Splits SmoothGestureController from RenderWidgetHostImpl

content/browser/renderer_host/smooth_scroll_gesture_controller.cc

+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "content/browser/renderer_host/smooth_scroll_gesture_controller.h"
+
+#include "base/debug/trace_event.h"
+#include "base/message_loop.h"
+#include "content/common/view_messages.h"
+#include "content/port/browser/render_widget_host_view_port.h"
+#include "content/port/browser/smooth_scroll_gesture.h"
+#include "content/public/browser/render_widget_host.h"
+
+namespace content {
+
+namespace {
+
+// How many milliseconds apart synthetic scroll messages should be sent.
+const int kSyntheticScrollMessageIntervalMs = 8;
+
+}  // namespace
+
+SmoothScrollGestureController::SmoothScrollGestureController()
+    : ALLOW_THIS_IN_INITIALIZER_LIST(weak_factory_(this)),
+      pending_input_event_count_(0),
+      tick_active_smooth_scroll_gesture_task_posted_(false) {
+}
+
+SmoothScrollGestureController::~SmoothScrollGestureController() {
+}
+
+bool SmoothScrollGestureController::OnBeginSmoothScroll(
+    RenderWidgetHostViewPort* view,
+    const ViewHostMsg_BeginSmoothScroll_Params& params) {
+  if (pending_smooth_scroll_gesture_)
+    return false;
+  pending_smooth_scroll_gesture_ = view->CreateSmoothScrollGesture(
+      params.scroll_down, params.pixels_to_scroll,
+      params.mouse_event_x, params.mouse_event_y);
+
+  // If an input ack is pending, then hold off ticking the gesture
+  // until we get an input ack.
+  if (pending_input_event_count_)
+    return true;
+  if (tick_active_smooth_scroll_gesture_task_posted_)
+    return true;
+  TickActiveSmoothScrollGesture(view->GetRenderWidgetHost());
+  return true;
+}
+
+void SmoothScrollGestureController::OnForwardInputEvent() {
+  ++pending_input_event_count_;
+}
+
+void SmoothScrollGestureController::OnInputEventACK(RenderWidgetHost* rwh) {
+  if (pending_input_event_count_ > 0)
+    --pending_input_event_count_;
+  // If an input ack is pending, then hold off ticking the gesture
+  // until we get an input ack.
+  if (!pending_input_event_count_ && pending_smooth_scroll_gesture_)
+    TickActiveSmoothScrollGesture(rwh);
+}
+
+int SmoothScrollGestureController::SyntheticScrollMessageInterval() const {
+  return kSyntheticScrollMessageIntervalMs;
+}
+
+void SmoothScrollGestureController::TickActiveSmoothScrollGesture(
+    RenderWidgetHost* rwh) {
+  TRACE_EVENT0("input", "RenderWidgetHostImpl::TickActiveSmoothScrollGesture");
+  tick_active_smooth_scroll_gesture_task_posted_ = false;
+  if (!pending_smooth_scroll_gesture_) {
+    TRACE_EVENT_INSTANT0("input", "EarlyOut_NoActiveScrollGesture",
+                         TRACE_EVENT_SCOPE_THREAD);
+    return;
+  }
+
+  base::TimeTicks now = base::TimeTicks::HighResNow();
+  base::TimeDelta preferred_interval =
+      base::TimeDelta::FromMilliseconds(kSyntheticScrollMessageIntervalMs);
+  base::TimeDelta time_until_next_ideal_interval =
+      (last_smooth_scroll_gesture_tick_time_ + preferred_interval) -
+      now;
+  if (time_until_next_ideal_interval.InMilliseconds() > 0) {
+    TRACE_EVENT_INSTANT1(
+        "input", "EarlyOut_TickedTooRecently", TRACE_EVENT_SCOPE_THREAD,
+        "delay", time_until_next_ideal_interval.InMilliseconds());
+    // Post a task.
+    tick_active_smooth_scroll_gesture_task_posted_ = true;
+    MessageLoop::current()->PostDelayedTask(
+        FROM_HERE,
+        base::Bind(
+            &SmoothScrollGestureController::TickActiveSmoothScrollGesture,
+            weak_factory_.GetWeakPtr(),
+            rwh),
+        time_until_next_ideal_interval);
+    return;
+  }
+
+  last_smooth_scroll_gesture_tick_time_ = now;
+
+
+  if (!pending_smooth_scroll_gesture_->ForwardInputEvents(now, rwh)) {
+    pending_smooth_scroll_gesture_ = NULL;
+    rwh->Send(new ViewMsg_SmoothScrollCompleted(rwh->GetRoutingID()));
+  }
+
+  // No need to post the next tick if an input is in flight.
+  if (pending_input_event_count_)
+    return;
+
+  TRACE_EVENT_INSTANT1("input", "PostTickTask", TRACE_EVENT_SCOPE_THREAD,
+                       "delay", preferred_interval.InMilliseconds());
+  tick_active_smooth_scroll_gesture_task_posted_ = true;
+  MessageLoop::current()->PostDelayedTask(
+      FROM_HERE,
+      base::Bind(&SmoothScrollGestureController::TickActiveSmoothScrollGesture,
+                 weak_factory_.GetWeakPtr(),
+                 rwh),
+      preferred_interval);
+}
+
+}  // namespace content