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From: Dr. Olaf Hoffmann <Dr.O.Hoffmann@gmx.de>
Date: Sun, 29 Mar 2009 15:15:08 +0100
To: www-style@w3.org
Message-Id: <200903291615.09298.Dr.O.Hoffmann@gmx.de>

these comments are related to

1. It is not obvious to me how to specify the values, the
transition appears between - ok, the initial value seems
to be what is called in SMIL/SVG animations the 
underlying value, how is the 'to-value' specified?
Is it possible to specify a transition from a 'to-value' to
the underlying value too?
Is it required to use the animation module or another 
language (like scripting) to specify all this?
If another language or scripting is required, this would be
disappointing and discouraging for many authors relying on 
declarative notations for styling and layout and simplicity.
Other authors would be forced to create constructions
not accessible anymore either without activated scripting or 
CSS, what would be bad/poor styling.

2. It is not obvious to me, how the native CSS works to begin
the transition or is this always triggered from outside of CSS
or with the onload event of the CSS file?
I think, it would be essential especially for authors, who want
to use these module to style (X)HTML or XML, to have a
native CSS method to start the transition. This is less important
for SVG authors, because SVG has already its own more
advanced animation methods covering this problem in a
convenient way.
This SVG/SMIL solution could be a guide, what is required
to start transitions.
Especially the events activate, beginEvent, endEvent, 
repeatEvent could already cover a lot of use cases.  
Device dependent events like click, mousedown, mouseup,
mouseout, mouseover, mousemove could be useful too,
however they have of course the problem, that they are
not accessible, if the user has no pointing device.
Another essential feature is the possibility to combine
the event with an identifier.

Currently CSS mainly seems to have :hover and :focus
to begin or to change something. If we have for example
the :hover, is the transition stopped, if :hover does not
apply anymore? This could be avoided of course with
something like ID.activate or ID.click as begin.

3. What means the value 'all' for the transition-property
exactly? If we change the value of transition property for
example in the given examples I and II. Does it apply
to anything or nothing or only to those properties we
add within the paranthesis, for example:

div {
    transition-property: all;
    transition-duration: 2s, 4s;
    opacity: 0.5;
    left: 10ex;

4. About the ‘transition-timing-function’ section:
Note, that the name of the man, who introduced
those curves is spelled in a different way, with
(X)HTML notation: 'B&eacute;zier' and not 'bezier'

Is it ok to reference a wikipedia article, everyone
can change at any time in a draft/specification?

In the prose is noted '(see Figure 1)'
this should be '(see Figure 2)'?

In Figure 2 the axis descriptions are 
Input/Output Percentages, however the
scale is only from 0 to 1 as what is to
note in the related values, these are
fractions, not percentages.

5. in section 4. it is not noted, how to animate
between keywords (they are mentioned
in 5. too). This will be the same as for
'visibility'? Or are the keywords always
converted into numbers for the current
animatable properties (seems to apply
only to vertical-align).

About paint-server - how to interpolate
between a radial and linear gradient?
Is the direction vector for linear gradients
interpolated too if different? Respectively 
the cx, cy, fx, fy, r for a radial gradient?
What about gradientUnits, gradientTransform,
spreadMethod, xlink:href? Or is the interpolation
done for each pixel of the output separately?
I think, it needs some more explanations
how this should work.

6. in section 5. Animatable properties
the transform property seems to miss,
but in 4. it is noted, that this is animatable too.

Why not animation for 'display'? This is already
now quite popular to be changed with :hover,
I think more than for example 'visibility'

Best wishes

Received on Sunday, 29 March 2009 15:36:53 UTC

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