Use scroll-boundary-behavior to control overscroll-refresh/glow on android.

content/browser/android/overscroll_controller_android.cc

 // 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/android/overscroll_controller_android.h"
 
 #include "base/android/build_info.h"
 #include "base/command_line.h"
 #include "base/memory/ptr_util.h"
 #include "cc/layers/layer.h"
@@ skipping 78 matching lines @@
           switches::kDisablePullToRefreshEffect)) {
     return nullptr;
   }
 
   return base::MakeUnique<OverscrollRefresh>(overscroll_refresh_handler);
 }
 
 }  // namespace
 
 OverscrollControllerAndroid::OverscrollControllerAndroid(
+    ui::WindowAndroidCompositor* compositor,
+    float dpi_scale,
+    ui::OverscrollGlow* glow_effect,
+    ui::OverscrollRefresh* refresh_effect)
+    : compositor_(compositor),
+      dpi_scale_(dpi_scale),
+      enabled_(true),
+      scroll_update_consumed_(false),
+      glow_effect_(glow_effect),
+      refresh_effect_(refresh_effect) {
+  DCHECK(compositor_);
+}
+
+OverscrollControllerAndroid::OverscrollControllerAndroid(
     ui::OverscrollRefreshHandler* overscroll_refresh_handler,
     ui::WindowAndroidCompositor* compositor,
     float dpi_scale)
-    : compositor_(compositor),
-      dpi_scale_(dpi_scale),
-      enabled_(true),
-      glow_effect_(CreateGlowEffect(this, dpi_scale_)),
-      refresh_effect_(CreateRefreshEffect(overscroll_refresh_handler)) {
-  DCHECK(compositor_);
+    : compositor_(compositor), dpi_scale_(dpi_scale) {
+  OverscrollControllerAndroid(

[majidvp, 2017/07/20 13:26:55]

This is not the correct way to do delegating constructor (see [1]).
If the constructor is actually delegated then there is no need to initialize
compositor_ and dpi_scale_ twice.

[1]
http://en.cppreference.com/w/cpp/language/initializer_list?#Delegating_constr...

[sunyunjia, 2017/07/21 13:52:23]

Done.

+      compositor, dpi_scale, CreateGlowEffect(this, dpi_scale_).get(),
+      CreateRefreshEffect(overscroll_refresh_handler).get());
 }
 
 OverscrollControllerAndroid::~OverscrollControllerAndroid() {
 }
 
 bool OverscrollControllerAndroid::WillHandleGestureEvent(
     const blink::WebGestureEvent& event) {
   if (!enabled_)
     return false;
 
   if (!refresh_effect_)
     return false;
 
   // Suppress refresh detection if the glow effect is still prominent.
   if (glow_effect_ && glow_effect_->IsActive()) {
     if (glow_effect_->GetVisibleAlpha() > MinGlowAlphaToDisableRefresh())
       return false;
   }
 
   bool handled = false;
   switch (event.GetType()) {
     case blink::WebInputEvent::kGestureScrollBegin:
       refresh_effect_->OnScrollBegin();
+      scroll_update_consumed_ = false;
       break;
 
     case blink::WebInputEvent::kGestureScrollUpdate: {
       gfx::Vector2dF scroll_delta(event.data.scroll_update.delta_x,
                                   event.data.scroll_update.delta_y);
       scroll_delta.Scale(dpi_scale_);
       handled = refresh_effect_->WillHandleScrollUpdate(scroll_delta);
     } break;
 
     case blink::WebInputEvent::kGestureScrollEnd:
@@ skipping 41 matching lines @@
   // sent from the renderer compositor.
   if (event.GetType() == blink::WebInputEvent::kGestureScrollEnd ||
       event.GetType() == blink::WebInputEvent::kGestureFlingStart) {
     OnOverscrolled(DidOverscrollParams());
   }
 
   if (event.GetType() == blink::WebInputEvent::kGestureScrollUpdate &&
       refresh_effect_) {
     // The effect should only be allowed if both the causal touch events go
     // unconsumed and the generated scroll events go unconsumed.
-    bool consumed =
+    scroll_update_consumed_ =
         ack_result == INPUT_EVENT_ACK_STATE_CONSUMED ||
         event.data.scroll_update.previous_update_in_sequence_prevented;
-    refresh_effect_->OnScrollUpdateAck(consumed);
   }
 }
 
 void OverscrollControllerAndroid::OnOverscrolled(
     const DidOverscrollParams& params) {
   if (!enabled_)
     return;
 
-  if (refresh_effect_ && (refresh_effect_->IsActive() ||
-                          refresh_effect_->IsAwaitingScrollUpdateAck())) {
-    // An active (or potentially active) refresh effect should always pre-empt
-    // the passive glow effect.
-    return;
+  if (refresh_effect_) {
+    bool can_navigate =
+        (!scroll_update_consumed_) &&
+        (params.scroll_boundary_behavior.y ==
+         cc::ScrollBoundaryBehavior::ScrollBoundaryBehaviorType::
+             kScrollBoundaryBehaviorTypeAuto);
+    refresh_effect_->OnOverscrolled(can_navigate);
+
+    if (refresh_effect_->IsActive() ||
+        refresh_effect_->IsAwaitingScrollUpdateAck()) {
+      // An active (or potentially active) refresh effect should always pre-empt
+      // the passive glow effect.
+      return;
+    }
+  }
+
+  gfx::Vector2dF accumulated_overscroll =
+      gfx::ScaleVector2d(params.accumulated_overscroll, dpi_scale_);
+  gfx::Vector2dF latest_overscroll_delta =
+      gfx::ScaleVector2d(params.latest_overscroll_delta, dpi_scale_);
+  gfx::Vector2dF current_fling_velocity =
+      gfx::ScaleVector2d(params.current_fling_velocity, dpi_scale_);
+
+  if (params.scroll_boundary_behavior.x ==
+      cc::ScrollBoundaryBehavior::ScrollBoundaryBehaviorType::
+          kScrollBoundaryBehaviorTypeNone) {
+    accumulated_overscroll.set_x(0);
+    latest_overscroll_delta.set_x(0);
+    current_fling_velocity.set_x(0);
+  }
+
+  if (params.scroll_boundary_behavior.y ==
+      cc::ScrollBoundaryBehavior::ScrollBoundaryBehaviorType::
+          kScrollBoundaryBehaviorTypeNone) {
+    accumulated_overscroll.set_y(0);
+    latest_overscroll_delta.set_y(0);
+    current_fling_velocity.set_y(0);
   }
 
   if (glow_effect_ &&
       glow_effect_->OnOverscrolled(
-          base::TimeTicks::Now(),
-          gfx::ScaleVector2d(params.accumulated_overscroll, dpi_scale_),
-          gfx::ScaleVector2d(params.latest_overscroll_delta, dpi_scale_),
-          gfx::ScaleVector2d(params.current_fling_velocity, dpi_scale_),
+          base::TimeTicks::Now(), accumulated_overscroll,
+          latest_overscroll_delta, current_fling_velocity,
           gfx::ScaleVector2d(
               params.causal_event_viewport_point.OffsetFromOrigin(),
               dpi_scale_))) {

[majidvp, 2017/07/20 13:26:55]

Although the last argument is not modified like others but it is better
to move it up next to the rest and give it a name. 
Mainly because then it becomes obvious to the reader that all these properties
are being scaled consistently.

[sunyunjia, 2017/07/21 13:52:23]

Done.

     SetNeedsAnimate();
   }
 }
 
 bool OverscrollControllerAndroid::Animate(base::TimeTicks current_time,
                                           cc::Layer* parent_layer) {
   DCHECK(parent_layer);
   if (!enabled_ || !glow_effect_)
     return false;
 
@@ skipping 44 matching lines @@
 std::unique_ptr<EdgeEffectBase>
 OverscrollControllerAndroid::CreateEdgeEffect() {
   return CreateGlowEdgeEffect(&compositor_->GetResourceManager(), dpi_scale_);
 }
 
 void OverscrollControllerAndroid::SetNeedsAnimate() {
   compositor_->SetNeedsAnimate();
 }
 
 }  // namespace content