
// FIXME(pcwalton): Percentages should be relative to any definite size per CSS-SIZING.
// This will likely need to be done by pushing down definite sizes during selector
// cascading.
let margin = if flags.contains(INTRINSIC_INLINE_SIZE_INCLUDES_MARGINS) {
let margin = style.logical_margin();
(MaybeAuto::from_style(margin.inline_start, Au(0)).specified_or_zero() +
MaybeAuto::from_style(margin.inline_end, Au(0)).specified_or_zero())
} else {
Au(0)
};
// FIXME(pcwalton): Percentages should be relative to any definite size per CSS-SIZING.
// This will likely need to be done by pushing down definite sizes during selector
// cascading.
let padding = if flags.contains(INTRINSIC_INLINE_SIZE_INCLUDES_PADDING) {
let padding = style.logical_padding();
(model::specified(padding.inline_start, Au(0)) +
model::specified(padding.inline_end, Au(0)))
} else {
Au(0)
};
let border = if flags.contains(INTRINSIC_INLINE_SIZE_INCLUDES_BORDER) {
self.border_width().inline_start_end()
} else {
Au(0)
};
margin + padding + border
}
/// Uses the style only to estimate the intrinsic inline-sizes. These may be modified for text
/// or replaced elements.
fn style_specified_intrinsic_inline_size(&self) -> IntrinsicISizesContribution {
let flags = self.quantities_included_in_intrinsic_inline_size();
let style = self.style();
let specified = if flags.contains(INTRINSIC_INLINE_SIZE_INCLUDES_SPECIFIED) {
MaybeAuto::from_style(style.content_inline_size(), Au(0)).specified_or_zero()
} else {
Au(0)
};
// FIXME(#2261, pcwalton): This won't work well for inlines: is this OK?
let surrounding_inline_size = self.surrounding_intrinsic_inline_size();
IntrinsicISizesContribution {
content_intrinsic_sizes: IntrinsicISizes {
minimum_inline_size: specified,
preferred_inline_size: specified,
},
surrounding_size: surrounding_inline_size,
}
}
pub fn calculate_line_height(&self, layout_context: &LayoutContext) -> Au {
let font_style = self.style.get_font_arc();
let font_metrics = text::font_metrics_for_style(layout_context.font_context(), font_style);
text::line_height_from_style(&*self.style, &font_metrics)
}
/// Returns the sum of the inline-sizes of all the borders of this fragment. Note that this
/// can be expensive to compute, so if possible use the `border_padding` field instead.
#[inline]
pub fn border_width(&self) -> LogicalMargin<Au> {
let style_border_width = match self.specific {
ScannedTextFragment(_) => LogicalMargin::zero(self.style.writing_mode),
_ => self.style().logical_border_width(),
};
match self.inline_context {
None => style_border_width,
Some(ref inline_fragment_context) => {
inline_fragment_context.styles.iter().fold(style_border_width,
|acc, style| acc + style.logical_border_width())
}
}
}
/// Computes the margins in the inline direction from the containing block inline-size and the
/// style. After this call, the inline direction of the `margin` field will be correct.
///
/// Do not use this method if the inline direction margins are to be computed some other way
/// (for example, via constraint solving for blocks).
pub fn compute_inline_direction_margins(&mut self, containing_block_inline_size: Au) {
match self.specific {
TableFragment | TableCellFragment | TableRowFragment | TableColumnFragment(_) => {
self.margin.inline_start = Au(0);
self.margin.inline_end = Au(0)
}
_ => {
let margin = self.style().logical_margin();
self.margin.inline_start =
MaybeAuto::from_style(margin.inline_start, containing_block_inline_size)
.specified_or_zero();
self.margin.inline_end =
MaybeAuto::from_style(margin.inline_end, containing_block_inline_size)
.specified_or_zero();
}
}
}
/// Computes the margins in the block direction from the containing block inline-size and the
/// style. After this call, the block direction of the `margin` field will be correct.
///
/// Do not use this method if the block direction margins are to be computed some other way
/// (for example, via constraint solving for absolutely-positioned flows).
pub fn compute_block_direction_margins(&mut self, containing_block_inline_size: Au) {
match self.specific {
TableFragment | TableCellFragment | TableRowFragment | TableColumnFragment(_) => {
self.margin.block_start = Au(0);
self.margin.block_end = Au(0)
}
_ => {
// NB: Percentages are relative to containing block inline-size (not block-size)
// per CSS 2.1.
let margin = self.style().logical_margin();
self.margin.block_start =
MaybeAuto::from_style(margin.block_start, containing_block_inline_size)
.specified_or_zero();
self.margin.block_end =
MaybeAuto::from_style(margin.block_end, containing_block_inline_size)
.specified_or_zero();
}
}
}
/// Computes the border and padding in both inline and block directions from the containing
/// block inline-size and the style. After this call, the `border_padding` field will be
/// correct.
pub fn compute_border_and_padding(&mut self, containing_block_inline_size: Au) {
// Compute border.
let border = self.border_width();
// Compute padding.
let padding = match self.specific {
TableColumnFragment(_) | TableRowFragment |
TableWrapperFragment => LogicalMargin::zero(self.style.writing_mode),
_ => {
let style_padding = match self.specific {
ScannedTextFragment(_) => LogicalMargin::zero(self.style.writing_mode),
_ => model::padding_from_style(self.style(), containing_block_inline_size),
};
match self.inline_context {
None => style_padding,
Some(ref inline_fragment_context) => {
inline_fragment_context.styles.iter().fold(style_padding,
|acc, style| acc + model::padding_from_style(&**style, Au(0)))
}
}
}
};
self.border_padding = border + padding;
}
// Return offset from original position because of `position: relative`.
pub fn relative_position(&self,
containing_block_size: &LogicalSize<Au>)
-> LogicalSize<Au> {
fn from_style(style: &ComputedValues, container_size: &LogicalSize<Au>)
-> LogicalSize<Au> {
let offsets = style.logical_position();
let offset_i = if offsets.inline_start != LPA_Auto {
MaybeAuto::from_style(offsets.inline_start, container_size.inline).specified_or_zero()
} else {
-MaybeAuto::from_style(offsets.inline_end, container_size.inline).specified_or_zero()
};
let offset_b = if offsets.block_start != LPA_Auto {
MaybeAuto::from_style(offsets.block_start, container_size.inline).specified_or_zero()
} else {
-MaybeAuto::from_style(offsets.block_end, container_size.inline).specified_or_zero()
};
LogicalSize::new(style.writing_mode, offset_i, offset_b)
}
// Go over the ancestor fragments and add all relative offsets (if any).
let mut rel_pos = if self.style().get_box().position == position::relative {
from_style(self.style(), containing_block_size)
} else {
LogicalSize::zero(self.style.writing_mode)
};
match self.inline_context {
None => {}
Some(ref inline_fragment_context) => {
for style in inline_fragment_context.styles.iter() {
if style.get_box().position == position::relative {
rel_pos = rel_pos + from_style(&**style, containing_block_size);
}
}
},
}
rel_pos
}
/// Always inline for SCCP.
///
/// FIXME(pcwalton): Just replace with the clear type from the style module for speed?
#[inline(always)]
pub fn clear(&self) -> Option<ClearType> {
let style = self.style();
match style.get_box().clear {
clear::none => None,
clear::left => Some(ClearLeft),
clear::right => Some(ClearRight),
clear::both => Some(ClearBoth),
}
}
#[inline(always)]
pub fn style<'a>(&'a self) -> &'a ComputedValues {
&*self.style
}
/// Returns the text alignment of the computed style of the nearest ancestor-or-self `Element`
/// node.
pub fn text_align(&self) -> text_align::T {
self.style().get_inheritedtext().text_align
}
pub fn vertical_align(&self) -> vertical_align::T {
self.style().get_box().vertical_align
}
pub fn white_space(&self) -> white_space::T {
self.style().get_inheritedtext().white_space
}
/// Returns the text decoration of this fragment, according to the style of the nearest ancestor
/// element.
///
/// NB: This may not be the actual text decoration, because of the override rules specified in
/// CSS 2.1 § 16.3.1. Unfortunately, computing this properly doesn't really fit into Servo's
/// model. Therefore, this is a best lower bound approximation, but the end result may actually
/// have the various decoration flags turned on afterward.
pub fn text_decoration(&self) -> text_decoration::T {
self.style().get_text().text_decoration
}
/// Returns the inline-start offset from margin edge to content edge.
///
/// FIXME(#2262, pcwalton): I think this method is pretty bogus, because it won't work for
/// inlines.
pub fn inline_start_offset(&self) -> Au {
match self.specific {
TableWrapperFragment => self.margin.inline_start,
TableFragment | TableCellFragment | TableRowFragment => self.border_padding.inline_start,
TableColumnFragment(_) => Au(0),
_ => self.margin.inline_start + self.border_padding.inline_start,
}
}
/// Returns true if this element can be split. This is true for text fragments.
pub fn can_split(&self) -> bool {
self.is_scanned_text_fragment()
}
/// Returns the newline positions of this fragment, if it's a scanned text fragment.
pub fn newline_positions(&self) -> Option<&Vec<CharIndex>> {
match self.specific {
ScannedTextFragment(ref info) => Some(&info.new_line_pos),
_ => None,
}
}
/// Returns the newline positions of this fragment, if it's a scanned text fragment.
pub fn newline_positions_mut(&mut self) -> Option<&mut Vec<CharIndex>> {
match self.specific {
ScannedTextFragment(ref mut info) => Some(&mut info.new_line_pos),
_ => None,
}
}
/// Returns true if and only if this is a scanned text fragment.
fn is_scanned_text_fragment(&self) -> bool {
match self.specific {
ScannedTextFragment(..) => true,
_ => false,
}
}
/// Computes the intrinsic inline-sizes of this fragment.
pub fn compute_intrinsic_inline_sizes(&mut self) -> IntrinsicISizesContribution {
let mut result = self.style_specified_intrinsic_inline_size();
match self.specific {
GenericFragment | IframeFragment(_) | TableFragment | TableCellFragment |
TableColumnFragment(_) | TableRowFragment | TableWrapperFragment |
InlineAbsoluteHypotheticalFragment(_) => {}
InlineBlockFragment(ref mut info) => {
let block_flow = info.flow_ref.as_block();
result.union_block(&block_flow.base.intrinsic_inline_sizes)
}
ImageFragment(ref mut image_fragment_info) => {
let image_inline_size = image_fragment_info.image_inline_size();
result.union_block(&IntrinsicISizes {
minimum_inline_size: image_inline_size,
preferred_inline_size: image_inline_size,
})
}
ScannedTextFragment(ref text_fragment_info) => {
let range = &text_fragment_info.range;
let min_line_inline_size = text_fragment_info.run.min_width_for_range(range);
// See http://dev.w3.org/csswg/css-sizing/#max-content-inline-size.
// TODO: Account for soft wrap opportunities.
let max_line_inline_size = text_fragment_info.run
.metrics_for_range(range)
.advance_width;
result.union_block(&IntrinsicISizes {
minimum_inline_size: min_line_inline_size,
preferred_inline_size: max_line_inline_size,
})
}
UnscannedTextFragment(..) => {
panic!("Unscanned text fragments should have been scanned by now!")
}
};
// Take borders and padding for parent inline fragments into account, if necessary.
if self.is_primary_fragment() {
match self.inline_context {
None => {}
Some(ref context) => {
for style in context.styles.iter() {
let border_width = style.logical_border_width().inline_start_end();
let padding_inline_size =
model::padding_from_style(&**style, Au(0)).inline_start_end();
result.surrounding_size = result.surrounding_size + border_width +
padding_inline_size;
}
}
}
}
result
}
/// TODO: What exactly does this function return? Why is it Au(0) for GenericFragment?
pub fn content_inline_size(&self) -> Au {
match self.specific {
GenericFragment | IframeFragment(_) | TableFragment | TableCellFragment |
TableRowFragment | TableWrapperFragment | InlineBlockFragment(_) |
InlineAbsoluteHypotheticalFragment(_) => Au(0),
ImageFragment(ref image_fragment_info) => {
image_fragment_info.computed_inline_size()
}
ScannedTextFragment(ref text_fragment_info) => {
let (range, run) = (&text_fragment_info.range, &text_fragment_info.run);
let text_bounds = run.metrics_for_range(range).bounding_box;
text_bounds.size.width
}
TableColumnFragment(_) => panic!("Table column fragments do not have inline_size"),
UnscannedTextFragment(_) => panic!("Unscanned text fragments should have been scanned by now!"),
}
}
/// Returns, and computes, the block-size of this fragment.
pub fn content_block_size(&self, layout_context: &LayoutContext) -> Au {
match self.specific {
GenericFragment | IframeFragment(_) | TableFragment | TableCellFragment |
TableRowFragment | TableWrapperFragment | InlineBlockFragment(_) |
InlineAbsoluteHypotheticalFragment(_) => Au(0),
ImageFragment(ref image_fragment_info) => {
image_fragment_info.computed_block_size()
}
ScannedTextFragment(_) => {
// Compute the block-size based on the line-block-size and font size.
self.calculate_line_height(layout_context)
}
TableColumnFragment(_) => panic!("Table column fragments do not have block_size"),
UnscannedTextFragment(_) => panic!("Unscanned text fragments should have been scanned by now!"),
}
}
/// Returns the dimensions of the content box.
///
/// This is marked `#[inline]` because it is frequently called when only one or two of the
/// values are needed and that will save computation.
#[inline]
pub fn content_box(&self) -> LogicalRect<Au> {
self.border_box - self.border_padding
}
/// Find the split of a fragment that includes a new-line character.
///
/// A return value of `None` indicates that the fragment is not splittable.
/// Otherwise the split information is returned. The right information is
/// optional due to the possibility of it being whitespace.
//
// TODO(bjz): The text run should be removed in the future, but it is currently needed for
// the current method of fragment splitting in the `inline::try_append_*` functions.
pub fn find_split_info_by_new_line(&self)
-> Option<(SplitInfo, Option<SplitInfo>, Arc<Box<TextRun>> /* TODO(bjz): remove */)> {
match self.specific {
GenericFragment | IframeFragment(_) | ImageFragment(_) | TableFragment | TableCellFragment |
TableRowFragment | TableWrapperFragment => None,
TableColumnFragment(_) => panic!("Table column fragments do not need to split"),
UnscannedTextFragment(_) => panic!("Unscanned text fragments should have been scanned by now!"),
InlineBlockFragment(_) | InlineAbsoluteHypotheticalFragment(_) => {
panic!("Inline blocks or inline absolute hypothetical fragments do not get split")
}
ScannedTextFragment(ref text_fragment_info) => {
let mut new_line_pos = text_fragment_info.new_line_pos.clone();
let cur_new_line_pos = new_line_pos.remove(0).unwrap();
let inline_start_range = Range::new(text_fragment_info.range.begin(),
cur_new_line_pos);
let inline_end_range = Range::new(
text_fragment_info.range.begin() + cur_new_line_pos + CharIndex(1),
text_fragment_info.range.length() - (cur_new_line_pos + CharIndex(1)));
// Left fragment is for inline-start text of first founded new-line character.
let inline_start_fragment = SplitInfo::new(inline_start_range,
&**text_fragment_info);
// Right fragment is for inline-end text of first founded new-line character.
let inline_end_fragment = if inline_end_range.length() > CharIndex(0) {
Some(SplitInfo::new(inline_end_range, &**text_fragment_info))
} else {
None
};
Some((inline_start_fragment, inline_end_fragment, text_fragment_info.run.clone()))
}
}
}
/// Attempts to find the split positions of a text fragment so that its inline-size is no more
/// than `max_inline_size`.
///
/// A return value of `None` indicates that the fragment could not be split. Otherwise the
/// information pertaining to the split is returned. The inline-start and inline-end split
/// information are both optional due to the possibility of them being whitespace.
pub fn calculate_split_position(&self, max_inline_size: Au, starts_line: bool)
-> Option<SplitResult> {
let text_fragment_info = match self.specific {
GenericFragment | IframeFragment(_) | ImageFragment(_) | TableFragment |
TableCellFragment | TableRowFragment | TableWrapperFragment | InlineBlockFragment(_) |
InlineAbsoluteHypotheticalFragment(_) => return None,
TableColumnFragment(_) => panic!("Table column fragments do not have inline_size"),
UnscannedTextFragment(_) => {
panic!("Unscanned text fragments should have been scanned by now!")
}
ScannedTextFragment(ref text_fragment_info) => text_fragment_info,
};
let mut flags = SplitOptions::empty();
if starts_line {
flags.insert(STARTS_LINE);
if self.style().get_inheritedtext().overflow_wrap == overflow_wrap::break_word {
flags.insert(RETRY_AT_CHARACTER_BOUNDARIES)
}
}
let natural_word_breaking_strategy =
text_fragment_info.run.natural_word_slices_in_range(&text_fragment_info.range);
self.calculate_split_position_using_breaking_strategy(natural_word_breaking_strategy,
max_inline_size,
flags)
}
/// A helper method that uses the breaking strategy described by `slice_iterator` (at present,
/// either natural word breaking or character breaking) to split this fragment.
fn calculate_split_position_using_breaking_strategy<'a,I>(&self,
mut slice_iterator: I,
max_inline_size: Au,
flags: SplitOptions)
-> Option<SplitResult>
where I: Iterator<TextRunSlice<'a>> {
let text_fragment_info = match self.specific {
GenericFragment | IframeFragment(_) | ImageFragment(_) | TableFragment |
TableCellFragment | TableRowFragment | TableWrapperFragment | InlineBlockFragment(_) |
InlineAbsoluteHypotheticalFragment(_) => return None,
TableColumnFragment(_) => panic!("Table column fragments do not have inline_size"),
UnscannedTextFragment(_) => {
panic!("Unscanned text fragments should have been scanned by now!")
}
ScannedTextFragment(ref text_fragment_info) => text_fragment_info,
};
let mut pieces_processed_count: uint = 0;
let mut remaining_inline_size = max_inline_size;
let mut inline_start_range = Range::new(text_fragment_info.range.begin(), CharIndex(0));
let mut inline_end_range = None;
debug!("calculate_split_position: splitting text fragment (strlen={}, range={}, \
max_inline_size={})",
text_fragment_info.run.text.len(),
text_fragment_info.range,
max_inline_size);
for slice in slice_iterator {
debug!("calculate_split_position: considering slice (offset={}, slice range={}, \
remaining_inline_size={})",
slice.offset,
slice.range,
remaining_inline_size);
let metrics = text_fragment_info.run.metrics_for_slice(slice.glyphs, &slice.range);
let advance = metrics.advance_width;
// Have we found the split point?
if advance <= remaining_inline_size || slice.glyphs.is_whitespace() {
// Keep going; we haven't found the split point yet.
if flags.contains(STARTS_LINE) && pieces_processed_count == 0 &&
slice.glyphs.is_whitespace() {
debug!("calculate_split_position: skipping leading trimmable whitespace");
inline_start_range.shift_by(slice.range.length());
} else {
debug!("split_to_inline_size: enlarging span");
remaining_inline_size = remaining_inline_size - advance;
inline_start_range.extend_by(slice.range.length());
}
pieces_processed_count += 1;
continue
}
// The advance is more than the remaining inline-size, so split here.
let slice_begin = slice.text_run_range().begin();
if slice_begin < text_fragment_info.range.end() {
// There still some things left over at the end of the line, so create the
// inline-end chunk.
let mut inline_end = slice.text_run_range();
inline_end.extend_to(text_fragment_info.range.end());
inline_end_range = Some(inline_end);
debug!("calculate_split_position: splitting remainder with inline-end range={}",
inline_end);
}
pieces_processed_count += 1;
break
}
// If we failed to find a suitable split point, we're on the verge of overflowing the line.
let inline_start_is_some = inline_start_range.length() > CharIndex(0);
if pieces_processed_count == 1 || !inline_start_is_some {
// If we've been instructed to retry at character boundaries (probably via
// `overflow-wrap: break-word`), do so.
if flags.contains(RETRY_AT_CHARACTER_BOUNDARIES) {
let character_breaking_strategy =
text_fragment_info.run.character_slices_in_range(&text_fragment_info.range);
let mut flags = flags;
flags.remove(RETRY_AT_CHARACTER_BOUNDARIES);
return self.calculate_split_position_using_breaking_strategy(
character_breaking_strategy,
max_inline_size,
flags)
}
// We aren't at the start of the line, so don't overflow. Let inline layout wrap to the
// next line instead.
if !flags.contains(STARTS_LINE) {
return None
}
}
let inline_start = if inline_start_is_some {
Some(SplitInfo::new(inline_start_range, &**text_fragment_info))
} else {
None
};
let inline_end = inline_end_range.map(|inline_end_range| {
SplitInfo::new(inline_end_range, &**text_fragment_info)
});
Some(SplitResult {
inline_start: inline_start,
inline_end: inline_end,
text_run: text_fragment_info.run.clone(),
})
}
/// Returns true if this fragment is an unscanned text fragment that consists entirely of
/// whitespace that should be stripped.
pub fn is_ignorable_whitespace(&self) -> bool {
match self.white_space() {
white_space::pre => return false,
white_space::normal | white_space::nowrap => {}
}
match self.specific {
UnscannedTextFragment(ref text_fragment_info) => {
is_whitespace(text_fragment_info.text.as_slice())
}
_ => false,
}
}
/// Assigns replaced inline-size, padding, and margins for this fragment only if it is replaced
/// content per CSS 2.1 § 10.3.2.
pub fn assign_replaced_inline_size_if_necessary(&mut self, container_inline_size: Au) {
match self.specific {
GenericFragment | IframeFragment(_) | TableFragment | TableCellFragment |
TableRowFragment | TableWrapperFragment => return,
TableColumnFragment(_) => panic!("Table column fragments do not have inline_size"),
UnscannedTextFragment(_) => {
panic!("Unscanned text fragments should have been scanned by now!")
}
ImageFragment(_) | ScannedTextFragment(_) | InlineBlockFragment(_) |
InlineAbsoluteHypotheticalFragment(_) => {}
};
let style_inline_size = self.style().content_inline_size();
let style_block_size = self.style().content_block_size();
let style_min_inline_size = self.style().min_inline_size();
let style_max_inline_size = self.style().max_inline_size();
let style_min_block_size = self.style().min_block_size();
let style_max_block_size = self.style().max_block_size();
let noncontent_inline_size = self.border_padding.inline_start_end();
match self.specific {
InlineAbsoluteHypotheticalFragment(ref mut info) => {
let block_flow = info.flow_ref.as_block();
block_flow.base.position.size.inline =
block_flow.base.intrinsic_inline_sizes.preferred_inline_size;
// This is a hypothetical box, so it takes up no space.
self.border_box.size.inline = Au(0);
}
InlineBlockFragment(ref mut info) => {
let block_flow = info.flow_ref.as_block();
self.border_box.size.inline =
block_flow.base.intrinsic_inline_sizes.preferred_inline_size;
block_flow.base.block_container_inline_size = self.border_box.size.inline;
}
ScannedTextFragment(ref info) => {
// Scanned text fragments will have already had their content inline-sizes assigned
// by this point.
self.border_box.size.inline = info.content_size.inline + noncontent_inline_size
}
ImageFragment(ref mut image_fragment_info) => {
// TODO(ksh8281): compute border,margin
let inline_size = ImageFragmentInfo::style_length(
style_inline_size,
image_fragment_info.dom_inline_size,
container_inline_size);
let inline_size = match inline_size {
Auto => {
let intrinsic_width = image_fragment_info.image_inline_size();
let intrinsic_height = image_fragment_info.image_block_size();
if intrinsic_height == Au(0) {
intrinsic_width
} else {
let ratio = intrinsic_width.to_f32().unwrap() /
intrinsic_height.to_f32().unwrap();
let specified_height = ImageFragmentInfo::style_length(
style_block_size,
image_fragment_info.dom_block_size,
Au(0));
let specified_height = match specified_height {
Auto => intrinsic_height,
Specified(h) => h,
};
let specified_height = ImageFragmentInfo::clamp_size(
specified_height,
style_min_block_size,
style_max_block_size,
Au(0));
Au((specified_height.to_f32().unwrap() * ratio) as i32)
}
},
Specified(w) => w,
};
let inline_size = ImageFragmentInfo::clamp_size(inline_size,
style_min_inline_size,
style_max_inline_size,
container_inline_size);
self.border_box.size.inline = inline_size + noncontent_inline_size;
image_fragment_info.computed_inline_size = Some(inline_size);
}
_ => panic!("this case should have been handled above"),
}
}
/// Assign block-size for this fragment if it is replaced content. The inline-size must have
/// been assigned first.
///
/// Ideally, this should follow CSS 2.1 § 10.6.2.
pub fn assign_replaced_block_size_if_necessary(&mut self, containing_block_block_size: Au) {
match self.specific {
GenericFragment | IframeFragment(_) | TableFragment | TableCellFragment |
TableRowFragment | TableWrapperFragment => return,
TableColumnFragment(_) => panic!("Table column fragments do not have block_size"),
UnscannedTextFragment(_) => {
panic!("Unscanned text fragments should have been scanned by now!")
}
ImageFragment(_) | ScannedTextFragment(_) | InlineBlockFragment(_) |
InlineAbsoluteHypotheticalFragment(_) => {}
}
let style_block_size = self.style().content_block_size();
let style_min_block_size = self.style().min_block_size();
let style_max_block_size = self.style().max_block_size();
let noncontent_block_size = self.border_padding.block_start_end();
match self.specific {
ImageFragment(ref mut image_fragment_info) => {
// TODO(ksh8281): compute border,margin,padding
let inline_size = image_fragment_info.computed_inline_size();
let block_size = ImageFragmentInfo::style_length(
style_block_size,
image_fragment_info.dom_block_size,
containing_block_block_size);
let block_size = match block_size {
Auto => {
let scale = image_fragment_info.image_inline_size().to_f32().unwrap()
/ inline_size.to_f32().unwrap();
Au((image_fragment_info.image_block_size().to_f32().unwrap() / scale)
as i32)
},
Specified(h) => {
h
}
};
let block_size = ImageFragmentInfo::clamp_size(block_size, style_min_block_size,
style_max_block_size,
Au(0));
image_fragment_info.computed_block_size = Some(block_size);
self.border_box.size.block = block_size + noncontent_block_size
}
ScannedTextFragment(ref info) => {
// Scanned text fragments' content block-sizes are calculated by the text run
// scanner during flow construction.
self.border_box.size.block = info.content_size.block + noncontent_block_size
}
InlineBlockFragment(ref mut info) => {
// Not the primary fragment, so we do not take the noncontent size into account.
let block_flow = info.flow_ref.as_block();
self.border_box.size.block = block_flow.base.position.size.block +
block_flow.fragment.margin.block_start_end()
}
InlineAbsoluteHypotheticalFragment(ref mut info) => {
// Not the primary fragment, so we do not take the noncontent size into account.
let block_flow = info.flow_ref.as_block();
self.border_box.size.block = block_flow.base.position.size.block;
}
_ => panic!("should have been handled above"),
}
}
/// Calculates block-size above baseline, depth below baseline, and ascent for this fragment when
/// used in an inline formatting context. See CSS 2.1 § 10.8.1.
pub fn inline_metrics(&self, layout_context: &LayoutContext) -> InlineMetrics {
match self.specific {
ImageFragment(ref image_fragment_info) => {
let computed_block_size = image_fragment_info.computed_block_size();
InlineMetrics {
block_size_above_baseline: computed_block_size + self.border_padding.block_start_end(),
depth_below_baseline: Au(0),
ascent: computed_block_size + self.border_padding.block_end,
}
}
ScannedTextFragment(ref text_fragment) => {
// See CSS 2.1 § 10.8.1.
let line_height = self.calculate_line_height(layout_context);
InlineMetrics::from_font_metrics(&text_fragment.run.font_metrics, line_height)
}
InlineBlockFragment(ref info) => {
// See CSS 2.1 § 10.8.1.
let block_flow = info.flow_ref.deref().as_immutable_block();
let font_style = self.style.get_font_arc();
let font_metrics = text::font_metrics_for_style(layout_context.font_context(),
font_style);
InlineMetrics::from_block_height(&font_metrics,
block_flow.base.position.size.block +
block_flow.fragment.margin.block_start_end())
}
InlineAbsoluteHypotheticalFragment(_) => {
// Hypothetical boxes take up no space.
InlineMetrics {
block_size_above_baseline: Au(0),
depth_below_baseline: Au(0),
ascent: Au(0),
}
}
_ => {
InlineMetrics {
block_size_above_baseline: self.border_box.size.block,
depth_below_baseline: Au(0),
ascent: self.border_box.size.block,
}
}
}
}
/// Returns true if this fragment is a hypothetical box. See CSS 2.1 § 10.3.7.
pub fn is_hypothetical(&self) -> bool {
match self.specific {
InlineAbsoluteHypotheticalFragment(_) => true,
_ => false,
}
}
/// Returns true if this fragment can merge with another adjacent fragment or false otherwise.
pub fn can_merge_with_fragment(&self, other: &Fragment) -> bool {
match (&self.specific, &other.specific) {
(&UnscannedTextFragment(_), &UnscannedTextFragment(_)) => {
// FIXME: Should probably use a whitelist of styles that can safely differ (#3165)
self.style().get_font() == other.style().get_font() &&
self.text_decoration() == other.text_decoration() &&
self.white_space() == other.white_space()
}
_ => false,
}
}
/// Returns true if and only if this is the *primary fragment* for the fragment's style object
/// (conceptually, though style sharing makes this not really true, of course). The primary
/// fragment is the one that draws backgrounds, borders, etc., and takes borders, padding and
/// margins into account. Every style object has at most one primary fragment.
///
/// At present, all fragments are primary fragments except for inline-block and table wrapper
/// fragments. Inline-block fragments are not primary fragments because the corresponding block
/// flow is the primary fragment, while table wrapper fragments are not primary fragments
/// because the corresponding table flow is the primary fragment.
pub fn is_primary_fragment(&self) -> bool {
match self.specific {
InlineBlockFragment(_) | InlineAbsoluteHypotheticalFragment(_) |
TableWrapperFragment => false,
GenericFragment | IframeFragment(_) | ImageFragment(_) | ScannedTextFragment(_) |
TableFragment | TableCellFragment | TableColumnFragment(_) | TableRowFragment |
UnscannedTextFragment(_) => true,
}
}
pub fn update_late_computed_inline_position_if_necessary(&mut self) {
match self.specific {
InlineAbsoluteHypotheticalFragment(ref mut info) => {
let position = self.border_box.start.i;
info.flow_ref.update_late_computed_inline_position_if_necessary(position)
}
_ => {}
}
}
pub fn update_late_computed_block_position_if_necessary(&mut self) {
match self.specific {
InlineAbsoluteHypotheticalFragment(ref mut info) => {
let position = self.border_box.start.b;
info.flow_ref.update_late_computed_block_position_if_necessary(position)
}
_ => {}
}
}
pub fn repair_style(&mut self, new_style: &Arc<ComputedValues>) {
self.style = (*new_style).clone()
}
/// Given the stacking-context-relative position of the containing flow, returns the boundaries
/// of this fragment relative to the parent stacking context.
pub fn stacking_relative_bounds(&self, stacking_relative_flow_origin: &Point2D<Au>)
-> Rect<Au> {
// FIXME(#2795): Get the real container size
let container_size = Size2D::zero();
self.border_box
.to_physical(self.style.writing_mode, container_size)
.translate(stacking_relative_flow_origin)
}
/// Returns true if this fragment establishes a new stacking context and false otherwise.
pub fn establishes_stacking_context(&self) -> bool {
if self.style().get_effects().opacity != 1.0 {
return true
}
match self.style().get_box().position {
position::absolute | position::fixed => {
// FIXME(pcwalton): This should only establish a new stacking context when
// `z-index` is not `auto`. But this matches what we did before.
true
}
position::relative | position::static_ => {
// FIXME(pcwalton): `position: relative` establishes a new stacking context if
// `z-index` is not `auto`. But this matches what we did before.
false
}
}
}
}
impl fmt::Show for Fragment {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
try!(write!(f, "({} {} ", self.debug_id(), self.specific.get_type()));
try!(write!(f, "bp {}", self.border_padding));
try!(write!(f, " "));
try!(write!(f, "m {}", self.margin));
write!(f, ")")
}
}
bitflags! {
flags QuantitiesIncludedInIntrinsicInlineSizes: u8 {
const INTRINSIC_INLINE_SIZE_INCLUDES_MARGINS = 0x01,
const INTRINSIC_INLINE_SIZE_INCLUDES_PADDING = 0x02,
const INTRINSIC_INLINE_SIZE_INCLUDES_BORDER = 0x04,
const INTRINSIC_INLINE_SIZE_INCLUDES_SPECIFIED = 0x08,
}
}
bitflags! {
// Various flags we can use when splitting fragments. See
// `calculate_split_position_using_breaking_strategy()`.
flags SplitOptions: u8 {
#[doc="True if this is the first fragment on the line."]
const STARTS_LINE = 0x01,
#[doc="True if we should attempt to split at character boundaries if this split fails. \
This is used to implement `overflow-wrap: break-word`."]
const RETRY_AT_CHARACTER_BOUNDARIES = 0x02
}
}
/// A top-down fragment bounds iteration handler.
pub trait FragmentBoundsIterator {
/// The operation to perform.
fn process(&mut self, fragment: &Fragment, bounds: Rect<Au>);
/// Returns true if this fragment must be processed in-order. If this returns false,
/// we skip the operation for this fragment, but continue processing siblings.
fn should_process(&mut self, fragment: &Fragment) -> bool;
}
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