Bug 184336 – When recording the drawing, the DisplayList should be initialized with the GraphicsContextState of the underlying GraphicsContext

• Status: RESOLVED
• Resolution: FIXED
• Component: Layout and Rendering

[Said Abou-Hallawa]

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

[Said Abou-Hallawa]

Created attachment 337281 [details]
Patch

[Said Abou-Hallawa]

Created attachment 337282 [details]
Patch

[WebKit Commit Bot]

Comment on attachment 337282 [details]
Patch

Clearing flags on attachment: 337282

Committed r230347: <https://trac.webkit.org/changeset/230347>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Radar WebKit Bug Importer]

<rdar://problem/39245569>