Align drag threshold across content types.

third_party/WebKit/Source/core/input/MouseEventManager.cpp

 // Copyright 2016 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 "core/input/MouseEventManager.h"
 
 #include "core/clipboard/DataObject.h"
 #include "core/clipboard/DataTransfer.h"
 #include "core/dom/Element.h"
 #include "core/dom/ElementTraversal.h"
@@ skipping 49 matching lines @@
 const double kFakeMouseMoveInterval = 0.1;
 
 #if OS(MACOSX)
 const double kTextDragDelay = 0.15;
 #else
 const double kTextDragDelay = 0.0;
 #endif
 
 // The link drag hysteresis is much larger than the others because there
 // needs to be enough space to cancel the link press without starting a link
 // drag, and because dragging links is rare.

[Peter Kasting, 2016/10/06 09:05:36]

This comment should be updated or removed.

[pwnall, 2016/10/20 01:40:39]

Done.

-const int kLinkDragHysteresis = 40;
+const int kLinkDragHysteresis = 5;

[Peter Kasting, 2016/10/06 09:05:36]

Perhaps we should just use the text/image values below (depending on whether the
link is text/image, or whatever) instead of having a custom link value.

[pwnall, 2016/10/20 01:40:39]

I opted to prepare the path for obeying the platform preferences for drag and
drop thresholds. I created separate X and Y constants because Windows has
separate X and Y thresholds. 

 const int kImageDragHysteresis = 5;
 const int kTextDragHysteresis = 3;
 const int kGeneralDragHysteresis = 3;
 
 }  // namespace
 
 enum class DragInitiator { Mouse, Touch };
 
 MouseEventManager::MouseEventManager(LocalFrame* frame,
                                      ScrollManager* scrollManager)
@@ skipping 931 matching lines @@
 
 void MouseEventManager::setClickCount(int clickCount) {
   m_clickCount = clickCount;
 }
 
 bool MouseEventManager::mouseDownMayStartDrag() {
   return m_mouseDownMayStartDrag;
 }
 
 }  // namespace blink