Unify Android Webview and Chrome's fling

android_webview/browser/browser_view_renderer.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 "android_webview/browser/browser_view_renderer.h"
 
 #include "android_webview/browser/browser_view_renderer_client.h"
 #include "android_webview/browser/child_frame.h"
 #include "base/auto_reset.h"
 #include "base/command_line.h"
@@ skipping 396 matching lines @@
 }
 
 void BrowserViewRenderer::OnDetachedFromWindow() {
   TRACE_EVENT0("android_webview", "BrowserViewRenderer::OnDetachedFromWindow");
   shared_renderer_state_.ReleaseHardwareDrawIfNeededOnUI();
   attached_to_window_ = false;
   DCHECK(!hardware_enabled_);
   UpdateCompositorIsActive();
 }
 
+void BrowserViewRenderer::OnComputeScroll(base::TimeTicks animation_time) {
+  if (pending_fling_animation_.is_null())
+    return;
+  TRACE_EVENT0("android_webview",
+               "BrowserViewRenderer::FlushPendingScrollAnimation");

[boliu, 2015/06/08 16:54:52]

Fix trace event name

[hush (inactive), 2015/06/09 19:11:33]

Done.

+  DCHECK(!pending_fling_animation_.is_null());
+  AnimationCallback animation = pending_fling_animation_;
+  pending_fling_animation_.Reset();
+  animation.Run(animation_time);
+}
+
 void BrowserViewRenderer::ReleaseHardware() {
   DCHECK(hardware_enabled_);
   ReturnUnusedResource(shared_renderer_state_.PassUncommittedFrameOnUI());
   ReturnResourceFromParent();
   DCHECK(shared_renderer_state_.ReturnedResourcesEmptyOnUI());
 
   if (compositor_) {
     compositor_->SetMemoryPolicy(0u);
   }
 
@@ skipping 117 matching lines @@
   DCHECK_LE(scroll_offset.x(), max_offset.x());
   DCHECK_LE(scroll_offset.y(), max_offset.y());
 
   client_->ScrollContainerViewTo(scroll_offset);
 }
 
 gfx::Vector2dF BrowserViewRenderer::GetTotalRootLayerScrollOffset() {
   return scroll_offset_dip_;
 }
 
-bool BrowserViewRenderer::IsExternalFlingActive() const {
-  return client_->IsFlingActive();
+bool BrowserViewRenderer::IsExternalScrollActive() const {
+  return client_->IsSmoothScrollingActive();
 }
 
 void BrowserViewRenderer::UpdateRootLayerState(
     const gfx::Vector2dF& total_scroll_offset_dip,
     const gfx::Vector2dF& max_scroll_offset_dip,
     const gfx::SizeF& scrollable_size_dip,
     float page_scale_factor,
     float min_page_scale_factor,
     float max_page_scale_factor) {
   TRACE_EVENT_INSTANT1(
@@ skipping 33 matching lines @@
   state->SetDouble("max_scroll_offset_dip.x", max_scroll_offset_dip_.x());
   state->SetDouble("max_scroll_offset_dip.y", max_scroll_offset_dip_.y());
 
   state->SetDouble("scrollable_size_dip.width", scrollable_size_dip.width());
   state->SetDouble("scrollable_size_dip.height", scrollable_size_dip.height());
 
   state->SetDouble("page_scale_factor", page_scale_factor_);
   return state;
 }
 
+void BrowserViewRenderer::SetNeedsAnimateScroll(
+    const AnimationCallback& scroll_animation) {
+  pending_fling_animation_ = scroll_animation;
+  PostInvalidateWithFallback();

[boliu, 2015/06/08 16:54:52]

Actually I'm eating my words. You said it's ok if compositor is not ticked. Also
fallback tick doesn't call computeScroll either. In that case, just call
client->PostInvalidate for now, and add a note why fallback tick is not needed.

We are close to removing the fallback tick altogether soon, so don't want to add
any more dependencies on it. Sounds like it's not necessary here anyway.

[hush (inactive), 2015/06/09 19:11:33]

Okay. I will just postInvalidate and add a comment there.

+}
+
 void BrowserViewRenderer::DidOverscroll(gfx::Vector2dF accumulated_overscroll,
                                         gfx::Vector2dF latest_overscroll_delta,
                                         gfx::Vector2dF current_fling_velocity) {
   const float physical_pixel_scale = dip_scale_ * page_scale_factor_;
   if (accumulated_overscroll == latest_overscroll_delta)
     overscroll_rounding_error_ = gfx::Vector2dF();
   gfx::Vector2dF scaled_overscroll_delta =
       gfx::ScaleVector2d(latest_overscroll_delta, physical_pixel_scale);
   gfx::Vector2d rounded_overscroll_delta = gfx::ToRoundedVector2d(
       scaled_overscroll_delta + overscroll_rounding_error_);
   overscroll_rounding_error_ =
       scaled_overscroll_delta - rounded_overscroll_delta;
-  client_->DidOverscroll(rounded_overscroll_delta);
+  gfx::Vector2dF fling_velocity_pixels =
+      gfx::ScaleVector2d(current_fling_velocity, physical_pixel_scale);
+
+  client_->DidOverscroll(rounded_overscroll_delta, fling_velocity_pixels);
 }
 
 void BrowserViewRenderer::PostInvalidate() {
   TRACE_EVENT_INSTANT0("android_webview", "BrowserViewRenderer::PostInvalidate",
                        TRACE_EVENT_SCOPE_THREAD);
   PostInvalidateWithFallback();
 }
 
 void BrowserViewRenderer::PostInvalidateWithFallback() {
   // Always call view invalidate. We rely the Android framework to ignore the
   // invalidate when it's not needed such as when view is not visible.
   client_->PostInvalidate();
 
   // Stop fallback ticks when one of these is true.
   // 1) Webview is paused. Also need to check we are not in clear view since
   // paused, offscreen still expect clear view to recover.
   // 2) If we are attached to window and the window is not visible (eg when
   // app is in the background). We are sure in this case the webview is used
   // "on-screen" but that updates are not needed when in the background.
   bool throttle_fallback_tick =
       (is_paused_ && !clear_view_) || (attached_to_window_ && !window_visible_);
 
-  if (throttle_fallback_tick || fallback_tick_pending_)
+  if (throttle_fallback_tick || fallback_tick_pending_ ||
+      !pending_fling_animation_.is_null())

[boliu, 2015/06/08 16:54:52]

don't forget to remove this

(Seems to be backwards anyway. The idea is cc *wants* fallback ticks if there is
a pending animation, in case the real draw doesn't come back.)

[hush (inactive), 2015/06/09 19:11:33]

okay,.. removed this. And yes. The logic here is backward :/

     return;
 
   DCHECK(post_fallback_tick_.IsCancelled());
   DCHECK(fallback_tick_fired_.IsCancelled());
 
   post_fallback_tick_.Reset(base::Bind(&BrowserViewRenderer::PostFallbackTick,
                                        base::Unretained(this)));
   ui_task_runner_->PostTask(FROM_HERE, post_fallback_tick_.callback());
   fallback_tick_pending_ = true;
 }
@@ skipping 72 matching lines @@
   base::StringAppendF(&str,
                       "overscroll_rounding_error_: %s ",
                       overscroll_rounding_error_.ToString().c_str());
   base::StringAppendF(
       &str, "on_new_picture_enable: %d ", on_new_picture_enable_);
   base::StringAppendF(&str, "clear_view: %d ", clear_view_);
   return str;
 }
 
 }  // namespace android_webview