[Win] BeginPaint should only be called in response to WM_PAINT.

• Component: WebKit Misc.
• Status: RESOLVED FIXED

According to the documentation (http://msdn.microsoft.com/en-us/library/windows/desktop/dd183362(v=vs.85).aspx), the Win32 api functions BeginPaint and EndPaint should only be called in response to a WM_PAINT message. Currently, the WebView window procedure might call these functions (via WebView::paint(0, 0)) for all types of messages. Also, there is potential double drawing. If some message is dispatched before WM_PAINT, WebView::paint(0, 0) will be called. This call does not validate the area drawn, so later the WM_PAINT will arrive, drawing the same area.

Created attachment 213770 [details]
Patch

[Brent Fulgham]

Comment on attachment 213770 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=213770&action=review

> Source/WebKit/win/WebView.cpp:2467
> +        ::UpdateWindow(hWnd);

Will this trigger the logic in webView->performLayeredWIndowUpdate()?

(In reply to comment #2)
> (From update of attachment 213770 [details])
> View in context: https://bugs.webkit.org/attachment.cgi?id=213770&action=review
> 
> > Source/WebKit/win/WebView.cpp:2467
> > +        ::UpdateWindow(hWnd);
> 
> Will this trigger the logic in webView->performLayeredWIndowUpdate()?

Yes, UpdateWindow will send the WM_PAINT message (synchronously) if there is an invalid area.

[Brent Fulgham]

Comment on attachment 213770 [details]
Patch

r=me

[Radar WebKit Bug Importer]

<rdar://problem/15187300>

(In reply to comment #4)
> (From update of attachment 213770 [details])
> r=me

Thanks for reviewing!

[WebKit Commit Bot]

Comment on attachment 213770 [details]
Patch

Clearing flags on attachment: 213770

Committed r157174: <http://trac.webkit.org/changeset/157174>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.