compositor: Move WebRender-ish messages and types to webrender_traits (#32315)

* Move WebRender related types to `webrender_traits`

This refactor moves several WebRender related types
from `compositing_traits`, `script_traits` and `net_traits`
crates to the `webrender_traits` crate.

This change also moves the `Image` type and associated
function out of `net_traits` and into the `pixels` crate.

Co-authored-by: Martin Robinson <mrobinson@igalia.com>
Signed-off-by: Mukilan Thiyagarajan <mukilan@igalia.com>

* Move `script_traits::WebrenderIpcSender` to `webrender_traits::WebRenderScriptApi`

---------

Signed-off-by: Mukilan Thiyagarajan <mukilan@igalia.com>
Co-authored-by: Martin Robinson <mrobinson@igalia.com>

components/shared/webrender/lib.rs

@@ -4,14 +4,26 @@
 
 #![deny(unsafe_code)]
 
+pub mod display_list;
+
 use std::collections::HashMap;
 use std::sync::{Arc, Mutex};
 
+use base::id::PipelineId;
+use crossbeam_channel::Sender;
+use display_list::{CompositorDisplayListInfo, ScrollTreeNodeId};
+use embedder_traits::Cursor;
 use euclid::default::Size2D;
-use webrender_api::units::TexelRect;
+use ipc_channel::ipc::{self, IpcBytesReceiver, IpcSender};
+use libc::c_void;
+use log::warn;
+use serde::{Deserialize, Deserializer, Serialize, Serializer};
+use webrender_api::units::{DevicePoint, LayoutPoint, TexelRect};
 use webrender_api::{
-    ExternalImage, ExternalImageHandler, ExternalImageId, ExternalImageSource, FontInstanceFlags,
-    FontInstanceKey, FontKey, NativeFontHandle,
+    BuiltDisplayList, BuiltDisplayListDescriptor, ExternalImage, ExternalImageData,
+    ExternalImageHandler, ExternalImageId, ExternalImageSource, ExternalScrollId,
+    FontInstanceFlags, FontInstanceKey, FontKey, HitTestFlags, ImageData, ImageDescriptor,
+    ImageKey, NativeFontHandle, PipelineId as WebRenderPipelineId,
 };
 
 /// This trait is used as a bridge between the different GL clients
@@ -178,3 +190,309 @@ pub trait WebRenderFontApi {
     fn add_font(&self, data: Arc<Vec<u8>>, index: u32) -> FontKey;
     fn add_system_font(&self, handle: NativeFontHandle) -> FontKey;
 }
+
+pub enum CanvasToCompositorMsg {
+    GenerateKey(Sender<ImageKey>),
+    UpdateImages(Vec<ImageUpdate>),
+}
+
+pub enum FontToCompositorMsg {
+    AddFontInstance(FontKey, f32, FontInstanceFlags, Sender<FontInstanceKey>),
+    AddFont(Sender<FontKey>, u32, IpcBytesReceiver),
+    AddSystemFont(Sender<FontKey>, NativeFontHandle),
+}
+
+#[derive(Deserialize, Serialize)]
+pub enum NetToCompositorMsg {
+    AddImage(ImageKey, ImageDescriptor, ImageData),
+    GenerateImageKey(IpcSender<ImageKey>),
+}
+
+/// The set of WebRender operations that can be initiated by the content process.
+#[derive(Deserialize, Serialize)]
+pub enum ScriptToCompositorMsg {
+    /// Inform WebRender of the existence of this pipeline.
+    SendInitialTransaction(WebRenderPipelineId),
+    /// Perform a scroll operation.
+    SendScrollNode(WebRenderPipelineId, LayoutPoint, ExternalScrollId),
+    /// Inform WebRender of a new display list for the given pipeline.
+    SendDisplayList {
+        /// The [CompositorDisplayListInfo] that describes the display list being sent.
+        display_list_info: CompositorDisplayListInfo,
+        /// A descriptor of this display list used to construct this display list from raw data.
+        display_list_descriptor: BuiltDisplayListDescriptor,
+        /// An [ipc::IpcBytesReceiver] used to send the raw data of the display list.
+        display_list_receiver: ipc::IpcBytesReceiver,
+    },
+    /// Perform a hit test operation. The result will be returned via
+    /// the provided channel sender.
+    HitTest(
+        Option<WebRenderPipelineId>,
+        DevicePoint,
+        HitTestFlags,
+        IpcSender<Vec<CompositorHitTestResult>>,
+    ),
+    /// Create a new image key. The result will be returned via the
+    /// provided channel sender.
+    GenerateImageKey(IpcSender<ImageKey>),
+    /// Perform a resource update operation.
+    UpdateImages(Vec<SerializedImageUpdate>),
+}
+
+/// A mechanism to send messages from networking to the WebRender instance.
+#[derive(Clone, Deserialize, Serialize)]
+pub struct WebRenderNetApi(IpcSender<NetToCompositorMsg>);
+
+impl WebRenderNetApi {
+    pub fn new(sender: IpcSender<NetToCompositorMsg>) -> Self {
+        Self(sender)
+    }
+
+    pub fn generate_image_key(&self) -> ImageKey {
+        let (sender, receiver) = ipc::channel().unwrap();
+        self.0
+            .send(NetToCompositorMsg::GenerateImageKey(sender))
+            .expect("error sending image key generation");
+        receiver.recv().expect("error receiving image key result")
+    }
+
+    pub fn add_image(&self, key: ImageKey, descriptor: ImageDescriptor, data: ImageData) {
+        if let Err(e) = self
+            .0
+            .send(NetToCompositorMsg::AddImage(key, descriptor, data))
+        {
+            warn!("Error sending image update: {}", e);
+        }
+    }
+}
+
+/// A mechanism to send messages from ScriptThread to the parent process' WebRender instance.
+#[derive(Clone, Deserialize, Serialize)]
+pub struct WebRenderScriptApi(IpcSender<ScriptToCompositorMsg>);
+
+impl WebRenderScriptApi {
+    /// Create a new WebrenderIpcSender object that wraps the provided channel sender.
+    pub fn new(sender: IpcSender<ScriptToCompositorMsg>) -> Self {
+        Self(sender)
+    }
+
+    /// Inform WebRender of the existence of this pipeline.
+    pub fn send_initial_transaction(&self, pipeline: WebRenderPipelineId) {
+        if let Err(e) = self
+            .0
+            .send(ScriptToCompositorMsg::SendInitialTransaction(pipeline))
+        {
+            warn!("Error sending initial transaction: {}", e);
+        }
+    }
+
+    /// Perform a scroll operation.
+    pub fn send_scroll_node(
+        &self,
+        pipeline_id: WebRenderPipelineId,
+        point: LayoutPoint,
+        scroll_id: ExternalScrollId,
+    ) {
+        if let Err(e) = self.0.send(ScriptToCompositorMsg::SendScrollNode(
+            pipeline_id,
+            point,
+            scroll_id,
+        )) {
+            warn!("Error sending scroll node: {}", e);
+        }
+    }
+
+    /// Inform WebRender of a new display list for the given pipeline.
+    pub fn send_display_list(
+        &self,
+        display_list_info: CompositorDisplayListInfo,
+        list: BuiltDisplayList,
+    ) {
+        let (display_list_data, display_list_descriptor) = list.into_data();
+        let (display_list_sender, display_list_receiver) = ipc::bytes_channel().unwrap();
+        if let Err(e) = self.0.send(ScriptToCompositorMsg::SendDisplayList {
+            display_list_info,
+            display_list_descriptor,
+            display_list_receiver,
+        }) {
+            warn!("Error sending display list: {}", e);
+        }
+
+        if let Err(error) = display_list_sender.send(&display_list_data.items_data) {
+            warn!("Error sending display list items: {}", error);
+        }
+        if let Err(error) = display_list_sender.send(&display_list_data.cache_data) {
+            warn!("Error sending display list cache data: {}", error);
+        }
+        if let Err(error) = display_list_sender.send(&display_list_data.spatial_tree) {
+            warn!("Error sending display spatial tree: {}", error);
+        }
+    }
+
+    /// Perform a hit test operation. Blocks until the operation is complete and
+    /// and a result is available.
+    pub fn hit_test(
+        &self,
+        pipeline: Option<WebRenderPipelineId>,
+        point: DevicePoint,
+        flags: HitTestFlags,
+    ) -> Vec<CompositorHitTestResult> {
+        let (sender, receiver) = ipc::channel().unwrap();
+        self.0
+            .send(ScriptToCompositorMsg::HitTest(
+                pipeline, point, flags, sender,
+            ))
+            .expect("error sending hit test");
+        receiver.recv().expect("error receiving hit test result")
+    }
+
+    /// Create a new image key. Blocks until the key is available.
+    pub fn generate_image_key(&self) -> Option<ImageKey> {
+        let (sender, receiver) = ipc::channel().unwrap();
+        self.0
+            .send(ScriptToCompositorMsg::GenerateImageKey(sender))
+            .ok()?;
+        receiver.recv().ok()
+    }
+
+    /// Perform a resource update operation.
+    pub fn update_images(&self, updates: Vec<ImageUpdate>) {
+        let mut senders = Vec::new();
+        // Convert `ImageUpdate` to `SerializedImageUpdate` because `ImageData` may contain large
+        // byes. With this conversion, we send `IpcBytesReceiver` instead and use it to send the
+        // actual bytes.
+        let updates = updates
+            .into_iter()
+            .map(|update| match update {
+                ImageUpdate::AddImage(k, d, data) => {
+                    let data = match data {
+                        ImageData::Raw(r) => {
+                            let (sender, receiver) = ipc::bytes_channel().unwrap();
+                            senders.push((sender, r));
+                            SerializedImageData::Raw(receiver)
+                        },
+                        ImageData::External(e) => SerializedImageData::External(e),
+                    };
+                    SerializedImageUpdate::AddImage(k, d, data)
+                },
+                ImageUpdate::DeleteImage(k) => SerializedImageUpdate::DeleteImage(k),
+                ImageUpdate::UpdateImage(k, d, data) => {
+                    let data = match data {
+                        ImageData::Raw(r) => {
+                            let (sender, receiver) = ipc::bytes_channel().unwrap();
+                            senders.push((sender, r));
+                            SerializedImageData::Raw(receiver)
+                        },
+                        ImageData::External(e) => SerializedImageData::External(e),
+                    };
+                    SerializedImageUpdate::UpdateImage(k, d, data)
+                },
+            })
+            .collect();
+
+        if let Err(e) = self.0.send(ScriptToCompositorMsg::UpdateImages(updates)) {
+            warn!("error sending image updates: {}", e);
+        }
+
+        senders.into_iter().for_each(|(tx, data)| {
+            if let Err(e) = tx.send(&data) {
+                warn!("error sending image data: {}", e);
+            }
+        });
+    }
+}
+
+#[derive(Deserialize, Serialize)]
+/// Serializable image updates that must be performed by WebRender.
+pub enum ImageUpdate {
+    /// Register a new image.
+    AddImage(ImageKey, ImageDescriptor, ImageData),
+    /// Delete a previously registered image registration.
+    DeleteImage(ImageKey),
+    /// Update an existing image registration.
+    UpdateImage(ImageKey, ImageDescriptor, ImageData),
+}
+
+#[derive(Deserialize, Serialize)]
+/// Serialized `ImageUpdate`.
+pub enum SerializedImageUpdate {
+    /// Register a new image.
+    AddImage(ImageKey, ImageDescriptor, SerializedImageData),
+    /// Delete a previously registered image registration.
+    DeleteImage(ImageKey),
+    /// Update an existing image registration.
+    UpdateImage(ImageKey, ImageDescriptor, SerializedImageData),
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+/// Serialized `ImageData`. It contains IPC byte channel receiver to prevent from loading bytes too
+/// slow.
+pub enum SerializedImageData {
+    /// A simple series of bytes, provided by the embedding and owned by WebRender.
+    /// The format is stored out-of-band, currently in ImageDescriptor.
+    Raw(ipc::IpcBytesReceiver),
+    /// An image owned by the embedding, and referenced by WebRender. This may
+    /// take the form of a texture or a heap-allocated buffer.
+    External(ExternalImageData),
+}
+
+impl SerializedImageData {
+    /// Convert to ``ImageData`.
+    pub fn to_image_data(&self) -> Result<ImageData, ipc::IpcError> {
+        match self {
+            SerializedImageData::Raw(rx) => rx.recv().map(ImageData::new),
+            SerializedImageData::External(image) => Ok(ImageData::External(*image)),
+        }
+    }
+}
+
+/// The address of a node. Layout sends these back. They must be validated via
+/// `from_untrusted_node_address` before they can be used, because we do not trust layout.
+#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
+pub struct UntrustedNodeAddress(pub *const c_void);
+
+#[allow(unsafe_code)]
+unsafe impl Send for UntrustedNodeAddress {}
+
+impl Serialize for UntrustedNodeAddress {
+    fn serialize<S: Serializer>(&self, s: S) -> Result<S::Ok, S::Error> {
+        (self.0 as usize).serialize(s)
+    }
+}
+
+impl<'de> Deserialize<'de> for UntrustedNodeAddress {
+    fn deserialize<D: Deserializer<'de>>(d: D) -> Result<UntrustedNodeAddress, D::Error> {
+        let value: usize = Deserialize::deserialize(d)?;
+        Ok(UntrustedNodeAddress::from_id(value))
+    }
+}
+
+impl UntrustedNodeAddress {
+    /// Creates an `UntrustedNodeAddress` from the given pointer address value.
+    #[inline]
+    pub fn from_id(id: usize) -> UntrustedNodeAddress {
+        UntrustedNodeAddress(id as *const c_void)
+    }
+}
+
+/// The result of a hit test in the compositor.
+#[derive(Clone, Debug, Deserialize, Serialize)]
+pub struct CompositorHitTestResult {
+    /// The pipeline id of the resulting item.
+    pub pipeline_id: PipelineId,
+
+    /// The hit test point in the item's viewport.
+    pub point_in_viewport: euclid::default::Point2D<f32>,
+
+    /// The hit test point relative to the item itself.
+    pub point_relative_to_item: euclid::default::Point2D<f32>,
+
+    /// The node address of the hit test result.
+    pub node: UntrustedNodeAddress,
+
+    /// The cursor that should be used when hovering the item hit by the hit test.
+    pub cursor: Option<Cursor>,
+
+    /// The scroll tree node associated with this hit test item.
+    pub scroll_tree_node: ScrollTreeNodeId,
+}