src/content/browser/renderer_host/input/gesture_text_selector.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "content/browser/renderer_host/input/gesture_text_selector.h"
   6
   7 #include "ui/events/event_constants.h"
   8 #include "ui/events/gesture_detection/gesture_detector.h"
   9 #include "ui/events/gesture_detection/gesture_provider_config_helper.h"
  10 #include "ui/events/gesture_detection/motion_event.h"
  11
  12 using ui::GestureDetector;
  13 using ui::MotionEvent;
  14
  15 namespace content {
  16 namespace {
  17 scoped_ptr<GestureDetector> CreateGestureDetector(
  18     ui::GestureListener* listener) {
  19   GestureDetector::Config config =
  20       ui::DefaultGestureProviderConfig().gesture_detector_config;
  21
  22   ui::DoubleTapListener* null_double_tap_listener = nullptr;
  23
  24   // Doubletap, showpress and longpress detection are not required, and
  25   // should be explicitly disabled for efficiency.
  26   scoped_ptr<ui::GestureDetector> detector(
  27       new ui::GestureDetector(config, listener, null_double_tap_listener));
  28   detector->set_longpress_enabled(false);
  29   detector->set_showpress_enabled(false);
  30
  31   return detector.Pass();
  32 }
  33
  34 }  // namespace
  35
  36 GestureTextSelector::GestureTextSelector(GestureTextSelectorClient* client)
  37     : client_(client),
  38       text_selection_triggered_(false),
  39       secondary_button_pressed_(false),
  40       anchor_x_(0.0f),
  41       anchor_y_(0.0f) {
  42   DCHECK(client);
  43 }
  44
  45 GestureTextSelector::~GestureTextSelector() {
  46 }
  47
  48 bool GestureTextSelector::OnTouchEvent(const MotionEvent& event) {
  49   if (event.GetAction() == MotionEvent::ACTION_DOWN) {
  50     // Only trigger selection on ACTION_DOWN to prevent partial touch or gesture
  51     // sequences from being forwarded.
  52     text_selection_triggered_ = ShouldStartTextSelection(event);
  53     secondary_button_pressed_ =
  54         event.GetButtonState() == MotionEvent::BUTTON_SECONDARY;
  55     anchor_x_ = event.GetX();
  56     anchor_y_ = event.GetY();
  57   }
  58
  59   if (!text_selection_triggered_)
  60     return false;
  61
  62   if (event.GetAction() == MotionEvent::ACTION_MOVE) {
  63     secondary_button_pressed_ =
  64         event.GetButtonState() == MotionEvent::BUTTON_SECONDARY;
  65     if (!secondary_button_pressed_) {
  66       anchor_x_ = event.GetX();
  67       anchor_y_ = event.GetY();
  68     }
  69   }
  70
  71   if (!gesture_detector_)
  72     gesture_detector_ = CreateGestureDetector(this);
  73
  74   gesture_detector_->OnTouchEvent(event);
  75
  76   // Always return true, even if |gesture_detector_| technically doesn't
  77   // consume the event, to prevent a partial touch stream from being forwarded.
  78   return true;
  79 }
  80
  81 bool GestureTextSelector::OnSingleTapUp(const MotionEvent& e) {
  82   DCHECK(text_selection_triggered_);
  83   client_->LongPress(e.GetEventTime(), e.GetX(), e.GetY());
  84   return true;
  85 }
  86
  87 bool GestureTextSelector::OnScroll(const MotionEvent& e1,
  88                                    const MotionEvent& e2,
  89                                    float distance_x,
  90                                    float distance_y) {
  91   DCHECK(text_selection_triggered_);
  92
  93   // Return if Stylus button is not pressed.
  94   if (!secondary_button_pressed_)
  95     return true;
  96
  97   // TODO(changwan): check if we can show handles after the scroll finishes
  98   // instead. Currently it is not possible as ShowSelectionHandles should
  99   // be called before we change the selection.
 100   client_->ShowSelectionHandlesAutomatically();
 101   client_->SelectRange(anchor_x_, anchor_y_, e2.GetX(), e2.GetY());
 102   return true;
 103 }
 104
 105 // static
 106 bool GestureTextSelector::ShouldStartTextSelection(const MotionEvent& event) {
 107   DCHECK_GT(event.GetPointerCount(), 0u);
 108   // Currently we are supporting stylus-only cases.
 109   const bool is_stylus = event.GetToolType(0) == MotionEvent::TOOL_TYPE_STYLUS;
 110   const bool is_only_secondary_button_pressed =
 111       event.GetButtonState() == MotionEvent::BUTTON_SECONDARY;
 112   return is_stylus && is_only_secondary_button_pressed;
 113 }
 114
 115 }  // namespace content