servo/components/script/dom/gpucanvascontext.rs
Andrei Volykhin 8a62984c2f
canvas: Use non rooted variant of HTMLCanvasElementOrOffscreenCanvas type (#38970)
Any RenderingContext/OffscreenRenderingContext type has readonly
"canvas" attribute
and associated native-code DOM context objects have reference to target
DOM canvas objects.
https://html.spec.whatwg.org/multipage/canvas.html#renderingcontext
https://html.spec.whatwg.org/multipage/canvas.html#offscreenrenderingcontext

And currently the reference to DOM canvas object is the rooting pointer
on the stack,
which leads to the circular reference problem.

The SpiderMonkey's (SM) garbage collector will not be able to free the
DOM canvas and context
objects (unreacheble from JS) because of the rooting pointer on stack
(see STACK_ROOTS).

And these objects will be stored until the associated script
runtime/thread will be terminated.

SM -> JS Roots -> DOM Canvas* (on heap) -> DOM Context (on heap)
SM -> Rust Roots -> Dom Canvas* (on stack) <- as "canvas" member field

Let's replace the rooting pointer to the traceble pointer (DomRoot ->
Dom)
in the "canvas" member field of DOM context object, which allows to
broke circular referencing problem.

Testing: No changes in existed tests

Signed-off-by: Andrei Volykhin <volykhin.andrei@huawei.com>
Co-authored-by: Andrei Volykhin <volykhin.andrei@huawei.com>
2025-09-03 19:24:48 +00:00

37 lines
1.2 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 https://mozilla.org/MPL/2.0/. */
use dom_struct::dom_struct;
use webrender_api::ImageKey;
use crate::canvas_context::LayoutCanvasRenderingContextHelpers;
use crate::dom::bindings::codegen::Bindings::GPUCanvasContextBinding::GPUCanvasContextMethods;
use crate::dom::bindings::codegen::UnionTypes::HTMLCanvasElementOrOffscreenCanvas as RootedHTMLCanvasElementOrOffscreenCanvas;
use crate::dom::bindings::reflector::Reflector;
use crate::dom::bindings::root::LayoutDom;
#[dom_struct]
pub(crate) struct GPUCanvasContext {
reflector_: Reflector,
}
impl GPUCanvasContext {
#[allow(dead_code)]
fn new_inherited() -> Self {
unimplemented!()
}
}
impl GPUCanvasContextMethods<crate::DomTypeHolder> for GPUCanvasContext {
/// <https://gpuweb.github.io/gpuweb/#dom-gpucanvascontext-canvas>
fn Canvas(&self) -> RootedHTMLCanvasElementOrOffscreenCanvas {
unimplemented!()
}
}
impl LayoutCanvasRenderingContextHelpers for LayoutDom<'_, GPUCanvasContext> {
fn canvas_data_source(self) -> Option<ImageKey> {
unimplemented!()
}
}