Fix mouse horizontal scrolling in app drawer

The old logic consider only horizontal scroll for ScrollEvent and
only vertical scroll for MouseWheelEvent. Vertical scroll on touchpad
seems to work only because unhandled ScrollEvent would be casted to
MouseWheelEvent in root_view.cc (and then be picked up by the app drawer
). The patch now lets both event handlers select the largest scrolling
direction and proceed on scrolling no matter it is horizontal or
vertical.

Contributed by sheckylin@chromium.org

BUG=248259
TEST=Tested on device.

Change-Id: I5ee647d886c47cec37c4f7d130c6d7b268051064

Review URL: https://chromiumcodereview.appspot.com/16757009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@206337 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 23 insertions, 9 deletions

diff --git a/ui/app_list/views/contents_view.cc b/ui/app_list/views/contents_view.cc
index 77c8fb0..5167b89 100644
--- a/ui/app_list/views/contents_view.cc
+++ b/ui/app_list/views/contents_view.cc
@@ -6,6 +6,7 @@
 
 #include <algorithm>
 
+#include "base/logging.h"
 #include "ui/app_list/app_list_constants.h"
 #include "ui/app_list/pagination_model.h"
 #include "ui/app_list/views/app_list_main_view.h"
@@ -182,10 +183,16 @@ bool ContentsView::OnMouseWheel(const ui::MouseWheelEvent& event) {
   if (show_state_ != SHOW_APPS)
     return false;
 
-  if (abs(event.y_offset()) > kMinMouseWheelToSwitchPage) {
+  int offset;
+  if (abs(event.x_offset()) > abs(event.y_offset()))
+    offset = event.x_offset();
+  else
+    offset = event.y_offset();
+
+  if (abs(offset) > kMinMouseWheelToSwitchPage) {
     if (!pagination_model_->has_transition()) {
       pagination_model_->SelectPageRelative(
-          event.y_offset() > 0 ? -1 : 1, true);
+          offset > 0 ? -1 : 1, true);
     }
     return true;
   }
@@ -231,17 +238,24 @@ void ContentsView::OnGestureEvent(ui::GestureEvent* event) {
 
 void ContentsView::OnScrollEvent(ui::ScrollEvent* event) {
   if (show_state_ != SHOW_APPS ||
-      event->type() == ui::ET_SCROLL_FLING_CANCEL ||
-      abs(event->x_offset()) < kMinScrollToSwitchPage) {
+      event->type() == ui::ET_SCROLL_FLING_CANCEL) {
     return;
   }
 
-  if (!pagination_model_->has_transition()) {
-    pagination_model_->SelectPageRelative(event->x_offset() > 0 ? -1 : 1,
-                                          true);
+  float offset;
+  if (abs(event->x_offset()) > abs(event->y_offset()))
+    offset = event->x_offset();
+  else
+    offset = event->y_offset();
+
+  if (abs(offset) > kMinScrollToSwitchPage) {
+    if (!pagination_model_->has_transition()) {
+      pagination_model_->SelectPageRelative(offset > 0 ? -1 : 1,
+                                            true);
+    }
+    event->SetHandled();
+    event->StopPropagation();
   }
-  event->SetHandled();
-  event->StopPropagation();
 }
 
 }  // namespace app_list