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fragment.rs
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fragment.rs
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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_block)]
use css::node_style::StyledNode;
use construct::FlowConstructor;
use context::LayoutContext;
use floats::{ClearBoth, ClearLeft, ClearRight, ClearType};
use flow::Flow;
use flow;
use flow_ref::FlowRef;
use inline::{InlineFragmentContext, InlineMetrics};
use layout_debug;
use model::{Auto, IntrinsicISizes, MaybeAuto, Specified, specified};
use model;
use text;
use util::{OpaqueNodeMethods, ToGfxColor};
use wrapper::{TLayoutNode, ThreadSafeLayoutNode};
use geom::{Point2D, Rect, Size2D, SideOffsets2D};
use geom::approxeq::ApproxEq;
use gfx::color::rgb;
use gfx::display_list::{BackgroundAndBorderLevel, BaseDisplayItem, BorderDisplayItem};
use gfx::display_list::{BorderDisplayItemClass, ClipDisplayItem, ClipDisplayItemClass};
use gfx::display_list::{ContentStackingLevel, DisplayItem, DisplayList, ImageDisplayItem};
use gfx::display_list::{ImageDisplayItemClass, LineDisplayItem};
use gfx::display_list::{LineDisplayItemClass, OpaqueNode, PseudoDisplayItemClass};
use gfx::display_list::{SolidColorDisplayItem, SolidColorDisplayItemClass, StackingLevel};
use gfx::display_list::{TextDisplayItem, TextDisplayItemClass};
use gfx::display_list::{Upright, SidewaysLeft, SidewaysRight};
use gfx::font::FontStyle;
use gfx::text::glyph::CharIndex;
use gfx::text::text_run::TextRun;
use serialize::{Encodable, Encoder};
use servo_msg::constellation_msg::{ConstellationChan, FrameRectMsg, 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 std::mem;
use std::num::Zero;
use style::{ComputedValues, TElement, TNode, cascade_anonymous, RGBA};
use style::computed_values::{LengthOrPercentage, LengthOrPercentageOrAuto};
use style::computed_values::{LengthOrPercentageOrNone};
use style::computed_values::{overflow, LPA_Auto, background_attachment};
use style::computed_values::{background_repeat, border_style, clear, position, text_align};
use style::computed_values::{text_decoration, vertical_align, visibility, 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.
///
/// FIXME(#2260, pcwalton): This can be slimmed down some.
#[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,
/// New-line chracter(\n)'s positions(relative, not absolute)
///
/// FIXME(#2260, pcwalton): This is very inefficient; remove.
pub new_line_pos: Vec<CharIndex>,
/// 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: uint,
}
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.
#[deriving(Clone)]
pub enum SpecificFragmentInfo {
GenericFragment,
IframeFragment(IframeFragmentInfo),
ImageFragment(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),
InputFragment(InputFragmentInfo),
ScannedTextFragment(ScannedTextFragmentInfo),
TableFragment,
TableCellFragment,
TableColumnFragment(TableColumnFragmentInfo),
TableRowFragment,
TableWrapperFragment,
UnscannedTextFragment(UnscannedTextFragmentInfo),
}
/// 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 displayable form element
#[deriving(Clone)]
pub struct InputFragmentInfo {
pub size: u32,
}
impl InputFragmentInfo {
/// Returns the original inline-size of the input.
fn input_inline_size(&self, font_style: &FontStyle, layout_context: &LayoutContext) -> Au {
let metrics = text::font_metrics_for_style(layout_context.font_context(), font_style);
// https://html.spec.whatwg.org/#converting-a-character-width-to-pixels
metrics.average_advance * (self.size as i32 - 1) + metrics.max_advance
}
}
/// 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,
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>>)
-> ImageFragmentInfo {
fn convert_length(node: &ThreadSafeLayoutNode, name: &str) -> 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, "width");
let dom_height = convert_length(node, "height");
ImageFragmentInfo {
image: ImageHolder::new(image_url, local_image_cache),
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().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().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>,
}
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>) -> ScannedTextFragmentInfo {
ScannedTextFragmentInfo {
run: run,
range: range,
}
}
}
#[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),
}
}
}
/// 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.
pub text: 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: node.text(),
}
}
/// Creates a new instance of `UnscannedTextFragmentInfo` from the given text.
#[inline]
pub fn from_text(text: String) -> UnscannedTextFragmentInfo {
UnscannedTextFragmentInfo {
text: text,
}
}
}
/// A fragment that represents a table column.
#[deriving(Clone)]
pub struct TableColumnFragmentInfo {
/// the number of columns a <col> element should span
pub span: Option<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!(""), "span").and_then(|string| {
let n: Option<int> = FromStr::from_str(string);
n
})
};
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,
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),
new_line_pos: vec!(),
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,
border_box: LogicalRect::zero(writing_mode),
border_padding: LogicalMargin::zero(writing_mode),
margin: LogicalMargin::zero(writing_mode),
specific: specific,
new_line_pos: vec!(),
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 it 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),
border_box: LogicalRect::zero(writing_mode),
border_padding: LogicalMargin::zero(writing_mode),
margin: LogicalMargin::zero(writing_mode),
specific: specific,
new_line_pos: vec!(),
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>,
specific: SpecificFragmentInfo)
-> Fragment {
let writing_mode = style.writing_mode;
Fragment {
node: node,
style: style,
border_box: LogicalRect::zero(writing_mode),
border_padding: LogicalMargin::zero(writing_mode),
margin: LogicalMargin::zero(writing_mode),
specific: specific,
new_line_pos: vec!(),
inline_context: None,
debug_id: layout_debug::generate_unique_debug_id(),
}
}
/// 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) -> uint {
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>, specific: SpecificFragmentInfo) -> Fragment {
Fragment {
node: self.node,
style: self.style.clone(),
border_box: LogicalRect::from_point_size(
self.style.writing_mode, self.border_box.start, size),
border_padding: self.border_padding,
margin: self.margin,
specific: specific,
new_line_pos: self.new_line_pos.clone(),
inline_context: self.inline_context.clone(),
debug_id: self.debug_id,
}
}
/// 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());
}
/// 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) -> IntrinsicISizes {
let (use_margins, use_padding) = match self.specific {
GenericFragment | IframeFragment(_) | ImageFragment(_) | InlineBlockFragment(_) |
InputFragment(_) => (true, true),
TableFragment | TableCellFragment => (false, true),
TableWrapperFragment => (true, false),
TableRowFragment => (false, false),
ScannedTextFragment(_) | TableColumnFragment(_) | UnscannedTextFragment(_) |
InlineAbsoluteHypotheticalFragment(_) => {
// Styles are irrelevant for these kinds of fragments.
return IntrinsicISizes::new()
}
};
let style = self.style();
let inline_size = MaybeAuto::from_style(style.content_inline_size(),
Au(0)).specified_or_zero();
let margin = style.logical_margin();
let (margin_inline_start, margin_inline_end) = if use_margins {
(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), Au(0))
};
let padding = style.logical_padding();
let (padding_inline_start, padding_inline_end) = if use_padding {
(model::specified(padding.inline_start, Au(0)),
model::specified(padding.inline_end, Au(0)))
} else {
(Au(0), Au(0))
};
// FIXME(#2261, pcwalton): This won't work well for inlines: is this OK?
let border = self.border_width();
let surround_inline_size = margin_inline_start + margin_inline_end + padding_inline_start + padding_inline_end +
border.inline_start_end();
IntrinsicISizes {
minimum_inline_size: inline_size,
preferred_inline_size: inline_size,
surround_inline_size: surround_inline_size,
}
}
pub fn calculate_line_height(&self, layout_context: &LayoutContext) -> Au {
let font_style = text::computed_style_to_font_style(&*self.style);
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 border, padding, and vertical margins from the containing block inline-size and the
/// style. After this call, the `border_padding` and the vertical direction of the `margin`
/// field will be correct.
pub fn compute_border_padding_margins(&mut self,
containing_block_inline_size: Au) {
// Compute vertical margins. Note that this value will be ignored by layout if the style
// specifies `auto`.
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()
}
}
// 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),
}
}
/// Converts this fragment's computed style to a font style used for rendering.
pub fn font_style(&self) -> FontStyle {
text::computed_style_to_font_style(self.style())
}
#[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 true if and only if this is a scanned text fragment.
fn is_scanned_text_fragment(&self) -> bool {
match self.specific {
ScannedTextFragment(..) => true,
_ => false,
}
}
/// Adds the display items necessary to paint the background of this fragment to the display
/// list if necessary.
pub fn build_display_list_for_background_if_applicable(&self,
style: &ComputedValues,
list: &mut DisplayList,
layout_context: &LayoutContext,
level: StackingLevel,
absolute_bounds: &Rect<Au>) {
// FIXME: This causes a lot of background colors to be displayed when they are clearly not
// needed. We could use display list optimization to clean this up, but it still seems
// inefficient. What we really want is something like "nearest ancestor element that
// doesn't have a fragment".
let background_color = style.resolve_color(style.get_background().background_color);
if !background_color.alpha.approx_eq(&0.0) {
let display_item = box SolidColorDisplayItem {
base: BaseDisplayItem::new(*absolute_bounds, self.node, level),
color: background_color.to_gfx_color(),
};
list.push(SolidColorDisplayItemClass(display_item))
}
// The background image is painted on top of the background color.
// Implements background image, per spec:
// http://www.w3.org/TR/CSS21/colors.html#background
let background = style.get_background();
let image_url = match background.background_image {
None => return,
Some(ref image_url) => image_url,
};
let mut holder = ImageHolder::new(image_url.clone(), layout_context.shared.image_cache.clone());
let image = match holder.get_image() {
None => {
// No image data at all? Do nothing.
//
// TODO: Add some kind of placeholder background image.
debug!("(building display list) no background image :(");
return
}
Some(image) => image,
};
debug!("(building display list) building background image");
let image_width = Au::from_px(image.width as int);
let image_height = Au::from_px(image.height as int);
let mut bounds = *absolute_bounds;
// Add clip item.
// TODO: Check the bounds to see if a clip item is actually required.
let mut clip_display_item = box ClipDisplayItem {
base: BaseDisplayItem::new(bounds, self.node, level),
children: DisplayList::new(),
};
// Use background-attachment to get the initial virtual origin
let (virtual_origin_x, virtual_origin_y) = match background.background_attachment {
background_attachment::scroll => {
(absolute_bounds.origin.x, absolute_bounds.origin.y)
}
background_attachment::fixed => {
(Au(0), Au(0))
}
};
// Use background-position to get the offset
let horizontal_position = model::specified(background.background_position.horizontal,
bounds.size.width - image_width);
let vertical_position = model::specified(background.background_position.vertical,
bounds.size.height - image_height);
let abs_x = virtual_origin_x + horizontal_position;
let abs_y = virtual_origin_y + vertical_position;
// Adjust origin and size based on background-repeat
match background.background_repeat {
background_repeat::no_repeat => {
bounds.origin.x = abs_x;
bounds.origin.y = abs_y;
bounds.size.width = image_width;
bounds.size.height = image_height;
}
background_repeat::repeat_x => {
bounds.origin.y = abs_y;
bounds.size.height = image_height;
ImageFragmentInfo::tile_image(&mut bounds.origin.x, &mut bounds.size.width,
abs_x, image.width);
}
background_repeat::repeat_y => {
bounds.origin.x = abs_x;
bounds.size.width = image_width;
ImageFragmentInfo::tile_image(&mut bounds.origin.y, &mut bounds.size.height,
abs_y, image.height);
}
background_repeat::repeat => {
ImageFragmentInfo::tile_image(&mut bounds.origin.x, &mut bounds.size.width,
abs_x, image.width);
ImageFragmentInfo::tile_image(&mut bounds.origin.y, &mut bounds.size.height,
abs_y, image.height);
}
};
// Create the image display item.
let image_display_item = ImageDisplayItemClass(box ImageDisplayItem {
base: BaseDisplayItem::new(bounds, self.node, level),
image: image.clone(),
stretch_size: Size2D(Au::from_px(image.width as int),
Au::from_px(image.height as int)),
});
clip_display_item.children.push(image_display_item);
list.push(ClipDisplayItemClass(clip_display_item))
}
/// Adds the display items necessary to paint the borders of this fragment to a display list if
/// necessary.
pub fn build_display_list_for_borders_if_applicable(&self,
style: &ComputedValues,
list: &mut DisplayList,
abs_bounds: &Rect<Au>,
level: StackingLevel) {
let border = style.logical_border_width();
if border.is_zero() {
return
}
let top_color = style.resolve_color(style.get_border().border_top_color);
let right_color = style.resolve_color(style.get_border().border_right_color);
let bottom_color = style.resolve_color(style.get_border().border_bottom_color);
let left_color = style.resolve_color(style.get_border().border_left_color);
// Append the border to the display list.
let border_display_item = box BorderDisplayItem {
base: BaseDisplayItem::new(*abs_bounds, self.node, level),
border: border.to_physical(style.writing_mode),
color: SideOffsets2D::new(top_color.to_gfx_color(),
right_color.to_gfx_color(),
bottom_color.to_gfx_color(),
left_color.to_gfx_color()),
style: SideOffsets2D::new(style.get_border().border_top_style,
style.get_border().border_right_style,
style.get_border().border_bottom_style,
style.get_border().border_left_style)
};
list.push(BorderDisplayItemClass(border_display_item))
}
fn build_debug_borders_around_text_fragments(&self,
display_list: &mut DisplayList,
flow_origin: Point2D<Au>,
text_fragment: &ScannedTextFragmentInfo) {
// FIXME(#2795): Get the real container size
let container_size = Size2D::zero();
// Fragment position wrt to the owning flow.
let fragment_bounds = self.border_box.to_physical(self.style.writing_mode, container_size);
let absolute_fragment_bounds = Rect(
fragment_bounds.origin + flow_origin,
fragment_bounds.size);
// Compute the text fragment bounds and draw a border surrounding them.
let border_display_item = box BorderDisplayItem {
base: BaseDisplayItem::new(absolute_fragment_bounds, self.node, ContentStackingLevel),
border: SideOffsets2D::new_all_same(Au::from_px(1)),
color: SideOffsets2D::new_all_same(rgb(0, 0, 200)),
style: SideOffsets2D::new_all_same(border_style::solid)
};
display_list.push(BorderDisplayItemClass(border_display_item));
// Draw a rectangle representing the baselines.
let ascent = text_fragment.run.ascent();
let mut baseline = self.border_box.clone();
baseline.start.b = baseline.start.b + ascent;
baseline.size.block = Au(0);
let mut baseline = baseline.to_physical(self.style.writing_mode, container_size);
baseline.origin = baseline.origin + flow_origin;
let line_display_item = box LineDisplayItem {
base: BaseDisplayItem::new(baseline, self.node, ContentStackingLevel),
color: rgb(0, 200, 0),
style: border_style::dashed,
};
display_list.push(LineDisplayItemClass(line_display_item));
}
fn build_debug_borders_around_fragment(&self,
display_list: &mut DisplayList,
flow_origin: Point2D<Au>) {
// FIXME(#2795): Get the real container size
let container_size = Size2D::zero();
// Fragment position wrt to the owning flow.
let fragment_bounds = self.border_box.to_physical(self.style.writing_mode, container_size);
let absolute_fragment_bounds = Rect(
fragment_bounds.origin + flow_origin,
fragment_bounds.size);
// This prints a debug border around the border of this fragment.
let border_display_item = box BorderDisplayItem {
base: BaseDisplayItem::new(absolute_fragment_bounds, self.node, ContentStackingLevel),
border: SideOffsets2D::new_all_same(Au::from_px(1)),
color: SideOffsets2D::new_all_same(rgb(0, 0, 200)),
style: SideOffsets2D::new_all_same(border_style::solid)
};
display_list.push(BorderDisplayItemClass(border_display_item))
}
/// Adds the display items for this fragment to the given stacking context.
///
/// Arguments:
///
/// * `display_list`: The unflattened display list to add display items to.
/// * `layout_context`: The layout context.
/// * `dirty`: The dirty rectangle in the coordinate system of the owning flow.
/// * `flow_origin`: Position of the origin of the owning flow wrt the display list root flow.
pub fn build_display_list(&self,
display_list: &mut DisplayList,
layout_context: &LayoutContext,
flow_origin: Point2D<Au>,
background_and_border_level: BackgroundAndBorderLevel)
-> ChildDisplayListAccumulator {
// FIXME(#2795): Get the real container size
let container_size = Size2D::zero();
let rect_to_absolute = |logical_rect: LogicalRect<Au>| {
let physical_rect = logical_rect.to_physical(self.style.writing_mode, container_size);
Rect(physical_rect.origin + flow_origin, physical_rect.size)