> On Nov 16, 2015, at 4:20 PM, Stephen White <[email protected]> wrote: > > Hi filter-folks, > > Should the bounding box used to compute filter region in CSS filter effects > include CSS transforms applied to child elements? > > E.g., > > <div id="parent" style="filter: url(#filter);"> > <div id="child" style="transform: scaleY(4);">X > </div> > </div> > > What's the bounding box for the filter on "parent"? Does it include the > scaleY(4) of the child element, or is it the original untransformed bounding > box? The spec currently has a link > <http://www.w3.org/TR/2011/REC-SVG11-20110816/coords.html#ObjectBoundingBoxUnits> > to the SVG 1.1 spec, which has no mention of transforms, so one could assume > they're implicitly included, but being an SVG spec, perhaps it doesn't fully > describe all possible implications for HTML. > > (See Chrome bug https://code.google.com/p/chromium/issues/detail?id=554169 > <https://code.google.com/p/chromium/issues/detail?id=554169> for further > reference/discussion.) > > Thanks in advance for your help,
It should include the extent of all the descendants (including transforms). Filters are a “graphical group” operation, so it’s as if the element and its descendants are rendered into a bitmap, the filter is applied to the bitmap, then the bitmap is rendered to the destination. Simon
