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Diffstat (limited to 'dom/base/ResizeObserver.h')
| -rw-r--r-- | dom/base/ResizeObserver.h | 254 |
1 files changed, 254 insertions, 0 deletions
diff --git a/dom/base/ResizeObserver.h b/dom/base/ResizeObserver.h new file mode 100644 index 000000000..2f56c580f --- /dev/null +++ b/dom/base/ResizeObserver.h @@ -0,0 +1,254 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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 http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_ResizeObserver_h
+#define mozilla_dom_ResizeObserver_h
+
+#include "mozilla/dom/ResizeObserverBinding.h"
+
+namespace mozilla {
+namespace dom {
+
+/**
+ * ResizeObserver interfaces and algorithms are based on
+ * https://wicg.github.io/ResizeObserver/#api
+ */
+class ResizeObserver final
+ : public nsISupports
+ , public nsWrapperCache
+{
+public:
+ NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+ NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(ResizeObserver)
+
+ ResizeObserver(already_AddRefed<nsPIDOMWindowInner>&& aOwner,
+ ResizeObserverCallback& aCb)
+ : mOwner(aOwner)
+ , mCallback(&aCb)
+ {
+ MOZ_ASSERT(mOwner, "Need a non-null owner window");
+ }
+
+ static already_AddRefed<ResizeObserver>
+ Constructor(const GlobalObject& aGlobal,
+ ResizeObserverCallback& aCb,
+ ErrorResult& aRv);
+
+ JSObject* WrapObject(JSContext* aCx,
+ JS::Handle<JSObject*> aGivenProto) override
+ {
+ return ResizeObserverBinding::Wrap(aCx, this, aGivenProto);
+ }
+
+ nsISupports* GetParentObject() const
+ {
+ return mOwner;
+ }
+
+ void Observe(Element* aTarget, ErrorResult& aRv);
+
+ void Unobserve(Element* aTarget, ErrorResult& aRv);
+
+ void Disconnect();
+
+ /*
+ * Gather all observations which have an observed target with size changed
+ * since last BroadcastActiveObservations() in this ResizeObserver.
+ * An observation will be skipped if the depth of its observed target is less
+ * or equal than aDepth. All gathered observations will be added to
+ * mActiveTargets.
+ */
+ void GatherActiveObservations(uint32_t aDepth);
+
+ /*
+ * Returns whether this ResizeObserver has any active observations
+ * since last GatherActiveObservations().
+ */
+ bool HasActiveObservations() const;
+
+ /*
+ * Returns whether this ResizeObserver has any skipped observations
+ * since last GatherActiveObservations().
+ */
+ bool HasSkippedObservations() const;
+
+ /*
+ * Deliver the callback function in JavaScript for all active observations
+ * and pass the sequence of ResizeObserverEntry so JavaScript can access them.
+ * The broadcast size of observations will be updated and mActiveTargets will
+ * be cleared. It also returns the shallowest depth of elements from active
+ * observations or UINT32_MAX if there is no any active observations.
+ */
+ uint32_t BroadcastActiveObservations();
+
+protected:
+ ~ResizeObserver()
+ {
+ mObservationList.clear();
+ }
+
+ nsCOMPtr<nsPIDOMWindowInner> mOwner;
+ RefPtr<ResizeObserverCallback> mCallback;
+ nsTArray<RefPtr<ResizeObservation>> mActiveTargets;
+ bool mHasSkippedTargets;
+
+ // Combination of HashTable and LinkedList so we can iterate through
+ // the elements of HashTable in order of insertion time.
+ // Will be nice if we have our own data structure for this in the future.
+ nsRefPtrHashtable<nsPtrHashKey<Element>, ResizeObservation> mObservationMap;
+ LinkedList<ResizeObservation> mObservationList;
+};
+
+/**
+ * ResizeObserverEntry is the entry that contains the information for observed
+ * elements. This object is the one that visible to JavaScript in callback
+ * function that is fired by ResizeObserver.
+ */
+class ResizeObserverEntry final
+ : public nsISupports
+ , public nsWrapperCache
+{
+public:
+ NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+ NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(ResizeObserverEntry)
+
+ ResizeObserverEntry(nsISupports* aOwner, Element* aTarget)
+ : mOwner(aOwner)
+ , mTarget(aTarget)
+ {
+ MOZ_ASSERT(mOwner, "Need a non-null owner");
+ MOZ_ASSERT(mTarget, "Need a non-null target element");
+ }
+
+ static already_AddRefed<ResizeObserverEntry>
+ Constructor(const GlobalObject& aGlobal,
+ Element* aTarget,
+ ErrorResult& aRv);
+
+ JSObject* WrapObject(JSContext* aCx,
+ JS::Handle<JSObject*> aGivenProto) override
+ {
+ return ResizeObserverEntryBinding::Wrap(aCx, this,
+ aGivenProto);
+ }
+
+ nsISupports* GetParentObject() const
+ {
+ return mOwner;
+ }
+
+ Element* Target() const
+ {
+ return mTarget;
+ }
+
+ /*
+ * Returns the DOMRectReadOnly of target's content rect so it can be
+ * accessed from JavaScript in callback function of ResizeObserver.
+ */
+ DOMRectReadOnly* GetContentRect() const
+ {
+ return mContentRect;
+ }
+
+ void SetContentRect(nsRect aRect);
+
+protected:
+ ~ResizeObserverEntry();
+
+ nsCOMPtr<nsISupports> mOwner;
+ nsCOMPtr<Element> mTarget;
+ RefPtr<DOMRectReadOnly> mContentRect;
+};
+
+/**
+ * We use ResizeObservation to store and sync the size information of one
+ * observed element so we can decide whether an observation should be fired
+ * or not.
+ */
+class ResizeObservation final
+ : public nsISupports
+ , public nsWrapperCache
+ , public LinkedListElement<ResizeObservation>
+{
+public:
+ NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+ NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(ResizeObservation)
+
+ ResizeObservation(nsISupports* aOwner, Element* aTarget)
+ : mOwner(aOwner)
+ , mTarget(aTarget)
+ , mBroadcastWidth(0)
+ , mBroadcastHeight(0)
+ {
+ MOZ_ASSERT(mOwner, "Need a non-null owner");
+ MOZ_ASSERT(mTarget, "Need a non-null target element");
+ }
+
+ static already_AddRefed<ResizeObservation>
+ Constructor(const GlobalObject& aGlobal,
+ Element* aTarget,
+ ErrorResult& aRv);
+
+ JSObject* WrapObject(JSContext* aCx,
+ JS::Handle<JSObject*> aGivenProto) override
+ {
+ return ResizeObservationBinding::Wrap(aCx, this, aGivenProto);
+ }
+
+ nsISupports* GetParentObject() const
+ {
+ return mOwner;
+ }
+
+ Element* Target() const
+ {
+ return mTarget;
+ }
+
+ nscoord BroadcastWidth() const
+ {
+ return mBroadcastWidth;
+ }
+
+ nscoord BroadcastHeight() const
+ {
+ return mBroadcastHeight;
+ }
+
+ /*
+ * Returns whether the observed target element size differs from current
+ * BroadcastWidth and BroadcastHeight
+ */
+ bool IsActive() const;
+
+ /*
+ * Update current BroadcastWidth and BroadcastHeight with size from aRect.
+ */
+ void UpdateBroadcastSize(nsRect aRect);
+
+ /*
+ * Returns the target's rect in the form of nsRect.
+ * If the target is SVG, width and height are determined from bounding box.
+ */
+ nsRect GetTargetRect() const;
+
+protected:
+ ~ResizeObservation();
+
+ nsCOMPtr<nsISupports> mOwner;
+ nsCOMPtr<Element> mTarget;
+
+ // Broadcast width and broadcast height are the latest recorded size
+ // of observed target.
+ nscoord mBroadcastWidth;
+ nscoord mBroadcastHeight;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_ResizeObserver_h
+
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