New AppListView Scroll Behavior.

ui/app_list/views/app_list_view.cc

 // Copyright (c) 2012 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 "ui/app_list/views/app_list_view.h"
 
 #include <algorithm>
 
 #include "base/command_line.h"
 #include "base/macros.h"
@@ skipping 17 matching lines @@
 #include "ui/aura/window.h"
 #include "ui/aura/window_tree_host.h"
 #include "ui/base/ui_base_switches.h"
 #include "ui/compositor/layer.h"
 #include "ui/compositor/layer_animation_observer.h"
 #include "ui/compositor/scoped_layer_animation_settings.h"
 #include "ui/display/display.h"
 #include "ui/display/screen.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/geometry/insets.h"
+#include "ui/gfx/geometry/vector2d_conversions.h"
 #include "ui/gfx/image/image_skia.h"
 #include "ui/gfx/path.h"
 #include "ui/gfx/skia_util.h"
 #include "ui/views/bubble/bubble_frame_view.h"
 #include "ui/views/bubble/bubble_window_targeter.h"
 #include "ui/views/controls/image_view.h"
 #include "ui/views/controls/textfield/textfield.h"
 #include "ui/views/layout/fill_layout.h"
 #include "ui/views/views_delegate.h"
 #include "ui/views/widget/widget.h"
@@ skipping 17 matching lines @@
 constexpr int kHalfAppListHeight = 561;
 
 // The fraction of app list height that the app list must be released at in
 // order to transition to the next state.
 constexpr int kAppListThresholdDenominator = 3;
 
 // The velocity the app list must be dragged in order to transition to the next
 // state, measured in DIPs/event.
 constexpr int kAppListDragVelocityThreshold = 25;
 
+// The scroll offset in order to transition from PEEKING to FULLSCREEN
+constexpr int kAppListMinScrollToSwitchStates = 20;
+
 // The DIP distance from the bezel that a drag event must end within to transfer
 // the |app_list_state_|.
 constexpr int kAppListBezelMargin = 50;
 
 // The opacity of the app list background.
 constexpr float kAppListOpacity = 0.8;
 
 // The vertical position for the appearing animation of the speech UI.
 constexpr float kSpeechUIAppearingPosition = 12;
 
@@ skipping 572 matching lines @@
 
 void AppListView::OnMaximizeModeChanged(bool started) {
   is_maximize_mode_ = started;
   if (is_maximize_mode_ && !is_fullscreen()) {
     // Set |app_list_state_| to a maximize mode friendly state.
     SetState(app_list_state_ == PEEKING ? FULLSCREEN_ALL_APPS
                                         : FULLSCREEN_SEARCH);
   }
 }
 
+bool AppListView::HandleScroll(const ui::Event* event) {
+  if (app_list_state_ != PEEKING)
+    return false;
+
+  switch (event->type()) {
+    case ui::ET_MOUSEWHEEL:
+      SetState(event->AsMouseWheelEvent()->y_offset() < 0 ? FULLSCREEN_ALL_APPS
+                                                          : CLOSED);
+      return true;
+    case ui::ET_SCROLL:
+    case ui::ET_SCROLL_FLING_START: {
+      int offset = event->AsScrollEvent()->y_offset();

[khmel, 2017/07/14 18:10:01]

 nit const int or even better inline

[newcomer, 2017/07/17 21:38:10]

Done.

+      if (abs(offset) > kAppListMinScrollToSwitchStates) {
+        SetState(offset < 0 ? FULLSCREEN_ALL_APPS : CLOSED);
+        return true;
+      }
+      break;
+    }
+    default:
+      break;
+  }
+  return false;
+}
+
 void AppListView::OnBeforeBubbleWidgetInit(views::Widget::InitParams* params,
                                            views::Widget* widget) const {
   if (!params->native_widget) {
     views::ViewsDelegate* views_delegate = views::ViewsDelegate::GetInstance();
     if (views_delegate && !views_delegate->native_widget_factory().is_null()) {
       params->native_widget =
           views_delegate->native_widget_factory().Run(*params, widget);
     }
   }
   // Apply a WM-provided shadow (see ui/wm/core/).
@@ skipping 13 matching lines @@
   return GetBubbleFrameView() != nullptr;
 }
 
 void AppListView::GetWidgetHitTestMask(gfx::Path* mask) const {
   DCHECK(mask);
   DCHECK(GetBubbleFrameView());
 
   mask->addRect(gfx::RectToSkRect(GetBubbleFrameView()->GetContentsBounds()));
 }
 
+void AppListView::OnScrollEvent(ui::ScrollEvent* event) {
+  if (!is_fullscreen_app_list_enabled_)
+    return;
+
+  if (event->type() == ui::ET_SCROLL_FLING_CANCEL)
+    return;
+
+  if (HandleScroll(event)) {

[khmel, 2017/07/14 18:10:01]

nit: 
we prefer following style:
if (!HandleScroll(event))
  return;
....

[newcomer, 2017/07/17 21:38:10]

Done.

+    event->SetHandled();
+    event->StopPropagation();
+  }
+}
+
 void AppListView::OnMouseEvent(ui::MouseEvent* event) {
   if (!is_fullscreen_app_list_enabled_)
     return;
 
   switch (event->type()) {
     case ui::ET_MOUSE_PRESSED:
       StartDrag(event->location());
       event->SetHandled();
       break;
     case ui::ET_MOUSE_DRAGGED:
       UpdateDrag(event->location());
       event->SetHandled();
       break;
     case ui::ET_MOUSE_RELEASED:
       EndDrag(event->location());
       event->SetHandled();
       break;
+    case ui::ET_MOUSEWHEEL: {
+      if (HandleScroll(event))
+        event->SetHandled();
+      break;
+    }
     default:
       break;
   }
 }
 
 void AppListView::OnGestureEvent(ui::GestureEvent* event) {
   if (!is_fullscreen_app_list_enabled_)
     return;
 
   switch (event->type()) {
@@ skipping 31 matching lines @@
     GetWidget()->Deactivate();
   }
 
   // Don't let DialogClientView handle the accelerator.
   return true;
 }
 
 void AppListView::Layout() {
   const gfx::Rect contents_bounds = GetContentsBounds();
 
-  // Make sure to layout |app_list_main_view_| and |speech_view_| at the center
-  // of the widget.
+  // Make sure to layout |app_list_main_view_| and |speech_view_| at the
+  // center of the widget.
   gfx::Rect centered_bounds = contents_bounds;
   centered_bounds.ClampToCenteredSize(gfx::Size(
       app_list_main_view_->contents_view()->GetDefaultContentsBounds().width(),
       contents_bounds.height()));
 
   app_list_main_view_->SetBoundsRect(centered_bounds);
 
   if (speech_view_) {
     gfx::Rect speech_bounds = centered_bounds;
     int preferred_height = speech_view_->GetPreferredSize().height();
@@ skipping 161 matching lines @@
   }
 
   // Prevent the search box from receiving events when hidden.
   search_box_view_->SetEnabled(!will_appear);
 
   if (will_appear) {
     speech_view_->SetVisible(true);
   } else {
     app_list_main_view_->SetVisible(true);
     // Refocus the search box. However, if the app list widget does not have
-    // focus, it means another window has already taken focus, and we *must not*
-    // focus the search box (or we would steal focus back into the app list).
+    // focus, it means another window has already taken focus, and we *must
+    // not* focus the search box (or we would steal focus back into the app
+    // list).
     if (GetWidget()->IsActive())
       search_box_view_->search_box()->RequestFocus();
   }
 }
 
 void AppListView::OnDisplayMetricsChanged(const display::Display& display,
                                           uint32_t changed_metrics) {
   if (!is_fullscreen_app_list_enabled_)
     return;
 
   // Set the |fullscreen_widget_| size to fit the new display metrics.
   gfx::Size size = display::Screen::GetScreen()
                        ->GetDisplayNearestView(parent_window())
                        .work_area()
                        .size();
   size.Enlarge(0, kShelfSize);
   fullscreen_widget_->SetSize(size);
 
   // Update the |fullscreen_widget_| bounds to accomodate the new work area.
   SetState(app_list_state_);
 }
 
 }  // namespace app_list