Right. And you'd use a non-zero distance to give an 'indent' look. If you
want an 'inner glow', the distance would be -0, the shadow would be inset with
no offset (and the angle would be irrelevant).
Nonetheless, I think it's this level of confusion that probably led w3c to add
a separate flag rather than overloading.
On 2010-11-01, at 16:47, Max Carlson wrote:
> I've attached a screen shot of the change with shadowdistance instead of
> shadowblurradius == -10 so you can see what I mean. The distance is where
> the shadow starts...
>
> On 11/1/10 1:43 PM, Max Carlson wrote:
>> Nope, sorry. We need to overload shadowblurradius, not shadowdistance.
>> It just doesn't work in practice to use distance, because it forces the
>> shadow to be offset according to the angle...
>>
>> So, I stand by my original change!
>>
>> Here's an updated testcase so you see what I mean:
>> <canvas>
>> <view x="10" y="10" shadowblurradius="-100" shadowdistance="0"
>> width="100" height="100" bgcolor="white"
>> oninit="this.animate('shadowblurradius', 100, 10000)"/>
>> </canvas>
>>
>> On 10/29/10 7:33 PM, P T Withington wrote:
>>> Shadow angle + distance are polar coordinates that are equivalent to
>>> the cartesian coordinates x-offset + y-offset. That's the transform
>>> we're making. x = d * cos(a), y = d * sin(a), right?
>>>
>>> Blur radius is the radius of the blur around the edge of the shadow.
>>> The shadow is at 100% at edge-radius and 0% at edge+radius. This is
>>> the same for us an CSS.
>>>
>>> CSS has an additional property 'spread distance', which is how much
>>> bigger/smaller the shadow is than the original box. That is, this
>>> value is added to the coordinates of the edge of the shadow box,
>>> making it correspondingly larger (or smaller for a negative value)
>>> than the original box. We have no equivalent parameter for this, that
>>> I can see.
>>>
>>> Finally, CSS has a flag, 'inset'.
>>>
>>> Since blur radius is the same in both models, it seems odd to me to
>>> use the sign of that to encode 'inset'.
>>>
>>> On the other hand, a negative distance in polar coordinates makes no
>>> sense, so it seemed reasonable to me for that to be the encoding for
>>> 'inset'. Especially where a distance of 0 is "no shadow", _unless_ you
>>> apply a blur, in which case you will see only the outside half of the
>>> blur (which I guess we call a glow).
>>>
>>> In fact, if you consider animating attributes, it makes a lot more
>>> sense to use the sign of distance to mean inset because by animating
>>> distance from from a positive to negative value, you would make the
>>> shadow go smoothly from giving an outdented appearance, through no
>>> shadow, to an indented appearance. Whereas animating the blur radius
>>> from positive to negative would make the shadow go from blurred to
>>> sharp, then suddenly jump to an inset shadow, that slowly gets blurred.
>>>
>>> I'd still like to see a separate flag, so you don't have to use `-0`
>>> to mean an 'inset glow', but I guess we might as well make use of the
>>> existence of -0.
>>>
>>> On 2010-10-29, at 19:48, Max Carlson wrote:
>>>
>>>> I thought we agreed on shadowblurradius. Otherwise, you can't set the
>>>> start of the shadow distinctly from where it ends: blurradius -
>>>> distance...
>>>
>>> I think you are confusing distance here with the CSS 'spread' value,
>>> which we don't have. And that is what that value is for, to make the
>>> shadow a different size than the box is is created from
>>>
>>> At least that's what I take from the reference Fred sent:
>>>
>>> http://www.w3.org/TR/css3-background/#the-box-shadow
>>>
>>>> On Oct 29, 2010, at 4:38 PM, P T Withington wrote:
>>>>
>>>>> I thought we agreed that we were going to use negative
>>>>> shadowdistance values to mean 'inset'?
>>>>>
>>>>> On 2010-10-29, at 19:34, Max Carlson wrote:
>>>>>
>>>>>> Change maxcarlson-20101029-Ujt by [email protected] on
>>>>>> 2010-10-29 16:16:27 PDT
>>>>>> in /Users/maxcarlson/openlaszlo/trunk2
>>>>>> for http://svn.openlaszlo.org/openlaszlo/trunk
>>>>>>
>>>>>> Summary: Add support for inner shadows to swf10 and DHTML
>>>>>>
>>>>>> Bugs Fixed: LPP-9466 - inner glow/shadow
>>>>>>
>>>>>> Technical Reviewer: ptw
>>>>>> QA Reviewer: ffeng
>>>>>>
>>>>>> Overview: Setting a negative shadowblurradius value will cause the
>>>>>> LzSprite.js - Set 'inset' property to work for negative
>>>>>> shadowblurradius values.
>>>>>>
>>>>>> Details: LzSprite.as - Set 'inner' property to work for negative
>>>>>> shadowblurradius values. Add typing, remove unneeded this.
>>>>>>
>>>>>> LaszloView - Snap values that are close to 0 to 0, update
>>>>>> documentation
>>>>>>
>>>>>> Tests: See LPP-9466 for a testcase.
>>>>>>
>>>>>> Files:
>>>>>> M WEB-INF/lps/lfc/kernel/dhtml/LzSprite.js
>>>>>> M WEB-INF/lps/lfc/kernel/swf9/LzSprite.as
>>>>>> M WEB-INF/lps/lfc/views/LaszloView.lzs
>>>>>>
>>>>>> Changeset:
>>>>>> http://svn.openlaszlo.org/openlaszlo/patches/maxcarlson-20101029-Ujt.tar
>>>>>>
>>>>>
>>>>
>>>
> <FirefoxScreenSnapz001.png>
