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LibWeb: Avoid spin_until in HTMLImageElement::decode_image

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Improve performance of overlapping decodes. Reject on src changes
during the operation.
This commit is contained in:
Jonathan Gamble 2026-02-21 16:35:30 -06:00 • committed by Jelle Raaijmakers
parent 49eb9d7a7a
commit 34742681de
Notes: github-actions[bot] 2026-02-23 09:12:10 +00:00
3 changed files with 106 additions and 57 deletions
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120
Libraries/LibWeb/HTML/HTMLImageElement.cpp
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@ -6,6 +6,7 @@
*/
#include <LibCore/Timer.h>
#include <LibGC/Weak.h>
#include <LibGfx/Bitmap.h>
#include <LibGfx/ImmutableBitmap.h>
#include <LibWeb/ARIA/Roles.h>
@ -417,85 +418,90 @@ WebIDL::ExceptionOr<GC::Ref<WebIDL::Promise>> HTMLImageElement::decode() const
// 1. Let global be this's relevant global object.
auto& global = relevant_global_object(*this);
auto reject_if_document_not_fully_active = [this, promise, &realm]() -> bool {
if (this->document().is_fully_active())
return false;
auto exception = WebIDL::EncodingError::create(realm, "Node document not fully active"_utf16);
auto reject_promise = [promise, &realm](Utf16String const& message) {
auto exception = WebIDL::EncodingError::create(realm, message);
HTML::TemporaryExecutionContext context(realm);
WebIDL::reject_promise(realm, promise, exception);
return true;
};
auto reject_if_current_request_state_broken = [this, promise, &realm]() {
if (this->current_request().state() != ImageRequest::State::Broken)
return false;
auto queue_reject_task = [reject_promise, &global, &realm](Utf16String const& message) {
queue_global_task(Task::Source::DOMManipulation, global, GC::create_function(realm.heap(), [reject_promise, message = message] {
reject_promise(message);
}));
};
auto exception = WebIDL::EncodingError::create(realm, "Current request state is broken"_utf16);
HTML::TemporaryExecutionContext context(realm);
WebIDL::reject_promise(realm, promise, exception);
return true;
auto queue_resolve_task = [promise, &realm, &global] {
queue_global_task(Task::Source::DOMManipulation, global, GC::create_function(realm.heap(), [&realm, promise] {
HTML::TemporaryExecutionContext context(realm);
WebIDL::resolve_promise(realm, promise, JS::js_undefined());
}));
};
// 2. If any of the following are true:
// - this's node document is not fully active;
// - or this's current request's state is broken,
// then reject promise with an "EncodingError" DOMException.
if (reject_if_document_not_fully_active() || reject_if_current_request_state_broken()) {
if (!document().is_fully_active()) {
// then reject promise with an "EncodingError" DOMException.
reject_promise("Node document not fully active"_utf16);
return;
}
// - or this's current request's state is broken,
auto& current_request = *m_current_request;
if (current_request.state() == ImageRequest::State::Broken) {
// then reject promise with an "EncodingError" DOMException.
reject_promise("Current request state is broken"_utf16);
return;
}
auto expected_request = m_current_request;
auto weak_this = GC::Weak<HTMLImageElement> { *this };
// 3. Otherwise, in parallel wait for one of the following cases to occur, and perform the corresponding actions:
Platform::EventLoopPlugin::the().deferred_invoke(GC::create_function(heap(), [this, promise, &realm, &global] {
Platform::EventLoopPlugin::the().spin_until(GC::create_function(heap(), [this, promise, &realm, &global] {
auto queue_reject_task = [promise, &realm, &global](Utf16String message) {
queue_global_task(Task::Source::DOMManipulation, global, GC::create_function(realm.heap(), [&realm, promise, message = move(message)] {
auto exception = WebIDL::EncodingError::create(realm, message);
HTML::TemporaryExecutionContext context(realm);
WebIDL::reject_promise(realm, promise, exception);
}));
};
if (current_request.state() == ImageRequest::State::CompletelyAvailable) {
queue_resolve_task();
return;
}
// -> This img element's node document stops being fully active
if (!document().is_fully_active()) {
// Queue a global task on the DOM manipulation task source with global to reject promise with an "EncodingError" DOMException.
current_request.add_callbacks(
[weak_this, expected_request, queue_resolve_task, queue_reject_task] {
if (!weak_this) {
queue_reject_task("Image element no longer available"_utf16);
return;
}
auto& image = *weak_this;
if (!image.document().is_fully_active()) {
queue_reject_task("Node document not fully active"_utf16);
return true;
return;
}
auto state = this->current_request().state();
// -> FIXME: This img element's current request changes or is mutated
if (false) {
// Queue a global task on the DOM manipulation task source with global to reject promise with an "EncodingError" DOMException.
if (image.m_current_request != expected_request) {
queue_reject_task("Current request changed or was mutated"_utf16);
return true;
return;
}
// -> This img element's current request's state becomes broken
if (state == ImageRequest::State::Broken) {
// Queue a global task on the DOM manipulation task source with global to reject promise with an "EncodingError" DOMException.
if (image.current_request().state() == ImageRequest::State::Broken) {
queue_reject_task("Current request state is broken"_utf16);
return true;
return;
}
queue_resolve_task();
},
[weak_this, expected_request, queue_reject_task] {
if (!weak_this) {
queue_reject_task("Image element no longer available"_utf16);
return;
}
auto& image = *weak_this;
if (!image.document().is_fully_active()) {
queue_reject_task("Node document not fully active"_utf16);
return;
}
// -> This img element's current request's state becomes completely available
if (state == ImageRequest::State::CompletelyAvailable) {
// FIXME: Decode the image.
// FIXME: If decoding does not need to be performed for this image (for example because it is a vector graphic) or the decoding process completes successfully, then queue a global task on the DOM manipulation task source with global to resolve promise with undefined.
// FIXME: If decoding fails (for example due to invalid image data), then queue a global task on the DOM manipulation task source with global to reject promise with an "EncodingError" DOMException.
// NOTE: For now we just resolve it.
queue_global_task(Task::Source::DOMManipulation, global, GC::create_function(realm.heap(), [&realm, promise] {
HTML::TemporaryExecutionContext context(realm);
WebIDL::resolve_promise(realm, promise, JS::js_undefined());
}));
return true;
if (image.m_current_request != expected_request) {
queue_reject_task("Current request changed or was mutated"_utf16);
return;
}
return false;
}));
}));
queue_reject_task("Current request state is broken"_utf16);
});
}));
// 3. Return promise.