1 files changed, 237 insertions, 0 deletions
diff --git a/gfx/layers/apz/util/ActiveElementManager.cpp b/gfx/layers/apz/util/ActiveElementManager.cpp
new file mode 100644
index 000000000..20d34aa2b
--- /dev/null
+++ b/gfx/layers/apz/util/ActiveElementManager.cpp
@@ -0,0 +1,237 @@
+/* -*- 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 "ActiveElementManager.h"
+#include "mozilla/EventStateManager.h"
+#include "mozilla/EventStates.h"
+#include "mozilla/StyleSetHandle.h"
+#include "mozilla/StyleSetHandleInlines.h"
+#include "mozilla/Preferences.h"
+#include "base/message_loop.h"
+#include "base/task.h"
+#include "mozilla/dom/Element.h"
+#include "nsIDocument.h"
+#include "nsStyleSet.h"
+
+#define AEM_LOG(...)
+// #define AEM_LOG(...) printf_stderr("AEM: " __VA_ARGS__)
+
+namespace mozilla {
+namespace layers {
+
+static int32_t sActivationDelayMs = 100;
+static bool sActivationDelayMsSet = false;
+
+ActiveElementManager::ActiveElementManager()
+  : mCanBePan(false),
+    mCanBePanSet(false),
+    mSetActiveTask(nullptr),
+    mActiveElementUsesStyle(false)
+{
+  if (!sActivationDelayMsSet) {
+    Preferences::AddIntVarCache(&sActivationDelayMs,
+                                "ui.touch_activation.delay_ms",
+                                sActivationDelayMs);
+    sActivationDelayMsSet = true;
+  }
+}
+
+ActiveElementManager::~ActiveElementManager() {}
+
+void
+ActiveElementManager::SetTargetElement(dom::EventTarget* aTarget)
+{
+  if (mTarget) {
+    // Multiple fingers on screen (since HandleTouchEnd clears mTarget).
+    AEM_LOG("Multiple fingers on-screen, clearing target element\n");
+    CancelTask();
+    ResetActive();
+    ResetTouchBlockState();
+    return;
+  }
+
+  mTarget = do_QueryInterface(aTarget);
+  AEM_LOG("Setting target element to %p\n", mTarget.get());
+  TriggerElementActivation();
+}
+
+void
+ActiveElementManager::HandleTouchStart(bool aCanBePan)
+{
+  AEM_LOG("Touch start, aCanBePan: %d\n", aCanBePan);
+  if (mCanBePanSet) {
+    // Multiple fingers on screen (since HandleTouchEnd clears mCanBePanSet).
+    AEM_LOG("Multiple fingers on-screen, clearing touch block state\n");
+    CancelTask();
+    ResetActive();
+    ResetTouchBlockState();
+    return;
+  }
+
+  mCanBePan = aCanBePan;
+  mCanBePanSet = true;
+  TriggerElementActivation();
+}
+
+void
+ActiveElementManager::TriggerElementActivation()
+{
+  // Both HandleTouchStart() and SetTargetElement() call this. They can be
+  // called in either order. One will set mCanBePanSet, and the other, mTarget.
+  // We want to actually trigger the activation once both are set.
+  if (!(mTarget && mCanBePanSet)) {
+    return;
+  }
+
+  // If the touch cannot be a pan, make mTarget :active right away.
+  // Otherwise, wait a bit to see if the user will pan or not.
+  if (!mCanBePan) {
+    SetActive(mTarget);
+  } else {
+    CancelTask();   // this is only needed because of bug 1169802. Fixing that
+                    // bug properly should make this unnecessary.
+    MOZ_ASSERT(mSetActiveTask == nullptr);
+
+    RefPtr<CancelableRunnable> task =
+      NewCancelableRunnableMethod<nsCOMPtr<dom::Element>>(this,
+                                                          &ActiveElementManager::SetActiveTask,
+                                                          mTarget);
+    mSetActiveTask = task;
+    MessageLoop::current()->PostDelayedTask(task.forget(), sActivationDelayMs);
+    AEM_LOG("Scheduling mSetActiveTask %p\n", mSetActiveTask);
+  }
+}
+
+void
+ActiveElementManager::ClearActivation()
+{
+  AEM_LOG("Clearing element activation\n");
+  CancelTask();
+  ResetActive();
+}
+
+void
+ActiveElementManager::HandleTouchEndEvent(bool aWasClick)
+{
+  AEM_LOG("Touch end event, aWasClick: %d\n", aWasClick);
+
+  // If the touch was a click, make mTarget :active right away.
+  // nsEventStateManager will reset the active element when processing
+  // the mouse-down event generated by the click.
+  CancelTask();
+  if (aWasClick) {
+    SetActive(mTarget);
+  } else {
+    // We might reach here if mCanBePan was false on touch-start and
+    // so we set the element active right away. Now it turns out the
+    // action was not a click so we need to reset the active element.
+    ResetActive();
+  }
+
+  ResetTouchBlockState();
+}
+
+void
+ActiveElementManager::HandleTouchEnd()
+{
+  AEM_LOG("Touch end, clearing pan state\n");
+  mCanBePanSet = false;
+}
+
+bool
+ActiveElementManager::ActiveElementUsesStyle() const
+{
+  return mActiveElementUsesStyle;
+}
+
+static nsPresContext*
+GetPresContextFor(nsIContent* aContent)
+{
+  if (!aContent) {
+    return nullptr;
+  }
+  nsIPresShell* shell = aContent->OwnerDoc()->GetShell();
+  if (!shell) {
+    return nullptr;
+  }
+  return shell->GetPresContext();
+}
+
+static bool
+ElementHasActiveStyle(dom::Element* aElement)
+{
+  nsPresContext* pc = GetPresContextFor(aElement);
+  if (!pc) {
+    return false;
+  }
+  StyleSetHandle styleSet = pc->StyleSet();
+  for (dom::Element* e = aElement; e; e = e->GetParentElement()) {
+    if (styleSet->HasStateDependentStyle(e, NS_EVENT_STATE_ACTIVE)) {
+      AEM_LOG("Element %p's style is dependent on the active state\n", e);
+      return true;
+    }
+  }
+  AEM_LOG("Element %p doesn't use active styles\n", aElement);
+  return false;
+}
+
+void
+ActiveElementManager::SetActive(dom::Element* aTarget)
+{
+  AEM_LOG("Setting active %p\n", aTarget);
+
+  if (nsPresContext* pc = GetPresContextFor(aTarget)) {
+    pc->EventStateManager()->SetContentState(aTarget, NS_EVENT_STATE_ACTIVE);
+    mActiveElementUsesStyle = ElementHasActiveStyle(aTarget);
+  }
+}
+
+void
+ActiveElementManager::ResetActive()
+{
+  AEM_LOG("Resetting active from %p\n", mTarget.get());
+
+  // Clear the :active flag from mTarget by setting it on the document root.
+  if (mTarget) {
+    dom::Element* root = mTarget->OwnerDoc()->GetDocumentElement();
+    if (root) {
+      AEM_LOG("Found root %p, making active\n", root);
+      SetActive(root);
+    }
+  }
+}
+
+void
+ActiveElementManager::ResetTouchBlockState()
+{
+  mTarget = nullptr;
+  mCanBePanSet = false;
+}
+
+void
+ActiveElementManager::SetActiveTask(const nsCOMPtr<dom::Element>& aTarget)
+{
+  AEM_LOG("mSetActiveTask %p running\n", mSetActiveTask);
+
+  // This gets called from mSetActiveTask's Run() method. The message loop
+  // deletes the task right after running it, so we need to null out
+  // mSetActiveTask to make sure we're not left with a dangling pointer.
+  mSetActiveTask = nullptr;
+  SetActive(aTarget);
+}
+
+void
+ActiveElementManager::CancelTask()
+{
+  AEM_LOG("Cancelling task %p\n", mSetActiveTask);
+
+  if (mSetActiveTask) {
+    mSetActiveTask->Cancel();
+    mSetActiveTask = nullptr;
+  }
+}
+
+} // namespace layers
+} // namespace mozilla