1034115 - Stop needlessly creating CSS-px-to-dev-pixel matrices when doing SVG hit-testing

Status: RESOLVED FIXED

(Core :: SVG, defect)

Description

[Jonathan Watt [:jwatt]]

Right now the various GetCanvasTM implementations usually return nsSVGIntegrationUtils::GetCSSPxToDevPxMatrix() when passed FOR_HIT_TESTING. There is no good reason for this, and it is very undesirable when we convert SVG hit-testing to Moz2D since it necessitates doing a Path::TransformedCopyToBuilder() call, which can be expensive. I'd like to fix this before fixing bug 988808.

Basically when GetCanvasTM() returns GetCSSPxToDevPxMatrix() for FOR_HIT_TESTING we should instead return the identity matrix and then adjust the consumers to understand that the transform no longer has the pointless css-to-dev-px component.

Comment 1

[Jonathan Watt [:jwatt]]

Attachment: patch

Comment 2

[Jonathan Watt [:jwatt]]

These code paths seem to be fairly well tested BTW, since I made a couple of typos when writing this patch and blew up a bunch of our mochitests.

Comment 3

[Robert Longson [:longsonr]]

Comment on attachment 8450242 [details] [diff] [review]
patch

> 
>+  SVGBBox& operator*=(float aFactor) {

Should make this a Scale method to match http://mxr.mozilla.org/mozilla-central/source/gfx/2d/BaseRect.h#385

>+    mBBox.x *= aFactor;
>+    mBBox.y *= aFactor;
>+    mBBox.width *= aFactor;
>+    mBBox.height *= aFactor;
>+    return *this;
>+  }
>+

r=longsonr with that

Comment 4

[Robert Longson [:longsonr]]

BTW did you test this at all with SVGDisplayListHitTestingEnabled false? Maybe it's time to bite the bullet and remove the false codepaths.

Comment 5

[Jonathan Watt [:jwatt]]

(In reply to Robert Longson from comment #4)
> BTW did you test this at all with SVGDisplayListHitTestingEnabled false?

I did a bit of testing.

> Maybe it's time to bite the bullet and remove the false codepaths.

See bug 829802 comment 6.

Comment 6

[Jonathan Watt [:jwatt]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/340b176d8f6b

Comment 7

[Tim Taubert [:ttaubert] (inactive)]

https://hg.mozilla.org/mozilla-central/rev/340b176d8f6b