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// Copyright 2018 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 "base/optional.h"
#include "third_party/blink/public/mojom/loader/navigation_predictor.mojom-blink.h"
#include "third_party/blink/renderer/core/core_export.h"
#include "third_party/blink/renderer/platform/heap/handle.h"
#include "third_party/blink/renderer/platform/wtf/allocator.h"
namespace blink {
class Document;
class HTMLAnchorElement;
// This class is used to hold metrics of an html anchor element. Metrics are
// extracted via static methods. Metrics can be recorded and converted to mojom
// message used to send to the browser process.
class CORE_EXPORT AnchorElementMetrics {
// Creates AnchorElementMetrics from anchor element if possible. Then records
// the metrics, and sends them to the browser process.
static base::Optional<AnchorElementMetrics> MaybeReportClickedMetricsOnClick(
const HTMLAnchorElement*);
// Gets anchor elements from |document|, extracts features of valid anchor
// elements and sends to the browser process.
static void MaybeReportViewportMetricsOnLoad(Document& document);
// Getters of anchor element features.
float GetRatioArea() const { return ratio_area_; }
float GetRatioVisibleArea() const { return ratio_visible_area_; }
float GetRatioDistanceTopToVisibleTop() const {
return ratio_distance_top_to_visible_top_;
float GetRatioDistanceCenterToVisibleTop() const {
return ratio_distance_center_to_visible_top_;
float GetRatioDistanceRootTop() const { return ratio_distance_root_top_; }
float GetRatioDistanceRootBottom() const {
return ratio_distance_root_bottom_;
bool GetIsInIframe() const { return is_in_iframe_; }
bool GetContainsImage() const { return contains_image_; }
bool GetIsSameHost() const { return is_same_host_; }
bool GetIsUrlIncrementedByOne() const { return is_url_incremented_by_one_; }
// The maximum number of anchor element metrics allowed to report to the
// browser on page load.
static const int kMaxAnchorElementMetricsSize;
// Extract features of the anchor element.
static base::Optional<AnchorElementMetrics> Create(const HTMLAnchorElement*);
// Returns the mojom struct used to send metrics to the browser process.
mojom::blink::AnchorElementMetricsPtr CreateMetricsPtr() const;
// Record metrics of |anchor_element_|. Function is called when the anchor
// element is clicked by the user.
void RecordMetricsOnClick() const;
// The anchor element that this class is associated with.
Member<const HTMLAnchorElement> anchor_element_;
// The ratio of the absolute/visible clickable region area of an anchor
// element, and the viewport area.
const float ratio_area_;
const float ratio_visible_area_;
// The distance between the top/center of the clickable region of an anchor
// element and the top edge of the visible region, divided by the viewport
// height.
const float ratio_distance_top_to_visible_top_;
const float ratio_distance_center_to_visible_top_;
// The distance between the top of the clickable region of an anchor element
// and the top edge of the root frame, divided by the viewport height.
const float ratio_distance_root_top_;
// The distance between the bottom of the clickable region of an anchor
// element and the bottom edge of the root frame, divided by the viewport
// height.
const float ratio_distance_root_bottom_;
// The hight of the root document, divided by the viewport height.
const float ratio_root_height_;
// Whether the anchor element is within an iframe.
const bool is_in_iframe_;
// Whether the anchor element contains an image element.
const bool contains_image_;
// Whether the link target has the same host as the root document.
const bool is_same_host_;
// Whether the target url and the host url only differ by one number,
// and the number in target url equals the one in host url plus one.
const bool is_url_incremented_by_one_;
inline AnchorElementMetrics(const HTMLAnchorElement* anchor_element,
float ratio_area,
float ratio_visible_area,
float ratio_distance_top_to_visible_top,
float ratio_distance_center_to_visible_top,
float ratio_distance_root_top,
float ratio_distance_root_bottom,
float ratio_root_height,
bool is_in_iframe,
bool contains_image,
bool is_same_host,
bool is_url_incremented_by_one)
: anchor_element_(anchor_element),
is_url_incremented_by_one_(is_url_incremented_by_one) {
DCHECK_LE(0, ratio_area_);
DCHECK_GE(1, ratio_area_);
DCHECK_LE(0, ratio_visible_area_);
DCHECK_GE(1, ratio_visible_area_);
} // namespace blink