It wasn't clear from your original message that the stroke bounds were much more expensive. Given that additional info I don't think my idea is practical. That makes it harder to decide. I like your choice of fill bounds to ease the ability to align the gradients, but I don't like the idea of not being able to use a gradient that goes to the edge of the stroke. Depending on the stroke width that could be a significant and very visible limitation.
I wonder how frequently aligning the gradient in the stroke and the fill comes up? It seems using the stroke bounds for the stroke and the fill bounds for the fill is more correct, even if it makes aligning the gradients more difficult. That alignment is nice, but having the gradient work consistently in terms of what 0% and 100% mean is probably important. Scott > On Nov 18, 2013, at 8:17 PM, Jim Graham <james.gra...@oracle.com> wrote: > > Hi Scott, > > That's an odd take on it. It wouldn't be readily obvious to a developer why > their background rectangle had the gradient a little off if they never > planned to ever stroke it. > > Also, keep in mind that while it might be slightly more expensive to > calculate tight bounds than loose bounds, it is MUCH more expensive to > calculate stroke bounds on a shape. It's not a trivial "OK, add a few pixels > for the stroke" type of case, you have to trace out the path and compute the > perpendicular extensions in many cases. So, basically you are saying "always > do the most expensive bounds operation for ever shape that is filled even if > the extra work would never come into play"...? > > ...jim > >> On 11/18/2013 4:58 PM, Scott Palmer wrote: >> I would lean towards using the stroke bounds for both. Those being the >> "real" bounds, and resulting in less mis-aligned gradients. Always >> calculate the stroke bounds as if the shape will be stroked, so it doesn't >> affect Canvas. >> If you don't want that to affect the bounds used for a gradient fill when >> you aren't stroking, set the stoke width to 0. >> >> >> Scott >> >>> On Nov 18, 2013, at 5:58 PM, Jim Graham <james.gra...@oracle.com> wrote: >>> >>> Felipe mentioned recently that we encountered some issues in fixing a bug >>> with SVGPath. >>> >>> The outcome of this fix could be a significant change in how your >>> proportional gradient fills look and so we'd like to get feedback on the >>> various ideas. You can read about them in that Jira issue, but I'll also >>> summarize below. Discussion would probably be better on the mailing list, >>> but we eventually need to work the salient points back into the Jira issue >>> for future maintenance. >>> >>> The basic issue is that we had a disagreement between the way that the >>> shape caching code worked and the way that uncached shapes were filled with >>> proportional paints. >>> >>> First, there is the concept of tight and loose bounds. Loose bounds are >>> very cheap to calculate, but can contain area not strictly inside the >>> shape. Tight bounds are more careful to figure out exactly how far curved >>> sections of the shape reach, but a fair number of calculations and >>> recursions are needed to accurately calculate those extents. >>> >>> Our current code will use loose bounds of the basic shape (i.e. the part >>> that is filled) to calculate the bounds for proportional paints when you >>> first paint a shape - whether you stroke it, fill it, or both. >>> >>> But, if you ran with shape mask caching (the default mode) then after a >>> rendering or 2 we would decide to cache the antialias coverage mask and we >>> would then use the node's content bounds to figure the bounds for the >>> proportional paint. The content bounds are calculated more precisely as >>> tight bounds, though, so they didn't always agree with the bounds used in >>> those first few uncached renderings. >>> >>> The net result is that the proportional paint would shift after the first >>> couple of frames unless you animated the shape and then it would revert >>> while you were animating and then shift back when it was stable. >>> >>> There is also the Canvas object that can also render proportional paints, >>> and it does so using the same code that the shape nodes use when they don't >>> have their coverage mask cached (i.e. loose fill bounds). >>> >>> We'd like to make all of this as consistent as possible. Here are the >>> various decisions and how they'd impact code: >>> >>> - Loose bounds are faster to calculate for shapes that aren't likely to be >>> reused. The uncached shape rendering used them because the shapes may >>> change before we need the bounds again. Canvas uses it because it is an >>> immediate mode API with no input on how often it may see a particular shape >>> again. >>> >>> - Tight bounds would likely be less suprising to developers and users, >>> though. They are better for hit testing and damage management because they >>> generate fewer false positive hits. They are also fairly fast to calculate >>> for most shapes and it is a rare shape that we'd have to recurse much to >>> get it right. Also, for straight edges there is no difference in >>> performance to calculate tight or loose bounds. >>> >>> All in all, it would probably be better for the FX API to standardize on >>> tight bounds and treat any cases where we noticeably affect performance >>> (which should be very rare) as opportunities for tuning. This may not be >>> compatible with the first rendering of current Shape nodes, but they would >>> shift back and forth anyway so we aren't worried about incompatibility with >>> an inconsistent system. >>> >>> The other part of the decision is which bounds to use. >>> >>> Currently uncached rendering uses fill bounds, and mask-cached rendering >>> uses the content bounds which depends on whether you supply a stroke or a >>> fill paint so it could be either fill bounds or stroke bounds. >>> >>> - For filled-only shapes we obviously want to use the "fill bounds". >>> >>> - For stroked and filled shapes, we have 3 choices: >>> >>> - - use fill bounds for both paints so that the geometry used for >>> proportional stroke and fill paints are similar for both parts of those >>> nodes. This helps line up any color discontinuities or highlights between >>> the two. >>> >>> - - use stroke bounds for both which also means the two are consistent, but >>> Canvas can't really do this because it doesn't know if you are filling and >>> stroking until it sees the latter operation >>> >>> - - use fill bounds for fill and stroke bounds for stroke which means the >>> geometries of the two are different and it makes it harder to line up the >>> transitions of proportional stroke+fill shapes, but Canvas can do this so >>> Canvas vs. Shape node remain consistent >>> >>> I'm not sure which of the above is the best, but I lean towards "fill >>> bounds for both" because it allows consistent geometry for stroke+fill and >>> it allows consistent behavior between Canvas and Shape node, at the >>> possible expense of "0% on a stroke isn't at the edge of the stroke". >>> >>> Thoughts? >>> >>> ...jim
