Touch gestures for System Tray/ IME/ Stylus/ Notifications

ash/system/tray_drag_controller.cc

Index: ash/system/tray_drag_controller.cc
diff --git a/ash/system/tray_drag_controller.cc b/ash/system/tray_drag_controller.cc
new file mode 100644
index 0000000000000000000000000000000000000000..2b9da05a6eb03881fe74eeb611d615e272d2ab0a
--- /dev/null
+++ b/ash/system/tray_drag_controller.cc
@@ -0,0 +1,118 @@
+// Copyright 2017 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 "ash/system/tray_drag_controller.h"
+
+#include "ash/shell.h"
+#include "ash/system/tray/tray_background_view.h"
+#include "ash/wm/maximize_mode/maximize_mode_controller.h"
+
+namespace ash {
+
+bool TrayDragController::ProcessGestureEvent(const ui::GestureEvent& event,
+                                             TrayBackgroundView* target_view,
+                                             bool is_on_bubble) {
+  target_view_ = target_view;
+  if (!Shell::Get()
+           ->maximize_mode_controller()
+           ->IsMaximizeModeWindowManagerEnabled() ||
+      !shelf_->IsHorizontalAlignment()) {

[msw, 2017/07/12 05:04:52]

Ah, this only works for horizontal alignments? Do we have plans for left/right?

[minch1, 2017/07/13 19:10:36]

Acknowledged.

+    return false;
+  }
+
+  is_on_bubble_ = is_on_bubble;
+  if (event.type() == ui::ET_GESTURE_SCROLL_BEGIN)
+    return StartGestureDrag(event);
+
+  if (!target_view_->HasBubble() || !is_in_drag_) {

[msw, 2017/07/12 05:04:52]

nit: curlies not needed for one-liners

[minch1, 2017/07/13 19:10:36]

Done.

+    return false;
+  }
+
+  if (event.type() == ui::ET_GESTURE_SCROLL_UPDATE) {
+    UpdateGestureDrag(event);
+    return true;
+  }
+
+  if (event.type() == ui::ET_GESTURE_SCROLL_END ||
+      event.type() == ui::ET_SCROLL_FLING_START) {
+    CompleteGestureDrag(event);
+    return true;
+  }
+
+  // Unexpected event. Reset the drag state and close the bubble.
+  is_in_drag_ = false;
+  target_view_->CloseBubble();
+  return false;
+}
+
+bool TrayDragController::StartGestureDrag(const ui::GestureEvent& gesture) {
+  if (!is_on_bubble_) {
+    // Dragging happens on the tray view. Close the bubble if there is already
+    // one opened. And return false to let shelf handle the event.
+    if (target_view_->HasBubble()) {
+      target_view_->CloseBubble();
+      return false;
+    }
+
+    // If the scroll sequence begins to scroll downward, return false so that
+    // the event will instead by handled by the shelf.
+    if (gesture.details().scroll_y_hint() > 0)
+      return false;
+
+    target_view_->ShowBubble();
+  }
+
+  is_in_drag_ = true;
+  gesture_drag_amount_ = 0.f;
+  tray_bubble_bounds_ =
+      target_view_->GetBubbleView()->GetWidget()->GetWindowBoundsInScreen();
+  UpdateBubbleBounds();
+  return true;
+}
+
+void TrayDragController::UpdateGestureDrag(const ui::GestureEvent& gesture) {
+  UpdateBubbleBounds();
+  gesture_drag_amount_ += gesture.details().scroll_y();

[msw, 2017/07/12 05:04:52]

should we be updating this value before calling UpdateBubbleBounds to preserve
the old behavior?

[minch1, 2017/07/13 19:10:36]

Thanks. I think we should update this value before calling UpdateBubbleBounds,
since update bounds based on |gesture_drag_amount_| now.

+}
+
+void TrayDragController::CompleteGestureDrag(const ui::GestureEvent& gesture) {
+  const bool hide_bubble = !ShouldShowBubbleAfterScrollSequence(gesture);
+  gfx::Rect target_bounds = tray_bubble_bounds_;
+
+  if (hide_bubble)
+    target_bounds.set_y(shelf_->GetIdealBounds().y());
+
+  target_view_->AnimateToTargetBounds(target_bounds, hide_bubble);
+  is_in_drag_ = false;
+}
+
+void TrayDragController::UpdateBubbleBounds() {
+  gfx::Rect bounds_on_location = tray_bubble_bounds_;

[msw, 2017/07/12 05:04:52]

nit: can you imagine a better name for this?

[minch1, 2017/07/13 19:10:36]

How about |current_tray_bubble_bounds|?

+  int bounds_y =
+      (is_on_bubble_ ? tray_bubble_bounds_.y() : shelf_->GetIdealBounds().y()) +
+      gesture_drag_amount_;
+  bounds_on_location.set_y(std::max(bounds_y, tray_bubble_bounds_.y()));
+  target_view_->GetBubbleView()->GetWidget()->SetBounds(bounds_on_location);
+}
+
+bool TrayDragController::ShouldShowBubbleAfterScrollSequence(
+    const ui::GestureEvent& sequence_end) {
+  // If the scroll sequence terminates with a fling, show the bubble if the
+  // fling was fast enough and in the correct direction.
+  if (sequence_end.type() == ui::ET_SCROLL_FLING_START &&
+      fabs(sequence_end.details().velocity_y()) > kFlingVelocity) {
+    return sequence_end.details().velocity_y() < 0;
+  }
+
+  DCHECK(sequence_end.type() == ui::ET_GESTURE_SCROLL_END ||
+         sequence_end.type() == ui::ET_SCROLL_FLING_START);
+
+  // Keep the bubble's original state if the |gesture_drag_amount_| doesn't
+  // exceed one-third of the bubble's height.
+  if (is_on_bubble_)
+    return gesture_drag_amount_ < tray_bubble_bounds_.height() / 3.0;
+  return -gesture_drag_amount_ >= tray_bubble_bounds_.height() / 3.0;
+}
+
+}  // namespace ash