- From: Alex Danilo <alex@abbra.com>
- Date: Sun, 08 Nov 2009 14:09:26 +1100
- To: www-svg <www-svg@w3.org>
Yes, good point. Totally different, and a lot more work too... The original post with the subject 'Pointer-events Suggestion' was about hit-testing from a point. checkIntersection adds a whole new level of pain for the implementer. That introduces polygonal intersections which generally are expensive operations (although the rectangle case makes things a bit less onerous). Alex --Original Message--: >All of this discussion misses the fact that we are not hit-testing a point, we have to hit-test a rectangle for checkIntersection. This means we really need to determine if the sides of the rectangle intersect any shape's fill or stroke depending on the value of pointer-events on that shape. Doesn't that make it a totally different algorithm altogether? > > >On Nov 7, 2009 7:37 PM, "Alex Danilo" <alex@abbra.com> wrote: > >Boris Zbarsky wrote: >Andreas Neumann wrote: >> I guess every implementor already has the prerequis... > >Well almost. > >Yes you do bail out when you get a hit, that's true. > >But the code to walk the tree and hit-test is there >already. So a bit of refactoring to handle that case >could inhibit the bail out, and instead accumulate >a list of hit nodes. The top most node in that list >is the traditionally hit node that would normally >cause a bail out. > >Normally, when you bail out it saves walking the rest >of the tree, but worst case requires a full walk of >the tree. Accumulating a list in the process of the >walk is the same cost, so it could be pretty cheap. >Much better to do this in the UA than trying to make >script authors walk through (slow) hoops. > >This discussion does bring up an interesting aside >with relation to the proposals for rendering order. >Current hit-testing is based in the tree/document order. >If rendering order changes come in, there will be >serious performance hits for the changed render model >so that needs to be included as part of all this too. > >In any case, what makes author's lives easier is >what we really want as much as poor implementors >have to suffer - but they only suffer the >implementation pain once... > >Alex > > >>-Boris >> >> >> > > > > > >
Received on Sunday, 8 November 2009 03:10:09 UTC