Add pressure information to touch event.

1. Add touch pressure information to the views::TouchEvent.
   The pressure is normalized to be in [0, 1] to conform with
   W3C Touch Event standard (draft)'s definition on pressure.

2. Augment TouchFactory with the ability to save/query the range of TouchParam.
In this patch, the max value of pressure is used to normalize the 
absolute pressure value extracted from the touch device.

BUG=None
TEST=None


Review URL: http://codereview.chromium.org/7149002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@89408 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 34 insertions, 10 deletions

diff --git a/views/events/event.cc b/views/events/event.cc
index 8ec7ea8..93e5735 100644
--- a/views/events/event.cc
+++ b/views/events/event.cc
@@ -187,12 +187,14 @@ TouchEvent::TouchEvent(ui::EventType type,
                        int touch_id,
                        float radius_x,
                        float radius_y,
-                       float angle)
+                       float angle,
+                       float force)
       : LocatedEvent(type, gfx::Point(x, y), flags),
         touch_id_(touch_id),
         radius_x_(radius_x),
         radius_y_(radius_y),
-        angle_(angle) {
+        rotation_angle_(angle),
+        force_(force) {
 }
 
 TouchEvent::TouchEvent(const TouchEvent& model, View* source, View* target)
@@ -200,7 +202,8 @@ TouchEvent::TouchEvent(const TouchEvent& model, View* source, View* target)
       touch_id_(model.touch_id_),
       radius_x_(model.radius_x_),
       radius_y_(model.radius_y_),
-      angle_(model.angle_) {
+      rotation_angle_(model.rotation_angle_),
+      force_(model.force_) {
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -211,7 +214,8 @@ TouchEvent::TouchEvent(const TouchEvent& model, View* root)
       touch_id_(model.touch_id_),
       radius_x_(model.radius_x_),
       radius_y_(model.radius_y_),
-      angle_(model.angle_) {
+      rotation_angle_(model.rotation_angle_),
+      force_(model.force_) {
 }
 #endif
 
diff --git a/views/events/event.h b/views/events/event.h
index 9b1d33a..531b506 100644
--- a/views/events/event.h
+++ b/views/events/event.h
@@ -263,7 +263,8 @@ class TouchEvent : public LocatedEvent {
              int touch_id,
              float radius_x,
              float radius_y,
-             float angle);
+             float angle,
+             float force);
 
   // Create a new TouchEvent which is identical to the provided model.
   // If source / target views are provided, the model location will be converted
@@ -274,7 +275,8 @@ class TouchEvent : public LocatedEvent {
 
   float radius_x() const { return radius_x_; }
   float radius_y() const { return radius_y_; }
-  float angle() const { return angle_; }
+  float rotation_angle() const { return rotation_angle_; }
+  float force() const { return force_; }
 
  private:
   friend class internal::RootView;
@@ -292,7 +294,10 @@ class TouchEvent : public LocatedEvent {
   const float radius_y_;
 
   // Angle of the major axis away from the X axis. Default 0.0.
-  const float angle_;
+  const float rotation_angle_;
+
+  // Force (pressure) of the touch. Normalized to be [0, 1]. Default to be 0.0.
+  const float force_;
 
   DISALLOW_COPY_AND_ASSIGN(TouchEvent);
 };
diff --git a/views/events/event_x.cc b/views/events/event_x.cc
index 0fa471e..ec1d722 100644
--- a/views/events/event_x.cc
+++ b/views/events/event_x.cc
@@ -254,6 +254,20 @@ float GetTouchParamFromXEvent(XEvent* xev,
   return default_value;
 }
 
+float GetTouchForceFromXEvent(XEvent* xev) {
+  float force = 0.0;
+#if defined(HAVE_XINPUT2)
+  force = GetTouchParamFromXEvent(xev, TouchFactory::TP_PRESSURE, 0.0);
+  unsigned int deviceid =
+      static_cast<XIDeviceEvent*>(xev->xcookie.data)->sourceid;
+  // Force is normalized to fall into [0, 1]
+  if (!TouchFactory::GetInstance()->NormalizeTouchParam(
+      deviceid, TouchFactory::TP_PRESSURE, &force))
+    force = 0.0;
+#endif
+  return force;
+}
+
 }  // namespace
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -387,9 +401,10 @@ TouchEvent::TouchEvent(NativeEvent2 native_event_2,
       radius_y_(GetTouchParamFromXEvent(native_event_2,
                                         TouchFactory::TP_TOUCH_MINOR,
                                         2.0) / 2.0),
-      angle_(GetTouchParamFromXEvent(native_event_2,
-                                     TouchFactory::TP_ORIENTATION,
-                                     0.0)) {
+      rotation_angle_(GetTouchParamFromXEvent(native_event_2,
+                                              TouchFactory::TP_ORIENTATION,
+                                              0.0)),
+      force_(GetTouchForceFromXEvent(native_event_2)) {
   if (type() == ui::ET_TOUCH_PRESSED || type() == ui::ET_TOUCH_RELEASED) {
     TouchFactory* factory = TouchFactory::GetInstance();
     float slot;