1612822 - Refactor & clean up computation of decoration line position/thickness

Status: RESOLVED FIXED

(Core :: Layout: Text and Fonts, task, P3)

Description

[Jonathan Kew [:jfkthame]]

The calculation of exactly where to draw text decoration lines (especially underlines) is a bit tricky, and currently there's quite a bit of duplication of the logic across various places that need to know. I think we can clean up and simplify this to make it more understandable and maintainable.

Comment 1

[Jonathan Kew [:jfkthame]]

Attachment: Bug 1612822 - Refactor text decoration offset/thickness computations. r=emilio

We replace SetWidthIfLength and SetOffsetIfLength with ComputeDecorationLine{Thickness,Offset} functions,
and consolidate more of the computation of the offset within this function to simplify callers.

Comment 2

[Jonathan Kew [:jfkthame]]

Here's at least a step along the way to making this more sane. I think we may be able to do more... e.g. it may be possible to eliminate the defaultLineThickness member in nsCSSRendering::DecorationRectParams altogether. But that will involve changes inside nsCSSRendering as well as in nsTextFrame's computation, so I'm leaving that for now.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/935e6045865a
Refactor text decoration offset/thickness computations. r=emilio

Comment 4

[Narcis Beleuzu [:NarcisB]]

https://hg.mozilla.org/mozilla-central/rev/935e6045865a