Drag image should always use the real device scale factor

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

 /*
  * Copyright (C) 2007, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Google Inc.
  *
  * 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
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 883 matching lines @@
         // We shouldn't be starting a drag for an image that can't provide an extension.
         // This is an early detection for problems encountered later upon drop.
         ASSERT(!image->filenameExtension().isEmpty());
         if (!dragImage) {
             const IntRect& imageRect = hitTestResult.imageRect();
             IntSize imageSizeInPixels = imageRect.size();
             // TODO(oshima): Remove this scaling and simply pass imageRect to dragImageForImage
             // once all platforms are migrated to use zoom for dsf.
             imageSizeInPixels.scale(src->host()->deviceScaleFactor());
 
-            float screenDeviceScaleFactor = src->page()->chromeClient().screenInfo().deviceScaleFactor;
+            float screenDeviceScaleFactor = src->page()->chromeClient().nonEmulatedDeviceScaleFactor();
+
             // Pass the selected image size in DIP becasue dragImageForImage clips the image in DIP.
             // The coordinates of the locations are in Viewport coordinates, and they're converted in the Blink client.
             // TODO(oshima): Currently, the dragged image on high DPI is scaled and can be blurry because of this.
             // Consider to clip in the screen coordinates to use high resolution image on high DPI screens.
             dragImage = dragImageForImage(element, image, screenDeviceScaleFactor, dragOrigin, imageRect.location(), imageSizeInPixels, dragLocation);
         }
         doSystemDrag(dragImage.get(), dragLocation, dragOrigin, dataTransfer, src, false);
     } else if (state.m_dragType == DragSourceActionLink) {
         if (linkURL.isEmpty())
             return false;
         if (src->selection().isCaret() && src->selection().isContentEditable()) {
             // a user can initiate a drag on a link without having any text
             // selected.  In this case, we should expand the selection to
             // the enclosing anchor element
             if (Node* node = enclosingAnchorElement(src->selection().base()))
                 src->selection().setSelection(VisibleSelection::selectionFromContentsOfNode(node));
         }
 
         if (!dragImage) {
             ASSERT(src->page());
-            float screenDeviceScaleFactor = src->page()->chromeClient().screenInfo().deviceScaleFactor;
+            float screenDeviceScaleFactor = src->page()->chromeClient().nonEmulatedDeviceScaleFactor();
+
             dragImage = dragImageForLink(linkURL, hitTestResult.textContent(), screenDeviceScaleFactor, mouseDraggedPoint, dragLocation);
         }
         doSystemDrag(dragImage.get(), dragLocation, mouseDraggedPoint, dataTransfer, src, true);
     } else if (state.m_dragType == DragSourceActionDHTML) {
         doSystemDrag(dragImage.get(), dragLocation, dragOrigin, dataTransfer, src, false);
     } else {
         ASSERT_NOT_REACHED();
         return false;
     }
 
@@ skipping 14 matching lines @@
     IntPoint adjustedDragLocation = mainFrameView->rootFrameToContents(frame->view()->contentsToRootFrame(dragLocation));
     IntPoint adjustedEventPos = mainFrameView->rootFrameToContents(frame->view()->contentsToRootFrame(eventPos));
     WebDragData dragData = dataTransfer->dataObject()->toWebDragData();
     WebDragOperationsMask dragOperationMask = static_cast<WebDragOperationsMask>(dataTransfer->sourceOperation());
     IntSize offsetSize(adjustedEventPos - adjustedDragLocation);
     WebPoint offsetPoint(offsetSize.width(), offsetSize.height());
     WebImage dragImage;
 
     if (image) {
         float resolutionScale = image->resolutionScale();
-        float deviceScaleFactor = m_page->chromeClient().screenInfo().deviceScaleFactor;
+        float deviceScaleFactor = m_page->chromeClient().nonEmulatedDeviceScaleFactor();
         if (deviceScaleFactor != resolutionScale) {
             DCHECK_GT(resolutionScale, 0);
             float scale = deviceScaleFactor / resolutionScale;
             image->scale(scale, scale);
         }
         dragImage = image->bitmap();
     }
 
     m_page->chromeClient().startDragging(frame, dragData, dragOperationMask, dragImage, offsetPoint);
 }
@@ skipping 21 matching lines @@
 
 DEFINE_TRACE(DragController)
 {
     visitor->trace(m_page);
     visitor->trace(m_documentUnderMouse);
     visitor->trace(m_dragInitiator);
     visitor->trace(m_fileInputElementUnderMouse);
 }
 
 } // namespace blink