118918 - Change nsIPresContext::GetDefaultFont() to avoid copy

Status: RESOLVED FIXED

(Core :: CSS Parsing and Computation, defect)

Description

[rbs]

Currently, the API is defined as:

NS_IMETHOD
nsIPresContext::GetDefaultFont(PRUint8 aFontID, nsFont& aResult)

And it showed up in one of the perf data posted by dbaron sometimes ago in the 
n.p.m.performance newsgroup, see
http://groups.google.com/groups?th=4600cc6332ac246d&rnum=1

Although its impact is marginal it can be eliminated totally from the perf radar 
by a simple change to a version that doesn't copy, e.g,

NS_IMETHOD 
nsIPresContext::GetDefaultFont(PRUint8 aFontID, const nsFont*& aResult)

so that a consumer can just do

    const nsFont* font;
    aPresContex->GetDefaultFont(aFontID, font);
    ... see it and nothing to free() since the signature implies that nothing is
    ... allocated for you

Comment 1

[rbs]

Attachment: collated patch in layout + content + xmlterm

Seeking hot r/sr

Comment 2

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Comment on attachment 64099 [details] [diff] [review]
collated patch in layout + content + xmlterm

r=dbaron, although in general I prefer getters that take |const nsFont**| (so
that it's clear from the calling code that the variable is to be filled in by
the function rather than passed to the function), so I don't mind if you change
that.

...I'd really love to see all that no-longer-used "quirks" form control code go
away sometime...

Comment 3

[rbs]

OK, will switch to your suggested signature. I don't mind it too.

Comment 4

[Chris Waterson]

Yeah, do what dbaron suggests and sr=waterson.

Comment 5

[rbs]

Fixed using |const nsFont**|.