Implemented smooth scrolling using xinput2 in X11.

ui/events/x/events_x.cc

 // Copyright (c) 2012 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/events/event_constants.h"
 
 #include <string.h>
 #include <X11/extensions/XInput.h>
 #include <X11/extensions/XInput2.h>
 #include <X11/XKBlib.h>
@@ skipping 420 matching lines @@
         }
         case XI_Motion: {
           bool is_cancel;
           DeviceDataManagerX11* devices = DeviceDataManagerX11::GetInstance();
           if (GetFlingData(native_event, NULL, NULL, NULL, NULL, &is_cancel))
             return is_cancel ? ET_SCROLL_FLING_CANCEL : ET_SCROLL_FLING_START;
           if (devices->IsScrollEvent(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))
             return ET_MOUSE_DRAGGED;
           return ET_MOUSE_MOVED;
         }
         case XI_KeyPress:
           return ET_KEY_PRESSED;
         case XI_KeyRelease:
           return ET_KEY_RELEASED;
@@ skipping 253 matching lines @@
   float x_offset, y_offset;
   if (GetScrollOffsets(
       native_event, &x_offset, &y_offset, NULL, NULL, NULL)) {
     return gfx::Vector2d(static_cast<int>(x_offset),
                          static_cast<int>(y_offset));
   }
 
   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();
   }
 }
 
 base::NativeEvent CopyNativeEvent(const base::NativeEvent& event) {
   if (!event || event->type == GenericEvent)
     return NULL;
   XEvent* copy = new XEvent;
   *copy = *event;
@@ skipping 63 matching lines @@
     force = 0.0;
   return force;
 }
 
 bool GetScrollOffsets(const base::NativeEvent& native_event,
                       float* x_offset,
                       float* y_offset,
                       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_;
 
-  // 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;
+  }
 
-  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,
                   float* vx,
                   float* vy,
                   float* vx_ordinal,
                   float* vy_ordinal,
                   bool* is_cancel) {
   if (!DeviceDataManagerX11::GetInstance()->IsFlingEvent(native_event))
     return false;
@@ skipping 60 matching lines @@
       xievent->detail =
           UpdateX11EventButton(event->changed_button_flags(), xievent->detail);
       break;
     }
     default:
       break;
   }
 }
 
 }  // namespace ui