1 files changed, 469 insertions, 0 deletions
diff --git a/layout/generic/ScrollbarActivity.cpp b/layout/generic/ScrollbarActivity.cpp
new file mode 100644
index 0000000000..78859bc2be
--- /dev/null
+++ b/layout/generic/ScrollbarActivity.cpp
@@ -0,0 +1,469 @@
+/* -*- Mode: C++; tab-width: 2; 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 "ScrollbarActivity.h"
+#include "nsIScrollbarMediator.h"
+#include "nsIContent.h"
+#include "nsICSSDeclaration.h"
+#include "nsIDOMEvent.h"
+#include "nsIDOMCSSStyleDeclaration.h"
+#include "nsIFrame.h"
+#include "nsContentUtils.h"
+#include "nsAString.h"
+#include "nsQueryFrame.h"
+#include "nsComponentManagerUtils.h"
+#include "nsStyledElement.h"
+#include "mozilla/LookAndFeel.h"
+#include "mozilla/Preferences.h"
+
+namespace mozilla {
+namespace layout {
+
+NS_IMPL_ISUPPORTS(ScrollbarActivity, nsIDOMEventListener)
+
+static bool
+GetForceAlwaysVisiblePref()
+{
+  static bool sForceAlwaysVisible;
+  static bool sForceAlwaysVisiblePrefCached = false;
+  if (!sForceAlwaysVisiblePrefCached) {
+    Preferences::AddBoolVarCache(&sForceAlwaysVisible,
+                                 "layout.testing.overlay-scrollbars.always-visible");
+    sForceAlwaysVisiblePrefCached = true;
+  }
+  return sForceAlwaysVisible;
+}
+
+void
+ScrollbarActivity::QueryLookAndFeelVals()
+{
+  // Fade animation constants
+  mScrollbarFadeBeginDelay =
+    LookAndFeel::GetInt(LookAndFeel::eIntID_ScrollbarFadeBeginDelay);
+  mScrollbarFadeDuration =
+    LookAndFeel::GetInt(LookAndFeel::eIntID_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::eIntID_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(nsIDOMEvent* 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<nsIDOMEventTarget> target;
+  aEvent->GetOriginalTarget(getter_AddRefs(target));
+  nsCOMPtr<nsIContent> targetContent = do_QueryInterface(target);
+
+  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,
+                                           nsIContent* aScrollbar,
+                                           bool* aStoredHoverState)
+{
+  if (!aTarget || !aScrollbar ||
+      !nsContentUtils::ContentIsDescendantOf(aTarget, 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 = do_QueryInterface(GetHorizontalScrollbar());
+  mVerticalScrollbar = do_QueryInterface(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);
+  nsCOMPtr<nsIDOMEventTarget> scrollAreaTarget
+    = do_QueryInterface(scrollArea->GetContent());
+  if (scrollAreaTarget) {
+    scrollAreaTarget->AddEventListener(NS_LITERAL_STRING("mousemove"), this,
+                                       true);
+  }
+  mListeningForScrollAreaEvents = true;
+}
+
+void
+ScrollbarActivity::StopListeningForScrollAreaEvents()
+{
+  if (!mListeningForScrollAreaEvents)
+    return;
+
+  nsIFrame* scrollArea = do_QueryFrame(mScrollableFrame);
+  nsCOMPtr<nsIDOMEventTarget> scrollAreaTarget = do_QueryInterface(scrollArea->GetContent());
+  if (scrollAreaTarget) {
+    scrollAreaTarget->RemoveEventListener(NS_LITERAL_STRING("mousemove"), this, true);
+  }
+  mListeningForScrollAreaEvents = false;
+}
+
+void
+ScrollbarActivity::AddScrollbarEventListeners(nsIDOMEventTarget* aScrollbar)
+{
+  if (aScrollbar) {
+    aScrollbar->AddEventListener(NS_LITERAL_STRING("mousedown"), this, true);
+    aScrollbar->AddEventListener(NS_LITERAL_STRING("mouseup"), this, true);
+    aScrollbar->AddEventListener(NS_LITERAL_STRING("mouseover"), this, true);
+    aScrollbar->AddEventListener(NS_LITERAL_STRING("mouseout"), this, true);
+  }
+}
+
+void
+ScrollbarActivity::RemoveScrollbarEventListeners(nsIDOMEventTarget* aScrollbar)
+{
+  if (aScrollbar) {
+    aScrollbar->RemoveEventListener(NS_LITERAL_STRING("mousedown"), this, true);
+    aScrollbar->RemoveEventListener(NS_LITERAL_STRING("mouseup"), this, true);
+    aScrollbar->RemoveEventListener(NS_LITERAL_STRING("mouseover"), this, true);
+    aScrollbar->RemoveEventListener(NS_LITERAL_STRING("mouseout"), 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, Flush_Style);
+  }
+}
+
+void
+ScrollbarActivity::UnregisterFromRefreshDriver()
+{
+  nsRefreshDriver* refreshDriver = GetRefreshDriver();
+  if (refreshDriver) {
+    refreshDriver->RemoveRefreshObserver(this, Flush_Style);
+  }
+}
+
+static void
+SetBooleanAttribute(nsIContent* aContent, nsIAtom* aAttribute, bool aValue)
+{
+  if (aContent) {
+    if (aValue) {
+      aContent->SetAttr(kNameSpaceID_None, aAttribute,
+                        NS_LITERAL_STRING("true"), true);
+    } else {
+      aContent->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)
+{
+  nsCOMPtr<nsStyledElement> inlineStyleContent =
+    do_QueryInterface(aContent);
+  if (inlineStyleContent) {
+    nsICSSDeclaration* decl = inlineStyleContent->Style();
+    nsAutoString str;
+    str.AppendFloat(aOpacity);
+    decl->SetProperty(NS_LITERAL_STRING("opacity"), str, EmptyString());
+  }
+}
+
+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.
+  nsWeakFrame 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)
+{
+  nsCOMPtr<nsStyledElement> inlineStyleContent =
+    do_QueryInterface(aContent);
+  if (inlineStyleContent) {
+    nsICSSDeclaration* decl = inlineStyleContent->Style();
+    nsAutoString dummy;
+    decl->RemoveProperty(NS_LITERAL_STRING("opacity"), dummy);
+  }
+}
+
+bool
+ScrollbarActivity::SetIsFading(bool aNewFading)
+{
+  if (mIsFading == aNewFading)
+    return true;
+
+  mIsFading = aNewFading;
+  if (!mIsFading) {
+    mFadeBeginTime = TimeStamp();
+    // 'this' may be getting destroyed during UnsetOpacityOnElement calls.
+    nsWeakFrame weakFrame((do_QueryFrame(mScrollableFrame)));
+    UnsetOpacityOnElement(GetHorizontalScrollbar());
+    if (!weakFrame.IsAlive()) {
+      return false;
+    }
+    UnsetOpacityOnElement(GetVerticalScrollbar());
+    if (!weakFrame.IsAlive()) {
+      return false;
+    }
+  }
+  return true;
+}
+
+void
+ScrollbarActivity::StartFadeBeginTimer()
+{
+  if (GetForceAlwaysVisiblePref()) {
+    return;
+  }
+  if (!mFadeBeginTimer) {
+    mFadeBeginTimer = do_CreateInstance("@mozilla.org/timer;1");
+  }
+  mFadeBeginTimer->InitWithNamedFuncCallback(
+    FadeBeginTimerFired, this, mScrollbarFadeBeginDelay,
+    nsITimer::TYPE_ONE_SHOT, "ScrollbarActivity::FadeBeginTimerFired");
+}
+
+void
+ScrollbarActivity::CancelFadeBeginTimer()
+{
+  if (mFadeBeginTimer) {
+    mFadeBeginTimer->Cancel();
+  }
+}
+
+void
+ScrollbarActivity::HoveredScrollbar(nsIContent* aScrollbar)
+{
+  SetBooleanAttribute(GetHorizontalScrollbar(), nsGkAtoms::hover, false);
+  SetBooleanAttribute(GetVerticalScrollbar(), nsGkAtoms::hover, false);
+  SetBooleanAttribute(aScrollbar, nsGkAtoms::hover, true);
+}
+
+nsRefreshDriver*
+ScrollbarActivity::GetRefreshDriver()
+{
+  nsIFrame* scrollableFrame = do_QueryFrame(mScrollableFrame);
+  return scrollableFrame->PresContext()->RefreshDriver();
+}
+
+nsIContent*
+ScrollbarActivity::GetScrollbarContent(bool aVertical)
+{
+  nsIFrame* box = mScrollableFrame->GetScrollbarBox(aVertical);
+  return box ? box->GetContent() : nullptr;
+}
+
+} // namespace layout
+} // namespace mozilla