[Webkit-unassigned] [Bug 184336] New: When recoding the drawing, the DisplayList should be initialized with the GraphicsContextState of the underlying GraphicsContext

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=184336

            Bug ID: 184336
           Summary: When recoding the drawing, the DisplayList should be
                    initialized with the GraphicsContextState of the
                    underlying GraphicsContext
           Product: WebKit
           Version: WebKit Nightly Build
          Hardware: Unspecified
                OS: Unspecified
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: Layout and Rendering
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: sabouhallawa at apple.com
                CC: bfulgham at webkit.org, simon.fraser at apple.com,
                    zalan at apple.com

The state of the drawing context has to be transfered to the recording DisplayList before recording. Many recording GraphicsContext functions will behave wrongly if get the default state. Here is a scenario of the bug:

-- context.m_state.fillColor = RED (context is the underlying GraphicsContext for the recorded DisplayList)
-- displayListRecorder is created to start recording.
-- displayListRecorder.m_stateStack[0].lastDrawingState.fillColor = BALCK (Because lastDrawingState was initialized by the default GraphicsContextState)
-- displayListContext is created which encapsulates the displayListRecorder
-- displayListContext.setFillColor(BALCK) is called
-- displayListContext.fillRect(rect) is called
-- displayListRecorder is replayed back into context

Result: 
-- displayListContext.fillRect() will end up calling Recorder::willAppendItem() which will call GraphicsContextStateChange::changesFromState()
-- GraphicsContextStateChange::changesFromState() will not find a change in the fillColor. The recording GraphicsContext has it BALCK and it was BALCK. So there is no change here and the flag FillColorChange will not be returned
-- Recorder::willAppendItem() will not append a new SetState item in the DisplayList
-- The rectangle is filled with the current fillColor which is RED instead of BALCK as the caller wanted

-- 
You are receiving this mail because:
You are the assignee for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.webkit.org/pipermail/webkit-unassigned/attachments/20180405/b107f3fb/attachment-0002.html>