third_party/blink/renderer/core/mobile_metrics/mobile_friendliness_checker.h

// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef THIRD_PARTY_BLINK_RENDERER_CORE_MOBILE_METRICS_MOBILE_FRIENDLINESS_CHECKER_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_MOBILE_METRICS_MOBILE_FRIENDLINESS_CHECKER_H_

#include <optional>

#include "base/time/time.h"
#include "third_party/blink/renderer/core/core_export.h"
#include "third_party/blink/renderer/core/frame/local_frame_view.h"
#include "third_party/blink/renderer/platform/heap/garbage_collected.h"
#include "third_party/blink/renderer/platform/heap/member.h"
#include "third_party/blink/renderer/platform/heap/visitor.h"

namespace blink {

class Document;
class LocalFrameView;
class TransformPaintPropertyNodeOrAlias;

// Calculates the mobile usability of current page, especially friendliness on
// smart phone devices are checked. The calculated value will be sent as a part
// of UKM.
class CORE_EXPORT MobileFriendlinessChecker
    : public GarbageCollected<MobileFriendlinessChecker> {
 public:
  explicit MobileFriendlinessChecker(LocalFrameView& frame_view);
  virtual ~MobileFriendlinessChecker();
  static MobileFriendlinessChecker* Create(LocalFrameView& frame_view);
  static MobileFriendlinessChecker* From(const Document&);

  void MaybeRecompute();
  void ComputeNowForTesting() { ComputeNow(); }

  void NotifyPaintBegin();
  void NotifyPaintEnd();
  void NotifyPaintTextFragment(
      const PhysicalRect& paint_rect,
      int font_size,
      const TransformPaintPropertyNodeOrAlias& current_transform);
  void NotifyPaintReplaced(
      const PhysicalRect& paint_rect,
      const TransformPaintPropertyNodeOrAlias& current_transform);

  void Trace(Visitor* visitor) const;

  struct AreaSizes {
    double small_font_area = 0;
    double total_text_area = 0;
    double content_beyond_viewport_area = 0;
    int TextContentsOutsideViewportPercentage(double viewport_area) const;
    int SmallTextRatio() const;
  };

  class PaintScope final {
    STACK_ALLOCATED();

   public:
    explicit PaintScope(MobileFriendlinessChecker& mfc) : mfc_(mfc) {
      mfc_.NotifyPaintBegin();
    }
    ~PaintScope() { mfc_.NotifyPaintEnd(); }

   private:
    MobileFriendlinessChecker& mfc_;
  };

  class IgnoreBeyondViewportScope final {
    STACK_ALLOCATED();

   public:
    explicit IgnoreBeyondViewportScope(MobileFriendlinessChecker& mfc)
        : mfc_(mfc) {
      mfc_.ignore_beyond_viewport_scope_count_++;
    }
    ~IgnoreBeyondViewportScope() { mfc_.ignore_beyond_viewport_scope_count_--; }

   private:
    MobileFriendlinessChecker& mfc_;
  };

 private:
  // Evaluate mobile friendliness of the page.
  void ComputeNow();

  // Returns percentage value [0-100] of bad tap targets in the area of the
  // first page. Returns kTimeBudgetExceeded if the time limit is exceeded.
  int ComputeBadTapTargetsRatio();

  void UpdateTextAreaSizes(const PhysicalRect& text_rect, int font_size);
  void UpdateBeyondViewportAreaSizes(
      const PhysicalRect& paint_rect,
      const TransformPaintPropertyNodeOrAlias& current_transform);

 private:
  Member<LocalFrameView> frame_view_;
  Member<const TransformPaintPropertyNodeOrAlias> viewport_transform_;
  Member<const TransformPaintPropertyNodeOrAlias> previous_transform_;
  float current_x_offset_ = 0.0;
  float viewport_width_;
  double viewport_scalar_ = 1.0;
  double initial_scale_ = 1.0;
  base::TimeTicks last_evaluated_;
  AreaSizes area_sizes_;
  bool viewport_device_width_ = false;
  bool allow_user_zoom_ = true;
  std::optional<int32_t> viewport_initial_scale_x10_;
  std::optional<int32_t> viewport_hardcoded_width_;
  uint32_t ignore_beyond_viewport_scope_count_ = 0;
  bool is_painting_ = false;
};

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_CORE_MOBILE_METRICS_MOBILE_FRIENDLINESS_CHECKER_H_