1024860 - Empty SVG Path getTotalLength() throws exception in JS

Status: RESOLVED FIXED

(Core :: SVG, defect)

Description

[alancutter]

User Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/36.0.1985.49 Safari/537.36

Steps to reproduce:

Call getTotalLength() on an SVG Path element with an empty data field.
http://jsfiddle.net/PGPqM/12/



Actual results:

[Exception... "Failure"  nsresult: "0x80004005 (NS_ERROR_FAILURE)"  location: "JS frame :: http://fiddle.jshell.net/PGPqM/12/show/ :: window.onload :: line 23"  data: no]



Expected results:

Total path length: 0
This test passes.

Comment 1

[Robert Longson [:longsonr]]

Attachment: length.txt

Comment 2

[Robert Longson [:longsonr]]

I'll adapt the mochitest from bug 1024926 to cover this case before landing i.e. start from a d="" measure and check that and then set the path in the bug 1024926 mochitest using setAttribute.

Comment 3

[Jonathan Watt [:jwatt]]

Comment on attachment 8441186 [details] [diff] [review]
length.txt

Review of attachment 8441186 [details] [diff] [review]:
-----------------------------------------------------------------

::: content/svg/content/src/SVGPathElement.cpp
@@ +347,5 @@
>      float authorsPathLengthEstimate = mPathLength.GetAnimValue();
>      if (authorsPathLengthEstimate > 0) {
>        RefPtr<Path> path = GetPathForLengthOrPositionMeasuring();
> +      if (!path) {
> +        return 0.0;       

Return 1.0 as we do at the end of this function. And remove the trailing whitespace from this line.

Comment 4

[Robert Longson [:longsonr]]

> Return 1.0 as we do at the end of this function. And remove the trailing
> whitespace from this line.

Returning 1.0 would be wrong at that point. RefPtr<Path> path = GetPathForLengthOrPositionMeasuring(); returns null if the path is empty i.e. its a zero length path. 

We want to return  path->ComputeLength() / authorsPathLengthEstimate; and we've tested that authorsPathLengthEstimate > 0 so in this inner bit of code that would come out as 0 (it used to do that before moz2d came along and made empty paths return nullptr)

You want some comments to help future readers?

Comment 5

[Jonathan Watt [:jwatt]]

Okay. And yes, a comment would be helpful. Thanks!

Comment 6

[Robert Longson [:longsonr]]

https://tbpl.mozilla.org/?tree=Try&rev=bd677df9cfe2

Comment 7

[Robert Longson [:longsonr]]

Comment on attachment 8441186 [details] [diff] [review]
length.txt

Apparently the webidl change needs a DOM peer review

Comment 8

[Boris Zbarsky [:bzbarsky]]

Comment on attachment 8441186 [details] [diff] [review]
length.txt

r=me

Comment 9

[Robert Longson [:longsonr]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/82210155467c

Comment 10

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/82210155467c