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/* -*- 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
* file, You can obtain one at */
#include "mozilla/Attributes.h"
#include "mozilla/dom/IDTracker.h"
#include "FrameProperties.h"
#include "nsID.h"
#include "nsIFrame.h" // only for LayoutFrameType
#include "nsIMutationObserver.h"
#include "nsISupportsBase.h"
#include "nsISupportsImpl.h"
#include "nsIReferrerInfo.h"
#include "nsStringFwd.h"
#include "nsStubMutationObserver.h"
#include "nsStyleStruct.h"
#include "nsCycleCollectionParticipant.h"
class nsAtom;
class nsIFrame;
class nsIURI;
namespace mozilla {
class SVGClipPathFrame;
class SVGFilterFrame;
class SVGMarkerFrame;
class SVGMaskFrame;
class SVGPaintServerFrame;
namespace dom {
class CanvasRenderingContext2D;
class Element;
class SVGGeometryElement;
} // namespace dom
} // namespace mozilla
namespace mozilla {
* This class contains URL and referrer information (referrer and referrer
* policy).
* We use it to pass to svg system instead of nsIURI. The object brings referrer
* and referrer policy so we can send correct Referer headers.
class URLAndReferrerInfo {
URLAndReferrerInfo(nsIURI* aURI, nsIReferrerInfo* aReferrerInfo)
: mURI(aURI), mReferrerInfo(aReferrerInfo) {
URLAndReferrerInfo(nsIURI* aURI, const URLExtraData& aExtraData)
: mURI(aURI), mReferrerInfo(aExtraData.ReferrerInfo()) {
nsIURI* GetURI() const { return mURI; }
nsIReferrerInfo* GetReferrerInfo() const { return mReferrerInfo; }
bool operator==(const URLAndReferrerInfo& aRHS) const;
~URLAndReferrerInfo() = default;
nsCOMPtr<nsIURI> mURI;
nsCOMPtr<nsIReferrerInfo> mReferrerInfo;
* This interface allows us to be notified when a piece of SVG content is
* re-rendered.
* Concrete implementations of this base class need to implement
* GetReferencedElementWithoutObserving to specify the SVG element that
* they'd like to monitor for rendering changes, and they need to implement
* OnRenderingChange to specify how we'll react when that content gets
* re-rendered. They also need to implement a constructor and destructor,
* which should call StartObserving and StopObserving, respectively.
* The referenced element is generally looked up and stored during
* construction. If the referenced element is in an extenal SVG resource
* document, the lookup code will initiate loading of the external resource and
* OnRenderingChange will be called once the element in the external resource
* is available.
* Although the referenced element may be found and stored during construction,
* observing for rendering changes does not start until requested.
class SVGRenderingObserver : public nsStubMutationObserver {
virtual ~SVGRenderingObserver() = default;
using Element = dom::Element;
SVGRenderingObserver() : mInObserverSet(false) {}
// nsIMutationObserver
* Called when non-DOM-mutation changes to the observed element should likely
* cause the rendering of our observer to change. This includes changes to
* CSS computed values, but also changes to rendering observers that the
* observed element itself may have (for example, when we're being used to
* observe an SVG pattern, and an element in that pattern references and
* observes a gradient that has changed).
void OnNonDOMMutationRenderingChange();
// When a SVGRenderingObserver list gets forcibly cleared, it uses this
// callback to notify every observer that's cleared from it, so they can
// react.
void NotifyEvictedFromRenderingObserverSet();
nsIFrame* GetAndObserveReferencedFrame();
* @param aOK this is only for the convenience of callers. We set *aOK to
* false if the frame is the wrong type
nsIFrame* GetAndObserveReferencedFrame(mozilla::LayoutFrameType aFrameType,
bool* aOK);
Element* GetAndObserveReferencedElement();
virtual bool ObservesReflow() { return false; }
void StartObserving();
void StopObserving();
* Called whenever the rendering of the observed element may have changed.
* More specifically, this method is called whenever DOM mutation occurs in
* the observed element's subtree, or whenever
* SVGObserverUtils::InvalidateRenderingObservers or
* SVGObserverUtils::InvalidateDirectRenderingObservers is called for the
* observed element's frame.
* Subclasses should override this method to handle rendering changes
* appropriately.
virtual void OnRenderingChange() = 0;
virtual Element* GetReferencedElementWithoutObserving() = 0;
#ifdef DEBUG
void DebugObserverSet();
// Whether we're in our observed element's observer set at this time.
bool mInObserverSet;
class SVGObserverUtils {
using CanvasRenderingContext2D = dom::CanvasRenderingContext2D;
using Element = dom::Element;
using SVGGeometryElement = dom::SVGGeometryElement;
using HrefToTemplateCallback = const std::function<void(nsAString&)>&;
* Ensures that that if the given frame requires any resources that are in
* SVG resource documents that the loading of those documents is initiated.
* This does not make aFrame start to observe any elements that it
* references.
static void InitiateResourceDocLoads(nsIFrame* aFrame);
* Called when changes to an element (e.g. CSS property changes) cause its
* frame to start/stop referencing (or reference different) SVG resource
* elements. (_Not_ called for changes to referenced resource elements.)
* This function handles such changes by discarding _all_ the frame's SVG
* effects frame properties (causing those properties to stop watching their
* target element). It also synchronously (re)creates the filter and marker
* frame properties (XXX why not the other properties?), which makes it
* useful for initializing those properties during first reflow.
* XXX rename to something more meaningful like RefreshResourceReferences?
static void UpdateEffects(nsIFrame* aFrame);
* @param aFrame must be a first-continuation.
static void AddRenderingObserver(Element* aElement,
SVGRenderingObserver* aObserver);
* @param aFrame must be a first-continuation.
static void RemoveRenderingObserver(Element* aElement,
SVGRenderingObserver* aObserver);
* Removes all rendering observers from aElement.
static void RemoveAllRenderingObservers(Element* aElement);
* This can be called on any frame. We invalidate the observers of aFrame's
* element, if any, or else walk up to the nearest observable SVG parent
* frame with observers and invalidate them instead.
* Note that this method is very different to e.g.
* MutationObservers::AttributeChanged which walks up the content node tree
* all the way to the root node (not stopping if it encounters a non-container
* SVG node) invalidating all mutation observers (not just
* SVGRenderingObservers) on all nodes along the way (not just the first
* node it finds with observers). In other words, by doing all the
* things in parentheses in the preceding sentence, this method uses
* knowledge about our implementation and what can be affected by SVG effects
* to make invalidation relatively lightweight when an SVG effect changes.
static void InvalidateRenderingObservers(nsIFrame* aFrame);
enum ReferenceState {
/// Has no references to SVG filters (may still have CSS filter functions!)
* This can be called on any element or frame. Only direct observers of this
* (frame's) element, if any, are invalidated.
static void InvalidateDirectRenderingObservers(Element* aElement,
uint32_t aFlags = 0);
static void InvalidateDirectRenderingObservers(nsIFrame* aFrame,
uint32_t aFlags = 0);
* Get the paint server for aPaintedFrame.
static SVGPaintServerFrame* GetAndObservePaintServer(
nsIFrame* aPaintedFrame, mozilla::StyleSVGPaint nsStyleSVG::*aPaint);
* Get the start/mid/end-markers for the given frame, and add the frame as
* an observer to those markers. Returns true if at least one marker type is
* found, false otherwise.
static bool GetAndObserveMarkers(nsIFrame* aMarkedFrame,
SVGMarkerFrame* (*aFrames)[3]);
* Get the frames of the SVG filters applied to the given frame, and add the
* frame as an observer to those filter frames.
* NOTE! A return value of eHasNoRefs does NOT mean that there are no filters
* to be applied, only that there are no references to SVG filter elements.
* XXX Callers other than ComputePostEffectsInkOverflowRect and
* SVGUtils::GetPostFilterInkOverflowRect should not need to initiate
* observing. If we have a bug that causes invalidation (which would remove
* observers) between reflow and painting, then we don't really want to
* re-add abservers during painting. That has the potential to hide logic
* bugs, or cause later invalidation problems. However, let's not change
* that behavior just yet due to the regression potential.
static ReferenceState GetAndObserveFilters(
nsIFrame* aFilteredFrame, nsTArray<SVGFilterFrame*>* aFilterFrames);
* If the given frame is already observing SVG filters, this function gets
* those filters. If the frame is not already observing filters this
* function assumes that it doesn't have anything to observe.
static ReferenceState GetFiltersIfObserving(
nsIFrame* aFilteredFrame, nsTArray<SVGFilterFrame*>* aFilterFrames);
* Starts observing filters for a <canvas> element's CanvasRenderingContext2D.
* Returns a RAII object that the caller should make sure is released once
* the CanvasRenderingContext2D is no longer using them (that is, when the
* CanvasRenderingContext2D "drawing style state" on which the filters were
* set is destroyed or has its filter style reset).
* XXXjwatt: It's a bit unfortunate that both we and
* CanvasRenderingContext2D::UpdateFilter process the list of StyleFilter
* objects separately. It would be better to refactor things so that we only
* do that work once.
static already_AddRefed<nsISupports> ObserveFiltersForCanvasContext(
CanvasRenderingContext2D* aContext, Element* aCanvasElement,
Span<const StyleFilter> aFilters);
* Called when cycle collecting CanvasRenderingContext2D, and requires the
* RAII object returned from ObserveFiltersForCanvasContext to be passed in.
* XXXjwatt: I don't think this is doing anything useful. All we do under
* this function is clear a raw C-style (i.e. not strong) pointer. That's
* clearly not helping in breaking any cycles. The fact that we MOZ_CRASH
* in OnRenderingChange if that pointer is null indicates that this isn't
* even doing anything useful in terms of preventing further invalidation
* from any observed filters.
static void DetachFromCanvasContext(nsISupports* aAutoObserver);
* Get the frame of the SVG clipPath applied to aClippedFrame, if any, and
* set up aClippedFrame as a rendering observer of the clipPath's frame, to
* be invalidated if it changes.
* Currently we only have support for 'clip-path' with a single item, but the
* spec. now says 'clip-path' can be set to an arbitrary number of items.
* Once we support that, aClipPathFrame will need to be an nsTArray as it
* is for 'filter' and 'mask'. Currently a return value of eHasNoRefs means
* that there is no clipping at all, but once we support more than one item
* then - as for filter and mask - we could still have basic shape clipping
* to apply even if there are no references to SVG clipPath elements.
* Note that, unlike for filters, a reference to an ID that doesn't exist
* is not invalid for clip-path or mask. We will return eHasNoRefs in that
* case.
static ReferenceState GetAndObserveClipPath(
nsIFrame* aClippedFrame, SVGClipPathFrame** aClipPathFrame);
* If masking is applied to aMaskedFrame, gets an array of any SVG masks
* that are referenced, setting up aMaskFrames as a rendering observer of
* those masks (if any).
* NOTE! A return value of eHasNoRefs does NOT mean that there are no masks
* to be applied, only that there are no references to SVG mask elements.
* Note that, unlike for filters, a reference to an ID that doesn't exist
* is not invalid for clip-path or mask. We will return eHasNoRefs in that
* case.
static ReferenceState GetAndObserveMasks(
nsIFrame* aMaskedFrame, nsTArray<SVGMaskFrame*>* aMaskFrames);
* Get the SVGGeometryElement that is referenced by aTextPathFrame, and make
* aTextPathFrame start observing rendering changes to that element.
static SVGGeometryElement* GetAndObserveTextPathsPath(
nsIFrame* aTextPathFrame);
* Make aTextPathFrame stop observing rendering changes to the
* SVGGeometryElement that it references, if any.
static void RemoveTextPathObserver(nsIFrame* aTextPathFrame);
* Gets the nsIFrame of a referenced SVG "template" element, if any, and
* makes aFrame start observing rendering changes to the template element.
* Template elements: some elements like gradients, pattern or filter can
* reference another element of the same type using their 'href' attribute,
* and use that element as a template that provides attributes or content
* that is missing from the referring element.
* The frames that this function is called for do not have a common base
* class, which is why it is necessary to pass in a function that can be
* used as a callback to lazily get the href value, if necessary.
static nsIFrame* GetAndObserveTemplate(nsIFrame* aFrame,
HrefToTemplateCallback aGetHref);
static void RemoveTemplateObserver(nsIFrame* aFrame);
* Gets an arbitrary element and starts observing it. Used to implement
* '-moz-element'.
* Note that bug 1496065 has been filed to remove support for referencing
* arbitrary elements using '-moz-element'.
static Element* GetAndObserveBackgroundImage(nsIFrame* aFrame,
const nsAtom* aHref);
* Gets an arbitrary element and starts observing it. Used to detect
* invalidation changes for background-clip:text.
static Element* GetAndObserveBackgroundClip(nsIFrame* aFrame);
* A helper function to resolve filter URL.
static already_AddRefed<URLAndReferrerInfo> GetFilterURI(
nsIFrame* aFrame, const StyleFilter& aFilter);
* Return a baseURL for resolving a local-ref URL.
* @param aContent an element which uses a local-ref property. Here are some
* examples:
* <rect fill=url(#foo)>
* <circle clip-path=url(#foo)>
* <use xlink:href="#foo">
static already_AddRefed<nsIURI> GetBaseURLForLocalRef(nsIContent* aContent,
nsIURI* aDocURI);
} // namespace mozilla