Implemented smooth scrolling using xinput2 in X11.

ui/events/x/events_x.cc

Index: ui/events/x/events_x.cc
diff --git a/ui/events/x/events_x.cc b/ui/events/x/events_x.cc
index 9bf87c0e24c4e4b2a25aeedddf4d00b1340f4d0e..4b6c9dd488062a1c9e9c1ce2b4993296f03e3772 100644
--- a/ui/events/x/events_x.cc
+++ b/ui/events/x/events_x.cc
@@ -438,6 +438,9 @@ EventType EventTypeFromNative(const base::NativeEvent& native_event) {
             return devices->IsTouchpadXInputEvent(native_event) ? ET_SCROLL
                                                                 : ET_MOUSEWHEEL;
           }
+          if (devices->GetScrollClassEventDetail(native_event) !=
+              SCROLL_TYPE_NO_SCROLL)
+            return ET_MOUSEWHEEL;

[sadrul, 2015/08/18 16:57:46]

Should IsScrollEvent() return true in this case, so that you don't have to make
this call here?

[Will Shackleton, 2015/08/26 19:52:48]

IsScrollEvent() detects XInput 1 scroll events - this detects XInput 2 scroll
events.

[sadrul, 2015/08/26 19:55:57]

Is there a reason to have separate API for this? Is it useful?

           if (devices->IsCMTMetricsEvent(native_event))
             return ET_UMA_DATA;
           if (GetButtonMaskForX2Event(xievent))
@@ -711,15 +714,22 @@ gfx::Vector2d GetMouseWheelOffset(const base::NativeEvent& native_event) {
   int button = native_event->type == GenericEvent ?
       EventButtonFromNative(native_event) : native_event->xbutton.button;
 
+  int scroll_class_type =
+    DeviceDataManagerX11::GetInstance()
+    ->GetScrollClassDeviceDetail(native_event);

[sadrul, 2015/08/18 16:57:46]

Indenting here is off (you can use 'git cl format')

+  bool vertical_scroll_class = scroll_class_type & SCROLL_TYPE_VERTICAL;
+  bool horizontal_scroll_class = scroll_class_type & SCROLL_TYPE_HORIZONTAL;
+
   switch (button) {
     case 4:
-      return gfx::Vector2d(0, kWheelScrollAmount);
+      return gfx::Vector2d(0, vertical_scroll_class ? 0 : kWheelScrollAmount);
     case 5:
-      return gfx::Vector2d(0, -kWheelScrollAmount);
+      return gfx::Vector2d(0, vertical_scroll_class ? 0 : -kWheelScrollAmount);
     case 6:
-      return gfx::Vector2d(kWheelScrollAmount, 0);
+      return gfx::Vector2d(horizontal_scroll_class ? 0 : kWheelScrollAmount, 0);
     case 7:
-      return gfx::Vector2d(-kWheelScrollAmount, 0);
+      return gfx::Vector2d(horizontal_scroll_class ? 0 : -kWheelScrollAmount,
+          0);
     default:
       return gfx::Vector2d();
   }
@@ -803,30 +813,41 @@ bool GetScrollOffsets(const base::NativeEvent& native_event,
                       float* x_offset_ordinal,
                       float* y_offset_ordinal,
                       int* finger_count) {
-  if (!DeviceDataManagerX11::GetInstance()->IsScrollEvent(native_event))
-    return false;
+  if (DeviceDataManagerX11::GetInstance()->IsScrollEvent(native_event)) {
+    // Temp values to prevent passing NULLs to DeviceDataManager.
+    float x_offset_, y_offset_;
+    float x_offset_ordinal_, y_offset_ordinal_;
+    int finger_count_;
+    if (!x_offset)
+      x_offset = &x_offset_;
+    if (!y_offset)
+      y_offset = &y_offset_;
+    if (!x_offset_ordinal)
+      x_offset_ordinal = &x_offset_ordinal_;
+    if (!y_offset_ordinal)
+      y_offset_ordinal = &y_offset_ordinal_;
+    if (!finger_count)
+      finger_count = &finger_count_;
+
+    DeviceDataManagerX11::GetInstance()->GetScrollOffsets(
+        native_event,
+        x_offset, y_offset,
+        x_offset_ordinal, y_offset_ordinal,
+        finger_count);
+    return true;
+  }
 
-  // Temp values to prevent passing NULLs to DeviceDataManager.
-  float x_offset_, y_offset_;
-  float x_offset_ordinal_, y_offset_ordinal_;
-  int finger_count_;
-  if (!x_offset)
-    x_offset = &x_offset_;
-  if (!y_offset)
-    y_offset = &y_offset_;
-  if (!x_offset_ordinal)
-    x_offset_ordinal = &x_offset_ordinal_;
-  if (!y_offset_ordinal)
-    y_offset_ordinal = &y_offset_ordinal_;
-  if (!finger_count)
-    finger_count = &finger_count_;
-
-  DeviceDataManagerX11::GetInstance()->GetScrollOffsets(
-      native_event,
-      x_offset, y_offset,
-      x_offset_ordinal, y_offset_ordinal,
-      finger_count);
-  return true;
+  if (DeviceDataManagerX11::GetInstance()->
+      GetScrollClassEventDetail(native_event) != SCROLL_TYPE_NO_SCROLL) {
+    double x_scroll_offset, y_scroll_offset;
+    DeviceDataManagerX11::GetInstance()->GetScrollClassOffsets(
+        native_event,
+        &x_scroll_offset, &y_scroll_offset);
+    *x_offset = x_scroll_offset * kWheelScrollAmount;
+    *y_offset = y_scroll_offset * kWheelScrollAmount;
+    return true;
+  }
+  return false;
 }
 
 bool GetFlingData(const base::NativeEvent& native_event,