Two Finger Tap

ui/chromeos/touch_exploration_controller.cc

Index: ui/chromeos/touch_exploration_controller.cc
diff --git a/ui/chromeos/touch_exploration_controller.cc b/ui/chromeos/touch_exploration_controller.cc
index 3670f1e948f213908d1884d9f844eacf35916a5c..c8ce0b64165c836fbc2500b4321b6b2e29d8d054 100644
--- a/ui/chromeos/touch_exploration_controller.cc
+++ b/ui/chromeos/touch_exploration_controller.cc
@@ -27,6 +27,10 @@ const base::TimeDelta kSoundDelay = base::TimeDelta::FromMilliseconds(150);
 
 // In ChromeOS, VKEY_LWIN is synonymous for the search key.
 const ui::KeyboardCode kChromeOSSearchKey = ui::VKEY_LWIN;
+
+// Delay to indicate that a two finger tap has occured.
+const base::TimeDelta kTwoFingerTap = base::TimeDelta::FromMilliseconds(50);
+
 }  // namespace
 
 TouchExplorationController::TouchExplorationController(
@@ -134,6 +138,8 @@ ui::EventRewriteStatus TouchExplorationController::RewriteEvent(
       return InOneFingerPassthrough(touch_event, rewritten_event);
     case WAIT_FOR_ONE_FINGER:
       return InWaitForOneFinger(touch_event, rewritten_event);
+    case TWO_FINGER_TAP:
+      return InTwoFingerTap(touch_event, rewritten_event);
   }
   NOTREACHED();
   return ui::EVENT_REWRITE_CONTINUE;
@@ -168,6 +174,11 @@ ui::EventRewriteStatus TouchExplorationController::InSingleTapPressed(
   const ui::EventType type = event.type();
 
   if (type == ui::ET_TOUCH_PRESSED) {
+    if ((event.time_stamp() - initial_press_->time_stamp()) < kTwoFingerTap) {
+      state_ = TWO_FINGER_TAP;
+      VLOG_STATE();
+      return EVENT_REWRITE_DISCARD;

[aboxhall, 2014/08/06 18:30:00]

Does this have any implications for multi-finger swipes?

[lisayin, 2014/08/06 20:41:35]

Once we need to merge the two, we'll have a slop check.

+    }
     // TODO (evy, lisayin) : add support for multifinger swipes.
     // For now, we wait for there to be only one finger down again.
     state_ = WAIT_FOR_ONE_FINGER;
@@ -549,6 +560,33 @@ ui::EventRewriteStatus TouchExplorationController::InSlideGesture(
   return ui::EVENT_REWRITE_DISCARD;
 }
 
+ui::EventRewriteStatus TouchExplorationController::InTwoFingerTap(
+    const ui::TouchEvent& event,
+    scoped_ptr<ui::Event>* rewritten_event) {
+  ui::EventType type = event.type();
+  if (type == ui::ET_TOUCH_PRESSED) {

[aboxhall, 2014/08/06 18:30:00]

And, does this have any implications for multi-finger swipes?

[evy, 2014/08/06 18:33:03]

Yeah, whoever finishes last gets to add the change :)
We're thinking that if it leaves the slop before a tap timer fire, it will then
go into gesture mode.
If a third finger is added, we can go into gesture mode too, since there's
nothing else that would lead to at this point.

+    state_ = WAIT_FOR_ONE_FINGER;
+    VLOG_STATE();
+    return ui::EVENT_REWRITE_DISCARD;
+  }
+
+  if (current_touch_ids_.size() != 0)
+    return ui::EVENT_REWRITE_DISCARD;
+
+  if (type == ui::ET_TOUCH_RELEASED) {
+    ui::KeyEvent control_down(
+        ui::ET_KEY_PRESSED, ui::VKEY_CONTROL, ui::EF_CONTROL_DOWN);
+    ui::KeyEvent control_up(ui::ET_KEY_RELEASED, ui::VKEY_CONTROL, ui::EF_NONE);
+
+    DispatchEvent(&control_down);
+    DispatchEvent(&control_up);
+
+    ResetToNoFingersDown();
+    return ui::EVENT_REWRITE_DISCARD;
+  }
+  return ui::EVENT_REWRITE_DISCARD;
+}
+
 base::TimeDelta TouchExplorationController::Now() {
   if (tick_clock_) {
     // This is the same as what EventTimeForNow() does, but here we do it
@@ -595,6 +633,10 @@ void TouchExplorationController::OnTapTimerFired() {
       state_ = TOUCH_EXPLORATION;
       VLOG_STATE();
       break;
+    case TWO_FINGER_TAP:
+      state_ = WAIT_FOR_ONE_FINGER;
+      VLOG_STATE();
+      break;
     default:
       return;
   }
@@ -875,6 +917,8 @@ const char* TouchExplorationController::EnumStateToString(State state) {
       return "ONE_FINGER_PASSTHROUGH";
     case WAIT_FOR_ONE_FINGER:
       return "WAIT_FOR_ONE_FINGER";
+    case TWO_FINGER_TAP:
+      return "TWO_FINGER_TAP";
   }
   return "Not a state";
 }