1 files changed, 410 insertions, 0 deletions
diff --git a/layout/generic/ScrollbarActivity.cpp b/layout/generic/ScrollbarActivity.cpp
new file mode 100644
index 0000000000..ac5ded26f8
--- /dev/null
+++ b/layout/generic/ScrollbarActivity.cpp
@@ -0,0 +1,410 @@
+/* -*- 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 "ScrollbarActivity.h"
+#include "nsIScrollbarMediator.h"
+#include "nsIContent.h"
+#include "nsICSSDeclaration.h"
+#include "nsIFrame.h"
+#include "nsContentUtils.h"
+#include "nsAString.h"
+#include "nsQueryFrame.h"
+#include "nsComponentManagerUtils.h"
+#include "nsStyledElement.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/Event.h"
+#include "mozilla/LookAndFeel.h"
+#include "mozilla/StaticPrefs_layout.h"
+
+namespace mozilla {
+namespace layout {
+
+using mozilla::dom::Element;
+
+NS_IMPL_ISUPPORTS(ScrollbarActivity, nsIDOMEventListener)
+
+void ScrollbarActivity::QueryLookAndFeelVals() {
+  // Fade animation constants
+  mScrollbarFadeBeginDelay =
+      LookAndFeel::GetInt(LookAndFeel::IntID::ScrollbarFadeBeginDelay);
+  mScrollbarFadeDuration =
+      LookAndFeel::GetInt(LookAndFeel::IntID::ScrollbarFadeDuration);
+  // Controls whether we keep the mouse move listener so we can display the
+  // scrollbars whenever the user moves the mouse within the scroll area.
+  mDisplayOnMouseMove =
+      LookAndFeel::GetInt(LookAndFeel::IntID::ScrollbarDisplayOnMouseMove);
+}
+
+void ScrollbarActivity::Destroy() {
+  StopListeningForScrollbarEvents();
+  StopListeningForScrollAreaEvents();
+  UnregisterFromRefreshDriver();
+  CancelFadeBeginTimer();
+}
+
+void ScrollbarActivity::ActivityOccurred() {
+  ActivityStarted();
+  ActivityStopped();
+}
+
+void ScrollbarActivity::ActivityStarted() {
+  mNestedActivityCounter++;
+  CancelFadeBeginTimer();
+  if (!SetIsFading(false)) {
+    return;
+  }
+  UnregisterFromRefreshDriver();
+  StartListeningForScrollbarEvents();
+  StartListeningForScrollAreaEvents();
+  SetIsActive(true);
+
+  NS_ASSERTION(mIsActive, "need to be active during activity");
+  NS_ASSERTION(!mIsFading, "must not be fading during activity");
+}
+
+void ScrollbarActivity::ActivityStopped() {
+  if (!IsActivityOngoing()) {
+    // This can happen if there was a frame reconstruction while the activity
+    // was ongoing. In this case we just do nothing. We should probably handle
+    // this case better.
+    return;
+  }
+  NS_ASSERTION(mIsActive, "need to be active during activity");
+  NS_ASSERTION(!mIsFading, "must not be fading during ongoing activity");
+
+  mNestedActivityCounter--;
+
+  if (!IsActivityOngoing()) {
+    StartFadeBeginTimer();
+
+    NS_ASSERTION(mIsActive, "need to be active right after activity");
+    NS_ASSERTION(!mIsFading, "must not be fading right after activity");
+  }
+}
+
+NS_IMETHODIMP
+ScrollbarActivity::HandleEvent(dom::Event* aEvent) {
+  if (!mDisplayOnMouseMove && !mIsActive) return NS_OK;
+
+  nsAutoString type;
+  aEvent->GetType(type);
+
+  if (type.EqualsLiteral("mousemove")) {
+    // Mouse motions anywhere in the scrollable frame should keep the
+    // scrollbars visible.
+    ActivityOccurred();
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIContent> targetContent =
+      do_QueryInterface(aEvent->GetOriginalTarget());
+
+  HandleEventForScrollbar(type, targetContent, GetHorizontalScrollbar(),
+                          &mHScrollbarHovered);
+  HandleEventForScrollbar(type, targetContent, GetVerticalScrollbar(),
+                          &mVScrollbarHovered);
+
+  return NS_OK;
+}
+
+void ScrollbarActivity::WillRefresh(TimeStamp aTime) {
+  NS_ASSERTION(mIsActive, "should only fade while scrollbars are visible");
+  NS_ASSERTION(!IsActivityOngoing(),
+               "why weren't we unregistered from the refresh driver when "
+               "scrollbar activity started?");
+  NS_ASSERTION(mIsFading, "should only animate fading during fade");
+
+  if (!UpdateOpacity(aTime)) {
+    return;
+  }
+
+  if (!IsStillFading(aTime)) {
+    EndFade();
+  }
+}
+
+bool ScrollbarActivity::IsStillFading(TimeStamp aTime) {
+  return !mFadeBeginTime.IsNull() && (aTime - mFadeBeginTime < FadeDuration());
+}
+
+void ScrollbarActivity::HandleEventForScrollbar(const nsAString& aType,
+                                                nsIContent* aTarget,
+                                                Element* aScrollbar,
+                                                bool* aStoredHoverState) {
+  if (!aTarget || !aScrollbar || !aTarget->IsInclusiveDescendantOf(aScrollbar))
+    return;
+
+  if (aType.EqualsLiteral("mousedown")) {
+    ActivityStarted();
+  } else if (aType.EqualsLiteral("mouseup")) {
+    ActivityStopped();
+  } else if (aType.EqualsLiteral("mouseover") ||
+             aType.EqualsLiteral("mouseout")) {
+    bool newHoveredState = aType.EqualsLiteral("mouseover");
+    if (newHoveredState && !*aStoredHoverState) {
+      ActivityStarted();
+      HoveredScrollbar(aScrollbar);
+    } else if (*aStoredHoverState && !newHoveredState) {
+      ActivityStopped();
+      // Don't call HoveredScrollbar(nullptr) here because we want the hover
+      // attribute to stick until the scrollbars are hidden.
+    }
+    *aStoredHoverState = newHoveredState;
+  }
+}
+
+void ScrollbarActivity::StartListeningForScrollbarEvents() {
+  if (mListeningForScrollbarEvents) return;
+
+  mHorizontalScrollbar = GetHorizontalScrollbar();
+  mVerticalScrollbar = GetVerticalScrollbar();
+
+  AddScrollbarEventListeners(mHorizontalScrollbar);
+  AddScrollbarEventListeners(mVerticalScrollbar);
+
+  mListeningForScrollbarEvents = true;
+}
+
+void ScrollbarActivity::StopListeningForScrollbarEvents() {
+  if (!mListeningForScrollbarEvents) return;
+
+  RemoveScrollbarEventListeners(mHorizontalScrollbar);
+  RemoveScrollbarEventListeners(mVerticalScrollbar);
+
+  mHorizontalScrollbar = nullptr;
+  mVerticalScrollbar = nullptr;
+  mListeningForScrollbarEvents = false;
+}
+
+void ScrollbarActivity::StartListeningForScrollAreaEvents() {
+  if (mListeningForScrollAreaEvents) return;
+
+  nsIFrame* scrollArea = do_QueryFrame(mScrollableFrame);
+  scrollArea->GetContent()->AddEventListener(u"mousemove"_ns, this, true);
+  mListeningForScrollAreaEvents = true;
+}
+
+void ScrollbarActivity::StopListeningForScrollAreaEvents() {
+  if (!mListeningForScrollAreaEvents) return;
+
+  nsIFrame* scrollArea = do_QueryFrame(mScrollableFrame);
+  scrollArea->GetContent()->RemoveEventListener(u"mousemove"_ns, this, true);
+  mListeningForScrollAreaEvents = false;
+}
+
+void ScrollbarActivity::AddScrollbarEventListeners(
+    dom::EventTarget* aScrollbar) {
+  if (aScrollbar) {
+    aScrollbar->AddEventListener(u"mousedown"_ns, this, true);
+    aScrollbar->AddEventListener(u"mouseup"_ns, this, true);
+    aScrollbar->AddEventListener(u"mouseover"_ns, this, true);
+    aScrollbar->AddEventListener(u"mouseout"_ns, this, true);
+  }
+}
+
+void ScrollbarActivity::RemoveScrollbarEventListeners(
+    dom::EventTarget* aScrollbar) {
+  if (aScrollbar) {
+    aScrollbar->RemoveEventListener(u"mousedown"_ns, this, true);
+    aScrollbar->RemoveEventListener(u"mouseup"_ns, this, true);
+    aScrollbar->RemoveEventListener(u"mouseover"_ns, this, true);
+    aScrollbar->RemoveEventListener(u"mouseout"_ns, this, true);
+  }
+}
+
+void ScrollbarActivity::BeginFade() {
+  NS_ASSERTION(mIsActive, "can't begin fade when we're already inactive");
+  NS_ASSERTION(!IsActivityOngoing(),
+               "why wasn't the fade begin timer cancelled when scrollbar "
+               "activity started?");
+  NS_ASSERTION(!mIsFading, "shouldn't be fading just yet");
+
+  CancelFadeBeginTimer();
+  mFadeBeginTime = TimeStamp::Now();
+  if (!SetIsFading(true)) {
+    return;
+  }
+  RegisterWithRefreshDriver();
+
+  NS_ASSERTION(mIsActive, "only fade while scrollbars are visible");
+  NS_ASSERTION(mIsFading, "should be fading now");
+}
+
+void ScrollbarActivity::EndFade() {
+  NS_ASSERTION(mIsActive, "still need to be active at this point");
+  NS_ASSERTION(!IsActivityOngoing(),
+               "why wasn't the fade end timer cancelled when scrollbar "
+               "activity started?");
+
+  if (!SetIsFading(false)) {
+    return;
+  }
+  SetIsActive(false);
+  UnregisterFromRefreshDriver();
+  StopListeningForScrollbarEvents();
+  if (!mDisplayOnMouseMove) {
+    StopListeningForScrollAreaEvents();
+  }
+
+  NS_ASSERTION(!mIsActive, "should have gone inactive after fade end");
+  NS_ASSERTION(!mIsFading, "shouldn't be fading anymore");
+}
+
+void ScrollbarActivity::RegisterWithRefreshDriver() {
+  nsRefreshDriver* refreshDriver = GetRefreshDriver();
+  if (refreshDriver) {
+    refreshDriver->AddRefreshObserver(this, FlushType::Style,
+                                      "Scrollbar fade animation");
+  }
+}
+
+void ScrollbarActivity::UnregisterFromRefreshDriver() {
+  nsRefreshDriver* refreshDriver = GetRefreshDriver();
+  if (refreshDriver) {
+    refreshDriver->RemoveRefreshObserver(this, FlushType::Style);
+  }
+}
+
+static void SetBooleanAttribute(Element* aElement, nsAtom* aAttribute,
+                                bool aValue) {
+  if (aElement) {
+    if (aValue) {
+      aElement->SetAttr(kNameSpaceID_None, aAttribute, u"true"_ns, true);
+    } else {
+      aElement->UnsetAttr(kNameSpaceID_None, aAttribute, true);
+    }
+  }
+}
+
+void ScrollbarActivity::SetIsActive(bool aNewActive) {
+  if (mIsActive == aNewActive) return;
+
+  mIsActive = aNewActive;
+  if (!mIsActive) {
+    // Clear sticky scrollbar hover status.
+    HoveredScrollbar(nullptr);
+  }
+
+  SetBooleanAttribute(GetHorizontalScrollbar(), nsGkAtoms::active, mIsActive);
+  SetBooleanAttribute(GetVerticalScrollbar(), nsGkAtoms::active, mIsActive);
+}
+
+static void SetOpacityOnElement(nsIContent* aContent, double aOpacity) {
+  if (RefPtr<nsStyledElement> inlineStyleContent =
+          nsStyledElement::FromNodeOrNull(aContent)) {
+    nsICSSDeclaration* decl = inlineStyleContent->Style();
+    nsAutoCString str;
+    str.AppendFloat(aOpacity);
+    decl->SetProperty("opacity"_ns, str, EmptyCString(), IgnoreErrors());
+  }
+}
+
+bool ScrollbarActivity::UpdateOpacity(TimeStamp aTime) {
+  // Avoid division by zero if mScrollbarFadeDuration is zero, just jump
+  // to the end of the fade animation
+  double progress = mScrollbarFadeDuration
+                        ? ((aTime - mFadeBeginTime) / FadeDuration())
+                        : 1.0;
+  double opacity = 1.0 - std::max(0.0, std::min(1.0, progress));
+
+  // 'this' may be getting destroyed during SetOpacityOnElement calls.
+  AutoWeakFrame weakFrame((do_QueryFrame(mScrollableFrame)));
+  SetOpacityOnElement(GetHorizontalScrollbar(), opacity);
+  if (!weakFrame.IsAlive()) {
+    return false;
+  }
+  SetOpacityOnElement(GetVerticalScrollbar(), opacity);
+  if (!weakFrame.IsAlive()) {
+    return false;
+  }
+  return true;
+}
+
+static void UnsetOpacityOnElement(nsIContent* aContent) {
+  if (RefPtr<nsStyledElement> inlineStyleContent =
+          nsStyledElement::FromNodeOrNull(aContent)) {
+    nsICSSDeclaration* decl = inlineStyleContent->Style();
+    nsAutoCString dummy;
+    decl->RemoveProperty("opacity"_ns, dummy, IgnoreErrors());
+  }
+}
+
+bool ScrollbarActivity::SetIsFading(bool aNewFading) {
+  if (mIsFading == aNewFading) return true;
+
+  mIsFading = aNewFading;
+  if (!mIsFading) {
+    mFadeBeginTime = TimeStamp();
+    // 'this' may be getting destroyed during UnsetOpacityOnElement calls.
+    AutoWeakFrame weakFrame((do_QueryFrame(mScrollableFrame)));
+    UnsetOpacityOnElement(GetHorizontalScrollbar());
+    if (!weakFrame.IsAlive()) {
+      return false;
+    }
+    UnsetOpacityOnElement(GetVerticalScrollbar());
+    if (!weakFrame.IsAlive()) {
+      return false;
+    }
+  }
+  return true;
+}
+
+void ScrollbarActivity::StartFadeBeginTimer() {
+  if (StaticPrefs::layout_testing_overlay_scrollbars_always_visible()) {
+    return;
+  }
+  if (!mFadeBeginTimer) {
+    mFadeBeginTimer = NS_NewTimer();
+  }
+  mFadeBeginTimer->InitWithNamedFuncCallback(
+      FadeBeginTimerFired, this, mScrollbarFadeBeginDelay,
+      nsITimer::TYPE_ONE_SHOT, "ScrollbarActivity::FadeBeginTimerFired");
+}
+
+void ScrollbarActivity::CancelFadeBeginTimer() {
+  if (mFadeBeginTimer) {
+    mFadeBeginTimer->Cancel();
+  }
+}
+
+static void MaybeInvalidateScrollbarForHover(
+    Element* aScrollbarToInvalidate, Element* aScrollbarAboutToGetHover) {
+  if (aScrollbarToInvalidate) {
+    bool hasHover =
+        aScrollbarToInvalidate->HasAttr(kNameSpaceID_None, nsGkAtoms::hover);
+    bool willHaveHover = (aScrollbarAboutToGetHover == aScrollbarToInvalidate);
+
+    if (hasHover != willHaveHover) {
+      if (nsIFrame* f = aScrollbarToInvalidate->GetPrimaryFrame()) {
+        f->SchedulePaint();
+      }
+    }
+  }
+}
+
+void ScrollbarActivity::HoveredScrollbar(Element* aScrollbar) {
+  Element* vertScrollbar = GetVerticalScrollbar();
+  Element* horzScrollbar = GetHorizontalScrollbar();
+  MaybeInvalidateScrollbarForHover(vertScrollbar, aScrollbar);
+  MaybeInvalidateScrollbarForHover(horzScrollbar, aScrollbar);
+
+  SetBooleanAttribute(horzScrollbar, nsGkAtoms::hover, false);
+  SetBooleanAttribute(vertScrollbar, nsGkAtoms::hover, false);
+  SetBooleanAttribute(aScrollbar, nsGkAtoms::hover, true);
+}
+
+nsRefreshDriver* ScrollbarActivity::GetRefreshDriver() {
+  nsIFrame* scrollableFrame = do_QueryFrame(mScrollableFrame);
+  return scrollableFrame->PresContext()->RefreshDriver();
+}
+
+Element* ScrollbarActivity::GetScrollbarContent(bool aVertical) {
+  nsIFrame* box = mScrollableFrame->GetScrollbarBox(aVertical);
+  return box ? box->GetContent()->AsElement() : nullptr;
+}
+
+}  // namespace layout
+}  // namespace mozilla