1751260 - Fix image frame's fragmentation for vertical writing-mode

Status: NEW

(Core :: Layout: Images, Video, and HTML Frames, defect)

Description

[Ting-Yu Lin [:TYLin] (PST, UTC-8)]

While working on bug 1748277, I add an assertion to assert the completeness of nsMathMLTokenFrame's children, and it bumps the assertion count.

The root cause is that nsImageFrame::Reflow [1] doesn't consider vertical writing-mode when fragmenting images, so we should rewrite it by using logical coordinates.

[1] https://searchfox.org/mozilla-central/rev/8012bca692dddb307c2787bac1d4dd48cb0d8243/layout/generic/nsImageFrame.cpp#1265-1275

Comment 1

[Ting-Yu Lin [:TYLin] (PST, UTC-8)]

Attachment: testcase 1

Comment 2

[Ting-Yu Lin [:TYLin] (PST, UTC-8)]

Note that with layout.display-list.improve-fragmentation enabled by default, we currently can already fragment images in vertical writing-mode in printing. (Hence lower the severity to S4.)

Converting nsImageFrame::Reflow() code to logical coordinates is probably not sufficient. Some callers in image painting related code use nsImageFrame::GetContinuationOffset() to calculate the consumed height from previous continuations. It won't work in the vertical writing-modes. nsSplittableFrame::CalcAndCacheConsumedBSize() should be used instead.

Comment 3

[Ting-Yu Lin [:TYLin] (PST, UTC-8)]

Attachment: Screenshot of bug 1805522's testcase in layout debugger's paged mode

This is the screenshot of https://bug1805522.bmoattachments.org/attachment.cgi?id=9308103 (Note: the browser will crash without the fix in bug 1805522.)

The image doesn't render correctly. There should be only one asterisk.