gecko-dev/servo/components/script_layout_interface/message.rs

/* 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/. */

use {OpaqueStyleAndLayoutData, TrustedNodeAddress, PendingImage};
use app_units::Au;
use euclid::{Point2D, Rect};
use gfx_traits::Epoch;
use ipc_channel::ipc::{IpcReceiver, IpcSender};
use metrics::PaintTimeMetrics;
use msg::constellation_msg::PipelineId;
use net_traits::image_cache::ImageCache;
use profile_traits::mem::ReportsChan;
use rpc::LayoutRPC;
use script_traits::{ConstellationControlMsg, LayoutControlMsg, LayoutMsg as ConstellationMsg};
use script_traits::{ScrollState, UntrustedNodeAddress, WindowSizeData};
use script_traits::Painter;
use servo_arc::Arc as ServoArc;
use servo_atoms::Atom;
use servo_url::ServoUrl;
use std::sync::Arc;
use std::sync::mpsc::{Receiver, Sender};
use style::context::{QuirksMode, ReflowGoal};
use style::properties::PropertyId;
use style::selector_parser::PseudoElement;
use style::stylesheets::Stylesheet;

/// Asynchronous messages that script can send to layout.
pub enum Msg {
    /// Adds the given stylesheet to the document. The second stylesheet is the
    /// insertion point (if it exists, the sheet needs to be inserted before
    /// it).
    AddStylesheet(ServoArc<Stylesheet>, Option<ServoArc<Stylesheet>>),

    /// Removes a stylesheet from the document.
    RemoveStylesheet(ServoArc<Stylesheet>),

    /// Change the quirks mode.
    SetQuirksMode(QuirksMode),

    /// Requests a reflow.
    Reflow(ScriptReflow),

    /// Get an RPC interface.
    GetRPC(Sender<Box<LayoutRPC + Send>>),

    /// Requests that the layout thread render the next frame of all animations.
    TickAnimations,

    /// Updates layout's timer for animation testing from script.
    ///
    /// The inner field is the number of *milliseconds* to advance, and the bool
    /// field is whether animations should be force-ticked.
    AdvanceClockMs(i32, bool),

    /// Destroys layout data associated with a DOM node.
    ///
    /// TODO(pcwalton): Maybe think about batching to avoid message traffic.
    ReapStyleAndLayoutData(OpaqueStyleAndLayoutData),

    /// Requests that the layout thread measure its memory usage. The resulting reports are sent back
    /// via the supplied channel.
    CollectReports(ReportsChan),

    /// Requests that the layout thread enter a quiescent state in which no more messages are
    /// accepted except `ExitMsg`. A response message will be sent on the supplied channel when
    /// this happens.
    PrepareToExit(Sender<()>),

    /// Requests that the layout thread immediately shut down. There must be no more nodes left after
    /// this, or layout will crash.
    ExitNow,

    /// Get the last epoch counter for this layout thread.
    GetCurrentEpoch(IpcSender<Epoch>),

    /// Asks the layout thread whether any Web fonts have yet to load (if true, loads are pending;
    /// false otherwise).
    GetWebFontLoadState(IpcSender<bool>),

    /// Creates a new layout thread.
    ///
    /// This basically exists to keep the script-layout dependency one-way.
    CreateLayoutThread(NewLayoutThreadInfo),

    /// Set the final Url.
    SetFinalUrl(ServoUrl),

    /// Tells layout about the new scrolling offsets of each scrollable stacking context.
    SetScrollStates(Vec<ScrollState>),

    /// Tells layout about a single new scrolling offset from the script. The rest will
    /// remain untouched and layout won't forward this back to script.
    UpdateScrollStateFromScript(ScrollState),

    /// Tells layout that script has added some paint worklet modules.
    RegisterPaint(Atom, Vec<Atom>, Box<Painter>),

    /// Send to layout the precise time when the navigation started.
    SetNavigationStart(f64),
}


/// Any query to perform with this reflow.
#[derive(Debug, PartialEq)]
pub enum ReflowQueryType {
    NoQuery,
    ContentBoxQuery(TrustedNodeAddress),
    ContentBoxesQuery(TrustedNodeAddress),
    NodeOverflowQuery(TrustedNodeAddress),
    HitTestQuery(Point2D<f32>, bool),
    NodeScrollRootIdQuery(TrustedNodeAddress),
    NodeGeometryQuery(TrustedNodeAddress),
    NodeScrollGeometryQuery(TrustedNodeAddress),
    ResolvedStyleQuery(TrustedNodeAddress, Option<PseudoElement>, PropertyId),
    OffsetParentQuery(TrustedNodeAddress),
    MarginStyleQuery(TrustedNodeAddress),
    TextIndexQuery(TrustedNodeAddress, i32, i32),
    NodesFromPoint(Point2D<f32>),
}

/// Information needed for a reflow.
pub struct Reflow {
    /// The goal of reflow: either to render to the screen or to flush layout info for script.
    pub goal: ReflowGoal,
    ///  A clipping rectangle for the page, an enlarged rectangle containing the viewport.
    pub page_clip_rect: Rect<Au>,
}

/// Information derived from a layout pass that needs to be returned to the script thread.
#[derive(Default)]
pub struct ReflowComplete {
    /// The list of images that were encountered that are in progress.
    pub pending_images: Vec<PendingImage>,
    /// The list of nodes that initiated a CSS transition.
    pub newly_transitioning_nodes: Vec<UntrustedNodeAddress>,
}

/// Information needed for a script-initiated reflow.
pub struct ScriptReflow {
    /// General reflow data.
    pub reflow_info: Reflow,
    /// The document node.
    pub document: TrustedNodeAddress,
    /// Whether the document's stylesheets have changed since the last script reflow.
    pub stylesheets_changed: bool,
    /// The current window size.
    pub window_size: WindowSizeData,
    /// The channel that we send a notification to.
    pub script_join_chan: Sender<ReflowComplete>,
    /// The type of query if any to perform during this reflow.
    pub query_type: ReflowQueryType,
    /// The number of objects in the dom #10110
    pub dom_count: u32,
}

pub struct NewLayoutThreadInfo {
    pub id: PipelineId,
    pub url: ServoUrl,
    pub is_parent: bool,
    pub layout_pair: (Sender<Msg>, Receiver<Msg>),
    pub pipeline_port: IpcReceiver<LayoutControlMsg>,
    pub constellation_chan: IpcSender<ConstellationMsg>,
    pub script_chan: IpcSender<ConstellationControlMsg>,
    pub image_cache: Arc<ImageCache>,
    pub content_process_shutdown_chan: Option<IpcSender<()>>,
    pub layout_threads: usize,
    pub paint_time_metrics: PaintTimeMetrics,
}