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Fix crash on request_animation_frame when destroying web runner (#4169)

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Previously, any frames in flight (`requestAnimationFrame`) on web were
not being cancelled (`cancelAnimationFrame`) when `WebRunner::destroy`
was called. If a user called `destroy`, then immediately removed the
canvas from the DOM, eframe could panic with a "failed to find (canvas)
element by id" error message.

This PR changes two things:
- The canvas element is directly referenced everywhere it's needed
instead of being looked up by `canvas_id`[^1]
- The RAF handle is stored in `WebRunner` and `cancelAnimationFrame` is
called on it inside of `WebRunner::destroy`[^2]

[^1]: The WebGL/WGPU backends were already holding onto the canvas (and
associated GPU context), so the change is just converting all the
`get_element_by_id` lookups to retrieve the canvas from the web runner
handle.

[^2]: There is only ever one frame in flight, so we store it directly as
a scalar field.
This commit is contained in:
Jan Procházka
2024-03-14 10:26:34 +01:00
committed by GitHub
parent 00e8ce6d7e
commit c5eaba43cd
9 changed files with 73 additions and 61 deletions
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26
crates/eframe/src/web/events.rs
View File

@@ -5,12 +5,12 @@ use super::*;
/// Calls `request_animation_frame` to schedule repaint.
///
/// It will only paint if needed, but will always call `request_animation_frame` immediately.
fn paint_and_schedule(runner_ref: &WebRunner) -> Result<(), JsValue> {
pub(crate) fn paint_and_schedule(runner_ref: &WebRunner) -> Result<(), JsValue> {
// Only paint and schedule if there has been no panic
if let Some(mut runner_lock) = runner_ref.try_lock() {
paint_if_needed(&mut runner_lock);
drop(runner_lock);
request_animation_frame(runner_ref.clone())?;
runner_ref.request_animation_frame()?;
}
Ok(())
}
@@ -45,14 +45,6 @@ fn paint_if_needed(runner: &mut AppRunner) {
runner.auto_save_if_needed();
}
pub(crate) fn request_animation_frame(runner_ref: WebRunner) -> Result<(), JsValue> {
let window = web_sys::window().unwrap();
let closure = Closure::once(move || paint_and_schedule(&runner_ref));
window.request_animation_frame(closure.as_ref().unchecked_ref())?;
closure.forget(); // We must forget it, or else the callback is canceled on drop
Ok(())
}
// ------------------------------------------------------------------------
pub(crate) fn install_document_events(runner_ref: &WebRunner) -> Result<(), JsValue> {
@@ -275,7 +267,7 @@ pub(crate) fn install_color_scheme_change_event(runner_ref: &WebRunner) -> Resul
}
pub(crate) fn install_canvas_events(runner_ref: &WebRunner) -> Result<(), JsValue> {
let canvas = canvas_element(runner_ref.try_lock().unwrap().canvas_id()).unwrap();
let canvas = runner_ref.try_lock().unwrap().canvas().clone();
{
let prevent_default_events = [
@@ -304,7 +296,7 @@ pub(crate) fn install_canvas_events(runner_ref: &WebRunner) -> Result<(), JsValu
let modifiers = modifiers_from_mouse_event(&event);
runner.input.raw.modifiers = modifiers;
if let Some(button) = button_from_mouse_event(&event) {
let pos = pos_from_mouse_event(runner.canvas_id(), &event);
let pos = pos_from_mouse_event(runner.canvas(), &event);
let modifiers = runner.input.raw.modifiers;
runner.input.raw.events.push(egui::Event::PointerButton {
pos,
@@ -331,7 +323,7 @@ pub(crate) fn install_canvas_events(runner_ref: &WebRunner) -> Result<(), JsValu
|event: web_sys::MouseEvent, runner| {
let modifiers = modifiers_from_mouse_event(&event);
runner.input.raw.modifiers = modifiers;
let pos = pos_from_mouse_event(runner.canvas_id(), &event);
let pos = pos_from_mouse_event(runner.canvas(), &event);
runner.input.raw.events.push(egui::Event::PointerMoved(pos));
runner.needs_repaint.repaint_asap();
event.stop_propagation();
@@ -343,7 +335,7 @@ pub(crate) fn install_canvas_events(runner_ref: &WebRunner) -> Result<(), JsValu
let modifiers = modifiers_from_mouse_event(&event);
runner.input.raw.modifiers = modifiers;
if let Some(button) = button_from_mouse_event(&event) {
let pos = pos_from_mouse_event(runner.canvas_id(), &event);
let pos = pos_from_mouse_event(runner.canvas(), &event);
let modifiers = runner.input.raw.modifiers;
runner.input.raw.events.push(egui::Event::PointerButton {
pos,
@@ -381,7 +373,7 @@ pub(crate) fn install_canvas_events(runner_ref: &WebRunner) -> Result<(), JsValu
"touchstart",
|event: web_sys::TouchEvent, runner| {
let mut latest_touch_pos_id = runner.input.latest_touch_pos_id;
let pos = pos_from_touch_event(runner.canvas_id(), &event, &mut latest_touch_pos_id);
let pos = pos_from_touch_event(runner.canvas(), &event, &mut latest_touch_pos_id);
runner.input.latest_touch_pos_id = latest_touch_pos_id;
runner.input.latest_touch_pos = Some(pos);
let modifiers = runner.input.raw.modifiers;
@@ -404,7 +396,7 @@ pub(crate) fn install_canvas_events(runner_ref: &WebRunner) -> Result<(), JsValu
"touchmove",
|event: web_sys::TouchEvent, runner| {
let mut latest_touch_pos_id = runner.input.latest_touch_pos_id;
let pos = pos_from_touch_event(runner.canvas_id(), &event, &mut latest_touch_pos_id);
let pos = pos_from_touch_event(runner.canvas(), &event, &mut latest_touch_pos_id);
runner.input.latest_touch_pos_id = latest_touch_pos_id;
runner.input.latest_touch_pos = Some(pos);
runner.input.raw.events.push(egui::Event::PointerMoved(pos));
@@ -467,7 +459,7 @@ pub(crate) fn install_canvas_events(runner_ref: &WebRunner) -> Result<(), JsValu
});
let scroll_multiplier = match unit {
egui::MouseWheelUnit::Page => canvas_size_in_points(runner.canvas_id()).y,
egui::MouseWheelUnit::Page => canvas_size_in_points(runner.canvas()).y,
egui::MouseWheelUnit::Line => {
#[allow(clippy::let_and_return)]
let points_per_scroll_line = 8.0; // Note that this is intentionally different from what we use in winit.