Refactor GestureNavigation to eliminate code redundancy

content/browser/web_contents/aura/overscroll_window_delegate.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_delegate.h"
+
+#include "base/i18n/rtl.h"
+#include "content/browser/frame_host/navigation_controller_impl.h"
+#include "content/browser/frame_host/navigation_entry_impl.h"
+#include "content/browser/renderer_host/overscroll_controller_delegate.h"
+#include "content/public/browser/overscroll_configuration.h"
+#include "ui/aura/window.h"
+#include "ui/gfx/image/image_png_rep.h"
+
+namespace content {
+
+OverscrollWindowDelegate::OverscrollWindowDelegate(
+    OverscrollControllerDelegate* delegate,
+    const gfx::Image& image)
+    : delegate_(delegate),
+      overscroll_mode_(OVERSCROLL_NONE),
+      delta_x_(0.f),
+      complete_threshold_ratio_(content::GetOverscrollConfig(
+          content::OVERSCROLL_CONFIG_HORIZ_THRESHOLD_COMPLETE)) {
+  SetImage(image);
+}
+
+OverscrollWindowDelegate::~OverscrollWindowDelegate() {
+}
+
+void OverscrollWindowDelegate::StartOverscroll() {
+  LOG(ERROR) << "OWD: StartOverscroll";
+  OverscrollMode old_mode = overscroll_mode_;
+  // TODO take into account RTL here?
+  if (delta_x_ > 0)
+    overscroll_mode_ = OVERSCROLL_EAST;
+  else
+    overscroll_mode_ = OVERSCROLL_WEST;
+  delegate_->OnOverscrollModeChange(old_mode, overscroll_mode_);
+}
+
+void OverscrollWindowDelegate::ResetOverscroll() {
+  LOG(ERROR) << "OWD: ResetOverscroll";
+  delegate_->OnOverscrollModeChange(overscroll_mode_, OVERSCROLL_NONE);
+  overscroll_mode_ = OVERSCROLL_NONE;
+  delta_x_ = 0;
+}
+
+void OverscrollWindowDelegate::CompleteOrResetOverscroll() {
+  LOG(ERROR) << "OWD: CompleteOrResetOverscroll";
+  if (overscroll_mode_ == OVERSCROLL_NONE)
+    return;
+  int width = delegate_->GetVisibleBounds().width();
+  float ratio = (fabs(delta_x_)) / width;
+  if (ratio < complete_threshold_ratio_) {
+    ResetOverscroll();
+    return;
+  }
+  delegate_->OnOverscrollComplete(overscroll_mode_);
+  overscroll_mode_ = OVERSCROLL_NONE;
+}
+
+void OverscrollWindowDelegate::UpdateOverscroll(float delta_x) {
+  LOG(ERROR) << "OWD: UpdateOverscroll";
+  delta_x_ += delta_x;
+  if (overscroll_mode_ == OVERSCROLL_NONE)
+    StartOverscroll();
+  delegate_->OnOverscrollUpdate(delta_x_, 0.f);
+}
+
+void OverscrollWindowDelegate::OnKeyEvent(ui::KeyEvent* event) {
+  ResetOverscroll();
+}
+
+void OverscrollWindowDelegate::OnMouseEvent(ui::MouseEvent* event) {
+  LOG(ERROR) << "OWD: OnMouseEvent";
+  // TODO is this a hack or something?
+  if (!(event->flags() & ui::EF_IS_SYNTHESIZED))
+    ResetOverscroll();
+}
+
+void OverscrollWindowDelegate::OnScrollEvent(ui::ScrollEvent* event) {
+  // TODO dafuq this does?

[mfomitchev, 2015/02/19 19:05:00]

Thresholds on how much you need to drag before the overscroll engages are
defined by start_threshold_touchpad_ and start_threshold_touchscreen_. This just
sets the appropriate value depending on whether you use touchscreen on touchpad.

[Nina, 2015/02/27 19:32:51]

Acknowledged.

+  // active_start_threshold_ = start_threshold_touchpad_;
+  LOG(ERROR) << "OWD: OnScrollEvent";
+  if (event->type() == ui::ET_SCROLL)
+    UpdateOverscroll(event->x_offset_ordinal());
+  else if (event->type() == ui::ET_SCROLL_FLING_START)
+    CompleteOrResetOverscroll();
+  else
+    ResetOverscroll();
+  event->SetHandled();
+}
+
+void OverscrollWindowDelegate::OnGestureEvent(ui::GestureEvent* event) {
+  LOG(ERROR) << "OWD: OnGestureEvent";
+  // active_start_threshold_ = start_threshold_touchscreen_;
+  switch (event->type()) {
+    case ui::ET_GESTURE_SCROLL_BEGIN:
+      // StartOverscroll();
+      break;
+
+    case ui::ET_GESTURE_SCROLL_UPDATE:
+      UpdateOverscroll(event->details().scroll_x());
+      break;
+
+    case ui::ET_GESTURE_SCROLL_END:
+      CompleteOrResetOverscroll();
+      break;
+
+    case ui::ET_SCROLL_FLING_START:
+      CompleteOrResetOverscroll();
+      break;
+
+    case ui::ET_GESTURE_PINCH_BEGIN:
+    case ui::ET_GESTURE_PINCH_UPDATE:
+    case ui::ET_GESTURE_PINCH_END:
+      ResetOverscroll();
+      break;
+
+    default:
+      break;
+  }
+
+  event->SetHandled();
+}
+
+}  // namespace content