1 files changed, 233 insertions, 0 deletions
diff --git a/gfx/layers/apz/src/FocusTarget.cpp b/gfx/layers/apz/src/FocusTarget.cpp
new file mode 100644
index 0000000000..f1f6463e5c
--- /dev/null
+++ b/gfx/layers/apz/src/FocusTarget.cpp
@@ -0,0 +1,233 @@
+/* -*- 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 http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/layers/FocusTarget.h"
+#include "mozilla/dom/BrowserBridgeChild.h"  // for BrowserBridgeChild
+#include "mozilla/dom/EventTarget.h"         // for EventTarget
+#include "mozilla/dom/RemoteBrowser.h"       // For RemoteBrowser
+#include "mozilla/EventDispatcher.h"         // for EventDispatcher
+#include "mozilla/PresShell.h"               // For PresShell
+#include "mozilla/StaticPrefs_apz.h"
+#include "nsIContentInlines.h"  // for nsINode::IsEditable()
+#include "nsLayoutUtils.h"      // for nsLayoutUtils
+
+static mozilla::LazyLogModule sApzFtgLog("apz.focustarget");
+#define FT_LOG(...) MOZ_LOG(sApzFtgLog, LogLevel::Debug, (__VA_ARGS__))
+
+using namespace mozilla::dom;
+using namespace mozilla::layout;
+
+namespace mozilla {
+namespace layers {
+
+static PresShell* GetRetargetEventPresShell(PresShell* aRootPresShell) {
+  MOZ_ASSERT(aRootPresShell);
+
+  // Use the last focused window in this PresShell and its
+  // associated PresShell
+  nsCOMPtr<nsPIDOMWindowOuter> window =
+      aRootPresShell->GetFocusedDOMWindowInOurWindow();
+  if (!window) {
+    return nullptr;
+  }
+
+  RefPtr<Document> retargetEventDoc = window->GetExtantDoc();
+  if (!retargetEventDoc) {
+    return nullptr;
+  }
+
+  return retargetEventDoc->GetPresShell();
+}
+
+// _BOUNDARY because Dispatch() with `targets` must not handle the event.
+MOZ_CAN_RUN_SCRIPT_BOUNDARY static bool HasListenersForKeyEvents(
+    nsIContent* aContent) {
+  if (!aContent) {
+    return false;
+  }
+
+  WidgetEvent event(true, eVoidEvent);
+  nsTArray<EventTarget*> targets;
+  nsresult rv = EventDispatcher::Dispatch(aContent, nullptr, &event, nullptr,
+                                          nullptr, nullptr, &targets);
+  NS_ENSURE_SUCCESS(rv, false);
+  for (size_t i = 0; i < targets.Length(); i++) {
+    if (targets[i]->HasNonSystemGroupListenersForUntrustedKeyEvents()) {
+      return true;
+    }
+  }
+  return false;
+}
+
+// _BOUNDARY because Dispatch() with `targets` must not handle the event.
+MOZ_CAN_RUN_SCRIPT_BOUNDARY static bool HasListenersForNonPassiveKeyEvents(
+    nsIContent* aContent) {
+  if (!aContent) {
+    return false;
+  }
+
+  WidgetEvent event(true, eVoidEvent);
+  nsTArray<EventTarget*> targets;
+  nsresult rv = EventDispatcher::Dispatch(aContent, nullptr, &event, nullptr,
+                                          nullptr, nullptr, &targets);
+  NS_ENSURE_SUCCESS(rv, false);
+  for (size_t i = 0; i < targets.Length(); i++) {
+    if (targets[i]
+            ->HasNonPassiveNonSystemGroupListenersForUntrustedKeyEvents()) {
+      return true;
+    }
+  }
+  return false;
+}
+
+static bool IsEditableNode(nsINode* aNode) {
+  return aNode && aNode->IsEditable();
+}
+
+FocusTarget::FocusTarget()
+    : mSequenceNumber(0),
+      mFocusHasKeyEventListeners(false),
+      mData(AsVariant(NoFocusTarget())) {}
+
+FocusTarget::FocusTarget(PresShell* aRootPresShell,
+                         uint64_t aFocusSequenceNumber)
+    : mSequenceNumber(aFocusSequenceNumber),
+      mFocusHasKeyEventListeners(false),
+      mData(AsVariant(NoFocusTarget())) {
+  MOZ_ASSERT(aRootPresShell);
+  MOZ_ASSERT(NS_IsMainThread());
+
+  // Key events can be retargeted to a child PresShell when there is an iframe
+  RefPtr<PresShell> presShell = GetRetargetEventPresShell(aRootPresShell);
+
+  if (!presShell) {
+    FT_LOG("Creating nil target with seq=%" PRIu64
+           " (can't find retargeted presshell)\n",
+           aFocusSequenceNumber);
+
+    return;
+  }
+
+  RefPtr<Document> document = presShell->GetDocument();
+  if (!document) {
+    FT_LOG("Creating nil target with seq=%" PRIu64 " (no document)\n",
+           aFocusSequenceNumber);
+
+    return;
+  }
+
+  // Find the focused content and use it to determine whether there are key
+  // event listeners or whether key events will be targeted at a different
+  // process through a remote browser.
+  nsCOMPtr<nsIContent> focusedContent =
+      presShell->GetFocusedContentInOurWindow();
+  nsCOMPtr<nsIContent> keyEventTarget = focusedContent;
+
+  // If there is no focused element then event dispatch goes to the body of
+  // the page if it exists or the root element.
+  if (!keyEventTarget) {
+    keyEventTarget = document->GetUnfocusedKeyEventTarget();
+  }
+
+  // Check if there are key event listeners that could prevent default or change
+  // the focus or selection of the page.
+  if (StaticPrefs::apz_keyboard_passive_listeners()) {
+    mFocusHasKeyEventListeners =
+        HasListenersForNonPassiveKeyEvents(keyEventTarget.get());
+  } else {
+    mFocusHasKeyEventListeners = HasListenersForKeyEvents(keyEventTarget.get());
+  }
+
+  // Check if the key event target is content editable or if the document
+  // is in design mode.
+  if (IsEditableNode(keyEventTarget) || IsEditableNode(document)) {
+    FT_LOG("Creating nil target with seq=%" PRIu64
+           ", kl=%d (disabling for editable node)\n",
+           aFocusSequenceNumber, static_cast<int>(mFocusHasKeyEventListeners));
+
+    return;
+  }
+
+  // Check if the key event target is a remote browser
+  if (RemoteBrowser* remoteBrowser = RemoteBrowser::GetFrom(keyEventTarget)) {
+    LayersId layersId = remoteBrowser->GetLayersId();
+
+    // The globally focused element for scrolling is in a remote layer tree
+    if (layersId.IsValid()) {
+      FT_LOG("Creating reflayer target with seq=%" PRIu64 ", kl=%d, lt=%" PRIu64
+             "\n",
+             aFocusSequenceNumber, mFocusHasKeyEventListeners, layersId.mId);
+
+      mData = AsVariant<LayersId>(std::move(layersId));
+      return;
+    }
+
+    FT_LOG("Creating nil target with seq=%" PRIu64
+           ", kl=%d (remote browser missing layers id)\n",
+           aFocusSequenceNumber, mFocusHasKeyEventListeners);
+
+    return;
+  }
+
+  // The content to scroll is either the focused element or the focus node of
+  // the selection. It's difficult to determine if an element is an interactive
+  // element requiring async keyboard scrolling to be disabled. So we only
+  // allow async key scrolling based on the selection, which doesn't have
+  // this problem and is more common.
+  if (focusedContent) {
+    FT_LOG("Creating nil target with seq=%" PRIu64
+           ", kl=%d (disabling for focusing an element)\n",
+           aFocusSequenceNumber, mFocusHasKeyEventListeners);
+
+    return;
+  }
+
+  nsCOMPtr<nsIContent> selectedContent =
+      presShell->GetSelectedContentForScrolling();
+
+  // Gather the scrollable frames that would be scrolled in each direction
+  // for this scroll target
+  nsIScrollableFrame* horizontal =
+      presShell->GetScrollableFrameToScrollForContent(
+          selectedContent.get(), HorizontalScrollDirection);
+  nsIScrollableFrame* vertical =
+      presShell->GetScrollableFrameToScrollForContent(selectedContent.get(),
+                                                      VerticalScrollDirection);
+
+  // We might have the globally focused element for scrolling. Gather a ViewID
+  // for the horizontal and vertical scroll targets of this element.
+  ScrollTargets target;
+  target.mHorizontal = nsLayoutUtils::FindIDForScrollableFrame(horizontal);
+  target.mVertical = nsLayoutUtils::FindIDForScrollableFrame(vertical);
+  mData = AsVariant(target);
+
+  FT_LOG("Creating scroll target with seq=%" PRIu64 ", kl=%d, h=%" PRIu64
+         ", v=%" PRIu64 "\n",
+         aFocusSequenceNumber, mFocusHasKeyEventListeners, target.mHorizontal,
+         target.mVertical);
+}
+
+bool FocusTarget::operator==(const FocusTarget& aRhs) const {
+  return mSequenceNumber == aRhs.mSequenceNumber &&
+         mFocusHasKeyEventListeners == aRhs.mFocusHasKeyEventListeners &&
+         mData == aRhs.mData;
+}
+
+const char* FocusTarget::Type() const {
+  if (mData.is<LayersId>()) {
+    return "LayersId";
+  }
+  if (mData.is<ScrollTargets>()) {
+    return "ScrollTargets";
+  }
+  if (mData.is<NoFocusTarget>()) {
+    return "NoFocusTarget";
+  }
+  return "<unknown>";
+}
+
+}  // namespace layers
+}  // namespace mozilla