Refactor GestureNavigation to eliminate code redundancy

content/browser/web_contents/aura/overscroll_window_animation.cc

+// Copyright (c) 2015 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/web_contents/aura/overscroll_window_animation.h"
+
+#include "base/i18n/rtl.h"
+#include "content/browser/web_contents/aura/overscroll_layer_wrapper.h"
+#include "ui/compositor/layer_animation_observer.h"
+#include "ui/compositor/scoped_layer_animation_settings.h"
+
+namespace content {
+
+namespace {
+
+OverscrollWindowAnimation::Direction GetDirectionForMode(OverscrollMode mode) {
+  LOG(ERROR) << "Getting navigation direction";
+  if (mode == (base::i18n::IsRTL() ? OVERSCROLL_EAST : OVERSCROLL_WEST))
+    return OverscrollWindowAnimation::FORWARD;
+  if (mode == (base::i18n::IsRTL() ? OVERSCROLL_WEST : OVERSCROLL_EAST))
+    return OverscrollWindowAnimation::BACKWARD;
+  return OverscrollWindowAnimation::NONE;
+}
+
+}  // namespace
+
+OverscrollWindowAnimation::OverscrollWindowAnimation()
+    : delegate_(nullptr),
+      direction_(NONE),
+      animation_active_(false) {
+}
+
+OverscrollWindowAnimation::~OverscrollWindowAnimation() {
+  LOG(ERROR) << "OWA destructor";
+}
+
+void OverscrollWindowAnimation::CancelOverscroll() {
+  LOG(ERROR) << "OWA: Cancelling overscroll";
+  ui::ScopedLayerAnimationSettings settings(layer_wrapper_->GetAnimator());
+  settings.SetPreemptionStrategy(
+      ui::LayerAnimator::IMMEDIATELY_ANIMATE_TO_NEW_TARGET);
+  settings.SetTweenType(gfx::Tween::EASE_OUT);
+  settings.AddObserver(this);
+  layer_wrapper_->SetTransform(gfx::Transform());
+  direction_ = NONE;
+}
+
+void OverscrollWindowAnimation::OnImplicitAnimationsCompleted() {
+  LOG(ERROR) << "OWA: On implicit animations completed";
+  animation_active_ = false;
+  delegate_->OnOverscrollCompleted();
+  layer_wrapper_.reset();
+}
+
+gfx::Vector2dF OverscrollWindowAnimation::GetTranslationForOverscroll(

[mfomitchev, 2015/02/27 21:33:42]

any reason this doesn't just return an int/float?

[Nina, 2015/03/09 15:54:52]

None, changed the code.

+    float delta_x) {
+  DCHECK(direction_ != NONE);
+  const float bounds_width = layer_wrapper_->GetBounds().width();
+  if (direction_ == FORWARD)
+    return gfx::Vector2dF(std::max(-bounds_width, delta_x), 0);

[mfomitchev, 2015/02/27 21:33:42]

confirm if delta_x is always positive

[Nina, 2015/03/09 15:54:52]

It isn't, and it shouldn't. However I do realize now that this code will most
likely not work for RTL.

+  else
+    return gfx::Vector2dF(std::min(bounds_width, delta_x), 0);
+}
+
+gfx::Rect OverscrollWindowAnimation::GetVisibleBounds() const {
+  return layer_wrapper_->GetBounds();
+}
+
+bool OverscrollWindowAnimation::OnOverscrollUpdate(float delta_x,
+                                                   float delta_y) {
+  if (direction_ == NONE)
+    return false;
+  LOG(ERROR) << "OWA: OnOverscrollUpdate";
+  gfx::Vector2dF translate = GetTranslationForOverscroll(delta_x);
+  gfx::Transform transform;
+  transform.Translate(translate.x(), translate.y());
+  layer_wrapper_->SetTransform(transform);
+  return true;
+}
+
+void OverscrollWindowAnimation::OnOverscrollModeChange(
+    OverscrollMode old_mode,
+    OverscrollMode new_mode) {
+  LOG(ERROR) << "OWA: OnOverscrollModeChange for mode " << new_mode;
+  direction_ = GetDirectionForMode(new_mode);
+
+  if (direction_ == NONE) {
+    // The user cancelled the in progress overscroll gesture.
+    // TODO(nsatragno): in this case, show a feedback animation.
+    LOG(ERROR) << "Direction: NONE";
+    if (is_animation_in_progress())
+      CancelOverscroll();
+    return;
+  }
+  LOG(ERROR) << "Preparing layer wrapper";
+  if (layer_wrapper_) {
+    LOG(ERROR) << "Aborting animations on layer wrapper";
+    layer_wrapper_->GetAnimator()->AbortAllAnimations();
+  }
+  animation_active_ = true;
+  layer_wrapper_ = direction_ == FORWARD ? delegate_->CreateFrontLayer()

[mfomitchev, 2015/02/27 21:33:42]

Leak old layer if you change the direction from East to West?

[Nina, 2015/03/09 15:54:52]

After some analysis it seems we don't. However, this code is bound to change
from offline discussions.

+                                         : delegate_->CreateBackLayer();
+  if (!layer_wrapper_) {
+    LOG(ERROR) << "Cannot navigate, setting direction to NONE";
+    animation_active_ = false;
+    direction_ = NONE;
+  }
+  LOG(ERROR) << "Done with OnOverscrollModeChange";
+}
+
+void OverscrollWindowAnimation::OnOverscrollComplete(
+    OverscrollMode overscroll_mode) {
+  LOG(ERROR) << "OWA: OnOverscrollComplete";
+  delegate_->OnOverscrollCompleting();
+  ui::ScopedLayerAnimationSettings settings(layer_wrapper_->GetAnimator());
+  settings.SetPreemptionStrategy(
+      ui::LayerAnimator::IMMEDIATELY_ANIMATE_TO_NEW_TARGET);
+  settings.SetTweenType(gfx::Tween::EASE_OUT);
+  settings.AddObserver(this);
+  gfx::Transform transform;
+  int content_width = layer_wrapper_->GetBounds().width();
+  float translate_x = static_cast<float>(
+      direction_ == FORWARD ? -content_width

[mfomitchev, 2015/02/27 21:33:42]

RTL?

+                            : content_width);
+  transform.Translate(translate_x, 0);
+  layer_wrapper_->SetTransform(transform);
+  direction_ = NONE;
+}
+
+}  // namespace content