WIP Hittest Component.

components/viz/hittest/hittest_aggregator.cc

+// 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 "components/viz/hittest/hittest_aggregator.h"
+#include "base/logging.h"
+
+namespace viz {
+
+namespace {
+
+#define INITIAL_COUNT 128
+}
+
+HittestAggregator::HittestAggregator() {
+  regions_[0] = (Element*)malloc(INITIAL_COUNT * sizeof(Element));

[rjkroege, 2017/06/02 22:45:45]

this is most certainly not how you want to do it if for no other reason that it
won't be shared. :-)

also, you should use new

+  regions_[1] = (Element*)malloc(INITIAL_COUNT * sizeof(Element));
+  regions_[0][0].child_count_ = LAST_REGION;
+  regions_[1][0].child_count_ = LAST_REGION;
+
+  current_regions_ = regions_[0];
+}
+HittestAggregator::~HittestAggregator() {}
+
+cc::SurfaceId HittestAggregator::SurfaceIdAtPoint(
+    cc::SurfaceId root_surface_id,
+    const gfx::Point& point,
+    gfx::Point* transformed_point) {
+  return root_surface_id;

[rjkroege, 2017/06/02 22:45:45]

that's not right.

+}
+
+void HittestAggregator::SubmitHittestData(
+    hittest::mojom::HittestDataPtr hittest_data) {
+  pending_[hittest_data->surface_id_] = std::move(hittest_data);

[rjkroege, 2017/06/02 22:45:45]

not sufficient. one surface may have multiple hittest data regions. e.g.: an
occluding div in the embedder may move. 

[gklassen, 2017/06/05 21:32:14]

I'd like to understand this better.  If there are multiple hittest data regions
in a surface then doesn't this still result in one HittestData object for the
surface with multiple regions?

+}
+
+void HittestAggregator::Aggregate(cc::SurfaceId display_surface_id) {}
+
+void HittestAggregator::swap() {

[rjkroege, 2017/06/02 22:45:45]

how is this connected up to BeginFrame?

+  if (current_regions_ == regions_[0]) {
+    current_regions_ = regions_[1];
+  } else {
+    current_regions_ = regions_[0];
+  }
+}
+
+void HittestAggregator::OnSurfaceDiscarded(const cc::SurfaceId& surface_id) {
+  pending_.erase(surface_id);
+  active_.erase(surface_id);
+}
+void HittestAggregator::OnSurfaceWillDraw(const cc::SurfaceId& surface_id) {
+  active_[surface_id] = std::move(pending_[surface_id]);
+}
+
+}  // namespace viz