Implemented smooth scrolling using xinput2 in X11.

ui/events/devices/x11/device_data_manager_x11.cc

Index: ui/events/devices/x11/device_data_manager_x11.cc
diff --git a/ui/events/devices/x11/device_data_manager_x11.cc b/ui/events/devices/x11/device_data_manager_x11.cc
index e02162049645fa807b1c05ebaa16b49cdcd6df77..5c15eb7a42281fe395eaefd7a570740b06bc69e6 100644
--- a/ui/events/devices/x11/device_data_manager_x11.cc
+++ b/ui/events/devices/x11/device_data_manager_x11.cc
@@ -215,6 +215,7 @@ bool DeviceDataManagerX11::IsXInput2Available() const {
 void DeviceDataManagerX11::UpdateDeviceList(Display* display) {
   cmt_devices_.reset();
   touchpads_.reset();
+  scrollclass_devices_.reset();
   master_pointers_.clear();
   for (int i = 0; i < kMaxDeviceNum; ++i) {
     valuator_count_[i] = 0;
@@ -222,6 +223,8 @@ void DeviceDataManagerX11::UpdateDeviceList(Display* display) {
     data_type_lookup_[i].clear();
     valuator_min_[i].clear();
     valuator_max_[i].clear();
+    scroll_data_[i].horizontal.number = -1;
+    scroll_data_[i].vertical.number = -1;

[sadrul, 2016/01/04 18:51:21]

This should reset |seen| too?

[Will Shackleton, 2016/01/04 21:07:41]

Acknowledged.

     for (int j = 0; j < kMaxSlotNum; j++)
       last_seen_valuator_[i][j].clear();
   }
@@ -277,21 +280,14 @@ void DeviceDataManagerX11::UpdateDeviceList(Display* display) {
     for (int j = 0; j < kMaxSlotNum; j++)
       last_seen_valuator_[deviceid][j].resize(DT_LAST_ENTRY, 0);
     for (int j = 0; j < info.num_classes; ++j) {
-      if (info.classes[j]->type != XIValuatorClass)
-        continue;
-
-      XIValuatorClassInfo* v =
-          reinterpret_cast<XIValuatorClassInfo*>(info.classes[j]);
-      for (int data_type = 0; data_type < DT_LAST_ENTRY; ++data_type) {
-        if (v->label == atoms[data_type]) {
-          valuator_lookup_[deviceid][data_type] = v->number;
-          data_type_lookup_[deviceid][v->number] = data_type;
-          valuator_min_[deviceid][data_type] = v->min;
-          valuator_max_[deviceid][data_type] = v->max;
-          if (IsCMTDataType(data_type))
-            possible_cmt = true;
-          break;
-        }
+      if (info.classes[j]->type == XIValuatorClass) {
+        if (UpdateValuatorClassDevice(
+                reinterpret_cast<XIValuatorClassInfo*>(info.classes[j]), atoms,
+                deviceid))
+          possible_cmt = true;
+      } else if (info.classes[j]->type == XIScrollClass) {
+        UpdateScrollClassDevice(
+            reinterpret_cast<XIScrollClassInfo*>(info.classes[j]), deviceid);
       }
     }
 
@@ -300,6 +296,46 @@ void DeviceDataManagerX11::UpdateDeviceList(Display* display) {
   }
 }
 
+bool DeviceDataManagerX11::UpdateValuatorClassDevice(

[sadrul, 2016/01/04 18:51:21]

This should be farther down (the function order in .cc should match the order in
.h)

+    XIValuatorClassInfo* valuator_class_info,
+    Atom* atoms,
+    int deviceid) {
+  DCHECK(deviceid >= 0 && deviceid < kMaxDeviceNum);
+  for (int data_type = 0; data_type < DT_LAST_ENTRY; ++data_type) {
+    if (valuator_class_info->label == atoms[data_type]) {
+      valuator_lookup_[deviceid][data_type] = valuator_class_info->number;
+      data_type_lookup_[deviceid][valuator_class_info->number] = data_type;
+      valuator_min_[deviceid][data_type] = valuator_class_info->min;
+      valuator_max_[deviceid][data_type] = valuator_class_info->max;
+      if (IsCMTDataType(data_type))
+        return true;
+    }

[sadrul, 2016/01/04 18:51:21]

The old code breaks out of the loop here. We should do the same here.

This code would be more readable like this:

  Atom* label = std::find(atoms, atoms + DT_LAST_ENTRY,
      valuator_class_info->label);
  if (label == atoms + DT_LAST_ENTRY)
    return false;

  int data_type = label - atoms;
  DCHECK_GE(data_type, 0);
  DCHECK_LT(data_type, DT_LAST_ENTRY);

  ... Update |valuator_lookup_| etc. here.

  return IsCMTDataType(data_type);

[Will Shackleton, 2016/01/04 21:07:41]

Acknowledged.

+  }
+  return false;
+}
+
+void DeviceDataManagerX11::UpdateScrollClassDevice(
+    XIScrollClassInfo* scroll_class_info,
+    int deviceid) {
+  DCHECK(deviceid >= 0 && deviceid < kMaxDeviceNum);
+  ScrollInfo& info = scroll_data_[deviceid];
+  switch (scroll_class_info->scroll_type) {
+    case XIScrollTypeVertical:
+      info.vertical.number = scroll_class_info->number;
+      info.vertical.increment = scroll_class_info->increment;
+      info.vertical.position = 0;
+      info.vertical.seen = false;
+      break;
+    case XIScrollTypeHorizontal:
+      info.horizontal.number = scroll_class_info->number;
+      info.horizontal.increment = scroll_class_info->increment;
+      info.horizontal.position = 0;
+      info.horizontal.seen = false;
+      break;
+  }
+  scrollclass_devices_[deviceid] = true;
+}
+
 bool DeviceDataManagerX11::GetSlotNumber(const XIDeviceEvent* xiev, int* slot) {
   ui::TouchFactory* factory = ui::TouchFactory::GetInstance();
   if (!factory->IsMultiTouchDevice(xiev->sourceid)) {
@@ -422,6 +458,42 @@ bool DeviceDataManagerX11::IsCMTDeviceEvent(
   return cmt_devices_[xievent->sourceid];
 }
 
+int DeviceDataManagerX11::GetScrollClassEventDetail(
+    const base::NativeEvent& native_event) const {
+  if (native_event->type != GenericEvent)
+    return SCROLL_TYPE_NO_SCROLL;
+
+  XIDeviceEvent* xievent =
+      static_cast<XIDeviceEvent*>(native_event->xcookie.data);
+  if (xievent->sourceid >= kMaxDeviceNum)
+    return SCROLL_TYPE_NO_SCROLL;
+  if (!scrollclass_devices_[xievent->sourceid])
+    return SCROLL_TYPE_NO_SCROLL;
+  int horizontal_id = scroll_data_[xievent->sourceid].horizontal.number;
+  int vertical_id = scroll_data_[xievent->sourceid].vertical.number;
+  return (XIMaskIsSet(xievent->valuators.mask, horizontal_id)
+              ? SCROLL_TYPE_HORIZONTAL
+              : 0) |
+         (XIMaskIsSet(xievent->valuators.mask, vertical_id)
+              ? SCROLL_TYPE_VERTICAL
+              : 0);
+}
+
+int DeviceDataManagerX11::GetScrollClassDeviceDetail(
+    const base::NativeEvent& native_event) const {
+  XEvent& xev = *native_event;
+  if (xev.type != GenericEvent)
+    return SCROLL_TYPE_NO_SCROLL;
+
+  XIDeviceEvent* xiev = static_cast<XIDeviceEvent*>(xev.xcookie.data);
+  if (xiev->sourceid >= kMaxDeviceNum || xiev->deviceid >= kMaxDeviceNum)
+    return SCROLL_TYPE_NO_SCROLL;
+  const int sourceid = xiev->sourceid;
+  ScrollInfo device_data = scroll_data_[sourceid];

[sadrul, 2016/01/04 18:51:21]

const &

(but we probably don't need this function anyway; see comment in events_x.cc)

+  return (device_data.vertical.number >= 0 ? SCROLL_TYPE_VERTICAL : 0) |
+         (device_data.horizontal.number >= 0 ? SCROLL_TYPE_HORIZONTAL : 0);
+}
+
 bool DeviceDataManagerX11::IsCMTGestureEvent(
     const base::NativeEvent& native_event) const {
   return (IsScrollEvent(native_event) ||
@@ -514,6 +586,64 @@ void DeviceDataManagerX11::GetScrollOffsets(
     *finger_count = static_cast<int>(data[DT_CMT_FINGER_COUNT]);
 }
 
+void DeviceDataManagerX11::GetScrollClassOffsets(
+    const base::NativeEvent& native_event,
+    double* x_offset,
+    double* y_offset) {
+  XEvent& xev = *native_event;

[sadrul, 2016/01/04 18:51:21]

DCHECK_NE(NO_SCROLL, GetScrollClassEventDetail(native_event))

[Will Shackleton, 2016/01/04 21:07:41]

Acknowledged.

+  if (xev.type != GenericEvent)
+    return;
+
+  *x_offset = 0;
+  *y_offset = 0;
+
+  XIDeviceEvent* xiev = static_cast<XIDeviceEvent*>(xev.xcookie.data);
+  if (xiev->sourceid >= kMaxDeviceNum || xiev->deviceid >= kMaxDeviceNum)
+    return;
+  const int sourceid = xiev->sourceid;
+  double* valuators = xiev->valuators.values;
+
+  ScrollInfo& info = scroll_data_[sourceid];

[sadrul, 2016/01/04 18:51:21]

Use a pointer here instead.

+
+  const int horizontal_number = info.horizontal.number;
+  const int vertical_number = info.vertical.number;
+
+  for (int i = 0; i <= valuator_count_[sourceid]; ++i) {
+    if (!XIMaskIsSet(xiev->valuators.mask, i))
+      continue;
+    if (i == horizontal_number) {
+      double value = *valuators;
+      double delta = 0;
+
+      if (info.horizontal.seen)
+        delta = info.horizontal.position - value;
+
+      info.horizontal.seen = true;
+      info.horizontal.position = value;
+      *x_offset = delta;
+      NormalizeScrollData(sourceid, true, x_offset);

[sadrul, 2016/01/04 18:51:21]

We already have |info| here. Any reason we can't just set:

  *x_offset = delta / info...increment;

(i.e. do we need NormalizeScrollData()?)

[Will Shackleton, 2016/01/04 21:07:41]

It originally did more iirc. Deleting.

+    } else if (i == vertical_number) {
+      double value = *valuators;
+      double delta = 0;
+      if (info.vertical.seen)
+        delta = info.vertical.position - value;
+
+      info.vertical.seen = true;
+      info.vertical.position = value;
+      *y_offset = delta;

[sadrul, 2016/01/04 18:51:21]

Let's have a helper function:

  if (i == horizontal_number)
    *x_offset = ExtractAndUpdateScrollOffset(&info->horizontal, *valuators);
  else if (i == vertical_number)
    *y_offset = ExtractAndUpdateScrollOffset(&info->vertical, *valuators);

and


double ExtractAndUpdateScrollOffset(ScrollInfo::AxisInfo* axis,
    double valuator) const {
  double offset = 0;
  if (axis->seen)
    offset = axis->position - valuator;
  axis->seen = true;
  axis->position = valuator;
  return offset / axis->increment;
}

[Will Shackleton, 2016/01/04 21:07:41]

Acknowledged.

+      NormalizeScrollData(sourceid, false, y_offset);
+    }
+    valuators++;
+  }
+}
+
+void DeviceDataManagerX11::InvalidateScrollClasses() {
+  for (int i = 0; i < kMaxDeviceNum; i++) {
+    scroll_data_[i].horizontal.seen = false;
+    scroll_data_[i].vertical.seen = false;
+  }
+}
+
 void DeviceDataManagerX11::GetFlingData(
     const base::NativeEvent& native_event,
     float* vx,
@@ -607,6 +737,22 @@ bool DeviceDataManagerX11::NormalizeData(int deviceid,
   return false;
 }
 
+bool DeviceDataManagerX11::NormalizeScrollData(unsigned int deviceid,
+                                               bool horizontal,
+                                               double* value) {
+  if (deviceid >= static_cast<unsigned int>(kMaxDeviceNum))
+    return false;
+  if (horizontal && scroll_data_[deviceid].horizontal.number < 0)
+    return false;
+  if (!horizontal && scroll_data_[deviceid].vertical.number < 0)
+    return false;
+  double increment = horizontal ? scroll_data_[deviceid].horizontal.increment
+                                : scroll_data_[deviceid].vertical.increment;
+
+  *value /= increment;
+  return true;
+}
+
 bool DeviceDataManagerX11::GetDataRange(int deviceid,
                                         const DataType type,
                                         double* min,