[whatwg] CanvasRenderingContext2D with addPath, currentPath

Rik Cabanier cabanier at gmail.com
Wed Dec 4 17:21:08 PST 2013

On Wed, Dec 4, 2013 at 11:32 AM, Jürg Lehni <lists at scratchdisk.com> wrote:

> On Nov 29, 2013, at 06:03 , Rik Cabanier <cabanier at gmail.com> wrote:
> > I agree it's not the most useful API but it will be helpful. From one of
> the previous message:
> > It would be a very fast way to set a cached path in the graphics state
> > and:
> In the case of Paper.js, this optimization was not possible precisely
> because the returned path has the matrices factored in. The draw loop in
> Paper.js iterates through the scene graph (our DOM) and on each level
> applies the stored matrix, then draws the item (in case of a group, this
> means just iterating through its children and repeating the same thing
> again for each child). I was reusing path descriptions through #currentPath
> in the Path item for a while, but had to stop using it again since it
> appeared to be applying matrices twice. And even if I would have decided to
> not apply matrices in such a case (or reset the matrix before drawing such
> an already transformed path), I would still end up having troubles as soon
> as I would use lineWidth, gradients or patterns, since they are transformed
> based on the current matrix too. Even the stroke itself is transformed by
> the matrix.

OK, so since the current proposal does NOT bake in the current matrix, it
should be possible.

> So other than using it for hit-regions, I really don't think I can see too
> many use cases.
> And perhaps that points towards an issue in the specification of
> hit-regions?

I'm not sure why that would be. Can you elaborate?

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