script: Move canvas stuff into dom/canvas folder (#39071)

Move all canvas stuff to canvas folder and 2d canvas to canvas/2d
folder. Webgl and webgpu context remain in respective folders as
outlined in
https://github.com/servo/servo/issues/38901#issuecomment-3243020235

Testing: Just refactor.
Part of https://github.com/servo/servo/issues/38901

---------

Signed-off-by: sagudev <16504129+sagudev@users.noreply.github.com>

components/script/dom/canvas/offscreencanvas.rs

@@ -0,0 +1,466 @@
+/* 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 https://mozilla.org/MPL/2.0/. */
+
+use std::cell::Cell;
+use std::collections::HashMap;
+use std::rc::Rc;
+
+use base::id::{OffscreenCanvasId, OffscreenCanvasIndex};
+use constellation_traits::{BlobImpl, TransferableOffscreenCanvas};
+use dom_struct::dom_struct;
+use euclid::default::Size2D;
+use js::rust::{HandleObject, HandleValue};
+use pixels::{EncodedImageType, Snapshot};
+use script_bindings::weakref::WeakRef;
+
+use crate::canvas_context::{CanvasContext, OffscreenRenderingContext};
+use crate::dom::bindings::cell::{DomRefCell, Ref};
+use crate::dom::bindings::codegen::Bindings::OffscreenCanvasBinding::{
+    ImageEncodeOptions, OffscreenCanvasMethods,
+    OffscreenRenderingContext as RootedOffscreenRenderingContext,
+};
+use crate::dom::bindings::codegen::UnionTypes::HTMLCanvasElementOrOffscreenCanvas;
+use crate::dom::bindings::error::{Error, Fallible};
+use crate::dom::bindings::refcounted::{Trusted, TrustedPromise};
+use crate::dom::bindings::reflector::{DomGlobal, reflect_dom_object_with_proto};
+use crate::dom::bindings::root::{Dom, DomRoot};
+use crate::dom::bindings::str::DOMString;
+use crate::dom::bindings::structuredclone::StructuredData;
+use crate::dom::bindings::transferable::Transferable;
+use crate::dom::blob::Blob;
+use crate::dom::eventtarget::EventTarget;
+use crate::dom::globalscope::GlobalScope;
+use crate::dom::html::htmlcanvaselement::HTMLCanvasElement;
+use crate::dom::imagebitmap::ImageBitmap;
+use crate::dom::imagebitmaprenderingcontext::ImageBitmapRenderingContext;
+use crate::dom::offscreencanvasrenderingcontext2d::OffscreenCanvasRenderingContext2D;
+use crate::dom::promise::Promise;
+use crate::realms::{AlreadyInRealm, InRealm};
+use crate::script_runtime::{CanGc, JSContext};
+
+/// <https://html.spec.whatwg.org/multipage/#offscreencanvas>
+#[dom_struct]
+pub(crate) struct OffscreenCanvas {
+    eventtarget: EventTarget,
+    width: Cell<u64>,
+    height: Cell<u64>,
+
+    /// Represents both the [bitmap] and the [context mode] of the canvas.
+    ///
+    /// [bitmap]: https://html.spec.whatwg.org/multipage/#offscreencanvas-bitmap
+    /// [context mode]: https://html.spec.whatwg.org/multipage/#offscreencanvas-context-mode
+    context: DomRefCell<Option<OffscreenRenderingContext>>,
+
+    /// <https://html.spec.whatwg.org/multipage/#offscreencanvas-placeholder>
+    placeholder: Option<WeakRef<HTMLCanvasElement>>,
+}
+
+impl OffscreenCanvas {
+    pub(crate) fn new_inherited(
+        width: u64,
+        height: u64,
+        placeholder: Option<WeakRef<HTMLCanvasElement>>,
+    ) -> OffscreenCanvas {
+        OffscreenCanvas {
+            eventtarget: EventTarget::new_inherited(),
+            width: Cell::new(width),
+            height: Cell::new(height),
+            context: DomRefCell::new(None),
+            placeholder,
+        }
+    }
+
+    pub(crate) fn new(
+        global: &GlobalScope,
+        proto: Option<HandleObject>,
+        width: u64,
+        height: u64,
+        placeholder: Option<WeakRef<HTMLCanvasElement>>,
+        can_gc: CanGc,
+    ) -> DomRoot<OffscreenCanvas> {
+        reflect_dom_object_with_proto(
+            Box::new(OffscreenCanvas::new_inherited(width, height, placeholder)),
+            global,
+            proto,
+            can_gc,
+        )
+    }
+
+    pub(crate) fn get_size(&self) -> Size2D<u32> {
+        Size2D::new(
+            self.Width().try_into().unwrap_or(u32::MAX),
+            self.Height().try_into().unwrap_or(u32::MAX),
+        )
+    }
+
+    pub(crate) fn origin_is_clean(&self) -> bool {
+        match *self.context.borrow() {
+            Some(ref context) => context.origin_is_clean(),
+            _ => true,
+        }
+    }
+
+    pub(crate) fn context(&self) -> Option<Ref<'_, OffscreenRenderingContext>> {
+        Ref::filter_map(self.context.borrow(), |ctx| ctx.as_ref()).ok()
+    }
+
+    pub(crate) fn get_image_data(&self) -> Option<Snapshot> {
+        match self.context.borrow().as_ref() {
+            Some(context) => context.get_image_data(),
+            None => {
+                let size = self.get_size();
+                if size.is_empty() ||
+                    pixels::compute_rgba8_byte_length_if_within_limit(
+                        size.width as usize,
+                        size.height as usize,
+                    )
+                    .is_none()
+                {
+                    None
+                } else {
+                    Some(Snapshot::cleared(size))
+                }
+            },
+        }
+    }
+
+    pub(crate) fn get_or_init_2d_context(
+        &self,
+        can_gc: CanGc,
+    ) -> Option<DomRoot<OffscreenCanvasRenderingContext2D>> {
+        if let Some(ctx) = self.context() {
+            return match *ctx {
+                OffscreenRenderingContext::Context2d(ref ctx) => Some(DomRoot::from_ref(ctx)),
+                _ => None,
+            };
+        }
+        let context = OffscreenCanvasRenderingContext2D::new(&self.global(), self, can_gc)?;
+        *self.context.borrow_mut() = Some(OffscreenRenderingContext::Context2d(Dom::from_ref(
+            &*context,
+        )));
+        Some(context)
+    }
+
+    /// <https://html.spec.whatwg.org/multipage/#offscreen-context-type-bitmaprenderer>
+    pub(crate) fn get_or_init_bitmaprenderer_context(
+        &self,
+        can_gc: CanGc,
+    ) -> Option<DomRoot<ImageBitmapRenderingContext>> {
+        // Return the same object as was returned the last time the method was
+        // invoked with this same first argument.
+        if let Some(ctx) = self.context() {
+            return match *ctx {
+                OffscreenRenderingContext::BitmapRenderer(ref ctx) => Some(DomRoot::from_ref(ctx)),
+                _ => None,
+            };
+        }
+
+        // Step 1. Let context be the result of running the
+        // ImageBitmapRenderingContext creation algorithm given this and
+        // options.
+        let context = ImageBitmapRenderingContext::new(
+            &self.global(),
+            HTMLCanvasElementOrOffscreenCanvas::OffscreenCanvas(DomRoot::from_ref(self)),
+            can_gc,
+        );
+
+        // Step 2. Set this's context mode to bitmaprenderer.
+        *self.context.borrow_mut() = Some(OffscreenRenderingContext::BitmapRenderer(
+            Dom::from_ref(&*context),
+        ));
+
+        // Step 3. Return context.
+        Some(context)
+    }
+
+    pub(crate) fn placeholder(&self) -> Option<DomRoot<HTMLCanvasElement>> {
+        self.placeholder
+            .as_ref()
+            .and_then(|placeholder| placeholder.root())
+    }
+}
+
+impl Transferable for OffscreenCanvas {
+    type Index = OffscreenCanvasIndex;
+    type Data = TransferableOffscreenCanvas;
+
+    /// <https://html.spec.whatwg.org/multipage/#the-offscreencanvas-interface:transfer-steps>
+    fn transfer(&self) -> Fallible<(OffscreenCanvasId, TransferableOffscreenCanvas)> {
+        // <https://html.spec.whatwg.org/multipage/#structuredserializewithtransfer>
+        // Step 5.2. If transferable has a [[Detached]] internal slot and
+        // transferable.[[Detached]] is true, then throw a "DataCloneError"
+        // DOMException.
+        if let Some(OffscreenRenderingContext::Detached) = *self.context.borrow() {
+            return Err(Error::DataClone(None));
+        }
+
+        // Step 1. If value's context mode is not equal to none, then throw an
+        // "InvalidStateError" DOMException.
+        if !self.context.borrow().is_none() {
+            return Err(Error::InvalidState);
+        }
+
+        // TODO(#37882): Allow to transfer with a placeholder canvas element.
+        if self.placeholder.is_some() {
+            return Err(Error::InvalidState);
+        }
+
+        // Step 2. Set value's context mode to detached.
+        *self.context.borrow_mut() = Some(OffscreenRenderingContext::Detached);
+
+        // Step 3. Let width and height be the dimensions of value's bitmap.
+        // Step 5. Unset value's bitmap.
+        let width = self.width.replace(0);
+        let height = self.height.replace(0);
+
+        // TODO(#37918) Step 4. Let language and direction be the values of
+        // value's inherited language and inherited direction.
+
+        // Step 6. Set dataHolder.[[Width]] to width and dataHolder.[[Height]]
+        // to height.
+
+        // TODO(#37918) Step 7. Set dataHolder.[[Language]] to language and
+        // dataHolder.[[Direction]] to direction.
+
+        // TODO(#37882) Step 8. Set dataHolder.[[PlaceholderCanvas]] to be a
+        // weak reference to value's placeholder canvas element, if value has
+        // one, or null if it does not.
+        let transferred = TransferableOffscreenCanvas { width, height };
+
+        Ok((OffscreenCanvasId::new(), transferred))
+    }
+
+    /// <https://html.spec.whatwg.org/multipage/#the-offscreencanvas-interface:transfer-receiving-steps>
+    fn transfer_receive(
+        owner: &GlobalScope,
+        _: OffscreenCanvasId,
+        transferred: TransferableOffscreenCanvas,
+    ) -> Result<DomRoot<Self>, ()> {
+        // Step 1. Initialize value's bitmap to a rectangular array of
+        // transparent black pixels with width given by dataHolder.[[Width]] and
+        // height given by dataHolder.[[Height]].
+
+        // TODO(#37918) Step 2. Set value's inherited language to
+        // dataHolder.[[Language]] and its inherited direction to
+        // dataHolder.[[Direction]].
+
+        // TODO(#37882) Step 3. If dataHolder.[[PlaceholderCanvas]] is not null,
+        // set value's placeholder canvas element to
+        // dataHolder.[[PlaceholderCanvas]] (while maintaining the weak
+        // reference semantics).
+        Ok(OffscreenCanvas::new(
+            owner,
+            None,
+            transferred.width,
+            transferred.height,
+            None,
+            CanGc::note(),
+        ))
+    }
+
+    fn serialized_storage<'a>(
+        data: StructuredData<'a, '_>,
+    ) -> &'a mut Option<HashMap<OffscreenCanvasId, Self::Data>> {
+        match data {
+            StructuredData::Reader(r) => &mut r.offscreen_canvases,
+            StructuredData::Writer(w) => &mut w.offscreen_canvases,
+        }
+    }
+}
+
+impl OffscreenCanvasMethods<crate::DomTypeHolder> for OffscreenCanvas {
+    /// <https://html.spec.whatwg.org/multipage/#dom-offscreencanvas>
+    fn Constructor(
+        global: &GlobalScope,
+        proto: Option<HandleObject>,
+        can_gc: CanGc,
+        width: u64,
+        height: u64,
+    ) -> Fallible<DomRoot<OffscreenCanvas>> {
+        Ok(OffscreenCanvas::new(
+            global, proto, width, height, None, can_gc,
+        ))
+    }
+
+    /// <https://html.spec.whatwg.org/multipage/#dom-offscreencanvas-getcontext>
+    fn GetContext(
+        &self,
+        _cx: JSContext,
+        id: DOMString,
+        _options: HandleValue,
+        can_gc: CanGc,
+    ) -> Fallible<Option<RootedOffscreenRenderingContext>> {
+        // Step 3. Throw an "InvalidStateError" DOMException if the
+        // OffscreenCanvas object's context mode is detached.
+        if let Some(OffscreenRenderingContext::Detached) = *self.context.borrow() {
+            return Err(Error::InvalidState);
+        }
+
+        match &*id {
+            "2d" => Ok(self
+                .get_or_init_2d_context(can_gc)
+                .map(RootedOffscreenRenderingContext::OffscreenCanvasRenderingContext2D)),
+            "bitmaprenderer" => Ok(self
+                .get_or_init_bitmaprenderer_context(can_gc)
+                .map(RootedOffscreenRenderingContext::ImageBitmapRenderingContext)),
+            /*"webgl" | "experimental-webgl" => self
+                .get_or_init_webgl_context(cx, options)
+                .map(OffscreenRenderingContext::WebGLRenderingContext),
+            "webgl2" | "experimental-webgl2" => self
+                .get_or_init_webgl2_context(cx, options)
+                .map(OffscreenRenderingContext::WebGL2RenderingContext),*/
+            _ => Err(Error::Type(String::from(
+                "Unrecognized OffscreenCanvas context type",
+            ))),
+        }
+    }
+
+    /// <https://html.spec.whatwg.org/multipage/#dom-offscreencanvas-width>
+    fn Width(&self) -> u64 {
+        self.width.get()
+    }
+
+    /// <https://html.spec.whatwg.org/multipage/#dom-offscreencanvas-width>
+    fn SetWidth(&self, value: u64, can_gc: CanGc) {
+        self.width.set(value);
+
+        if let Some(canvas_context) = self.context() {
+            canvas_context.resize();
+        }
+
+        if let Some(canvas) = self.placeholder() {
+            canvas.set_natural_width(value as _, can_gc)
+        }
+    }
+
+    /// <https://html.spec.whatwg.org/multipage/#dom-offscreencanvas-height>
+    fn Height(&self) -> u64 {
+        self.height.get()
+    }
+
+    /// <https://html.spec.whatwg.org/multipage/#dom-offscreencanvas-height>
+    fn SetHeight(&self, value: u64, can_gc: CanGc) {
+        self.height.set(value);
+
+        if let Some(canvas_context) = self.context() {
+            canvas_context.resize();
+        }
+
+        if let Some(canvas) = self.placeholder() {
+            canvas.set_natural_height(value as _, can_gc)
+        }
+    }
+
+    /// <https://html.spec.whatwg.org/multipage/#dom-offscreencanvas-transfertoimagebitmap>
+    fn TransferToImageBitmap(&self, can_gc: CanGc) -> Fallible<DomRoot<ImageBitmap>> {
+        // Step 1. If the value of this OffscreenCanvas object's [[Detached]]
+        // internal slot is set to true, then throw an "InvalidStateError"
+        // DOMException.
+        if let Some(OffscreenRenderingContext::Detached) = *self.context.borrow() {
+            return Err(Error::InvalidState);
+        }
+
+        // Step 2. If this OffscreenCanvas object's context mode is set to none,
+        // then throw an "InvalidStateError" DOMException.
+        if self.context.borrow().is_none() {
+            return Err(Error::InvalidState);
+        }
+
+        // Step 3. Let image be a newly created ImageBitmap object that
+        // references the same underlying bitmap data as this OffscreenCanvas
+        // object's bitmap.
+        let Some(snapshot) = self.get_image_data() else {
+            return Err(Error::InvalidState);
+        };
+
+        let image_bitmap = ImageBitmap::new(&self.global(), snapshot, can_gc);
+        image_bitmap.set_origin_clean(self.origin_is_clean());
+
+        // Step 4. Set this OffscreenCanvas object's bitmap to reference a newly
+        // created bitmap of the same dimensions and color space as the previous
+        // bitmap, and with its pixels initialized to transparent black, or
+        // opaque black if the rendering context's alpha is false.
+        if let Some(canvas_context) = self.context() {
+            canvas_context.reset_bitmap();
+        }
+
+        // Step 5. Return image.
+        Ok(image_bitmap)
+    }
+
+    /// <https://html.spec.whatwg.org/multipage/#dom-offscreencanvas-converttoblob>
+    fn ConvertToBlob(&self, options: &ImageEncodeOptions, can_gc: CanGc) -> Rc<Promise> {
+        // Step 5. Let result be a new promise object.
+        let in_realm_proof = AlreadyInRealm::assert::<crate::DomTypeHolder>();
+        let promise = Promise::new_in_current_realm(InRealm::Already(&in_realm_proof), can_gc);
+
+        // Step 1. If the value of this's [[Detached]] internal slot is true,
+        // then return a promise rejected with an "InvalidStateError"
+        // DOMException.
+        if let Some(OffscreenRenderingContext::Detached) = *self.context.borrow() {
+            promise.reject_error(Error::InvalidState, can_gc);
+            return promise;
+        }
+
+        // Step 2. If this's context mode is 2d and the rendering context's
+        // output bitmap's origin-clean flag is set to false, then return a
+        // promise rejected with a "SecurityError" DOMException.
+        if !self.origin_is_clean() {
+            promise.reject_error(Error::Security, can_gc);
+            return promise;
+        }
+
+        // Step 3. If this's bitmap has no pixels (i.e., either its horizontal
+        // dimension or its vertical dimension is zero), then return a promise
+        // rejected with an "IndexSizeError" DOMException.
+        if self.Width() == 0 || self.Height() == 0 {
+            promise.reject_error(Error::IndexSize, can_gc);
+            return promise;
+        }
+
+        // Step 4. Let bitmap be a copy of this's bitmap.
+        let Some(mut snapshot) = self.get_image_data() else {
+            promise.reject_error(Error::InvalidState, can_gc);
+            return promise;
+        };
+
+        // Step 7. Run these steps in parallel:
+        // Step 7.1. Let file be a serialization of bitmap as a file, with
+        // options's type and quality if present.
+        // Step 7.2. Queue a global task on the canvas blob serialization task
+        // source given global to run these steps:
+        let trusted_this = Trusted::new(self);
+        let trusted_promise = TrustedPromise::new(promise.clone());
+
+        let image_type = EncodedImageType::from(options.type_.to_string());
+        let quality = options.quality;
+
+        self.global()
+            .task_manager()
+            .canvas_blob_task_source()
+            .queue(task!(convert_to_blob: move || {
+                let this = trusted_this.root();
+                let promise = trusted_promise.root();
+
+                let mut encoded: Vec<u8> = vec![];
+
+                if snapshot.encode_for_mime_type(&image_type, quality, &mut encoded).is_err() {
+                    // Step 7.2.1. If file is null, then reject result with an
+                    // "EncodingError" DOMException.
+                    promise.reject_error(Error::Encoding, CanGc::note());
+                    return;
+                };
+
+                // Step 7.2.2. Otherwise, resolve result with a new Blob object,
+                // created in global's relevant realm, representing file.
+                let blob_impl = BlobImpl::new_from_bytes(encoded, image_type.as_mime_type());
+                let blob = Blob::new(&this.global(), blob_impl, CanGc::note());
+
+                promise.resolve_native(&blob, CanGc::note());
+            }));
+
+        // Step 8. Return result.
+        promise
+    }
+}