380062 - Uneven justification with new textframe when multiple text runs on one line

Status: VERIFIED FIXED

(Core :: Graphics, defect)

Description

[Simon Montagu :smontagu]

Attachment: screenshot with and without new textframe

This is hard to describe in words, but I hope the attached screenshot will make it clear. When there is only one text run on a line, justification spaces are added evenly across the line, but when there is more than one (because of a font change or a change of direction in bidirectional text) all the justification spaces are added between text runs creating an uneven effect.

Comment 1

[Simon Montagu :smontagu]

Attachment: Testcase

Comment 2

[Simon Montagu :smontagu]

This is caused by the condition 
  if (!(mFrame->GetStateBits() & TEXT_END_OF_LINE))
    return;
at the beginning of PropertyProvider::FindEndOfJustificationRange() http://mxr.mozilla.org/seamonkey/source/layout/generic/nsTextFrameThebes.cpp#2135

As it stands, that is clearly wrong, but I don't know if we want to just remove it or add some other condition to cover the case that is failing here (e.g. the first frame on the second and fourth lines in the screenshot). Roc, can you advise?

Comment 3

[Robert O'Callahan (:roc) (email my personal email if necessary)]

FindEndOfJustificationRange should return the end of the text when the frame is not at the end of the line. So that END_OF_LINE check should move below the call to SetOriginalOffset that's setting aIter to the end of the text.

Comment 4

[Simon Montagu :smontagu]

Attachment: Patch

Yeah, that works.

Comment 5

[Robert O'Callahan (:roc) (email my personal email if necessary)]

You seem to have checked this in ... thanks!

Comment 6

[Jeff Walden [:Waldo]]

An idea for how to test this would be to do a not-equals test between:

- a single justified line of text with two different text runs, each
  containing whitespace
- the same two text runs, except floated left and floated right

If the floating is done correctly, I *think* this would produce the same rendering with the bug in effect but would not if the bug were not in effect.