Add support for new scroll valuators coming from CMT

ui/base/x/scroll_factory.cc

Index: ui/base/x/scroll_factory.cc
diff --git a/ui/base/x/scroll_factory.cc b/ui/base/x/scroll_factory.cc
new file mode 100644
index 0000000000000000000000000000000000000000..5df8f5d9b588ae9a4afcf639ed1470135728bde1
--- /dev/null
+++ b/ui/base/x/scroll_factory.cc
@@ -0,0 +1,110 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "ui/base/x/scroll_factory.h"
+
+#include <stdio.h>
+#include <X11/cursorfont.h>
+#include <X11/extensions/XInput.h>
+#include <X11/extensions/XInput2.h>
+#include <X11/extensions/XIproto.h>
+
+#include "ui/base/x/x11_util.h"
+
+// Copied from xserver-properties.h
+#define AXIS_LABEL_PROP_REL_HWHEEL      "Rel Horiz Wheel"
+#define AXIS_LABEL_PROP_REL_WHEEL       "Rel Vert Wheel"
+
+namespace ui {
+
+// static
+ScrollFactory* ScrollFactory::GetInstance() {
+  return Singleton<ScrollFactory>::get();
+}
+
+void ScrollFactory::UpdateDeviceList(Display* display) {
+  int count;
+  scroll_devices_.reset();
+  device_to_valuators_.clear();
+  XDeviceInfo* dev_list = XListInputDevices(display, &count);
+  Atom xi_touchpad = XInternAtom(display, XI_TOUCHPAD, false);
+  for (int i = 0; i < count; ++i) {
+    XDeviceInfo* dev = dev_list + i;
+    if (dev->type == xi_touchpad)
+      scroll_devices_[dev_list[i].id] = true;
+  }
+  if (dev_list)
+    XFreeDeviceList(dev_list);
+
+  XIDeviceInfo* info_list = XIQueryDevice(display, XIAllDevices, &count);
+  Atom x_axis = XInternAtom(display, AXIS_LABEL_PROP_REL_HWHEEL, false);
+  Atom y_axis = XInternAtom(display, AXIS_LABEL_PROP_REL_WHEEL, false);
+  for (int i = 0; i < count; ++i) {
+    XIDeviceInfo* info = info_list + i;
+
+    if (!scroll_devices_[info->deviceid])
+      continue;
+
+    if (info->use != XISlavePointer && info->use != XIFloatingSlave) {
+      scroll_devices_[info->deviceid] = false;
+      continue;
+    }
+
+    Valuators valuators = {-1, -1};
+    for (int j = 0; j < info->num_classes; ++j) {
+      if (info->classes[j]->type != XIValuatorClass)
+        continue;
+
+      XIValuatorClassInfo* v =
+          reinterpret_cast<XIValuatorClassInfo*>(info->classes[j]);
+      if (v->label == x_axis)
+        valuators.x_scroll = v->number;
+      else if (v->label == y_axis)
+        valuators.y_scroll = v->number;
+    }
+    if (valuators.x_scroll >= 0 && valuators.y_scroll >= 0)
+      device_to_valuators_[info->deviceid] = valuators;
+    else
+      scroll_devices_[info->deviceid] = false;
+  }
+}
+
+bool ScrollFactory::GetScrollOffsets(const XEvent& xev,
+                                     float* x_offset,
+                                     float* y_offset) {
+  XIDeviceEvent* xiev = static_cast<XIDeviceEvent*>(xev.xcookie.data);
+  if (!scroll_devices_[xiev->deviceid])
+    return false;
+
+  int x_scroll = device_to_valuators_[xiev->deviceid].x_scroll;
+  int y_scroll = device_to_valuators_[xiev->deviceid].y_scroll;
+
+  bool has_x_offset = XIMaskIsSet(xiev->valuators.mask, x_scroll);
+  bool has_y_offset = XIMaskIsSet(xiev->valuators.mask, y_scroll);
+  bool is_scroll = has_x_offset || has_y_offset;
+
+  if (!x_offset && !y_offset)
+    return is_scroll;
+
+  double* valuators = xiev->valuators.values;
+  for (int i = 0; i < xiev->valuators.mask_len * 8; ++i) {
+    if (XIMaskIsSet(xiev->valuators.mask, i)) {
+      if (x_offset && x_scroll == i)
+        *x_offset = -(*valuators);
+      else if (y_offset && y_scroll == i)
+        *y_offset = -(*valuators);
+      valuators++;
+    }
+  }
+
+  return is_scroll;
+}
+
+ScrollFactory::ScrollFactory() {
+  UpdateDeviceList(ui::GetXDisplay());
+}
+
+ScrollFactory::~ScrollFactory() {}
+
+} // namespace ui