337145 - One copy of nsIDOMSVGMatrix -> cairo_matrix_t code

Status: RESOLVED FIXED

(Core :: SVG, defect)

Description

[tor]

Comment 1

[tor]

Attachment: single version of conversion, in nsSVGMatrix

Comment 2

[Jonathan Watt [:jwatt]]

Comment on attachment 221316 [details] [diff] [review]
single version of conversion,  in nsSVGMatrix

>+cairo_matrix_t
>+ConvertSVGMatrixToCairo(nsIDOMSVGMatrix *aMatrix)
>+{
>+  float A, B, C, D, E, F;
>+  aMatrix->GetA(&A);
>+  aMatrix->GetB(&B);
>+  aMatrix->GetC(&C);
>+  aMatrix->GetD(&D);
>+  aMatrix->GetE(&E);
>+  aMatrix->GetF(&F);
>+  cairo_matrix_t m = { A, B, C, D, E, F };
>+  return m;
>+}

Does that really work? Isn't that a stack allocated object you're returning there?

Comment 3

[tor]

No, structure returns are allowed.  It does indicate a copy needs to be done, unless the compiler's optimizer is smart enough to see what's happening.

Comment 4

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

In this case no copy will be done.

Comment 5

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

Shouldn't this function be in nsSVGUtils? Or perhaps we need nsSVGContentUtils.

Comment 6

[tor]

(In reply to comment #5)
> Shouldn't this function be in nsSVGUtils? Or perhaps we need nsSVGContentUtils.

From the patch:

+/*
+ * Helper to convert a nsIDOMSVGMatrix to a cairo_matrix_t.  Defined
+ * here instead of in nsSVGUtils.h because that file is needed in
+ * several places where it would be inappropriate to include cairo.h.
+ */

Comment 7

[Jonathan Watt [:jwatt]]

Comment on attachment 221316 [details] [diff] [review]
single version of conversion,  in nsSVGMatrix

r=jwatt

(In reply to comment #3)
> No, structure returns are allowed.  It does indicate a copy needs to be done,
> unless the compiler's optimizer is smart enough to see what's happening.

Doh! Right.

(In reply to comment #4)
> In this case no copy will be done.

How can you say?

Comment 8

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

http://www.devx.com/tips/Tip/5716

Comment 9

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

Comment on attachment 221316 [details] [diff] [review]
single version of conversion,  in nsSVGMatrix

sr+ with the NS_ change

Comment 10

[tor]

Attachment: version for checkin - update to tip, NS_ change

Comment 11

[tor]

Checked in.