Bug 114894 – RenderText::computePreferredLogicalWidths use of isBreakable() is inefficient

• Status: NEW
• Component: Layout and Rendering

[Glenn Adams]

RenderText::computePreferredLogicalWidths uses isBreakable() twice, each time ignoring the nextBreakable out parameter. Since isBreakable(), by mapping to nextBreakblePosition(), iterates forward to the next break point rather than simply determining if the specified position is breakable, it performs unneeded and unused computation, e.g., by repeatedly calling textBreakFollowing() which maps (on ICU platforms) to ubrk_following().

I propose a variant of isBreakable() that doesn't take a nextBreakable parameter be used in these two cases in computePreferredLogicalWidths, which would use a simplified form of nextBreakablePosition that only checks if the specified position is breakable.