Source code
Revision control
Copy as Markdown
Other Tools
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
/*
* A base class which implements nsIImageLoadingContent and can be
* subclassed by various content nodes that want to provide image
* loading functionality (eg <img>, <object>, etc).
*/
#ifndef nsImageLoadingContent_h__
#define nsImageLoadingContent_h__
#include "imgINotificationObserver.h"
#include "mozilla/CORSMode.h"
#include "mozilla/TimeStamp.h"
#include "nsCOMPtr.h"
#include "nsIContentPolicy.h"
#include "nsIImageLoadingContent.h"
#include "nsIRequest.h"
#include "mozilla/dom/BindingDeclarations.h"
#include "mozilla/dom/Promise.h"
#include "mozilla/dom/RustTypes.h"
#include "nsAttrValue.h"
#include "Units.h"
class nsINode;
class nsIURI;
class nsPresContext;
class nsIContent;
class imgRequestProxy;
namespace mozilla {
class AsyncEventDispatcher;
class ErrorResult;
namespace dom {
struct BindContext;
class Document;
class Element;
enum class FetchPriority : uint8_t;
} // namespace dom
} // namespace mozilla
#ifdef LoadImage
// Undefine LoadImage to prevent naming conflict with Windows.
# undef LoadImage
#endif
class nsImageLoadingContent : public nsIImageLoadingContent {
protected:
template <typename T>
using Maybe = mozilla::Maybe<T>;
using Nothing = mozilla::Nothing;
using OnNonvisible = mozilla::OnNonvisible;
using Visibility = mozilla::Visibility;
/* METHODS */
public:
nsImageLoadingContent();
virtual ~nsImageLoadingContent();
NS_DECL_IMGINOTIFICATIONOBSERVER
NS_DECL_NSIIMAGELOADINGCONTENT
// Web IDL binding methods.
// Note that the XPCOM SetLoadingEnabled method is OK for Web IDL bindings
// to use as well, since it does not throw when called via the Web IDL
// bindings.
bool LoadingEnabled() const { return mLoadingEnabled; }
void AddObserver(imgINotificationObserver* aObserver);
void RemoveObserver(imgINotificationObserver* aObserver);
already_AddRefed<imgIRequest> GetRequest(int32_t aRequestType,
mozilla::ErrorResult& aError);
int32_t GetRequestType(imgIRequest* aRequest, mozilla::ErrorResult& aError);
already_AddRefed<nsIURI> GetCurrentURI();
already_AddRefed<nsIURI> GetCurrentRequestFinalURI();
void ForceReload(bool aNotify, mozilla::ErrorResult& aError);
mozilla::dom::Element* FindImageMap();
static mozilla::dom::Element* FindImageMap(mozilla::dom::Element*);
/**
* Toggle whether or not to synchronously decode an image on draw.
*/
void SetSyncDecodingHint(bool aHint);
/**
* Notify us that the document state has changed. Called by nsDocument so that
* we may reject any promises which require the document to be active.
*/
void NotifyOwnerDocumentActivityChanged();
// Trigger text recognition for the current image request.
already_AddRefed<mozilla::dom::Promise> RecognizeCurrentImageText(
mozilla::ErrorResult&);
protected:
enum ImageLoadType {
// Most normal image loads
eImageLoadType_Normal,
// From a <img srcset> or <picture> context. Affects type given to content
// policy.
eImageLoadType_Imageset
};
/**
* LoadImage is called by subclasses when the appropriate
* attributes (eg 'src' for <img> tags) change. The string passed
* in is the new uri string; this consolidates the code for getting
* the charset, constructing URI objects, and any other incidentals
* into this superclass.
*
* @param aNewURI the URI spec to be loaded (may be a relative URI)
* @param aForce If true, make sure to load the URI. If false, only
* load if the URI is different from the currently loaded URI.
* @param aNotify If true, nsIDocumentObserver state change notifications
* will be sent as needed.
* @param aImageLoadType The ImageLoadType for this request
* @param aTriggeringPrincipal Optional parameter specifying the triggering
* principal to use for the image load
*/
nsresult LoadImage(const nsAString& aNewURI, bool aForce, bool aNotify,
ImageLoadType aImageLoadType,
nsIPrincipal* aTriggeringPrincipal = nullptr);
/**
* ImageState is called by subclasses that are computing their content state.
* The return value will have the ElementState::BROKEN bit set as needed.
*
* Note that this state assumes that this node is "trying" to be an
* image (so for example complete lack of attempt to load an image will lead
* to ElementState::BROKEN being set). Subclasses that are not "trying" to
* be an image (eg an HTML <input> of type other than "image") should just
* not call this method when computing their intrinsic state.
*/
mozilla::dom::ElementState ImageState() const;
/**
* LoadImage is called by subclasses when the appropriate
* attributes (eg 'src' for <img> tags) change. If callers have an
* URI object already available, they should use this method.
*
* @param aNewURI the URI to be loaded
* @param aForce If true, make sure to load the URI. If false, only
* load if the URI is different from the currently loaded URI.
* @param aNotify If true, nsIDocumentObserver state change notifications
* will be sent as needed.
* @param aImageLoadType The ImageLoadType for this request
* @param aDocument Optional parameter giving the document this node is in.
* This is purely a performance optimization.
* @param aLoadFlags Optional parameter specifying load flags to use for
* the image load
* @param aTriggeringPrincipal Optional parameter specifying the triggering
* principal to use for the image load
*/
nsresult LoadImage(nsIURI* aNewURI, bool aForce, bool aNotify,
ImageLoadType aImageLoadType, nsLoadFlags aLoadFlags,
mozilla::dom::Document* aDocument = nullptr,
nsIPrincipal* aTriggeringPrincipal = nullptr);
nsresult LoadImage(nsIURI* aNewURI, bool aForce, bool aNotify,
ImageLoadType aImageLoadType,
nsIPrincipal* aTriggeringPrincipal) {
return LoadImage(aNewURI, aForce, aNotify, aImageLoadType, LoadFlags(),
nullptr, aTriggeringPrincipal);
}
/**
* helpers to get the document for this content (from the nodeinfo
* and such). Not named GetOwnerDoc/GetCurrentDoc to prevent ambiguous
* method names in subclasses
*
* @return the document we belong to
*/
mozilla::dom::Document* GetOurOwnerDoc();
mozilla::dom::Document* GetOurCurrentDoc();
/**
* Helper function to get the frame associated with this content. Not named
* GetPrimaryFrame to prevent ambiguous method names in subclasses.
*
* @return The frame we own, or nullptr if it doesn't exist, or isn't
* associated with any of our requests.
*/
nsIFrame* GetOurPrimaryImageFrame();
/**
* Helper function to get the PresContext associated with this content's
* frame. Not named GetPresContext to prevent ambiguous method names in
* subclasses.
*
* @return The nsPresContext associated with our frame, or nullptr if either
* the frame doesn't exist, or the frame's prescontext doesn't exist.
*/
nsPresContext* GetFramePresContext();
/**
* CancelImageRequests is called by subclasses when they want to
* cancel all image requests (for example when the subclass is
* somehow not an image anymore).
*/
void CancelImageRequests(bool aNotify);
/**
* Derived classes of nsImageLoadingContent MUST call Destroy from their
* destructor, or earlier. It does things that cannot be done in
* ~nsImageLoadingContent because they rely on being able to QueryInterface to
* other derived classes, which cannot happen once the derived class
* destructor has started calling the base class destructors.
*/
void Destroy();
/**
* Returns the CORS mode that will be used for all future image loads. The
* default implementation returns CORS_NONE unconditionally.
*/
virtual mozilla::CORSMode GetCORSMode();
// Subclasses are *required* to call BindToTree/UnbindFromTree.
void BindToTree(mozilla::dom::BindContext&, nsINode& aParent);
void UnbindFromTree();
void OnLoadComplete(imgIRequest* aRequest, uint32_t aImageStatus);
void OnUnlockedDraw();
void OnImageIsAnimated(imgIRequest* aRequest);
// The nsContentPolicyType we would use for this ImageLoadType
static nsContentPolicyType PolicyTypeForLoad(ImageLoadType aImageLoadType);
void AsyncEventRunning(mozilla::AsyncEventDispatcher* aEvent);
// Get ourselves as an nsIContent*. Not const because some of the callers
// want a non-const nsIContent.
virtual nsIContent* AsContent() = 0;
virtual mozilla::dom::FetchPriority GetFetchPriorityForImage() const;
/**
* Get width and height of the current request, using given image request if
* attributes are unset.
*/
MOZ_CAN_RUN_SCRIPT mozilla::CSSIntSize GetWidthHeightForImage();
/**
* Create a promise and queue a microtask which will ensure the current
* request (after any pending loads are applied) has requested a full decode.
* The promise is fulfilled once the request has a fully decoded surface that
* is available for drawing, or an error condition occurrs (e.g. broken image,
* current request is updated, etc).
*
*/
already_AddRefed<mozilla::dom::Promise> QueueDecodeAsync(
mozilla::ErrorResult& aRv);
enum class ImageDecodingType : uint8_t {
Auto,
Async,
Sync,
};
static const nsAttrValue::EnumTable kDecodingTable[];
static const nsAttrValue::EnumTable* kDecodingTableDefault;
private:
/**
* Enqueue and/or fulfill a promise created by QueueDecodeAsync.
*/
void DecodeAsync(RefPtr<mozilla::dom::Promise>&& aPromise,
uint32_t aRequestGeneration);
/**
* Attempt to resolve all queued promises based on the state of the current
* request. If the current request does not yet have all of the encoded data,
* or the decoding has not yet completed, it will return without changing the
* promise states.
*/
void MaybeResolveDecodePromises();
/**
* Reject all queued promises with the given status.
*/
void RejectDecodePromises(nsresult aStatus);
/**
* Age the generation counter if we have a new current request with a
* different URI. If the generation counter is aged, then all queued promises
* will also be rejected.
*/
void MaybeAgeRequestGeneration(nsIURI* aNewURI);
/**
* Deregister as an observer for the owner document's activity notifications
* if we have no outstanding decode promises.
*/
void MaybeDeregisterActivityObserver();
/**
* Struct used to manage the native image observers.
*/
struct ImageObserver {
explicit ImageObserver(imgINotificationObserver* aObserver);
~ImageObserver();
nsCOMPtr<imgINotificationObserver> mObserver;
ImageObserver* mNext;
};
/**
* Struct used to manage the scripted/XPCOM image observers.
*/
class ScriptedImageObserver final {
public:
NS_INLINE_DECL_REFCOUNTING(ScriptedImageObserver)
ScriptedImageObserver(imgINotificationObserver* aObserver,
RefPtr<imgRequestProxy>&& aCurrentRequest,
RefPtr<imgRequestProxy>&& aPendingRequest);
bool CancelRequests();
nsCOMPtr<imgINotificationObserver> mObserver;
RefPtr<imgRequestProxy> mCurrentRequest;
RefPtr<imgRequestProxy> mPendingRequest;
private:
~ScriptedImageObserver();
};
/**
* Method to fire an event once we know what's going on with the image load.
*
* @param aEventType "load", or "error" depending on how things went
* @param aIsCancelable true if event is cancelable.
*/
nsresult FireEvent(const nsAString& aEventType, bool aIsCancelable = false);
/**
* Method to cancel and null-out pending event if they exist.
*/
void CancelPendingEvent();
RefPtr<mozilla::AsyncEventDispatcher> mPendingEvent;
protected:
/**
* UpdateImageState recomputes the current state of this image loading
* content and updates what ImageState() returns accordingly. It will also
* fire a ContentStatesChanged() notification as needed if aNotify is true.
*/
void UpdateImageState(bool aNotify);
/**
* Method to create an nsIURI object from the given string (will
* handle getting the right charset, base, etc). You MUST pass in a
* non-null document to this function.
*
* @param aSpec the string spec (from an HTML attribute, eg)
* @param aDocument the document we belong to
* @return the URI we want to be loading
*/
nsresult StringToURI(const nsAString& aSpec,
mozilla::dom::Document* aDocument, nsIURI** aURI);
/**
* Prepare and returns a reference to the "next request". If there's already
* a _usable_ current request (one with SIZE_AVAILABLE), this request is
* "pending" until it becomes usable. Otherwise, this becomes the current
* request.
*
* @param aImageLoadType The ImageLoadType for this request
* @param aNewURI The uri that we're going to load
*/
RefPtr<imgRequestProxy>& PrepareNextRequest(ImageLoadType, nsIURI* aNewURI);
/**
* Returns a COMPtr reference to the current/pending image requests, cleaning
* up and canceling anything that was there before. Note that if you just want
* to get rid of one of the requests, you should call
* Clear*Request(NS_BINDING_ABORTED) instead.
*
* @param aImageLoadType The ImageLoadType for this request
* @param aNewURI The uri that we're going to load
*/
RefPtr<imgRequestProxy>& PrepareCurrentRequest(ImageLoadType,
nsIURI* aNewURI);
RefPtr<imgRequestProxy>& PreparePendingRequest(ImageLoadType);
/**
* Switch our pending request to be our current request.
* mPendingRequest must be non-null!
*/
void MakePendingRequestCurrent();
/**
* Cancels and nulls-out the "current" and "pending" requests if they exist.
*
* @param aNonvisibleAction An action to take if the image is no longer
* visible as a result; see |UntrackImage|.
*/
void ClearCurrentRequest(
nsresult aReason,
const Maybe<OnNonvisible>& aNonvisibleAction = Nothing());
void ClearPendingRequest(
nsresult aReason,
const Maybe<OnNonvisible>& aNonvisibleAction = Nothing());
/**
* Static helper method to tell us if we have the size of a request. The
* image may be null.
*/
static bool HaveSize(imgIRequest* aImage);
/**
* Adds/Removes a given imgIRequest from our document's tracker.
*
* No-op if aImage is null.
*
* @param aFrame If called from FrameCreated the frame passed to FrameCreated.
* This is our frame, but at the time of the FrameCreated call
* our primary frame pointer hasn't been set yet, so this is
* only way to get our frame.
*
* @param aNonvisibleAction A requested action if the frame has become
* nonvisible. If Nothing(), no action is
* requested. If DISCARD_IMAGES is specified, the
* frame is requested to ask any images it's
* associated with to discard their surfaces if
* possible.
*/
void TrackImage(imgIRequest* aImage, nsIFrame* aFrame = nullptr);
void UntrackImage(imgIRequest* aImage,
const Maybe<OnNonvisible>& aNonvisibleAction = Nothing());
nsLoadFlags LoadFlags();
/* MEMBERS */
RefPtr<imgRequestProxy> mCurrentRequest;
RefPtr<imgRequestProxy> mPendingRequest;
uint8_t mCurrentRequestFlags = 0;
uint8_t mPendingRequestFlags = 0;
enum {
// Set if the request is currently tracked with the document.
REQUEST_IS_TRACKED = 1 << 0,
// Set if this is an imageset request, such as from <img srcset> or
// <picture>
REQUEST_IS_IMAGESET = 1 << 1,
};
// If the image was blocked or if there was an error loading, it's nice to
// still keep track of what the URI was despite not having an imgIRequest.
// We only maintain this in those situations (in the common case, this is
// always null).
nsCOMPtr<nsIURI> mCurrentURI;
private:
/**
* Clones the given "current" or "pending" request for each scripted observer.
*/
void CloneScriptedRequests(imgRequestProxy* aRequest);
/**
* Cancels and nulls-out the "current" or "pending" requests if they exist
* for each scripted observer.
*/
void ClearScriptedRequests(int32_t aRequestType, nsresult aReason);
/**
* Moves the "pending" request into the "current" request for each scripted
* observer. If there is an existing "current" request, it will cancel it
* first.
*/
void MakePendingScriptedRequestsCurrent();
/**
* Depending on the configured decoding hint, and/or how recently we updated
* the image request, force or stop the frame from decoding the image
* synchronously when it is drawn.
* @param aPrepareNextRequest True if this is when updating the image request.
* @param aFrame If called from FrameCreated the frame passed to FrameCreated.
* This is our frame, but at the time of the FrameCreated call
* our primary frame pointer hasn't been set yet, so this is
* only way to get our frame.
*/
void MaybeForceSyncDecoding(bool aPrepareNextRequest,
nsIFrame* aFrame = nullptr);
/**
* Typically we will have only one observer (our frame in the screen
* prescontext), so we want to only make space for one and to
* heap-allocate anything past that (saves memory and malloc churn
* in the common case). The storage is a linked list, we just
* happen to actually hold the first observer instead of a pointer
* to it.
*/
ImageObserver mObserverList;
/**
* Typically we will have no scripted observers, as this is only used by
* chrome, legacy extensions, and some mochitests. An empty array reserves
* minimal memory.
*/
nsTArray<RefPtr<ScriptedImageObserver>> mScriptedObservers;
/**
* Promises created by QueueDecodeAsync that are still waiting to be
* fulfilled by the image being fully decoded.
*/
nsTArray<RefPtr<mozilla::dom::Promise>> mDecodePromises;
mozilla::TimeStamp mMostRecentRequestChange;
/**
* Total number of outstanding decode promises, including those stored in
* mDecodePromises and those embedded in runnables waiting to be enqueued.
* This is used to determine whether we need to register as an observer for
* document activity notifications.
*/
size_t mOutstandingDecodePromises;
/**
* An incrementing counter representing the current request generation;
* Each time mCurrentRequest is modified with a different URI, this will
* be incremented. Each QueueDecodeAsync call will cache the generation
* of the current request so that when it is processed, it knows if it
* should have rejected because the request changed.
*/
uint32_t mRequestGeneration;
protected:
bool mLoadingEnabled : 1;
/**
* Flag to indicate whether the channel should be mark as urgent-start.
* It should be set in *Element and passed to nsContentUtils::LoadImage.
* True if we want to set nsIClassOfService::UrgentStart to the channel to
* get the response ASAP for better user responsiveness.
*/
bool mUseUrgentStartForChannel : 1;
// Represents the image is deferred loading until this element gets visible.
bool mLazyLoading : 1;
// Whether we have a pending load task scheduled (HTMLImageElement only).
bool mHasPendingLoadTask : 1;
// If true, force frames to synchronously decode images on draw.
bool mSyncDecodingHint : 1;
// Whether we're in the doc responsive content set (HTMLImageElement only).
bool mInDocResponsiveContent : 1;
private:
// Flags to indicate whether each of the current and pending requests are
// registered with the refresh driver.
bool mCurrentRequestRegistered;
bool mPendingRequestRegistered;
};
#endif // nsImageLoadingContent_h__