- From: Andrew Fedoniouk <news@terrainformatica.com>
- Date: Sat, 22 Aug 2009 23:59:04 -0700
- To: Brad Kemper <brad.kemper@gmail.com>
- CC: www-style <www-style@w3.org>
Brad Kemper wrote: > > On Aug 22, 2009, at 9:41 PM, Andrew Fedoniouk wrote: > >> Brad Kemper wrote: >>> On Aug 22, 2009, at 8:30 PM, Andrew Fedoniouk wrote: >>>> Reading this document >>>> http://www.w3.org/TR/2008/WD-css3-background-20080910/#the-border-radius >>>> >>>> got couple of questions. >>>> >>>> Phrase after [Example XXI]: >>>> >>>> "(In such cases its center might not coincide with that of the outer >>>> border curve.)" >>>> >>>> Not clear what it means. Center of circle having radius zero? It's a >>>> point then. Has no center... Or is this about something else? >>> That is how I read it. A point does have a center (it's the same point). >> >> Mathematically speaking - yes, someone can say that point is a circle of >> radius zero but that is pretty unusual way of saying "point". >> >>> That point would no longer align with the center of the center of the >>> circle describing the outside of the border, when the border >>> thickness is thicker than the corner-radius. There may be a better >>> way to say this... >> >> In case of borders of different thickness centers of outer and inner >> circles are different. Is this what you are trying to say? > > No. But given that fact, if you have, say a 20px border and a 10px > border-radius, the inner "circle" (actually a corner), will not be at > the center of the 10px circle. I believe that's what it is saying, > although it seems kind of self evident to me. I can't really imagine it > some other way. Sorry, this is somehow hard to understand. "will not be at the center of the 10px circle" but where? > >> >>>> [...] >>>> And the main question: >>>> >>>> "Other effects that clip to the border or padding edge (such as >>>> ‘overflow’) also must clip to the curve." >>>> >>>> Clipping of content on such border may lead to information lost. >>>> Text behind rounded corner will not be seen at all [top-left corner, >>>> case #8 above]. >>> Text that goes outside its boundaries is also "information lost" when >>> overflow is 'hidden'. Thus it is within the author's ability to >>> obscure text with overflow, as always. If I don't want the text to be >>> clipped by the corners, then I can add padding. >> >> It is about overflow:auto rather than hidden. >> You cannot see that portion even with overflow:auto. That is the point. > > If I consider that a problem when I'm authoring, then I will add padding > to prevent it. CSS does not prevent authors from hiding content that > users can't get to. It happens all the time with negative absolute > positioning, for instance, or can happen with overflow:hidden. It can > also happen with black text on top of a black border with border-radius. > So instead of trying to prevent authors from creating unreadable text, > let us just be responsible for our own design decisions. I think it is > completely reasonable and expected that any border that would clip > content should also do so at the curved corners. Take a look on this case: http://www.terrainformatica.com/w3/border-radius-text.png Paddings will not help you here. > >> I think we just need to remove "Other effects that clip to the border >> or padding edge (such as ‘overflow’) also must clip to the curve." >> statement. It does not create solutions - just problems. > > I disagree. Could you provide some usable case then where you will need overflow clipping of content on rounded border? > >> Technically it is even not possible to do such clipping if >> antialiasing is used. Border should be drawn on top of content but not >> underneath as the spec mandates. > > I don't see how that prevents you from clipping the content (including > antialiasing) to the same path as what is under the content. > Ok, technically *and* practically. I don't know modern platform that has clipping with antialiasing exposed in public API. There is simply no need for such function. -- Andrew Fedoniouk. http://terrainformatica.com
Received on Sunday, 23 August 2009 06:59:39 UTC