Implement Middle Click Autoscroll on all platforms not just Windows

third_party/WebKit/Source/core/page/AutoscrollController.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2012 Digia Plc. and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
@@ skipping 56 matching lines @@
     return m_autoscrollType == AutoscrollForSelection;
 }
 
 bool AutoscrollController::autoscrollInProgress(const LayoutBox* layoutObject) const
 {
     return m_autoscrollLayoutObject == layoutObject;
 }
 
 void AutoscrollController::startAutoscrollForSelection(LayoutObject* layoutObject)
 {
-    // We don't want to trigger the autoscroll or the panScroll if it's already active
+    // We don't want to trigger the autoscroll or the middleClickAutoscroll if it's already active
     if (m_autoscrollType != NoAutoscroll)
         return;
     LayoutBox* scrollable = LayoutBox::findAutoscrollable(layoutObject);
     if (!scrollable)
         scrollable = layoutObject->isListBox() ? toLayoutListBox(layoutObject) : nullptr;
     if (!scrollable)
         return;
 
     m_pressedLayoutObject = layoutObject && layoutObject->isBox() ? toLayoutBox(layoutObject) : nullptr;
     m_autoscrollType = AutoscrollForSelection;
     m_autoscrollLayoutObject = scrollable;
     startAutoscroll();
 }
 
 void AutoscrollController::stopAutoscroll()
 {
     if (m_pressedLayoutObject) {
         m_pressedLayoutObject->stopAutoscroll();
         m_pressedLayoutObject = nullptr;
     }
     LayoutBox* scrollable = m_autoscrollLayoutObject;
     m_autoscrollLayoutObject = nullptr;
 
     if (!scrollable)
         return;
 
-#if OS(WIN)
-    if (panScrollInProgress()) {
+    if (RuntimeEnabledFeatures::middleClickAutoscrollEnabled() && middleClickAutoscrollInProgress()) {
         if (FrameView* view = scrollable->frame()->view()) {
             view->setCursor(pointerCursor());
         }
     }
-#endif
-
     m_autoscrollType = NoAutoscroll;
 }
 
 void AutoscrollController::stopAutoscrollIfNeeded(LayoutObject* layoutObject)
 {
     if (m_pressedLayoutObject == layoutObject)
         m_pressedLayoutObject = nullptr;
 
     if (m_autoscrollLayoutObject != layoutObject)
         return;
     m_autoscrollLayoutObject = nullptr;
     m_autoscrollType = NoAutoscroll;
 }
 
 void AutoscrollController::updateAutoscrollLayoutObject()
 {
     if (!m_autoscrollLayoutObject)
         return;
 
     LayoutObject* layoutObject = m_autoscrollLayoutObject;
 
-#if OS(WIN)
-    HitTestResult hitTest = layoutObject->frame()->eventHandler().hitTestResultAtPoint(m_panScrollStartPos, HitTestRequest::ReadOnly | HitTestRequest::Active);
+    if (RuntimeEnabledFeatures::middleClickAutoscrollEnabled()) {
+        HitTestResult hitTest = layoutObject->frame()->eventHandler().hitTestResultAtPoint(m_middleClickAutoscrollStartPos, HitTestRequest::ReadOnly | HitTestRequest::Active);
 
-    if (Node* nodeAtPoint = hitTest.innerNode())
-        layoutObject = nodeAtPoint->layoutObject();
-#endif
+        if (Node* nodeAtPoint = hitTest.innerNode())
+            layoutObject = nodeAtPoint->layoutObject();
+    }
 
     while (layoutObject && !(layoutObject->isBox() && toLayoutBox(layoutObject)->canAutoscroll()))
         layoutObject = layoutObject->parent();
 
     m_autoscrollLayoutObject = layoutObject && layoutObject->isBox() ? toLayoutBox(layoutObject) : nullptr;
 
     if (m_autoscrollType != NoAutoscroll && !m_autoscrollLayoutObject)
         m_autoscrollType = NoAutoscroll;
 }
 
@@ skipping 31 matching lines @@
         m_autoscrollType = AutoscrollForDragAndDrop;
         m_autoscrollLayoutObject = scrollable;
         m_dragAndDropAutoscrollStartTime = eventTime;
         startAutoscroll();
     } else if (m_autoscrollLayoutObject != scrollable) {
         m_dragAndDropAutoscrollStartTime = eventTime;
         m_autoscrollLayoutObject = scrollable;
     }
 }
 
-#if OS(WIN)
 void AutoscrollController::handleMouseReleaseForPanScrolling(LocalFrame* frame, const PlatformMouseEvent& mouseEvent)
 {
     if (!frame->isMainFrame())
         return;
     switch (m_autoscrollType) {
     case AutoscrollForPan:
         if (mouseEvent.pointerProperties().button == WebPointerProperties::Button::Middle)
             m_autoscrollType = AutoscrollForPanCanStop;
         break;
     case AutoscrollForPanCanStop:
         stopAutoscroll();
         break;
     case AutoscrollForDragAndDrop:
     case AutoscrollForSelection:
     case NoAutoscroll:
         // Nothing to do.
         break;
     }
 }
 
-bool AutoscrollController::panScrollInProgress() const
+bool AutoscrollController::middleClickAutoscrollInProgress() const
 {
     return m_autoscrollType == AutoscrollForPanCanStop || m_autoscrollType == AutoscrollForPan;
 }
 
 void AutoscrollController::startPanScrolling(LayoutBox* scrollable, const IntPoint& lastKnownMousePosition)
 {
-    // We don't want to trigger the autoscroll or the panScroll if it's already active
+    // We don't want to trigger the autoscroll or the middleClickAutoscroll if it's already active
     if (m_autoscrollType != NoAutoscroll)
         return;
 
     m_autoscrollType = AutoscrollForPan;
     m_autoscrollLayoutObject = scrollable;
-    m_panScrollStartPos = lastKnownMousePosition;
+    m_middleClickAutoscrollStartPos = lastKnownMousePosition;
 
     startAutoscroll();
 }
-#else
-bool AutoscrollController::panScrollInProgress() const
-{
-    return false;
-}
-#endif
 
 // FIXME: This would get get better animation fidelity if it used the monotonicFrameBeginTime instead
 // of WTF::currentTime().
 void AutoscrollController::animate(double)
 {
     if (!m_autoscrollLayoutObject) {
         stopAutoscroll();
         return;
     }
 
     EventHandler& eventHandler = m_autoscrollLayoutObject->frame()->eventHandler();
     switch (m_autoscrollType) {
     case AutoscrollForDragAndDrop:
         if (WTF::currentTime() - m_dragAndDropAutoscrollStartTime > autoscrollDelay)
             m_autoscrollLayoutObject->autoscroll(m_dragAndDropAutoscrollReferencePosition);
         break;
     case AutoscrollForSelection:
         if (!eventHandler.mousePressed()) {
             stopAutoscroll();
             return;
         }
         eventHandler.updateSelectionForMouseDrag();
         m_autoscrollLayoutObject->autoscroll(eventHandler.lastKnownMousePosition());
         break;
     case NoAutoscroll:
         break;
-#if OS(WIN)
     case AutoscrollForPanCanStop:
     case AutoscrollForPan:

[bokan, 2016/09/07 16:33:46]

Please add a DCHECK here that the middleClickAutoScroll WebRuntimeFeature is
enabled.

-        if (!panScrollInProgress()) {
+        if (!middleClickAutoscrollInProgress()) {
             stopAutoscroll();
             return;
         }
         if (FrameView* view = m_autoscrollLayoutObject->frame()->view())
             updatePanScrollState(view, eventHandler.lastKnownMousePosition());
-        m_autoscrollLayoutObject->panScroll(m_panScrollStartPos);
+        m_autoscrollLayoutObject->middleClickAutoscroll(m_middleClickAutoscrollStartPos);
         break;
-#endif
     }
     if (m_autoscrollType != NoAutoscroll && m_autoscrollLayoutObject)
         m_page->chromeClient().scheduleAnimation(m_autoscrollLayoutObject->frame()->view());
 }
 
 void AutoscrollController::startAutoscroll()
 {
     m_page->chromeClient().scheduleAnimation(m_autoscrollLayoutObject->frame()->view());
 }
 
-#if OS(WIN)
 void AutoscrollController::updatePanScrollState(FrameView* view, const IntPoint& lastKnownMousePosition)
 {
     // At the original click location we draw a 4 arrowed icon. Over this icon there won't be any scroll
     // So we don't want to change the cursor over this area
-    bool east = m_panScrollStartPos.x() < (lastKnownMousePosition.x() - noPanScrollRadius);
-    bool west = m_panScrollStartPos.x() > (lastKnownMousePosition.x() + noPanScrollRadius);
-    bool north = m_panScrollStartPos.y() > (lastKnownMousePosition.y() + noPanScrollRadius);
-    bool south = m_panScrollStartPos.y() < (lastKnownMousePosition.y() - noPanScrollRadius);
+    bool east = m_middleClickAutoscrollStartPos.x() < (lastKnownMousePosition.x() - noPanScrollRadius);
+    bool west = m_middleClickAutoscrollStartPos.x() > (lastKnownMousePosition.x() + noPanScrollRadius);
+    bool north = m_middleClickAutoscrollStartPos.y() > (lastKnownMousePosition.y() + noPanScrollRadius);
+    bool south = m_middleClickAutoscrollStartPos.y() < (lastKnownMousePosition.y() - noPanScrollRadius);
 
     if (m_autoscrollType == AutoscrollForPan && (east || west || north || south))
         m_autoscrollType = AutoscrollForPanCanStop;
 
     if (north) {
         if (east)
             view->setCursor(northEastPanningCursor());
         else if (west)
             view->setCursor(northWestPanningCursor());
         else
             view->setCursor(northPanningCursor());
     } else if (south) {
         if (east)
             view->setCursor(southEastPanningCursor());
         else if (west)
             view->setCursor(southWestPanningCursor());
         else
             view->setCursor(southPanningCursor());
     } else if (east) {
         view->setCursor(eastPanningCursor());
     } else if (west) {
         view->setCursor(westPanningCursor());
     } else {
         view->setCursor(middlePanningCursor());
     }
 }
-#endif
 
 } // namespace blink