Synthesize ctrl-wheel events on touchpad pinch

content/common/input/web_input_event_traits.cc

 // Copyright 2013 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 "content/common/input/web_input_event_traits.h"
 
 #include <bitset>
+#include <limits>
 
 #include "base/logging.h"
 
 using blink::WebGestureEvent;
 using blink::WebInputEvent;
 using blink::WebKeyboardEvent;
 using blink::WebMouseEvent;
 using blink::WebMouseWheelEvent;
 using blink::WebTouchEvent;
+using std::numeric_limits;
 
 namespace content {
 namespace {
 
 const int kInvalidTouchIndex = -1;
 
 bool CanCoalesce(const WebKeyboardEvent& event_to_coalesce,
                  const WebKeyboardEvent& event) {
   return false;
 }
@@ skipping 139 matching lines @@
 void Coalesce(const WebGestureEvent& event_to_coalesce,
               WebGestureEvent* event) {
   DCHECK(CanCoalesce(event_to_coalesce, *event));
   if (event->type == WebInputEvent::GestureScrollUpdate) {
     event->data.scrollUpdate.deltaX +=
         event_to_coalesce.data.scrollUpdate.deltaX;
     event->data.scrollUpdate.deltaY +=
         event_to_coalesce.data.scrollUpdate.deltaY;
   } else if (event->type == WebInputEvent::GesturePinchUpdate) {
     event->data.pinchUpdate.scale *= event_to_coalesce.data.pinchUpdate.scale;
+    // Ensure the scale remains bounded above 0 and below Infinity so that
+    // we can reliably perform operations like log on the values.
+    if (event->data.pinchUpdate.scale < numeric_limits<float>::min())
+      event->data.pinchUpdate.scale = numeric_limits<float>::min();
+    else if (event->data.pinchUpdate.scale > numeric_limits<float>::max())
+      event->data.pinchUpdate.scale = numeric_limits<float>::max();
   }
 }
 
 struct WebInputEventSize {
   template <class EventType>
   bool Execute(WebInputEvent::Type /* type */, size_t* type_size) const {
     *type_size = sizeof(EventType);
     return true;
   }
 };
@@ skipping 168 matching lines @@
     case WebInputEvent::TouchStart:
     case WebInputEvent::TouchMove:
     case WebInputEvent::TouchEnd:
       return !static_cast<const WebTouchEvent&>(event).cancelable;
     default:
       return false;
   }
 }
 
 }  // namespace content