Bug 44180 – WebView::paint fails to paint a child WebView of a Layered Window

• Component: WebKit Misc.
• Status: RESOLVED FIXED

[Jessie Berlin]

Even though GetUpdateRect and GetUpdateRgn for a child WebView of a Layered Window report that the region that should be painted as non-empty in WebView::paint before the call to BeginPaint (http://msdn.microsoft.com/en-us/library/aa922023.aspx), BeginPaint still fills the rcPaint field of the PAINTSTRUCT with an empty RECT.

This means http://trac.webkit.org/changeset/58900 causes WebView::paint to end the paint early, before painting the contents of child WebView of a Layered Window.

A fix would be to check if the m_backingStoreBitmap is null after the call to ensureBackingStore (which will notice that the WebView isn't zero-sized in the case of the child WebView of a Layered Window that isn't zero-sized) instead of checking if the rcPaint rect is empty in order to determine whether to continue on with the paint or not.

[Jessie Berlin]

Created attachment 64724 [details]
Check if m_backingStoreBitmap is null instead of whether rcPaint is empty

[Adam Roben (:aroben)]

Comment on attachment 64724 [details]
Check if m_backingStoreBitmap is null instead of whether rcPaint is empty

> +    bool backingStoreCompletelyDirty = ensureBackingStore();
> +    if (!m_backingStoreBitmap) {
> +        EndPaint(m_viewWindow, &ps);
>          return;
>      }

We should only call EndPaint if a dc was passed to this function. Otherwise we won't have called BeginPaint.

r=me

[Jessie Berlin]

(In reply to comment #2)
> (From update of attachment 64724 [details])
> > +    bool backingStoreCompletelyDirty = ensureBackingStore();
> > +    if (!m_backingStoreBitmap) {
> > +        EndPaint(m_viewWindow, &ps);
> >          return;
> >      }
> 
> We should only call EndPaint if a dc was passed to this function. Otherwise we won't have called BeginPaint.

Added in the check for whether there was a dc passed in.

> 
> r=me

Thanks!

[Jessie Berlin]

Comment on attachment 64724 [details]
Check if m_backingStoreBitmap is null instead of whether rcPaint is empty

Committed in r65618

http://trac.webkit.org/changeset/65618