[whatwg] Canvas arcTo all points on a line

Dirk Schulze vbs85 at gmx.de
Sat Dec 27 01:37:07 PST 2008


have two questions to the "all points on a line" part of canvas' arcTo.
A short example:

arcTo(100,0,  0,0, 10);

This should add a new, from p1 infinite far away, point to the subpath
and draw a straight line to it.

Two questions.

1) If I add lineTo(50, 50); after arcTo(..). Wouldn't it draw a "quasi
parallel" line to the line of arcTo? Because (Xx, Yx) (mentioned in the
spec) is infinite far away. That means, we will never reach this point
in reality.

2) We don't allow infinite values for moveTo or lineTo, but can make
this happen with arcTo.
The example above would be the same as lineTo(-Infinite, 0);
But we can make moveTo(-Infinite, 0) too with the example above. Just
make strokeStyle transparent, use arcTo from above and you're done. And
moveTo(infinite, infinite); would be possible too.

thanks Dirk

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