servo/components/layout/display_list_builder.rs
2014-12-08 14:05:49 +09:00

979 lines
47 KiB
Rust

/* 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/. */
//! Builds display lists from flows and fragments.
//!
//! Other browser engines sometimes call this "painting", but it is more accurately called display
//! list building, as the actual painting does not happen here—only deciding *what* we're going to
//! paint.
#![deny(unsafe_blocks)]
use block::BlockFlow;
use context::LayoutContext;
use flow::{mod, Flow, NEEDS_LAYER};
use fragment::{Fragment, GenericFragment, IframeFragment, IframeFragmentInfo, ImageFragment};
use fragment::{ImageFragmentInfo, InlineAbsoluteHypotheticalFragment, InlineBlockFragment};
use fragment::{ScannedTextFragment, ScannedTextFragmentInfo, TableFragment};
use fragment::{TableCellFragment, TableColumnFragment, TableRowFragment, TableWrapperFragment};
use fragment::{UnscannedTextFragment};
use model;
use util::{OpaqueNodeMethods, ToGfxColor};
use geom::approxeq::ApproxEq;
use geom::{Point2D, Rect, Size2D, SideOffsets2D};
use gfx::color;
use gfx::display_list::{BaseDisplayItem, BorderDisplayItem, BorderDisplayItemClass, DisplayItem};
use gfx::display_list::{DisplayList, GradientDisplayItem, GradientDisplayItemClass, GradientStop};
use gfx::display_list::{ImageDisplayItem, ImageDisplayItemClass, LineDisplayItem, BorderRadii};
use gfx::display_list::{LineDisplayItemClass, PseudoDisplayItemClass, SidewaysLeft, SidewaysRight};
use gfx::display_list::{SolidColorDisplayItem, SolidColorDisplayItemClass, StackingContext};
use gfx::display_list::{TextDisplayItem, TextDisplayItemClass, Upright};
use gfx::paint_task::PaintLayer;
use servo_msg::compositor_msg::{FixedPosition, Scrollable};
use servo_msg::constellation_msg::{ConstellationChan, FrameRectMsg};
use servo_net::image::holder::ImageHolder;
use servo_util::geometry::{mod, Au, ZERO_POINT, ZERO_RECT};
use servo_util::logical_geometry::{LogicalRect, WritingMode};
use servo_util::opts;
use std::default::Default;
use style::computed::{AngleAoc, CornerAoc, LP_Length, LP_Percentage, LengthOrPercentage};
use style::computed::{LinearGradient, LinearGradientImage, UrlImage};
use style::computed_values::{background_attachment, background_repeat, border_style, overflow};
use style::computed_values::{visibility};
use style::{ComputedValues, Bottom, Left, RGBA, Right, Top};
use style::style_structs::Border;
use sync::Arc;
use url::Url;
/// The results of display list building for a single flow.
pub enum DisplayListBuildingResult {
NoDisplayListBuildingResult,
StackingContextResult(Arc<StackingContext>),
DisplayListResult(Box<DisplayList>),
}
impl DisplayListBuildingResult {
/// Adds the display list items contained within this display list building result to the given
/// display list, preserving stacking order. If this display list building result does not
/// consist of an entire stacking context, it will be emptied.
pub fn add_to(&mut self, display_list: &mut DisplayList) {
match *self {
NoDisplayListBuildingResult => return,
StackingContextResult(ref mut stacking_context) => {
display_list.children.push_back((*stacking_context).clone())
}
DisplayListResult(ref mut source_display_list) => {
display_list.append_from(&mut **source_display_list)
}
}
}
}
pub trait FragmentDisplayListBuilding {
/// Adds the display items necessary to paint the background of this fragment to the display
/// list if necessary.
fn build_display_list_for_background_if_applicable(&self,
style: &ComputedValues,
display_list: &mut DisplayList,
layout_context: &LayoutContext,
level: StackingLevel,
absolute_bounds: &Rect<Au>,
clip_rect: &Rect<Au>);
/// Adds the display items necessary to paint the background image of this fragment to the
/// display list at the appropriate stacking level.
fn build_display_list_for_background_image(&self,
style: &ComputedValues,
display_list: &mut DisplayList,
layout_context: &LayoutContext,
level: StackingLevel,
absolute_bounds: &Rect<Au>,
clip_rect: &Rect<Au>,
image_url: &Url);
/// Adds the display items necessary to paint the background linear gradient of this fragment
/// to the display list at the appropriate stacking level.
fn build_display_list_for_background_linear_gradient(&self,
display_list: &mut DisplayList,
level: StackingLevel,
absolute_bounds: &Rect<Au>,
clip_rect: &Rect<Au>,
gradient: &LinearGradient,
style: &ComputedValues);
/// Adds the display items necessary to paint the borders of this fragment to a display list if
/// necessary.
fn build_display_list_for_borders_if_applicable(&self,
style: &ComputedValues,
display_list: &mut DisplayList,
abs_bounds: &Rect<Au>,
level: StackingLevel,
clip_rect: &Rect<Au>);
fn build_debug_borders_around_text_fragments(&self,
display_list: &mut DisplayList,
flow_origin: Point2D<Au>,
text_fragment: &ScannedTextFragmentInfo,
clip_rect: &Rect<Au>);
fn build_debug_borders_around_fragment(&self,
display_list: &mut DisplayList,
flow_origin: Point2D<Au>,
clip_rect: &Rect<Au>);
/// Adds the display items for this fragment to the given display list.
///
/// Arguments:
///
/// * `display_list`: The 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.
/// * `clip_rect`: The rectangle to clip the display items to.
fn build_display_list(&mut self,
display_list: &mut DisplayList,
layout_context: &LayoutContext,
flow_origin: Point2D<Au>,
background_and_border_level: BackgroundAndBorderLevel,
clip_rect: &Rect<Au>);
/// Sends the size and position of this iframe fragment to the constellation. This is out of
/// line to guide inlining.
fn finalize_position_and_size_of_iframe(&self,
iframe_fragment: &IframeFragmentInfo,
offset: Point2D<Au>,
layout_context: &LayoutContext);
fn clip_rect_for_children(&self, current_clip_rect: Rect<Au>, flow_origin: Point2D<Au>)
-> Rect<Au>;
}
fn build_border_radius(abs_bounds: &Rect<Au>, border_style: &Border) -> BorderRadii<Au> {
// TODO(cgaebel): Support border radii even in the case of multiple border widths.
// This is an extennsion of supporting elliptical radii. For now, all percentage
// radii will be relative to the width.
BorderRadii {
top_left: model::specified(border_style.border_top_left_radius.radius, abs_bounds.size.width),
top_right: model::specified(border_style.border_top_right_radius.radius, abs_bounds.size.width),
bottom_right: model::specified(border_style.border_bottom_right_radius.radius, abs_bounds.size.width),
bottom_left: model::specified(border_style.border_bottom_left_radius.radius, abs_bounds.size.width),
}
}
impl FragmentDisplayListBuilding for Fragment {
fn build_display_list_for_background_if_applicable(&self,
style: &ComputedValues,
display_list: &mut DisplayList,
layout_context: &LayoutContext,
level: StackingLevel,
absolute_bounds: &Rect<Au>,
clip_rect: &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) {
display_list.push(SolidColorDisplayItemClass(box SolidColorDisplayItem {
base: BaseDisplayItem::new(*absolute_bounds, self.node, *clip_rect),
color: background_color.to_gfx_color(),
}), level);
}
// 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();
match background.background_image {
None => {}
Some(LinearGradientImage(ref gradient)) => {
self.build_display_list_for_background_linear_gradient(display_list,
level,
absolute_bounds,
clip_rect,
gradient,
style)
}
Some(UrlImage(ref image_url)) => {
self.build_display_list_for_background_image(style,
display_list,
layout_context,
level,
absolute_bounds,
clip_rect,
image_url)
}
}
}
fn build_display_list_for_background_image(&self,
style: &ComputedValues,
display_list: &mut DisplayList,
layout_context: &LayoutContext,
level: StackingLevel,
absolute_bounds: &Rect<Au>,
clip_rect: &Rect<Au>,
image_url: &Url) {
let background = style.get_background();
let mut holder = ImageHolder::new(image_url.clone(),
layout_context.shared.image_cache.clone());
let image = match holder.get_image(self.node.to_untrusted_node_address()) {
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;
// Clip.
//
// TODO: Check the bounds to see if a clip item is actually required.
let clip_rect = clip_rect.intersection(&bounds).unwrap_or(ZERO_RECT);
// 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.
display_list.push(ImageDisplayItemClass(box ImageDisplayItem {
base: BaseDisplayItem::new(bounds, self.node, clip_rect),
image: image.clone(),
stretch_size: Size2D(Au::from_px(image.width as int),
Au::from_px(image.height as int)),
}), level);
}
fn build_display_list_for_background_linear_gradient(&self,
display_list: &mut DisplayList,
level: StackingLevel,
absolute_bounds: &Rect<Au>,
clip_rect: &Rect<Au>,
gradient: &LinearGradient,
style: &ComputedValues) {
let clip_rect = clip_rect.intersection(absolute_bounds).unwrap_or(ZERO_RECT);
// This is the distance between the center and the ending point; i.e. half of the distance
// between the starting point and the ending point.
let delta = match gradient.angle_or_corner {
AngleAoc(angle) => {
Point2D(Au((angle.radians().sin() *
absolute_bounds.size.width.to_f64().unwrap() / 2.0) as i32),
Au((-angle.radians().cos() *
absolute_bounds.size.height.to_f64().unwrap() / 2.0) as i32))
}
CornerAoc(horizontal, vertical) => {
let x_factor = match horizontal {
Left => -1,
Right => 1,
};
let y_factor = match vertical {
Top => -1,
Bottom => 1,
};
Point2D(Au(x_factor * absolute_bounds.size.width.to_i32().unwrap() / 2),
Au(y_factor * absolute_bounds.size.height.to_i32().unwrap() / 2))
}
};
// This is the length of the gradient line.
let length = Au((delta.x.to_f64().unwrap() * 2.0).hypot(delta.y.to_f64().unwrap() * 2.0)
as i32);
// Determine the position of each stop per CSS-IMAGES § 3.4.
//
// FIXME(#3908, pcwalton): Make sure later stops can't be behind earlier stops.
let (mut stops, mut stop_run) = (Vec::new(), None);
for (i, stop) in gradient.stops.iter().enumerate() {
let offset = match stop.position {
None => {
if stop_run.is_none() {
// Initialize a new stop run.
let start_offset = if i == 0 {
0.0
} else {
// `unwrap()` here should never fail because this is the beginning of
// a stop run, which is always bounded by a length or percentage.
position_to_offset(gradient.stops[i - 1].position.unwrap(), length)
};
let (end_index, end_offset) =
match gradient.stops
.as_slice()
.slice_from(i)
.iter()
.enumerate()
.find(|&(_, ref stop)| stop.position.is_some()) {
None => (gradient.stops.len() - 1, 1.0),
Some((end_index, end_stop)) => {
// `unwrap()` here should never fail because this is the end of
// a stop run, which is always bounded by a length or
// percentage.
(end_index,
position_to_offset(end_stop.position.unwrap(), length))
}
};
stop_run = Some(StopRun {
start_offset: start_offset,
end_offset: end_offset,
start_index: i,
stop_count: end_index - i,
})
}
let stop_run = stop_run.unwrap();
let stop_run_length = stop_run.end_offset - stop_run.start_offset;
if stop_run.stop_count == 0 {
stop_run.end_offset
} else {
stop_run.start_offset +
stop_run_length * (i - stop_run.start_index) as f32 /
(stop_run.stop_count as f32)
}
}
Some(position) => {
stop_run = None;
position_to_offset(position, length)
}
};
stops.push(GradientStop {
offset: offset,
color: style.resolve_color(stop.color).to_gfx_color()
})
}
let center = Point2D(absolute_bounds.origin.x + absolute_bounds.size.width / 2,
absolute_bounds.origin.y + absolute_bounds.size.height / 2);
let gradient_display_item = GradientDisplayItemClass(box GradientDisplayItem {
base: BaseDisplayItem::new(*absolute_bounds, self.node, clip_rect),
start_point: center - delta,
end_point: center + delta,
stops: stops,
});
display_list.push(gradient_display_item, level)
}
fn build_display_list_for_borders_if_applicable(&self,
style: &ComputedValues,
display_list: &mut DisplayList,
abs_bounds: &Rect<Au>,
level: StackingLevel,
clip_rect: &Rect<Au>) {
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.
display_list.push(BorderDisplayItemClass(box BorderDisplayItem {
base: BaseDisplayItem::new(*abs_bounds, self.node, *clip_rect),
border_widths: 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),
radius: build_border_radius(abs_bounds, style.get_border()),
}), level);
}
fn build_debug_borders_around_text_fragments(&self,
display_list: &mut DisplayList,
flow_origin: Point2D<Au>,
text_fragment: &ScannedTextFragmentInfo,
clip_rect: &Rect<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);
// Compute the text fragment bounds and draw a border surrounding them.
display_list.content.push_back(BorderDisplayItemClass(box BorderDisplayItem {
base: BaseDisplayItem::new(absolute_fragment_bounds, self.node, *clip_rect),
border_widths: SideOffsets2D::new_all_same(Au::from_px(1)),
color: SideOffsets2D::new_all_same(color::rgb(0, 0, 200)),
style: SideOffsets2D::new_all_same(border_style::solid),
radius: Default::default(),
}));
// 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, *clip_rect),
color: color::rgb(0, 200, 0),
style: border_style::dashed,
};
display_list.content.push_back(LineDisplayItemClass(line_display_item));
}
fn build_debug_borders_around_fragment(&self,
display_list: &mut DisplayList,
flow_origin: Point2D<Au>,
clip_rect: &Rect<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.
display_list.content.push_back(BorderDisplayItemClass(box BorderDisplayItem {
base: BaseDisplayItem::new(absolute_fragment_bounds, self.node, *clip_rect),
border_widths: SideOffsets2D::new_all_same(Au::from_px(1)),
color: SideOffsets2D::new_all_same(color::rgb(0, 0, 200)),
style: SideOffsets2D::new_all_same(border_style::solid),
radius: Default::default(),
}));
}
fn build_display_list(&mut self,
display_list: &mut DisplayList,
layout_context: &LayoutContext,
flow_origin: Point2D<Au>,
background_and_border_level: BackgroundAndBorderLevel,
clip_rect: &Rect<Au>) {
// Compute the fragment position relative to the parent stacking context. If the fragment
// itself establishes a stacking context, then the origin of its position will be (0, 0)
// for the purposes of this computation.
let stacking_relative_flow_origin = if self.establishes_stacking_context() {
ZERO_POINT
} else {
flow_origin
};
let absolute_fragment_bounds =
self.stacking_relative_bounds(&stacking_relative_flow_origin);
// FIXME(#2795): Get the real container size
let container_size = Size2D::zero();
let rect_to_absolute = |writing_mode: WritingMode, logical_rect: LogicalRect<Au>| {
let physical_rect = logical_rect.to_physical(writing_mode, container_size);
Rect(physical_rect.origin + stacking_relative_flow_origin, physical_rect.size)
};
debug!("Fragment::build_display_list at rel={}, abs={}: {}",
self.border_box,
absolute_fragment_bounds,
self);
debug!("Fragment::build_display_list: dirty={}, flow_origin={}",
layout_context.shared.dirty,
flow_origin);
if self.style().get_inheritedbox().visibility != visibility::visible {
return
}
if !absolute_fragment_bounds.intersects(&layout_context.shared.dirty) {
debug!("Fragment::build_display_list: Did not intersect...");
return
}
if !absolute_fragment_bounds.intersects(clip_rect) {
return;
}
debug!("Fragment::build_display_list: intersected. Adding display item...");
if self.is_primary_fragment() {
let level =
StackingLevel::from_background_and_border_level(background_and_border_level);
// Add a pseudo-display item for content box queries. This is a very bogus thing to do.
let base_display_item = box BaseDisplayItem::new(absolute_fragment_bounds,
self.node,
*clip_rect);
display_list.push(PseudoDisplayItemClass(base_display_item), level);
// Add the background to the list, if applicable.
match self.inline_context {
Some(ref inline_context) => {
for style in inline_context.styles.iter().rev() {
self.build_display_list_for_background_if_applicable(
&**style,
display_list,
layout_context,
level,
&absolute_fragment_bounds,
clip_rect);
}
}
None => {}
}
match self.specific {
ScannedTextFragment(_) => {},
_ => {
self.build_display_list_for_background_if_applicable(
&*self.style,
display_list,
layout_context,
level,
&absolute_fragment_bounds,
clip_rect);
}
}
// Add a border, if applicable.
//
// TODO: Outlines.
match self.inline_context {
Some(ref inline_context) => {
for style in inline_context.styles.iter().rev() {
self.build_display_list_for_borders_if_applicable(
&**style,
display_list,
&absolute_fragment_bounds,
level,
clip_rect);
}
}
None => {}
}
match self.specific {
ScannedTextFragment(_) => {},
_ => {
self.build_display_list_for_borders_if_applicable(
&*self.style,
display_list,
&absolute_fragment_bounds,
level,
clip_rect);
}
}
}
let content_box = self.content_box();
let absolute_content_box = rect_to_absolute(self.style.writing_mode, content_box);
// Create special per-fragment-type display items.
match self.specific {
UnscannedTextFragment(_) => panic!("Shouldn't see unscanned fragments here."),
TableColumnFragment(_) => panic!("Shouldn't see table column fragments here."),
ScannedTextFragment(ref text_fragment) => {
// Create the text display item.
let orientation = if self.style.writing_mode.is_vertical() {
if self.style.writing_mode.is_sideways_left() {
SidewaysLeft
} else {
SidewaysRight
}
} else {
Upright
};
let metrics = &text_fragment.run.font_metrics;
let baseline_origin = {
let mut content_box_start = content_box.start;
content_box_start.b = content_box_start.b + metrics.ascent;
content_box_start.to_physical(self.style.writing_mode, container_size)
+ flow_origin
};
display_list.content.push_back(TextDisplayItemClass(box TextDisplayItem {
base: BaseDisplayItem::new(absolute_content_box, self.node, *clip_rect),
text_run: text_fragment.run.clone(),
range: text_fragment.range,
text_color: self.style().get_color().color.to_gfx_color(),
orientation: orientation,
baseline_origin: baseline_origin,
}));
// Create display items for text decoration
{
let line = |maybe_color: Option<RGBA>, rect: || -> LogicalRect<Au>| {
match maybe_color {
None => {}
Some(color) => {
let bounds = rect_to_absolute(self.style.writing_mode, rect());
display_list.content.push_back(SolidColorDisplayItemClass(
box SolidColorDisplayItem {
base: BaseDisplayItem::new(bounds, self.node, *clip_rect),
color: color.to_gfx_color(),
}))
}
}
};
let text_decorations =
self.style().get_inheritedtext()._servo_text_decorations_in_effect;
line(text_decorations.underline, || {
let mut rect = content_box.clone();
rect.start.b = rect.start.b + metrics.ascent - metrics.underline_offset;
rect.size.block = metrics.underline_size;
rect
});
line(text_decorations.overline, || {
let mut rect = content_box.clone();
rect.size.block = metrics.underline_size;
rect
});
line(text_decorations.line_through, || {
let mut rect = content_box.clone();
rect.start.b = rect.start.b + metrics.ascent - metrics.strikeout_offset;
rect.size.block = metrics.strikeout_size;
rect
});
}
if opts::get().show_debug_fragment_borders {
self.build_debug_borders_around_text_fragments(display_list,
flow_origin,
&**text_fragment,
clip_rect);
}
}
GenericFragment | IframeFragment(..) | TableFragment | TableCellFragment |
TableRowFragment | TableWrapperFragment | InlineBlockFragment(_) |
InlineAbsoluteHypotheticalFragment(_) => {
if opts::get().show_debug_fragment_borders {
self.build_debug_borders_around_fragment(display_list,
flow_origin,
clip_rect);
}
}
ImageFragment(ref mut image_fragment) => {
let image_ref = &mut image_fragment.image;
match image_ref.get_image(self.node.to_untrusted_node_address()) {
Some(image) => {
debug!("(building display list) building image fragment");
// Place the image into the display list.
display_list.content.push_back(ImageDisplayItemClass(box ImageDisplayItem {
base: BaseDisplayItem::new(absolute_content_box,
self.node,
*clip_rect),
image: image.clone(),
stretch_size: absolute_content_box.size,
}));
}
None => {
// No image data at all? Do nothing.
//
// TODO: Add some kind of placeholder image.
debug!("(building display list) no image :(");
}
}
}
}
if opts::get().show_debug_fragment_borders {
self.build_debug_borders_around_fragment(display_list,
flow_origin,
clip_rect)
}
// If this is an iframe, then send its position and size up to the constellation.
//
// FIXME(pcwalton): Doing this during display list construction seems potentially
// problematic if iframes are outside the area we're computing the display list for, since
// they won't be able to reflow at all until the user scrolls to them. Perhaps we should
// separate this into two parts: first we should send the size only to the constellation
// once that's computed during assign-block-sizes, and second we should should send the
// origin to the constellation here during display list construction. This should work
// because layout for the iframe only needs to know size, and origin is only relevant if
// the iframe is actually going to be displayed.
match self.specific {
IframeFragment(ref iframe_fragment) => {
self.finalize_position_and_size_of_iframe(&**iframe_fragment,
absolute_fragment_bounds.origin,
layout_context)
}
_ => {}
}
}
#[inline(never)]
fn finalize_position_and_size_of_iframe(&self,
iframe_fragment: &IframeFragmentInfo,
offset: Point2D<Au>,
layout_context: &LayoutContext) {
let border_padding = (self.border_padding).to_physical(self.style.writing_mode);
let content_size = self.content_box().size.to_physical(self.style.writing_mode);
let iframe_rect = Rect(Point2D(geometry::to_frac_px(offset.x + border_padding.left) as f32,
geometry::to_frac_px(offset.y + border_padding.top) as f32),
Size2D(geometry::to_frac_px(content_size.width) as f32,
geometry::to_frac_px(content_size.height) as f32));
debug!("finalizing position and size of iframe for {},{}",
iframe_fragment.pipeline_id,
iframe_fragment.subpage_id);
let ConstellationChan(ref chan) = layout_context.shared.constellation_chan;
chan.send(FrameRectMsg(iframe_fragment.pipeline_id,
iframe_fragment.subpage_id,
iframe_rect));
}
fn clip_rect_for_children(&self, current_clip_rect: Rect<Au>, flow_origin: Point2D<Au>)
-> Rect<Au> {
// Don't clip if we're text.
match self.specific {
ScannedTextFragment(_) => return current_clip_rect,
_ => {}
}
// Only clip if `overflow` tells us to.
match self.style.get_box().overflow {
overflow::hidden | overflow::auto | overflow::scroll => {}
_ => return current_clip_rect,
}
// Create a new clip rect.
//
// FIXME(#2795): Get the real container size.
let physical_rect = self.border_box.to_physical(self.style.writing_mode, Size2D::zero());
current_clip_rect.intersection(&Rect(physical_rect.origin + flow_origin,
physical_rect.size)).unwrap_or(ZERO_RECT)
}
}
pub trait BlockFlowDisplayListBuilding {
fn build_display_list_for_block_base(&mut self,
display_list: &mut DisplayList,
layout_context: &LayoutContext,
background_border_level: BackgroundAndBorderLevel);
fn build_display_list_for_block(&mut self,
layout_context: &LayoutContext,
background_border_level: BackgroundAndBorderLevel);
fn build_display_list_for_absolutely_positioned_block(&mut self,
layout_context: &LayoutContext);
fn build_display_list_for_floating_block(&mut self, layout_context: &LayoutContext);
fn create_stacking_context(&self,
display_list: Box<DisplayList>,
layer: Option<Arc<PaintLayer>>)
-> Arc<StackingContext>;
}
impl BlockFlowDisplayListBuilding for BlockFlow {
fn build_display_list_for_block_base(&mut self,
display_list: &mut DisplayList,
layout_context: &LayoutContext,
background_border_level: BackgroundAndBorderLevel) {
// Add the box that starts the block context.
let stacking_relative_fragment_origin =
self.base.stacking_relative_position_of_child_fragment(&self.fragment);
self.fragment.build_display_list(display_list,
layout_context,
stacking_relative_fragment_origin,
background_border_level,
&self.base.clip_rect);
for kid in self.base.children.iter_mut() {
flow::mut_base(kid).display_list_building_result.add_to(display_list);
}
}
fn build_display_list_for_block(&mut self,
layout_context: &LayoutContext,
background_border_level: BackgroundAndBorderLevel) {
let mut display_list = box DisplayList::new();
self.build_display_list_for_block_base(&mut *display_list,
layout_context,
background_border_level);
self.base.display_list_building_result = if self.fragment.establishes_stacking_context() {
StackingContextResult(self.create_stacking_context(display_list, None))
} else {
DisplayListResult(display_list)
}
}
fn build_display_list_for_absolutely_positioned_block(&mut self,
layout_context: &LayoutContext) {
let mut display_list = box DisplayList::new();
self.build_display_list_for_block_base(&mut *display_list,
layout_context,
RootOfStackingContextLevel);
if !self.base.absolute_position_info.layers_needed_for_positioned_flows &&
!self.base.flags.contains(NEEDS_LAYER) {
// We didn't need a layer.
self.base.display_list_building_result =
StackingContextResult(self.create_stacking_context(display_list, None));
return
}
// If we got here, then we need a new layer.
let scroll_policy = if self.is_fixed() {
FixedPosition
} else {
Scrollable
};
let transparent = color::rgba(1.0, 1.0, 1.0, 0.0);
let stacking_context =
self.create_stacking_context(display_list,
Some(Arc::new(PaintLayer::new(self.layer_id(0),
transparent,
scroll_policy))));
self.base.display_list_building_result = StackingContextResult(stacking_context)
}
fn build_display_list_for_floating_block(&mut self, layout_context: &LayoutContext) {
let mut display_list = box DisplayList::new();
self.build_display_list_for_block_base(&mut *display_list,
layout_context,
RootOfStackingContextLevel);
display_list.form_float_pseudo_stacking_context();
self.base.display_list_building_result = if self.fragment.establishes_stacking_context() {
StackingContextResult(self.create_stacking_context(display_list, None))
} else {
DisplayListResult(display_list)
}
}
fn create_stacking_context(&self,
display_list: Box<DisplayList>,
layer: Option<Arc<PaintLayer>>)
-> Arc<StackingContext> {
let bounds = Rect(self.base.stacking_relative_position,
self.base.overflow.size.to_physical(self.base.writing_mode));
let z_index = self.fragment.style().get_box().z_index.number_or_zero();
let opacity = self.fragment.style().get_effects().opacity as f32;
Arc::new(StackingContext::new(display_list, bounds, z_index, opacity, layer))
}
}
// A helper data structure for gradients.
struct StopRun {
start_offset: f32,
end_offset: f32,
start_index: uint,
stop_count: uint,
}
fn fmin(a: f32, b: f32) -> f32 {
if a < b {
a
} else {
b
}
}
fn position_to_offset(position: LengthOrPercentage, Au(total_length): Au) -> f32 {
match position {
LP_Length(Au(length)) => fmin(1.0, (length as f32) / (total_length as f32)),
LP_Percentage(percentage) => percentage as f32,
}
}
/// "Steps" as defined by CSS 2.1 § E.2.
#[deriving(Clone, PartialEq, Show)]
pub enum StackingLevel {
/// The border and backgrounds for the root of this stacking context: steps 1 and 2.
BackgroundAndBordersStackingLevel,
/// Borders and backgrounds for block-level descendants: step 4.
BlockBackgroundsAndBordersStackingLevel,
/// All other content.
ContentStackingLevel,
}
impl StackingLevel {
#[inline]
pub fn from_background_and_border_level(level: BackgroundAndBorderLevel) -> StackingLevel {
match level {
RootOfStackingContextLevel => BackgroundAndBordersStackingLevel,
BlockLevel => BlockBackgroundsAndBordersStackingLevel,
ContentLevel => ContentStackingLevel,
}
}
}
/// Which level to place backgrounds and borders in.
pub enum BackgroundAndBorderLevel {
RootOfStackingContextLevel,
BlockLevel,
ContentLevel,
}
trait StackingContextConstruction {
/// Adds the given display item at the specified level to this display list.
fn push(&mut self, display_item: DisplayItem, level: StackingLevel);
}
impl StackingContextConstruction for DisplayList {
fn push(&mut self, display_item: DisplayItem, level: StackingLevel) {
match level {
BackgroundAndBordersStackingLevel => {
self.background_and_borders.push_back(display_item)
}
BlockBackgroundsAndBordersStackingLevel => {
self.block_backgrounds_and_borders.push_back(display_item)
}
ContentStackingLevel => self.content.push_back(display_item),
}
}
}