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// Copyright 2015 The Cobalt Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "cobalt/dom/html_image_element.h"
#include <memory>
#include <string>
#include <utility> // for std::move
#include "base/message_loop/message_loop.h"
#include "base/trace_event/trace_event.h"
#include "cobalt/base/polymorphic_downcast.h"
#include "cobalt/dom/csp_delegate.h"
#include "cobalt/dom/document.h"
#include "cobalt/dom/dom_settings.h"
#include "cobalt/dom/html_element_context.h"
#include "cobalt/dom/window.h"
#include "cobalt/script/global_environment.h"
#include "url/gurl.h"
namespace cobalt {
namespace dom {
// static
const char HTMLImageElement::kTagName[] = "img";
HTMLImageElement::HTMLImageElement(script::EnvironmentSettings* env_settings)
: HTMLElement(base::polymorphic_downcast<DOMSettings*>(env_settings)
->window()
->document()
.get(),
base::Token(kTagName)) {}
void HTMLImageElement::PurgeCachedBackgroundImagesOfNodeAndDescendants() {
if (!cached_image_loaded_callback_handler_) {
return;
}
// While we are still loading, treat this as an error.
OnLoadingError();
}
void HTMLImageElement::OnSetAttribute(const std::string& name,
const std::string& value) {
// A user agent that obtains images immediately must synchronously update the
// image data of an img element whenever that element is created with a src
// attribute. A user agent that obtains images immediately must also
// synchronously update the image data of an img element whenever that element
// has its src or crossorigin attribute set, changed, or removed.
if (name == "src") {
UpdateImageData();
} else {
HTMLElement::OnSetAttribute(name, value);
}
}
void HTMLImageElement::OnRemoveAttribute(const std::string& name) {
// A user agent that obtains images immediately must synchronously update the
// image data of an img element whenever that element is created with a src
// attribute. A user agent that obtains images immediately must also
// synchronously update the image data of an img element whenever that element
// has its src or crossorigin attribute set, changed, or removed.
if (name == "src") {
UpdateImageData();
} else {
HTMLElement::OnRemoveAttribute(name);
}
}
// Algorithm for UpdateTheImageData:
// https://www.w3.org/TR/html50/embedded-content-0.html#update-the-image-data
void HTMLImageElement::UpdateImageData() {
DCHECK(base::MessageLoop::current());
DCHECK(node_document());
TRACE_EVENT0("cobalt::dom", "HTMLImageElement::UpdateImageData()");
// 1. Not needed by Cobalt.
// 2. If an instance of the fetching algorithm is still running for this
// element, then abort that algorithm, discarding any pending tasks generated
// by that algorithm.
// 3. Forget the img element's current image data, if any.
if (cached_image_loaded_callback_handler_) {
cached_image_loaded_callback_handler_.reset();
prevent_gc_until_load_complete_.reset();
node_document()->DecreaseLoadingCounter();
}
// Keep the old weak cached image reference (if it exists) alive until after
// we're done updating to the new one.
std::unique_ptr<loader::image::WeakCachedImage> old_weak_cached_image =
std::move(weak_cached_image_);
// 4. If the user agent cannot support images, or its support for images has
// been disabled, then abort these steps.
// 5. Otherwise, if the element has a src attribute specified and its value is
// not the empty string, let selected source be the value of the element's src
// attribute, and selected pixel density be 1.0. Otherwise, let selected
// source be null and selected pixel density be undefined.
const auto src_attr = GetAttribute("src");
const std::string src = src_attr.value_or("");
// 6. Not needed by Cobalt.
// 7. If selected source is not null, run these substeps:
scoped_refptr<loader::image::CachedImage> cached_image;
if (!src.empty()) {
// 7.1. Resolve selected source, relative to the element. If that is not
// successful, abort these steps.
const GURL& base_url = node_document()->url_as_gurl();
const GURL selected_source = base_url.Resolve(src);
if (!selected_source.is_valid()) {
LOG(WARNING) << src << " cannot be resolved based on " << base_url << ".";
return;
}
// 7.2 Let key be a tuple consisting of the resulting absolute URL, the img
// element's cross origin attribute's mode, and, if that mode is not No
// CORS, the Document object's origin.
// 7.3 If the list of available images contains an entry for key, then set
// the img element to the completely available state, update the
// presentation of the image appropriately, queue a task to fire a simple
// event named load at the img element, and abort these steps.
auto image_cache = node_document()->html_element_context()->image_cache();
cached_image = image_cache->GetOrCreateCachedResource(selected_source,
loader::Origin());
DCHECK(cached_image);
weak_cached_image_ = image_cache->CreateWeakCachedResource(cached_image);
DCHECK(weak_cached_image_);
if (cached_image->TryGetResource()) {
PreventGarbageCollectionUntilEventIsDispatched(base::Tokens::load());
return;
}
} else {
// 8. 9. Not needed by Cobalt.
// 10. If selected source is null, then set the element to the broken state,
// queue a task to fire a simple event named error at the img element, and
// abort these steps.
if (src_attr) {
PreventGarbageCollectionUntilEventIsDispatched(base::Tokens::error());
}
return;
}
// 11. Not needed by Cobalt.
// 12. Do a potentially CORS-enabled fetch of the absolute URL that resulted
// from the earlier step, with the mode being the current state of the
// element's crossorigin content attribute, the origin being the origin of the
// img element's Document, and the default origin behaviour set to taint.
// 13. Not needed by Cobalt.
// 14. If the download was successful, fire a simple event named load at the
// img element. Otherwise, queue a task to first fire a simple event named
// error at the img element.
DCHECK(!prevent_gc_until_load_complete_);
prevent_gc_until_load_complete_.reset(
new script::GlobalEnvironment::ScopedPreventGarbageCollection(
html_element_context()->script_runner()->GetGlobalEnvironment(),
this));
node_document()->IncreaseLoadingCounter();
cached_image_loaded_callback_handler_.reset(
new loader::image::CachedImage::OnLoadedCallbackHandler(
cached_image,
base::Bind(&HTMLImageElement::OnLoadingSuccess,
base::Unretained(this)),
base::Bind(&HTMLImageElement::OnLoadingError,
base::Unretained(this))));
}
void HTMLImageElement::OnLoadingSuccess() {
TRACE_EVENT0("cobalt::dom", "HTMLImageElement::OnLoadingSuccess()");
AllowGarbageCollectionAfterEventIsDispatched(
base::Tokens::load(), std::move(prevent_gc_until_load_complete_));
if (node_document()) {
node_document()->DecreaseLoadingCounterAndMaybeDispatchLoadEvent();
}
cached_image_loaded_callback_handler_.reset();
}
void HTMLImageElement::OnLoadingError() {
TRACE_EVENT0("cobalt::dom", "HTMLImageElement::OnLoadingError()");
AllowGarbageCollectionAfterEventIsDispatched(
base::Tokens::error(), std::move(prevent_gc_until_load_complete_));
if (node_document()) {
node_document()->DecreaseLoadingCounterAndMaybeDispatchLoadEvent();
}
cached_image_loaded_callback_handler_.reset();
}
void HTMLImageElement::PreventGarbageCollectionUntilEventIsDispatched(
base::Token event_name) {
std::unique_ptr<script::GlobalEnvironment::ScopedPreventGarbageCollection>
prevent_gc_until_event_dispatch(
new script::GlobalEnvironment::ScopedPreventGarbageCollection(
html_element_context()->script_runner()->GetGlobalEnvironment(),
this));
AllowGarbageCollectionAfterEventIsDispatched(
event_name, std::move(prevent_gc_until_event_dispatch));
}
void HTMLImageElement::AllowGarbageCollectionAfterEventIsDispatched(
base::Token event_name,
std::unique_ptr<script::GlobalEnvironment::ScopedPreventGarbageCollection>
scoped_prevent_gc) {
PostToDispatchEventNameAndRunCallback(
FROM_HERE, event_name,
base::Bind(&HTMLImageElement::DestroyScopedPreventGC,
base::AsWeakPtr<HTMLImageElement>(this),
base::Passed(&scoped_prevent_gc)));
}
void HTMLImageElement::DestroyScopedPreventGC(
std::unique_ptr<script::GlobalEnvironment::ScopedPreventGarbageCollection>
scoped_prevent_gc) {
scoped_prevent_gc.reset();
}
} // namespace dom
} // namespace cobalt