1824877 - Rename nsHTMLScrollFrame to mozilla::ScrollContainerFrame

Status: RESOLVED FIXED

(Core :: Layout: Scrolling and Overflow, task, P3)

Description

[Ting-Yu Lin [:TYLin] (PDT, UTC-7)]

After bug 1823455, we can rename nsHTMLScrollFrame to mozilla::ScrollFrame, and rename nsGfxScrollFrame.h/cpp to ScrollFrame.h/cpp.

Comment 1

[Ting-Yu Lin [:TYLin] (PDT, UTC-7)]

Per https://phabricator.services.mozilla.com/D201893#6924920, we should consider removing nsIScrollableFrame since nsHTMLScrollFrame is the only class implementing nsIScrollableFrame.

Comment 2

[Ting-Yu Lin [:TYLin] (PDT, UTC-7)]

Attachment: Bug 1824877 Part 1 - Rename nsGfxScrollFrame.{h,cpp} to ScrollContainerFrame.{h,cpp}. r?#layout

Remove the #include from nsFrameState.cpp because it is not used.

Comment 3

[Ting-Yu Lin [:TYLin] (PDT, UTC-7)]

Attachment: Bug 1824877 Part 2 - Rename nsHTMLScrollFrame to mozilla::ScrollContainerFrame. r?#layout

• Change the ScrollFrame::GetFrameName() to return "Scroll" instead of
  "HTMLScroll".

• Replace NS_NewHTMLScrollFrame() with ScrollFrame::New() because I failed to
  make the friend declaration work after the rename. I keep getting build
  error: "calling a protected constructor of class 'mozilla::ScrollFrame'".

Comment 4

[Ting-Yu Lin [:TYLin] (PDT, UTC-7)]

Let's name it ScrollContainerFrame to align with the spec term https://drafts.csswg.org/css-overflow-3/#scroll-container

Comment 5

[Ting-Yu Lin [:TYLin] (PDT, UTC-7)]

Attachment: Bug 1824877 Part 3 - Change ScrollContainerFrame's type from Scroll to ScrollContainer. r?#layout

This effectively changes the IsScrollFrame() helper to
IsScrollContainerFrame().

Comment 6

[Ting-Yu Lin [:TYLin] (PDT, UTC-7)]

Attachment: Bug 1824877 Part 4 - Drop unnecessary using declarations and mozilla namespace qualifiers. r?#layout

We can simplify them because ScrollContainerFrame is within mozilla
namespace.

Comment 7

[Ting-Yu Lin [:TYLin] (PDT, UTC-7)]

Attachment: Bug 1824877 Part 5 - Revise build scroll container frame APIs in frame constructor. r?#layout

Comment 8

[Ting-Yu Lin [:TYLin] (PDT, UTC-7)]

Attachment: Bug 1824877 Part 6 - Rename IsScrollContainer() to IsScrollContainerOrSubclass(). r?#layout,dholbert,tnikkel

This is to avoid confusion with IsScrollContainerFrame() introduced in Part 3.

A note to performance concern:

We've used IsScrollContainerOrSubclass() in bug 1873414 to avoid expensive
nsIScrollableFrame* sf = do_QueryFrame(). Per [1], casting from nsIFrame* to
nsIScrollableFrame* has no fast path.

Ideally, ScrollContainerFrame* sf = do_QueryFrame() should be fast, and we can
use it to implement IsScrollContainerOrSubclass() like
IsImageFrameOrSubclass(). However, in this patch, I intend to keep the
performance metrics unchanged.

Remove GetAsScrollContainer() since it's only used in MOZ_ASSERT, and I'm
planning to remove nsIScrollableFrame in bug 1896516.

[1] https://searchfox.org/mozilla-central/rev/dd6e430c1bc2db90d9b3b1dd7e5215b4edc4d51a/layout/generic/nsQueryFrame.h#117-121

Comment 9

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/416d4c538f83
Part 1 - Rename nsGfxScrollFrame.{h,cpp} to ScrollContainerFrame.{h,cpp}. r=dholbert
https://hg.mozilla.org/integration/autoland/rev/ef4c00fe4624
Part 2 - Rename nsHTMLScrollFrame to mozilla::ScrollContainerFrame. r=dholbert
https://hg.mozilla.org/integration/autoland/rev/ce99fe13a24e
Part 3 - Change ScrollContainerFrame's type from Scroll to ScrollContainer. r=dholbert
https://hg.mozilla.org/integration/autoland/rev/2a498d6dc8b4
Part 4 - Drop unnecessary using declarations and mozilla namespace qualifiers. r=dholbert
https://hg.mozilla.org/integration/autoland/rev/78bbb09a4cc5
Part 5 - Revise build scroll container frame APIs in frame constructor. r=dholbert
https://hg.mozilla.org/integration/autoland/rev/b033344df9c7
Part 6 - Rename IsScrollContainer() to IsScrollContainerOrSubclass(). r=dholbert

Comment 10

[Cristian Tuns]

https://hg.mozilla.org/mozilla-central/rev/416d4c538f83
https://hg.mozilla.org/mozilla-central/rev/ef4c00fe4624
https://hg.mozilla.org/mozilla-central/rev/ce99fe13a24e
https://hg.mozilla.org/mozilla-central/rev/2a498d6dc8b4
https://hg.mozilla.org/mozilla-central/rev/78bbb09a4cc5
https://hg.mozilla.org/mozilla-central/rev/b033344df9c7