1
    2
    3
    4
    5
    6
    7
    8
    9
   10
   11
   12
   13
   14
   15
   16
   17
   18
   19
   20
   21
   22
   23
   24
   25
   26
   27
   28
   29
   30
   31
   32
   33
   34
   35
   36
   37
   38
   39
   40
   41
   42
   43
   44
   45
   46
   47
   48
   49
   50
   51
   52
   53
   54
   55
   56
   57
   58
   59
   60
   61
   62
   63
   64
   65
   66
   67
   68
   69
   70
   71
   72
   73
   74
   75
   76
   77
   78
   79
   80
   81
   82
   83
   84
   85
   86
   87
   88
   89
   90
   91
   92
   93
   94
   95
   96
   97
   98
   99
  100
  101
  102
  103
  104
  105
  106
  107
  108
  109
  110
  111
  112
  113
  114
  115
  116
  117
  118
  119
  120
  121
  122
  123
  124
  125
  126
  127
  128
  129
  130
  131
  132
  133
  134
  135
  136
  137
  138
  139
  140
  141
  142
  143
  144
  145
  146
  147
  148
  149
  150
  151
  152
  153
  154
  155
  156
  157


content / browser / renderer_host / input / stylus_text_selector.cc [blame]

// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "content/browser/renderer_host/input/stylus_text_selector.h"

#include "base/check_op.h"
#include "base/notreached.h"
#include "ui/events/event_constants.h"
#include "ui/events/gesture_detection/gesture_detector.h"
#include "ui/events/gesture_detection/gesture_provider_config_helper.h"
#include "ui/events/velocity_tracker/motion_event.h"

using ui::GestureDetector;
using ui::MotionEvent;

namespace content {
namespace {
std::unique_ptr<GestureDetector> CreateGestureDetector(
    ui::GestureListener* listener) {
  GestureDetector::Config config =
      ui::GetGestureProviderConfig(
          ui::GestureProviderConfigType::CURRENT_PLATFORM)
          .gesture_detector_config;

  ui::DoubleTapListener* null_double_tap_listener = nullptr;

  // Doubletap, showpress and longpress detection are not required, and
  // should be explicitly disabled for efficiency.
  std::unique_ptr<ui::GestureDetector> detector(
      new ui::GestureDetector(config, listener, null_double_tap_listener));
  detector->set_press_and_hold_enabled(false);
  detector->set_showpress_enabled(false);

  return detector;
}

}  // namespace

StylusTextSelector::StylusTextSelector(StylusTextSelectorClient* client)
    : client_(client),
      text_selection_triggered_(false),
      secondary_button_pressed_(false),
      drag_state_(NO_DRAG),
      anchor_x_(0.0f),
      anchor_y_(0.0f) {
  DCHECK(client);
}

StylusTextSelector::~StylusTextSelector() {
}

bool StylusTextSelector::OnTouchEvent(const MotionEvent& event) {
  // Only trigger selection on ACTION_DOWN to prevent partial touch or gesture
  // sequences from being forwarded.
  if (event.GetAction() == MotionEvent::Action::DOWN)
    text_selection_triggered_ = ShouldStartTextSelection(event);

  if (!text_selection_triggered_)
    return false;

  // For Android version < M, stylus button pressed state is BUTTON_SECONDARY.
  // From Android M, this state has changed to BUTTON_STYLUS_PRIMARY.
  secondary_button_pressed_ =
      event.GetButtonState() == MotionEvent::BUTTON_SECONDARY ||
      event.GetButtonState() == MotionEvent::BUTTON_STYLUS_PRIMARY;

  switch (event.GetAction()) {
    case MotionEvent::Action::DOWN:
      drag_state_ = NO_DRAG;
      anchor_x_ = event.GetX();
      anchor_y_ = event.GetY();
      break;

    case MotionEvent::Action::MOVE:
      if (!secondary_button_pressed_) {
        if (drag_state_ == DRAGGING_WITH_BUTTON_PRESSED)
          drag_state_ = DRAGGING_WITH_BUTTON_RELEASED;
        anchor_x_ = event.GetX();
        anchor_y_ = event.GetY();
      }
      break;

    case MotionEvent::Action::UP:
    case MotionEvent::Action::CANCEL:
      if (drag_state_ == DRAGGING_WITH_BUTTON_PRESSED ||
          drag_state_ == DRAGGING_WITH_BUTTON_RELEASED)
        client_->OnStylusSelectEnd(event.GetX(), event.GetY());
      drag_state_ = NO_DRAG;
      break;

    case MotionEvent::Action::POINTER_UP:
    case MotionEvent::Action::POINTER_DOWN:
      break;
    case MotionEvent::Action::NONE:
    case MotionEvent::Action::HOVER_ENTER:
    case MotionEvent::Action::HOVER_EXIT:
    case MotionEvent::Action::HOVER_MOVE:
    case MotionEvent::Action::BUTTON_PRESS:
    case MotionEvent::Action::BUTTON_RELEASE:
      NOTREACHED_IN_MIGRATION();
      break;
  }

  if (!gesture_detector_)
    gesture_detector_ = CreateGestureDetector(this);

  gesture_detector_->OnTouchEvent(event, false /* should_process_double_tap */);

  // Always return true, even if |gesture_detector_| technically doesn't
  // consume the event. This prevents forwarding of a partial touch stream.
  return true;
}

bool StylusTextSelector::OnSingleTapUp(const MotionEvent& e, int tap_count) {
  DCHECK(text_selection_triggered_);
  DCHECK_NE(DRAGGING_WITH_BUTTON_PRESSED, drag_state_);
  client_->OnStylusSelectTap(e.GetEventTime(), e.GetX(), e.GetY());
  return true;
}

bool StylusTextSelector::OnScroll(const MotionEvent& e1,
                                  const MotionEvent& e2,
                                  const MotionEvent& secondary_pointer_down,
                                  float distance_x,
                                  float distance_y) {
  DCHECK(text_selection_triggered_);

  // Return if Stylus button is not pressed.
  if (!secondary_button_pressed_)
    return true;

  if (drag_state_ == NO_DRAG || drag_state_ == DRAGGING_WITH_BUTTON_RELEASED) {
    drag_state_ = DRAGGING_WITH_BUTTON_PRESSED;
    client_->OnStylusSelectBegin(anchor_x_, anchor_y_, e2.GetX(), e2.GetY());
  } else {
    client_->OnStylusSelectUpdate(e2.GetX(), e2.GetY());
  }

  return true;
}

// static
bool StylusTextSelector::ShouldStartTextSelection(const MotionEvent& event) {
  DCHECK_GT(event.GetPointerCount(), 0u);
  // Currently we are supporting stylus-only cases.
  const bool is_stylus = event.GetToolType(0) == MotionEvent::ToolType::STYLUS;

  // For Android version < M, stylus button pressed state is BUTTON_SECONDARY.
  // From Android M, this state has changed to BUTTON_STYLUS_PRIMARY.
  const bool is_only_secondary_button_pressed =
      event.GetButtonState() == MotionEvent::BUTTON_SECONDARY ||
      event.GetButtonState() == MotionEvent::BUTTON_STYLUS_PRIMARY;
  return is_stylus && is_only_secondary_button_pressed;
}

}  // namespace content