[Webkit-unassigned] [Bug 185216] New: Hiding then showing an <object> of type image makes the underlaying image disappear

bugzilla-daemon at webkit.org bugzilla-daemon at webkit.org
Wed May 2 14:17:40 PDT 2018


https://bugs.webkit.org/show_bug.cgi?id=185216

            Bug ID: 185216
           Summary: Hiding then showing an <object> of type image makes
                    the underlaying image disappear
           Product: WebKit
           Version: WebKit Nightly Build
          Hardware: Unspecified
                OS: Unspecified
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: Images
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: sabouhallawa at apple.com

Created attachment 339339

  --> https://bugs.webkit.org/attachment.cgi?id=339339&action=review

test case

Open the attached test case.

The test case contains an <object> element of type image. The script hides the <object> then it shows the <object> again.

Result: An outline rectangle is drawn.
Expected: The underlaying image of the <object> element is shown.

The reason for this bug is the following:
-- The ImageLoader and the <object> element stay alive but the RenderImage is destroyed when the element is made hidden. 
-- When the <object> element is shown again, a new RenderImage is created. 
-- ImageLoader::updateFromElement() does not call updateRenderer() or dispatchPendingBeforeLoadEvent() because the image is already loaded i.e. (newImage == oldImage).
-- Therefore we do not set the CachedImage of the RenderImageResource of the RenderImage.
-- When RenderImage::paintReplaced() is called after the image is made visible again, it does not find a CachedImage for its RenderImageResource.
-- So RenderImage::paintReplaced() draws an outline rectangle instead.

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