User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1b1pre) Gecko/20080916043910 Minefield/3.1b1pre
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1b1pre) Gecko/20080916043910 Minefield/3.1b1pre
The feImage filter is supposed to support document fragments (see http://www.w3.org/TR/SVG/filters.html#feImage ), including but not limited to fragments of the current document, in practice emulating the "use" element and rendering the output to the current buffer.
Basically, this deprives SVG filters of any way to work with dynamic data, like canvas and instead forces webdevelopers to instead use very slow JS implementations of those filters. For example, to recreate the old Java "waves" demo, the canvas could be fed into an feDisplacement filter.
Steps to Reproduce:
1. Open the attached testcase in Firefox
2. Open it again in Inkscape
Firefox doesn't display the green rectangle inserted into the rendering chain through an feImage. Output of Inkscape and Firefox differ.
The green rectangle should be added to the rendering via the feImage filter, overlaying the red background-
Created attachment 339387 [details]
Testcase for feImage xlink:href document fragment bug.
I can confirm this bug in
Mozilla/5.0 (Macintosh; U; PPC Mac OS X 10.5; en-US; rv:18.104.22.168)
This is really just another example of bug 272288.
Confirming, although this is likely to simply be marked as a a duplicate of bug 272288 eventually.
To get this to work (for <feImage xlink:href="#idOfSomeElement">), I think we actually need to import the <use> behavior for into <feImage>, right? (to clone a subtree, or at least generate the document with that subtree if the targeted ID is in a different document)
We could almost fall back on moz-element here, except that the targeted element could be in a completely different document from the one we're displaying (e.g. xlink:href="foo.svg#SomeNodeID"), and IIUC, -moz-element only works for elements in the same document. Still, we might be able to take advantage of some of moz-element's underlying mechanics.
(In reply to comment #3)
> This is really just another example of bug 272288.
I think this is actually distinct from bug 272288 (which is about <image>) -- this bug is about using fragment IDs, and the <image> tag doesn't accept those...
> Unlike ‘use’, the ‘image’ element cannot reference elements within an SVG file.
...whereas the <feImage> tag does accept fragment IDs (as noted in comment 0).
*** Bug 703987 has been marked as a duplicate of this bug. ***
It might be time for someone to work on this. Safari and Chrome(Canary) as well as IE now support importing document fragments correctly into filter streams. aka
Now displays correctly except in Firefox.
*** Bug 882434 has been marked as a duplicate of this bug. ***
There will be increasing interest in blending modes since they are heavily used in the iOS7 visual style. Because of the lack of support for enable-background in every browser except IE10, the only way to achieve these effects in SVG is to use document fragments via feImage. And Firefox is now the only browser that doesn't support these.
I would also like to add my support to resolving this issue.
I'm really sorry I do not have the technical proficiency to help fix it but as more and more people turn to SVG as a non-resolution dependent graphics format it is a real tragedy that Firefox does not allow the use of feImage with a document fragment. It restricts the use of using many filter options and Michael Mullany has said, is now the only modern browser without this support.
Please try to resist commenting unless you are interested in fixing it. There is a voting mechanism you can use to express support if not.
Do the other browsers handle dynamic changes to the referenced content updating the filter? What do they do if the referenced content itself uses the filter? Do they handle <foreignObject> content inside the referenced content subtree?
I think I would implement this in a way similar to the way -moz-element is implemented. nsImageRenderer in nsCSSRendering implements that.
having used this property extensively, they definitely do handle dynamic updates to the referenced image. In one of my cases its a group of svg paths, this group gets periodically added to and also the paths them selves get points added to them in realtime.. it all updates correctly in safari/chrome, and fast.
ForeignObject is a good question.. obviously if combined with canvas, then canvas turned to png, it could be used to read the image values of some sections of the dom that are not allowed for cross origin or for user privy reasons ( visited links for example ), tho i assume that canvas that reference svg that have foreign object already can be turned to a png
As for having a circular reference, this is also a good question.. care must be taken not to either crash the browser or make it totally un responsive.. tho circular references can exist in css for example ( you can make an item which moves when hovered, then moves out of hover when you do then back in etc.. it will jump about like mad.. ) so maybe this should behave the same, every time the frame is updated it recalls, giving a new view based on the total calculation of the last, or maybe it should just not allow a circular reference ..
Other use cases for feImage fragments:
If you want to do a linear focus blur on text then you need to be able to get a gradient into your filter chain in some way.
If you want to do distortion effects on text then it's handy to import linear and radial gradients as displacement inputs.
Other browsers update the in-filter feImage when the referenced object is updated. Erik Dahlstrom's ripple distortion effect is a good demo:
Wonderful to finally see this feature implemented in Firefox! I have been trying it out and it mostly works as advertised.
The second strange behavior seem to be when applying a filter with an feImage to a non rectangular shape, or at least a circle.
The svg from Michael Mullany above at http://codepen.io/mullany/pen/rKLdJ displays corrector in chrome / safari but shows nothing in firefox nightly! i tried simplifying the solution and tracked it down to applying filters with feImage to circles. It also behaves oddly with polygon's too.
Beware comment 17, its wrong, this feature hasn't been implemented. If it had, this bug would be marked fixed rather than new.
In my testing, it did work as expected when trying the attached "Testcase for feImage xlink:href document fragment bug" in firefox, tho the test case is not that clear how it works .. i tried again and it still seems to behave as i would expect if the feature worked .. it defiantly does not work for non rectangular elements tho.
This is a feature i and a lot of other keen SVG developers would love to see working reliably however!
*** Bug 1215575 has been marked as a duplicate of this bug. ***