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Merged
mrobinson merged 1 commit into from
Apr 29, 2025
Merged

canvas: Apply large size limitations #36445

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9 changes: 8 additions & 1 deletion components/canvas/canvas_data.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,10 @@ use webrender_api::{ImageDescriptor, ImageDescriptorFlags, ImageFormat, ImageKey

use crate::raqote_backend::Repetition;

// Asserts on WR texture cache update for zero sized image with raw data.
// https://github.com/servo/webrender/blob/main/webrender/src/texture_cache.rs#L1475
const MIN_WR_IMAGE_SIZE: Size2D<u64> = Size2D::new(1, 1);

fn to_path(path: &[PathSegment], mut builder: Box<dyn GenericPathBuilder>) -> Path {
let mut build_ref = PathBuilderRef {
builder: &mut builder,
Expand Down Expand Up @@ -595,6 +599,7 @@ impl<'a> CanvasData<'a> {
compositor_api: CrossProcessCompositorApi,
font_context: Arc<FontContext>,
) -> CanvasData<'a> {
let size = size.max(MIN_WR_IMAGE_SIZE);
let backend = create_backend();
let draw_target = backend.create_drawtarget(size);
let image_key = compositor_api.generate_image_key().unwrap();
Expand Down Expand Up @@ -1402,7 +1407,9 @@ impl<'a> CanvasData<'a> {
}

pub fn recreate(&mut self, size: Option<Size2D<u64>>) {
let size = size.unwrap_or_else(|| self.drawtarget.get_size().to_u64());
let size = size
.unwrap_or_else(|| self.drawtarget.get_size().to_u64())
.max(MIN_WR_IMAGE_SIZE);
self.drawtarget = self
.backend
.create_drawtarget(Size2D::new(size.width, size.height));
Expand Down
87 changes: 68 additions & 19 deletions components/script/canvas_state.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -152,6 +152,8 @@ pub(crate) struct CanvasState {
canvas_id: CanvasId,
#[no_trace]
image_key: ImageKey,
#[no_trace]
size: Cell<Size2D<u64>>,
state: DomRefCell<CanvasContextState>,
origin_clean: Cell<bool>,
#[ignore_malloc_size_of = "Arc"]
Expand All @@ -176,6 +178,7 @@ impl CanvasState {
profiled_ipc::channel(global.time_profiler_chan().clone()).unwrap();
let script_to_constellation_chan = global.script_to_constellation_chan();
debug!("Asking constellation to create new canvas thread.");
let size = adjust_canvas_size(size);
script_to_constellation_chan
.send(ScriptToConstellationMessage::CreateCanvasPaintThread(
size, sender,
Expand All @@ -194,6 +197,7 @@ impl CanvasState {
CanvasState {
ipc_renderer,
canvas_id,
size: Cell::new(size),
state: DomRefCell::new(CanvasContextState::new()),
origin_clean: Cell::new(true),
image_cache: global.image_cache(),
Expand Down Expand Up @@ -221,14 +225,26 @@ impl CanvasState {
self.canvas_id
}

pub(crate) fn is_paintable(&self) -> bool {
!self.size.get().is_empty()
}

pub(crate) fn send_canvas_2d_msg(&self, msg: Canvas2dMsg) {
if !self.is_paintable() {
return;
}

self.ipc_renderer
.send(CanvasMsg::Canvas2d(msg, self.get_canvas_id()))
.unwrap()
}

/// Updates WR image and blocks on completion
pub(crate) fn update_rendering(&self) {
if !self.is_paintable() {
return;
}

let (sender, receiver) = ipc::channel().unwrap();
self.ipc_renderer
.send(CanvasMsg::Canvas2d(
Expand All @@ -239,16 +255,27 @@ impl CanvasState {
receiver.recv().unwrap();
}

// https://html.spec.whatwg.org/multipage/#concept-canvas-set-bitmap-dimensions
/// <https://html.spec.whatwg.org/multipage/#concept-canvas-set-bitmap-dimensions>
pub(crate) fn set_bitmap_dimensions(&self, size: Size2D<u64>) {
self.reset_to_initial_state();

self.size.replace(adjust_canvas_size(size));

self.ipc_renderer
.send(CanvasMsg::Recreate(Some(size), self.get_canvas_id()))
.send(CanvasMsg::Recreate(
Some(self.size.get()),
self.get_canvas_id(),
))
.unwrap();
}

pub(crate) fn reset(&self) {
self.reset_to_initial_state();

if !self.is_paintable() {
return;
}

self.ipc_renderer
.send(CanvasMsg::Recreate(None, self.get_canvas_id()))
.unwrap();
Expand Down Expand Up @@ -347,7 +374,6 @@ impl CanvasState {

pub(crate) fn get_rect(&self, canvas_size: Size2D<u64>, rect: Rect<u64>) -> Vec<u8> {
assert!(self.origin_is_clean());

assert!(Rect::from_size(canvas_size).contains_rect(&rect));

let (sender, receiver) = ipc::channel().unwrap();
Expand Down Expand Up @@ -398,18 +424,22 @@ impl CanvasState {
dw: Option<f64>,
dh: Option<f64>,
) -> ErrorResult {
if !self.is_paintable() {
return Ok(());
}

let result = match image {
CanvasImageSource::HTMLCanvasElement(ref canvas) => {
// https://html.spec.whatwg.org/multipage/#check-the-usability-of-the-image-argument
if !canvas.is_valid() {
// <https://html.spec.whatwg.org/multipage/#check-the-usability-of-the-image-argument>
if canvas.get_size().is_empty() {
return Err(Error::InvalidState);
}

self.draw_html_canvas_element(canvas, htmlcanvas, sx, sy, sw, sh, dx, dy, dw, dh)
},
CanvasImageSource::OffscreenCanvas(ref canvas) => {
// https://html.spec.whatwg.org/multipage/#check-the-usability-of-the-image-argument
if !canvas.is_valid() {
// <https://html.spec.whatwg.org/multipage/#check-the-usability-of-the-image-argument>
if canvas.get_size().is_empty() {
return Err(Error::InvalidState);
}

Expand Down Expand Up @@ -528,11 +558,6 @@ impl CanvasState {
dw: Option<f64>,
dh: Option<f64>,
) -> ErrorResult {
// 1. Check the usability of the image argument
if !canvas.is_valid() {
return Err(Error::InvalidState);
}

let canvas_size = canvas.get_size();
let dw = dw.unwrap_or(canvas_size.width as f64);
let dh = dh.unwrap_or(canvas_size.height as f64);
Expand Down Expand Up @@ -1403,13 +1428,13 @@ impl CanvasState {
},
};

ImageData::new(
global,
size.width,
size.height,
Some(self.get_rect(canvas_size, read_rect)),
can_gc,
)
let data = if self.is_paintable() {
Some(self.get_rect(canvas_size, read_rect))
} else {
None
};

ImageData::new(global, size.width, size.height, data, can_gc)
}

// https://html.spec.whatwg.org/multipage/#dom-context-2d-putimagedata
Expand Down Expand Up @@ -1445,6 +1470,10 @@ impl CanvasState {
dirty_width: i32,
dirty_height: i32,
) {
if !self.is_paintable() {
return;
}

// FIXME(nox): There are many arithmetic operations here that can
// overflow or underflow, this should probably be audited.

Expand Down Expand Up @@ -2013,3 +2042,23 @@ where
style.font_family.to_css_string()
)
}

fn adjust_canvas_size(size: Size2D<u64>) -> Size2D<u64> {
// Firefox limits width/height to 32767 pixels and Chromium to 65535 pixels,
// but slows down dramatically before it reaches that limit.
// We limit by area instead, giving us larger maximum dimensions,
// in exchange for a smaller maximum canvas size.
const MAX_CANVAS_AREA: u64 = 32768 * 8192;
// Max width/height to 65535 in CSS pixels.
const MAX_CANVAS_SIZE: u64 = 65535;

if !size.is_empty() &&
size.greater_than(Size2D::new(MAX_CANVAS_SIZE, MAX_CANVAS_SIZE))
.none() &&
size.area() < MAX_CANVAS_AREA
{
size
} else {
Size2D::zero()
}
}
36 changes: 10 additions & 26 deletions components/script/dom/canvasrenderingcontext2d.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@

use canvas_traits::canvas::{Canvas2dMsg, CanvasId, CanvasMsg, FromScriptMsg};
use dom_struct::dom_struct;
use euclid::default::{Point2D, Rect, Size2D};
use euclid::default::Size2D;
use profile_traits::ipc;
use script_bindings::inheritance::Castable;
use script_layout_interface::HTMLCanvasDataSource;
Expand Down Expand Up @@ -74,23 +74,12 @@ impl CanvasRenderingContext2D {
reflect_dom_object(boxed, global, can_gc)
}

// https://html.spec.whatwg.org/multipage/#concept-canvas-set-bitmap-dimensions
pub(crate) fn set_bitmap_dimensions(&self, size: Size2D<u32>) {
self.reset_to_initial_state();
self.canvas_state
.get_ipc_renderer()
.send(CanvasMsg::Recreate(
Some(size.to_u64()),
self.canvas_state.get_canvas_id(),
))
.unwrap();
}

// https://html.spec.whatwg.org/multipage/#reset-the-rendering-context-to-its-default-state
fn reset_to_initial_state(&self) {
self.canvas_state.reset_to_initial_state();
}

/// <https://html.spec.whatwg.org/multipage/#concept-canvas-set-bitmap-dimensions>
pub(crate) fn set_canvas_bitmap_dimensions(&self, size: Size2D<u64>) {
self.canvas_state.set_bitmap_dimensions(size);
}
Expand All @@ -106,20 +95,17 @@ impl CanvasRenderingContext2D {
pub(crate) fn send_canvas_2d_msg(&self, msg: Canvas2dMsg) {
self.canvas_state.send_canvas_2d_msg(msg)
}

pub(crate) fn get_rect(&self, rect: Rect<u32>) -> Vec<u8> {
let rect = Rect::new(
Point2D::new(rect.origin.x as u64, rect.origin.y as u64),
Size2D::new(rect.size.width as u64, rect.size.height as u64),
);
self.canvas_state.get_rect(self.canvas.size(), rect)
}
}

impl LayoutCanvasRenderingContextHelpers for LayoutDom<'_, CanvasRenderingContext2D> {
fn canvas_data_source(self) -> HTMLCanvasDataSource {
let canvas_state = &self.unsafe_get().canvas_state;
HTMLCanvasDataSource::Image(canvas_state.image_key())

if canvas_state.is_paintable() {
HTMLCanvasDataSource::Image(canvas_state.image_key())
} else {
HTMLCanvasDataSource::Empty
}
}
}

Expand All @@ -139,13 +125,11 @@ impl CanvasContext for CanvasRenderingContext2D {
}

fn resize(&self) {
self.set_bitmap_dimensions(self.size().cast())
self.set_canvas_bitmap_dimensions(self.size().cast())
}

fn get_image_data(&self) -> Option<Snapshot> {
let size = self.size();

if size.is_empty() {
if !self.canvas_state.is_paintable() {
return None;
}

Expand Down
2 changes: 1 addition & 1 deletion components/script/dom/offscreencanvasrenderingcontext2d.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -65,7 +65,7 @@ impl OffscreenCanvasRenderingContext2D {
}

pub(crate) fn set_canvas_bitmap_dimensions(&self, size: Size2D<u64>) {
self.context.set_bitmap_dimensions(size.cast());
self.context.set_canvas_bitmap_dimensions(size.cast());
}

pub(crate) fn send_canvas_2d_msg(&self, msg: Canvas2dMsg) {
Expand Down
2 changes: 0 additions & 2 deletions tests/wpt/meta/html/canvas/element/canvas-host/2d.canvas.host.size.large.html.ini
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2 changes: 0 additions & 2 deletions tests/wpt/meta/html/canvas/offscreen/canvas-host/2d.canvas.host.size.large.html.ini
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2 changes: 0 additions & 2 deletions tests/wpt/meta/html/canvas/offscreen/canvas-host/2d.canvas.host.size.large.worker.js.ini
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