gesture nav: An alternate UI for gesture nav.

This change introduces GestureNavSimple, which is an implementation of the
OverscrollControllerDelegate used when the 'simple' gesture-nav is selected. The
implementation simply shows an arrow as the visual hint during the gesture, and
does back/forward navigation when the gesture completes.

BUG=344573
R=sky@chromium.org

Review URL: https://codereview.chromium.org/185233006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254674 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 286 insertions, 0 deletions

diff --git a/content/browser/web_contents/aura/gesture_nav_simple.cc b/content/browser/web_contents/aura/gesture_nav_simple.cc
new file mode 100644
index 0000000..7ae0557
--- /dev/null
+++ b/content/browser/web_contents/aura/gesture_nav_simple.cc
@@ -0,0 +1,231 @@
+// Copyright 2014 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/gesture_nav_simple.h"
+
+#include "cc/layers/layer.h"
+#include "content/browser/frame_host/navigation_controller_impl.h"
+#include "content/browser/renderer_host/overscroll_controller.h"
+#include "content/browser/web_contents/web_contents_impl.h"
+#include "content/public/browser/overscroll_configuration.h"
+#include "content/public/browser/web_contents_view.h"
+#include "content/public/common/content_client.h"
+#include "grit/ui_resources.h"
+#include "ui/aura/window.h"
+#include "ui/compositor/layer.h"
+#include "ui/compositor/layer_animation_observer.h"
+#include "ui/compositor/layer_delegate.h"
+#include "ui/compositor/scoped_layer_animation_settings.h"
+#include "ui/gfx/animation/tween.h"
+#include "ui/gfx/canvas.h"
+#include "ui/gfx/image/image.h"
+
+namespace content {
+
+namespace {
+
+const int kArrowHeight = 280;
+const int kArrowWidth = 140;
+const float kMinOpacity = 0.25f;
+
+bool ShouldNavigateForward(const NavigationController& controller,
+                           OverscrollMode mode) {
+  return mode == (base::i18n::IsRTL() ? OVERSCROLL_EAST : OVERSCROLL_WEST) &&
+         controller.CanGoForward();
+}
+
+bool ShouldNavigateBack(const NavigationController& controller,
+                        OverscrollMode mode) {
+  return mode == (base::i18n::IsRTL() ? OVERSCROLL_WEST : OVERSCROLL_EAST) &&
+         controller.CanGoBack();
+}
+
+// An animation observers that deletes itself and a pointer after the end of the
+// animation.
+template <class T>
+class DeleteAfterAnimation : public ui::ImplicitAnimationObserver {
+ public:
+  explicit DeleteAfterAnimation(scoped_ptr<T> object)
+      : object_(object.Pass()) {}
+
+ private:
+  friend class base::DeleteHelper<DeleteAfterAnimation<T> >;
+
+  virtual ~DeleteAfterAnimation() {}
+
+  // ui::ImplicitAnimationObserver:
+  virtual void OnImplicitAnimationsCompleted() OVERRIDE {
+    // Deleting an observer when a ScopedLayerAnimationSettings is iterating
+    // over them can cause a crash (which can happen during tests). So instead,
+    // schedule this observer to be deleted soon.
+    BrowserThread::DeleteSoon(BrowserThread::UI, FROM_HERE, this);
+  }
+
+  scoped_ptr<T> object_;
+  DISALLOW_COPY_AND_ASSIGN(DeleteAfterAnimation);
+};
+
+}  // namespace
+
+// A layer delegate that paints the shield with the arrow in it.
+class ArrowLayerDelegate : public ui::LayerDelegate {
+ public:
+  explicit ArrowLayerDelegate(int resource_id)
+      : image_(GetContentClient()->GetNativeImageNamed(resource_id)),
+        left_arrow_(resource_id == IDR_BACK_ARROW) {
+    CHECK(!image_.IsEmpty());
+  }
+
+  virtual ~ArrowLayerDelegate() {}
+
+  bool left() const { return left_arrow_; }
+
+ private:
+  // ui::LayerDelegate:
+  virtual void OnPaintLayer(gfx::Canvas* canvas) OVERRIDE {
+    SkPaint paint;
+    paint.setColor(SkColorSetARGB(0xa0, 0, 0, 0));
+    paint.setStyle(SkPaint::kFill_Style);
+    paint.setAntiAlias(true);
+
+    canvas->DrawCircle(
+        gfx::Point(left_arrow_ ? 0 : kArrowWidth, kArrowHeight / 2),
+        kArrowWidth,
+        paint);
+    canvas->DrawImageInt(*image_.ToImageSkia(),
+                         left_arrow_ ? 0 : kArrowWidth - image_.Width(),
+                         (kArrowHeight - image_.Height()) / 2);
+  }
+
+  virtual void OnDeviceScaleFactorChanged(float device_scale_factor) OVERRIDE {}
+
+  virtual base::Closure PrepareForLayerBoundsChange() OVERRIDE {
+    return base::Closure();
+  }
+
+  const gfx::Image& image_;
+  const bool left_arrow_;
+
+  DISALLOW_COPY_AND_ASSIGN(ArrowLayerDelegate);
+};
+
+GestureNavSimple::GestureNavSimple(WebContentsImpl* web_contents)
+    : web_contents_(web_contents),
+      completion_threshold_(0.f) {}
+
+GestureNavSimple::~GestureNavSimple() {}
+
+void GestureNavSimple::ApplyEffectsAndDestroy(const gfx::Transform& transform,
+                                              float opacity) {
+  ui::Layer* layer = arrow_.get();
+  ui::ScopedLayerAnimationSettings settings(arrow_->GetAnimator());
+  settings.AddObserver(
+      new DeleteAfterAnimation<ArrowLayerDelegate>(arrow_delegate_.Pass()));
+  settings.AddObserver(new DeleteAfterAnimation<ui::Layer>(arrow_.Pass()));
+  settings.AddObserver(new DeleteAfterAnimation<ui::Layer>(clip_layer_.Pass()));
+  layer->SetTransform(transform);
+  layer->SetOpacity(opacity);
+}
+
+void GestureNavSimple::AbortGestureAnimation() {
+  if (!arrow_)
+    return;
+  gfx::Transform transform;
+  transform.Translate(arrow_delegate_->left() ? -kArrowWidth : kArrowWidth, 0);
+  ApplyEffectsAndDestroy(transform, kMinOpacity);
+}
+
+void GestureNavSimple::CompleteGestureAnimation() {
+  if (!arrow_)
+    return;
+  // Make sure the fade-out starts from the complete state.
+  ApplyEffectsForDelta(completion_threshold_);
+  ApplyEffectsAndDestroy(arrow_->transform(), 0.f);
+}
+
+void GestureNavSimple::ApplyEffectsForDelta(float delta_x) {
+  if (!arrow_)
+    return;
+  CHECK_GT(completion_threshold_, 0.f);
+  CHECK_GE(delta_x, 0.f);
+  double complete = std::min(1.f, delta_x / completion_threshold_);
+  float translate_x = gfx::Tween::FloatValueBetween(complete, -kArrowWidth, 0);
+  gfx::Transform transform;
+  transform.Translate(arrow_delegate_->left() ? translate_x : -translate_x,
+                      0.f);
+  arrow_->SetTransform(transform);
+  arrow_->SetOpacity(gfx::Tween::FloatValueBetween(complete, kMinOpacity, 1.f));
+}
+
+gfx::Rect GestureNavSimple::GetVisibleBounds() const {
+  return web_contents_->GetView()->GetNativeView()->bounds();
+}
+
+void GestureNavSimple::OnOverscrollUpdate(float delta_x, float delta_y) {
+  ApplyEffectsForDelta(std::abs(delta_x) + 50.f);
+}
+
+void GestureNavSimple::OnOverscrollComplete(OverscrollMode overscroll_mode) {
+  CompleteGestureAnimation();
+
+  NavigationControllerImpl& controller = web_contents_->GetController();
+  if (ShouldNavigateForward(controller, overscroll_mode))
+    controller.GoForward();
+  else if (ShouldNavigateBack(controller, overscroll_mode))
+    controller.GoBack();
+}
+
+void GestureNavSimple::OnOverscrollModeChange(OverscrollMode old_mode,
+                                              OverscrollMode new_mode) {
+  NavigationControllerImpl& controller = web_contents_->GetController();
+  if (!ShouldNavigateForward(controller, new_mode) &&
+      !ShouldNavigateBack(controller, new_mode)) {
+    AbortGestureAnimation();
+    return;
+  }
+
+  arrow_.reset(new ui::Layer(ui::LAYER_TEXTURED));
+  // Note that RTL doesn't affect the arrow that should be displayed.
+  int resource_id = 0;
+  if (new_mode == OVERSCROLL_WEST)
+    resource_id = IDR_FORWARD_ARROW;
+  else if (new_mode == OVERSCROLL_EAST)
+    resource_id = IDR_BACK_ARROW;
+  else
+    NOTREACHED();
+
+  arrow_delegate_.reset(new ArrowLayerDelegate(resource_id));
+  arrow_->set_delegate(arrow_delegate_.get());
+  arrow_->SetFillsBoundsOpaquely(false);
+
+  aura::Window* window = web_contents_->GetView()->GetNativeView();
+  const gfx::Rect& window_bounds = window->bounds();
+  completion_threshold_ = window_bounds.width() *
+      GetOverscrollConfig(OVERSCROLL_CONFIG_HORIZ_THRESHOLD_COMPLETE);
+
+  // Align on the left or right edge.
+  int x = (resource_id == IDR_BACK_ARROW) ? 0 :
+      (window_bounds.width() - kArrowWidth);
+  // Align in the center vertically.
+  int y = std::max(0, (window_bounds.height() - kArrowHeight) / 2);
+  arrow_->SetBounds(gfx::Rect(x, y, kArrowWidth, kArrowHeight));
+  ApplyEffectsForDelta(0.f);
+
+  // Adding the arrow as a child of the content window is not sufficient,
+  // because it is possible for a new layer to be parented on top of the arrow
+  // layer (e.g. when the navigated-to page is displayed while the completion
+  // animation is in progress). So instead, a clip layer (that doesn't paint) is
+  // installed on top of the content window as its sibling, and the arrow layer
+  // is added to that clip layer.
+  clip_layer_.reset(new ui::Layer(ui::LAYER_NOT_DRAWN));
+  clip_layer_->SetBounds(window->layer()->bounds());
+  clip_layer_->SetMasksToBounds(true);
+  clip_layer_->Add(arrow_.get());
+
+  ui::Layer* parent = window->layer()->parent();
+  parent->Add(clip_layer_.get());
+  parent->StackAtTop(clip_layer_.get());
+}
+
+}  // namespace content
diff --git a/content/browser/web_contents/aura/gesture_nav_simple.h b/content/browser/web_contents/aura/gesture_nav_simple.h
new file mode 100644
index 0000000..e8466e5
--- /dev/null
+++ b/content/browser/web_contents/aura/gesture_nav_simple.h
@@ -0,0 +1,55 @@
+// Copyright 2014 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.
+
+#ifndef CONTENT_BROWSER_WEB_CONTENTS_AURA_GESTURE_NAV_SIMPLE_H_
+#define CONTENT_BROWSER_WEB_CONTENTS_AURA_GESTURE_NAV_SIMPLE_H_
+
+#include "base/memory/scoped_ptr.h"
+#include "content/browser/renderer_host/overscroll_controller_delegate.h"
+
+namespace gfx {
+class Transform;
+}
+
+namespace ui {
+class Layer;
+}
+
+namespace content {
+
+class ArrowLayerDelegate;
+class WebContentsImpl;
+
+// A simple delegate for the overscroll controller that paints an arrow on top
+// of the web-contents as a hint for pending navigations from overscroll.
+class GestureNavSimple : public OverscrollControllerDelegate {
+ public:
+  explicit GestureNavSimple(WebContentsImpl* web_contents);
+  virtual ~GestureNavSimple();
+
+ private:
+  void ApplyEffectsAndDestroy(const gfx::Transform& transform, float opacity);
+  void AbortGestureAnimation();
+  void CompleteGestureAnimation();
+  void ApplyEffectsForDelta(float delta_x);
+
+  // OverscrollControllerDelegate:
+  virtual gfx::Rect GetVisibleBounds() const OVERRIDE;
+  virtual void OnOverscrollUpdate(float delta_x, float delta_y) OVERRIDE;
+  virtual void OnOverscrollComplete(OverscrollMode overscroll_mode) OVERRIDE;
+  virtual void OnOverscrollModeChange(OverscrollMode old_mode,
+                                      OverscrollMode new_mode) OVERRIDE;
+
+  WebContentsImpl* web_contents_;
+  scoped_ptr<ui::Layer> clip_layer_;
+  scoped_ptr<ui::Layer> arrow_;
+  scoped_ptr<ArrowLayerDelegate> arrow_delegate_;
+  float completion_threshold_;
+
+  DISALLOW_COPY_AND_ASSIGN(GestureNavSimple);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_WEB_CONTENTS_AURA_GESTURE_NAV_SIMPLE_H_