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/*
* Copyright (C) 2020 Igalia S.L.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "LazyLoadImageObserver.h"
#include "HTMLImageElement.h"
#include "IntersectionObserverCallback.h"
#include "IntersectionObserverEntry.h"
#include "LocalFrame.h"
#include <limits>
namespace WebCore {
class LazyImageLoadIntersectionObserverCallback final : public IntersectionObserverCallback {
public:
static Ref<LazyImageLoadIntersectionObserverCallback> create(Document& document)
{
return adoptRef(*new LazyImageLoadIntersectionObserverCallback(document));
}
private:
bool hasCallback() const final { return true; }
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<HTMLImageElement>(element)) {
downcast<HTMLImageElement>(*element).loadDeferredImage();
element->document().lazyLoadImageObserver().unobserve(*element, element->document());
}
}
return { };
}
LazyImageLoadIntersectionObserverCallback(Document& document)
: IntersectionObserverCallback(&document)
{
}
};
void LazyLoadImageObserver::observe(Element& element)
{
auto& observer = element.document().lazyLoadImageObserver();
auto* intersectionObserver = observer.intersectionObserver(element.document());
if (!intersectionObserver)
return;
intersectionObserver->observe(element);
}
void LazyLoadImageObserver::unobserve(Element& element, Document& document)
{
if (auto& observer = document.lazyLoadImageObserver().m_observer)
observer->unobserve(element);
}
IntersectionObserver* LazyLoadImageObserver::intersectionObserver(Document& document)
{
if (!m_observer) {
auto callback = LazyImageLoadIntersectionObserverCallback::create(document);
static NeverDestroyed<const String> lazyLoadingRootMarginFallback(MAKE_STATIC_STRING_IMPL("100%"));
IntersectionObserver::Init options { &document, lazyLoadingRootMarginFallback, { } };
auto observer = IntersectionObserver::create(document, WTFMove(callback), WTFMove(options));
if (observer.hasException())
return nullptr;
m_observer = observer.returnValue().ptr();
}
return m_observer.get();
}
bool LazyLoadImageObserver::isObserved(Element& element) const
{
return m_observer && m_observer->isObserving(element);
}
}
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