Issue #1643 - Part 2: Implement ResizeObserver API

Implements ResizeObserver, ResizeObserverEntry and ResizeObservation

dom/base/ResizeObserver.cpp

@@ -0,0 +1,304 @@
+/* -*- 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/. */
+
+#include "mozilla/dom/ResizeObserver.h"
+
+#include "mozilla/dom/DOMRect.h"
+#include "nsContentUtils.h"
+#include "nsIFrame.h"
+#include "nsSVGUtils.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(ResizeObserver)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(ResizeObserver)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(ResizeObserver)
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(ResizeObserver)
+
+NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(ResizeObserver)
+  NS_IMPL_CYCLE_COLLECTION_TRACE_PRESERVED_WRAPPER
+NS_IMPL_CYCLE_COLLECTION_TRACE_END
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(ResizeObserver)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_PRESERVED_WRAPPER
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mOwner)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mCallback)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mObservationMap)
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(ResizeObserver)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mOwner)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mCallback)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mObservationMap)
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+already_AddRefed<ResizeObserver>
+ResizeObserver::Constructor(const GlobalObject& aGlobal,
+                            ResizeObserverCallback& aCb,
+                            ErrorResult& aRv)
+{
+  nsCOMPtr<nsPIDOMWindowInner> window =
+    do_QueryInterface(aGlobal.GetAsSupports());
+
+  if (!window) {
+    aRv.Throw(NS_ERROR_FAILURE);
+    return nullptr;
+  }
+
+  nsCOMPtr<nsIDocument> document = window->GetExtantDoc();
+
+  if (!document) {
+    aRv.Throw(NS_ERROR_FAILURE);
+    return nullptr;
+  }
+
+  RefPtr<ResizeObserver> observer = new ResizeObserver(window.forget(), aCb);
+  // TODO: Add the new ResizeObserver to document here in the later patch.
+
+  return observer.forget();
+}
+
+void
+ResizeObserver::Observe(Element* aTarget,
+                        ErrorResult& aRv)
+{
+  if (!aTarget) {
+    aRv.Throw(NS_ERROR_DOM_NOT_FOUND_ERR);
+    return;
+  }
+
+  RefPtr<ResizeObservation> observation;
+
+  if (!mObservationMap.Get(aTarget, getter_AddRefs(observation))) {
+    observation = new ResizeObservation(this, aTarget);
+
+    mObservationMap.Put(aTarget, observation);
+    mObservationList.insertBack(observation);
+
+    // Per the spec, we need to trigger notification in event loop that
+    // contains ResizeObserver observe call even when resize/reflow does
+    // not happen.
+    // TODO: Implement the notification scheduling in the later patch.
+  }
+}
+
+void
+ResizeObserver::Unobserve(Element* aTarget,
+                          ErrorResult& aRv)
+{
+  if (!aTarget) {
+    aRv.Throw(NS_ERROR_DOM_NOT_FOUND_ERR);
+    return;
+  }
+
+  RefPtr<ResizeObservation> observation;
+
+  if (mObservationMap.Get(aTarget, getter_AddRefs(observation))) {
+    mObservationMap.Remove(aTarget);
+
+    MOZ_ASSERT(!mObservationList.isEmpty(),
+               "If ResizeObservation found for an element, observation list "
+               "must be not empty.");
+
+    observation->remove();
+  }
+}
+
+void
+ResizeObserver::Disconnect()
+{
+  mObservationMap.Clear();
+  mObservationList.clear();
+  mActiveTargets.Clear();
+}
+
+void
+ResizeObserver::GatherActiveObservations(uint32_t aDepth)
+{
+  mActiveTargets.Clear();
+  mHasSkippedTargets = false;
+
+  for (auto observation : mObservationList) {
+    if (observation->IsActive()) {
+      uint32_t targetDepth =
+        nsContentUtils::GetNodeDepth(observation->Target());
+
+      if (targetDepth > aDepth) {
+        mActiveTargets.AppendElement(observation);
+      } else {
+        mHasSkippedTargets = true;
+      }
+    }
+  }
+}
+
+bool
+ResizeObserver::HasActiveObservations() const
+{
+  return !mActiveTargets.IsEmpty();
+}
+
+bool
+ResizeObserver::HasSkippedObservations() const
+{
+  return mHasSkippedTargets;
+}
+
+uint32_t
+ResizeObserver::BroadcastActiveObservations()
+{
+  uint32_t shallowestTargetDepth = UINT32_MAX;
+
+  if (HasActiveObservations()) {
+    Sequence<OwningNonNull<ResizeObserverEntry>> entries;
+
+    for (auto observation : mActiveTargets) {
+      RefPtr<ResizeObserverEntry> entry =
+        new ResizeObserverEntry(this, observation->Target());
+
+      nsRect rect = observation->GetTargetRect();
+      entry->SetContentRect(rect);
+
+      if (!entries.AppendElement(entry.forget(), fallible)) {
+        // Out of memory.
+        break;
+      }
+
+      // Sync the broadcast size of observation so the next size inspection
+      // will be based on the updated size from last delivered observations.
+      observation->UpdateBroadcastSize(rect);
+
+      uint32_t targetDepth =
+        nsContentUtils::GetNodeDepth(observation->Target());
+
+      if (targetDepth < shallowestTargetDepth) {
+        shallowestTargetDepth = targetDepth;
+      }
+    }
+
+    mCallback->Call(this, entries, *this);
+    mActiveTargets.Clear();
+    mHasSkippedTargets = false;
+  }
+
+  return shallowestTargetDepth;
+}
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(ResizeObserverEntry)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(ResizeObserverEntry)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(ResizeObserverEntry)
+
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(ResizeObserverEntry,
+                                      mTarget, mContentRect,
+                                      mOwner)
+
+already_AddRefed<ResizeObserverEntry>
+ResizeObserverEntry::Constructor(const GlobalObject& aGlobal,
+                                 Element* aTarget,
+                                 ErrorResult& aRv)
+{
+  RefPtr<ResizeObserverEntry> observerEntry =
+    new ResizeObserverEntry(aGlobal.GetAsSupports(), aTarget);
+  return observerEntry.forget();
+}
+
+void
+ResizeObserverEntry::SetContentRect(nsRect aRect)
+{
+  RefPtr<DOMRect> contentRect = new DOMRect(mTarget);
+  nsIFrame* frame = mTarget->GetPrimaryFrame();
+
+  if (frame) {
+    nsMargin padding = frame->GetUsedPadding();
+
+    // Per the spec, we need to include padding in contentRect of
+    // ResizeObserverEntry.
+    aRect.x = padding.left;
+    aRect.y = padding.top;
+  }
+
+  contentRect->SetLayoutRect(aRect);
+  mContentRect = contentRect.forget();
+}
+
+ResizeObserverEntry::~ResizeObserverEntry()
+{
+}
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(ResizeObservation)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(ResizeObservation)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(ResizeObservation)
+
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(ResizeObservation,
+                                      mTarget, mOwner)
+
+already_AddRefed<ResizeObservation>
+ResizeObservation::Constructor(const GlobalObject& aGlobal,
+                               Element* aTarget,
+                               ErrorResult& aRv)
+{
+  RefPtr<ResizeObservation> observation =
+    new ResizeObservation(aGlobal.GetAsSupports(), aTarget);
+  return observation.forget();
+}
+
+bool
+ResizeObservation::IsActive() const
+{
+  nsRect rect = GetTargetRect();
+  return (rect.width != mBroadcastWidth || rect.height != mBroadcastHeight);
+}
+
+void
+ResizeObservation::UpdateBroadcastSize(nsRect aRect)
+{
+  mBroadcastWidth = aRect.width;
+  mBroadcastHeight = aRect.height;
+}
+
+nsRect
+ResizeObservation::GetTargetRect() const
+{
+  nsRect rect;
+  nsIFrame* frame = mTarget->GetPrimaryFrame();
+
+  if (frame) {
+    if (mTarget->IsSVGElement()) {
+      gfxRect bbox = nsSVGUtils::GetBBox(frame);
+      rect.width = NSFloatPixelsToAppUnits(bbox.width, AppUnitsPerCSSPixel());
+      rect.height = NSFloatPixelsToAppUnits(bbox.height, AppUnitsPerCSSPixel());
+    } else {
+      // Per the spec, non-replaced inline Elements will always have an empty
+      // content rect.
+      if (frame->IsFrameOfType(nsIFrame::eReplaced) ||
+          !frame->IsFrameOfType(nsIFrame::eLineParticipant)) {
+        rect = frame->GetContentRectRelativeToSelf();
+      }
+    }
+  }
+
+  return rect;
+}
+
+ResizeObservation::~ResizeObservation()
+{
+}
+
+} // namespace dom
+} // namespace mozilla