Add support for <iframe> elements for Layout 2020

This change adds support for the <iframe> element to Layout 2020. In
addition, certain aspects of the implementation are made the same
between both layout systems.

components/layout_2020/display_list/mod.rs

@@ -10,8 +10,10 @@ use crate::replaced::IntrinsicSizes;
 use crate::style_ext::ComputedValuesExt;
 use embedder_traits::Cursor;
 use euclid::{Point2D, SideOffsets2D, Size2D};
+use fnv::FnvHashMap;
 use gfx::text::glyph::GlyphStore;
 use mitochondria::OnceCell;
+use msg::constellation_msg::BrowsingContextId;
 use net_traits::image_cache::UsePlaceholder;
 use script_traits::compositor::CompositorDisplayListInfo;
 use std::sync::Arc;
@@ -22,6 +24,7 @@ use style::properties::ComputedValues;
 use style::values::computed::{BorderStyle, Length, LengthPercentage};
 use style::values::specified::text::TextDecorationLine;
 use style::values::specified::ui::CursorKind;
+use style_traits::CSSPixel;
 use webrender_api::{self as wr, units};
 
 mod background;
@@ -48,6 +51,7 @@ pub struct DisplayListBuilder<'a> {
     pub context: &'a LayoutContext<'a>,
     pub wr: wr::DisplayListBuilder,
     pub compositor_info: CompositorDisplayListInfo,
+    pub iframe_sizes: FnvHashMap<BrowsingContextId, Size2D<f32, CSSPixel>>,
 
     /// Contentful paint, for the purpose of
     /// https://w3c.github.io/paint-timing/#first-contentful-paint
@@ -69,6 +73,7 @@ impl<'a> DisplayListBuilder<'a> {
             context,
             wr: wr::DisplayListBuilder::new(pipeline_id, fragment_tree.scrollable_overflow()),
             compositor_info: CompositorDisplayListInfo::default(),
+            iframe_sizes: FnvHashMap::default(),
         }
     }
 
@@ -142,6 +147,34 @@ impl Fragment {
                 Visibility::Hidden => (),
                 Visibility::Collapse => (),
             },
+            Fragment::IFrame(iframe) => match iframe.style.get_inherited_box().visibility {
+                Visibility::Visible => {
+                    builder.is_contentful = true;
+                    let rect = iframe
+                        .rect
+                        .to_physical(iframe.style.writing_mode, containing_block)
+                        .translate(containing_block.origin.to_vector());
+
+                    builder.iframe_sizes.insert(
+                        iframe.browsing_context_id,
+                        Size2D::new(rect.size.width.px(), rect.size.height.px()),
+                    );
+
+                    let common = builder.common_properties(rect.to_webrender(), &iframe.style);
+                    builder.wr.push_iframe(
+                        rect.to_webrender(),
+                        common.clip_rect,
+                        &wr::SpaceAndClipInfo {
+                            spatial_id: common.spatial_id,
+                            clip_id: common.clip_id,
+                        },
+                        iframe.pipeline_id.to_webrender(),
+                        true,
+                    );
+                },
+                Visibility::Hidden => (),
+                Visibility::Collapse => (),
+            },
             Fragment::Text(t) => match t.parent_style.get_inherited_box().visibility {
                 Visibility::Visible => {
                     self.build_display_list_for_text_fragment(t, builder, containing_block)

components/layout_2020/display_list/stacking_context.rs

@@ -482,7 +482,7 @@ impl Fragment {
                     stacking_context,
                 );
             },
-            Fragment::Text(_) | Fragment::Image(_) => {
+            Fragment::Text(_) | Fragment::Image(_) | Fragment::IFrame(_) => {
                 stacking_context.fragments.push(StackingContextFragment {
                     section: StackingContextSection::Content,
                     space_and_clip: builder.current_space_and_clip,

components/layout_2020/dom_traversal.rs

@@ -11,6 +11,7 @@ use crate::style_ext::{Display, DisplayGeneratingBox, DisplayInside, DisplayOuts
 use crate::wrapper::GetStyleAndLayoutData;
 use atomic_refcell::AtomicRefMut;
 use html5ever::LocalName;
+use msg::constellation_msg::{BrowsingContextId, PipelineId};
 use net_traits::image::base::Image as NetImage;
 use script_layout_interface::wrapper_traits::{
     LayoutNode, ThreadSafeLayoutElement, ThreadSafeLayoutNode,
@@ -396,6 +397,7 @@ pub(crate) trait NodeExt<'dom>: 'dom + Copy + LayoutNode<'dom> + Send + Sync {
     /// adjusted for `image_density`.
     fn as_image(self) -> Option<(Option<Arc<NetImage>>, PhysicalSize<f64>)>;
     fn as_canvas(self) -> Option<(CanvasInfo, PhysicalSize<f64>)>;
+    fn as_iframe(self) -> Option<(PipelineId, BrowsingContextId)>;
     fn first_child(self) -> Option<Self>;
     fn next_sibling(self) -> Option<Self>;
     fn parent_node(self) -> Option<Self>;
@@ -462,6 +464,16 @@ where
         ))
     }
 
+    fn as_iframe(self) -> Option<(PipelineId, BrowsingContextId)> {
+        let node = self.to_threadsafe();
+        match (node.iframe_pipeline_id(), node.iframe_browsing_context_id()) {
+            (Some(pipeline_id), Some(browsing_context_id)) => {
+                Some((pipeline_id, browsing_context_id))
+            },
+            _ => None,
+        }
+    }
+
     fn first_child(self) -> Option<Self> {
         TNode::first_child(&self)
     }

components/layout_2020/flow/root.rs

@@ -475,6 +475,7 @@ impl FragmentTree {
                     .to_physical(fragment.parent_style.writing_mode, &containing_block),
                 Fragment::AbsoluteOrFixedPositioned(_) |
                 Fragment::Image(_) |
+                Fragment::IFrame(_) |
                 Fragment::Anonymous(_) => return None,
             };
 
@@ -506,6 +507,7 @@ impl FragmentTree {
                 Fragment::Box(_) |
                 Fragment::Text(_) |
                 Fragment::Image(_) |
+                Fragment::IFrame(_) |
                 Fragment::Anonymous(_) => return None,
             };
 

components/layout_2020/fragments.rs

@@ -13,6 +13,7 @@ use gfx::font::FontMetrics as GfxFontMetrics;
 use gfx::text::glyph::GlyphStore;
 use gfx_traits::print_tree::PrintTree;
 use gfx_traits::{combine_id_with_fragment_type, FragmentType};
+use msg::constellation_msg::{BrowsingContextId, PipelineId};
 #[cfg(not(debug_assertions))]
 use serde::ser::{Serialize, Serializer};
 use servo_arc::Arc as ServoArc;
@@ -70,6 +71,7 @@ pub(crate) enum Fragment {
     AbsoluteOrFixedPositioned(AbsoluteOrFixedPositionedFragment),
     Text(TextFragment),
     Image(ImageFragment),
+    IFrame(IFrameFragment),
 }
 
 #[derive(Serialize)]
@@ -174,6 +176,16 @@ pub(crate) struct ImageFragment {
     pub image_key: ImageKey,
 }
 
+#[derive(Serialize)]
+pub(crate) struct IFrameFragment {
+    pub debug_id: DebugId,
+    pub pipeline_id: PipelineId,
+    pub browsing_context_id: BrowsingContextId,
+    pub rect: Rect<Length>,
+    #[serde(skip_serializing)]
+    pub style: ServoArc<ComputedValues>,
+}
+
 impl Fragment {
     pub fn offset_inline(&mut self, offset: &Length) {
         let position = match self {
@@ -182,6 +194,7 @@ impl Fragment {
             Fragment::Anonymous(f) => &mut f.rect.start_corner,
             Fragment::Text(f) => &mut f.rect.start_corner,
             Fragment::Image(f) => &mut f.rect.start_corner,
+            Fragment::IFrame(f) => &mut f.rect.start_corner,
         };
 
         position.inline += *offset;
@@ -193,7 +206,8 @@ impl Fragment {
             Fragment::Text(fragment) => Some(fragment.tag),
             Fragment::AbsoluteOrFixedPositioned(_) |
             Fragment::Anonymous(_) |
-            Fragment::Image(_) => None,
+            Fragment::Image(_) |
+            Fragment::IFrame(_) => None,
         }
     }
 
@@ -204,6 +218,7 @@ impl Fragment {
             Fragment::Anonymous(fragment) => fragment.print(tree),
             Fragment::Text(fragment) => fragment.print(tree),
             Fragment::Image(fragment) => fragment.print(tree),
+            Fragment::IFrame(fragment) => fragment.print(tree),
         }
     }
 
@@ -221,6 +236,9 @@ impl Fragment {
             Fragment::Image(fragment) => fragment
                 .rect
                 .to_physical(fragment.style.writing_mode, &containing_block),
+            Fragment::IFrame(fragment) => fragment
+                .rect
+                .to_physical(fragment.style.writing_mode, &containing_block),
         }
     }
 
@@ -462,6 +480,16 @@ impl ImageFragment {
     }
 }
 
+impl IFrameFragment {
+    pub fn print(&self, tree: &mut PrintTree) {
+        tree.add_item(format!(
+            "IFrame\
+                \npipeline={:?} rect={:?}",
+            self.pipeline_id, self.rect
+        ));
+    }
+}
+
 impl CollapsedBlockMargins {
     pub fn from_margin(margin: &Sides<Length>) -> Self {
         Self {

components/layout_2020/query.rs

@@ -10,7 +10,6 @@ use app_units::Au;
 use euclid::default::{Point2D, Rect};
 use euclid::Size2D;
 use euclid::Vector2D;
-use ipc_channel::ipc::IpcSender;
 use msg::constellation_msg::PipelineId;
 use script_layout_interface::rpc::TextIndexResponse;
 use script_layout_interface::rpc::{ContentBoxResponse, ContentBoxesResponse, LayoutRPC};
@@ -19,7 +18,6 @@ use script_layout_interface::rpc::{OffsetParentResponse, ResolvedStyleResponse};
 use script_layout_interface::wrapper_traits::{
     LayoutNode, ThreadSafeLayoutElement, ThreadSafeLayoutNode,
 };
-use script_traits::LayoutMsg as ConstellationMsg;
 use script_traits::UntrustedNodeAddress;
 use servo_arc::Arc as ServoArc;
 use std::collections::HashMap;
@@ -43,9 +41,6 @@ use webrender_api::ExternalScrollId;
 ///
 /// This needs to be protected by a mutex so we can do fast RPCs.
 pub struct LayoutThreadData {
-    /// The channel on which messages can be sent to the constellation.
-    pub constellation_chan: IpcSender<ConstellationMsg>,
-
     /// The root stacking context.
     pub display_list: Option<webrender_api::DisplayListBuilder>,
 
@@ -427,6 +422,7 @@ fn process_offset_parent_query_inner(
                     .to_physical(fragment.parent_style.writing_mode, &containing_block),
                 Fragment::AbsoluteOrFixedPositioned(_) |
                 Fragment::Image(_) |
+                Fragment::IFrame(_) |
                 Fragment::Anonymous(_) => unreachable!(),
             };
             let border_box = fragment_relative_rect.translate(containing_block.origin.to_vector());
@@ -503,6 +499,7 @@ fn process_offset_parent_query_inner(
                 Fragment::AbsoluteOrFixedPositioned(_) |
                 Fragment::Text(_) |
                 Fragment::Image(_) |
+                Fragment::IFrame(_) |
                 Fragment::Anonymous(_) => None,
             };
 
@@ -552,6 +549,7 @@ fn process_offset_parent_query_inner(
                         Fragment::Box(_) |
                         Fragment::Text(_) |
                         Fragment::Image(_) |
+                        Fragment::IFrame(_) |
                         Fragment::Anonymous(_) => None,
                     }
                 })

components/layout_2020/replaced.rs

@@ -4,7 +4,7 @@
 
 use crate::context::LayoutContext;
 use crate::dom_traversal::NodeExt;
-use crate::fragments::{DebugId, Fragment, ImageFragment};
+use crate::fragments::{DebugId, Fragment, IFrameFragment, ImageFragment};
 use crate::geom::flow_relative::{Rect, Vec2};
 use crate::geom::PhysicalSize;
 use crate::sizing::ContentSizes;
@@ -12,6 +12,7 @@ use crate::style_ext::{ComputedValuesExt, PaddingBorderMargin};
 use crate::ContainingBlock;
 use canvas_traits::canvas::{CanvasId, CanvasMsg, FromLayoutMsg};
 use ipc_channel::ipc::{self, IpcSender};
+use msg::constellation_msg::{BrowsingContextId, PipelineId};
 use net_traits::image::base::Image;
 use net_traits::image_cache::{ImageOrMetadataAvailable, UsePlaceholder};
 use servo_arc::Arc as ServoArc;
@@ -41,6 +42,9 @@ pub(crate) struct ReplacedContent {
 ///
 /// * For SVG, see https://svgwg.org/svg2-draft/coords.html#SizingSVGInCSS
 ///   and again https://github.com/w3c/csswg-drafts/issues/4572.
+///
+/// * IFrames do not have intrinsic width and height or intrinsic ratio according
+///   to https://drafts.csswg.org/css-images/#intrinsic-dimensions.
 #[derive(Debug, Serialize)]
 pub(crate) struct IntrinsicSizes {
     pub width: Option<Length>,
@@ -75,9 +79,16 @@ pub(crate) struct CanvasInfo {
     pub canvas_id: CanvasId,
 }
 
+#[derive(Debug, Serialize)]
+pub(crate) struct IFrameInfo {
+    pub pipeline_id: PipelineId,
+    pub browsing_context_id: BrowsingContextId,
+}
+
 #[derive(Debug, Serialize)]
 pub(crate) enum ReplacedContentKind {
     Image(Option<Arc<Image>>),
+    IFrame(IFrameInfo),
     Canvas(CanvasInfo),
 }
 
@@ -85,35 +96,51 @@ impl ReplacedContent {
     pub fn for_element<'dom>(element: impl NodeExt<'dom>) -> Option<Self> {
         let (kind, intrinsic_size_in_dots) = {
             if let Some((image, intrinsic_size_in_dots)) = element.as_image() {
-                (ReplacedContentKind::Image(image), intrinsic_size_in_dots)
+                (
+                    ReplacedContentKind::Image(image),
+                    Some(intrinsic_size_in_dots),
+                )
             } else if let Some((canvas_info, intrinsic_size_in_dots)) = element.as_canvas() {
                 (
                     ReplacedContentKind::Canvas(canvas_info),
-                    intrinsic_size_in_dots,
+                    Some(intrinsic_size_in_dots),
+                )
+            } else if let Some((pipeline_id, browsing_context_id)) = element.as_iframe() {
+                (
+                    ReplacedContentKind::IFrame(IFrameInfo {
+                        pipeline_id,
+                        browsing_context_id,
+                    }),
+                    None,
                 )
             } else {
                 return None;
             }
         };
 
-        // FIXME: should 'image-resolution' (when implemented) be used *instead* of
-        // `script::dom::htmlimageelement::ImageRequest::current_pixel_density`?
-
-        // https://drafts.csswg.org/css-images-4/#the-image-resolution
-        let dppx = 1.0;
-
-        let width = (intrinsic_size_in_dots.width as CSSFloat) / dppx;
-        let height = (intrinsic_size_in_dots.height as CSSFloat) / dppx;
-
-        return Some(Self {
-            kind,
-            intrinsic: IntrinsicSizes {
-                width: Some(Length::new(width)),
-                height: Some(Length::new(height)),
-                // FIXME https://github.com/w3c/csswg-drafts/issues/4572
-                ratio: Some(width / height),
+        let intrinsic = intrinsic_size_in_dots.map_or_else(
+            || IntrinsicSizes {
+                width: None,
+                height: None,
+                ratio: None,
             },
-        });
+            |intrinsic_size_in_dots| {
+                // FIXME: should 'image-resolution' (when implemented) be used *instead* of
+                // `script::dom::htmlimageelement::ImageRequest::current_pixel_density`?
+                // https://drafts.csswg.org/css-images-4/#the-image-resolution
+                let dppx = 1.0;
+                let width = (intrinsic_size_in_dots.width as CSSFloat) / dppx;
+                let height = (intrinsic_size_in_dots.height as CSSFloat) / dppx;
+                IntrinsicSizes {
+                    width: Some(Length::new(width)),
+                    height: Some(Length::new(height)),
+                    // FIXME https://github.com/w3c/csswg-drafts/issues/4572
+                    ratio: Some(width / height),
+                }
+            },
+        );
+
+        return Some(Self { kind, intrinsic });
     }
 
     pub fn from_image_url<'dom>(
@@ -203,6 +230,18 @@ impl ReplacedContent {
                 })
                 .into_iter()
                 .collect(),
+            ReplacedContentKind::IFrame(iframe) => {
+                vec![Fragment::IFrame(IFrameFragment {
+                    debug_id: DebugId::new(),
+                    style: style.clone(),
+                    pipeline_id: iframe.pipeline_id,
+                    browsing_context_id: iframe.browsing_context_id,
+                    rect: Rect {
+                        start_corner: Vec2::zero(),
+                        size,
+                    },
+                })]
+            },
             ReplacedContentKind::Canvas(canvas_info) => {
                 if self.intrinsic.width == Some(Length::zero()) ||
                     self.intrinsic.height == Some(Length::zero())
@@ -264,6 +303,7 @@ impl ReplacedContent {
 
         let default_object_size = || {
             // FIXME:
+            // https://drafts.csswg.org/css-images/#default-object-size
             // “If 300px is too wide to fit the device, UAs should use the width of
             //  the largest rectangle that has a 2:1 ratio and fits the device instead.”
             // “height of the largest rectangle that has a 2:1 ratio, has a height not greater