LazyLoadFrameObserver.cpp [plain text]
#include "config.h"
#include "LazyLoadFrameObserver.h"
#include "Frame.h"
#include "HTMLIFrameElement.h"
#include "IntersectionObserverCallback.h"
#include "RenderStyle.h"
#include <limits>
namespace WebCore {
class LazyFrameLoadIntersectionObserverCallback final : public IntersectionObserverCallback {
public:
static Ref<LazyFrameLoadIntersectionObserverCallback> create(Document& document)
{
return adoptRef(*new LazyFrameLoadIntersectionObserverCallback(document));
}
private:
CallbackResult<void> handleEvent(IntersectionObserver&, const Vector<Ref<IntersectionObserverEntry>>& entries, IntersectionObserver&) final
{
ASSERT(!entries.isEmpty());
for (auto& entry : entries) {
if (!entry->isIntersecting())
continue;
auto* element = entry->target();
if (is<HTMLIFrameElement>(element)) {
downcast<HTMLIFrameElement>(*element).lazyLoadFrameObserver().unobserve();
downcast<HTMLIFrameElement>(*element).loadDeferredFrame();
}
}
return { };
}
LazyFrameLoadIntersectionObserverCallback(Document& document)
: IntersectionObserverCallback(&document)
{
}
};
LazyLoadFrameObserver::LazyLoadFrameObserver(HTMLIFrameElement& element)
: m_element(element)
{
}
void LazyLoadFrameObserver::observe(const AtomString& frameURL, const ReferrerPolicy& referrerPolicy)
{
auto& frameObserver = m_element.lazyLoadFrameObserver();
auto* intersectionObserver = frameObserver.intersectionObserver(m_element.document());
if (!intersectionObserver)
return;
m_frameURL = frameURL;
m_referrerPolicy = referrerPolicy;
intersectionObserver->observe(m_element);
}
void LazyLoadFrameObserver::unobserve()
{
auto& frameObserver = m_element.lazyLoadFrameObserver();
ASSERT(frameObserver.isObserved(m_element));
frameObserver.m_observer->unobserve(m_element);
}
IntersectionObserver* LazyLoadFrameObserver::intersectionObserver(Document& document)
{
if (!m_observer) {
auto callback = LazyFrameLoadIntersectionObserverCallback::create(document);
IntersectionObserver::Init options { WTF::nullopt, emptyString(), { } };
auto observer = IntersectionObserver::create(document, WTFMove(callback), WTFMove(options));
if (observer.hasException())
return nullptr;
m_observer = observer.releaseReturnValue();
}
return m_observer.get();
}
bool LazyLoadFrameObserver::isObserved(Element& element) const
{
return m_observer && m_observer->observationTargets().contains(&element);
}
}