CSS

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focus, and a thick red line when it is active, the following rules can be used:
:focus { outline: thick solid black }
:active { outline: thick solid red }
18.5 Magnification
The CSS working group considers that the magnification of a document or
portions of a document should not be specified through style sheets. User agents
may support such magnification in different ways (e.g., larger images, louder
sounds, etc.)
When magnifying a page, UAs should preserve the relationships between posi-
tioned elements. For example, a comic strip may be composed of images with
overlaid text elements. When magnifying this page, a user agent should keep the
text within the comic strip balloon.
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19 Aural style sheets
Contents
19.1 Introduction to aural style sheets
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19.2 Volume properties: ’volume’ .
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19.3 Speaking properties: ’speak’
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19.4 Pause properties: ’pause-before’, ’pause-after’, and ’pause’
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19.5 Cue properties: ’cue-before’, ’cue-after’, and ’cue’
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19.6 Mixing properties: ’play-during’
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19.7 Spatial properties: ’azimuth’ and ’elevation’
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19.8 Voice characteristic properties: ’speech-rate’, ’voice-family’, ’pitch’,
’pitch-range’, ’stress’, and ’richness’
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19.9 Speech properties: ’speak-punctuation’ and ’speak-numeral’ .
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19.1 Introduction to aural style sheets
The aural rendering of a document, already commonly used by the blind and
print-impaired communities, combines speech synthesis and "auditory icons."
Often such aural presentation occurs by converting the document to plain text
and feeding this to a screen reader -- software or hardware that simply reads all
the characters on the screen. This results in less effective presentation than
would be the case if the document structure were retained. Style sheet properties
for aural presentation may be used together with visual properties (mixed media)
or as an aural alternative to visual presentation.
Besides the obvious accessibility advantages, there are other large markets for
listening to information, including in-car use, industrial and medical documenta-
tion systems (intranets), home entertainment, and to help users learning to read
or who have difficulty reading.
When using aural properties, the canvas consists of a three-dimensional physi-
cal space (sound surrounds) and a temporal space (one may specify sounds
before, during, and after other sounds). The CSS properties also allow authors to
vary the quality of synthesized speech (voice type, frequency, inflection, etc.).
Example(s):
H1, H2, H3, H4, H5, H6 {
voice-family: paul;
stress: 20;
richness: 90;
cue-before: url("ping.au")
}
P.heidi { azimuth: center-left }
P.peter { azimuth: right }
P.goat { volume: x-soft }
This will direct the speech synthesizer to speak headers in a voice (a kind of
"audio font") called "paul", on a flat tone, but in a very rich voice. Before speaking
the headers, a sound sample will be played from the given URL. Paragraphs with
class "heidi" will appear to come from front left (if the sound system is capable of
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spatial audio), and paragraphs of class "peter" from the right. Paragraphs with
class "goat" will be very soft.
19.2 Volume properties: ’volume’
’volume’
Value:
number | percentage | silent | x-soft | soft | medium | loud
| x-loud | inherit
Initial:
medium
Applies to:
all elements
Inherited:
yes
Percentages: refer to inherited value
Media:
aural
Volume refers to the median volume of the waveform. In other words, a highly
inflected voice at a volume of 50 might peak well above that. The overall values
are likely to be human adjustable for comfort, for example with a physical volume
control (which would increase both the 0 and 100 values proportionately); what
this property does is adjust the dynamic range.
Values have the following meanings:
number
Any number between ’0’ and ’100’. ’0’ represents the minimum audible
volume level and 100 corresponds to the maximum comfortable level.
percentage
Percentage values are calculated relative to the inherited value, and are
then clipped to the range ’0’ to ’100’.
silent
No sound at all. The value ’0’ does not mean the same as ’silent’.
x-soft
Same as ’0’.
soft
Same as ’25’.
medium
Same as ’50’.
loud
Same as ’75’.
x-loud
Same as ’100’.
User agents should allow the values corresponding to ’0’ and ’100’ to be set by
the listener. No one setting is universally applicable; suitable values depend on
the equipment in use (speakers, headphones), the environment (in car, home
theater, library) and personal preferences. Some examples:
A browser for in-car use has a setting for when there is lots of background
noise. ’0’ would map to a fairly high level and ’100’ to a quite high level. The
speech is easily audible over the road noise but the overall dynamic range is
compressed. Cars with better insulation might allow a wider dynamic range.
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Another speech browser is being used in an apartment, late at night, or in a
shared study room. ’0’ is set to a very quiet level and ’100’ to a fairly quiet
level, too. As with the first example, there is a low slope; the dynamic range
is reduced. The actual volumes are low here, whereas they were high in the
first example.
In a quiet and isolated house, an expensive hi-fi home theater setup. ’0’ is
set fairly low and ’100’ to quite high; there is wide dynamic range.
The same author style sheet could be used in all cases, simply by mapping the
’0’ and ’100’ points suitably at the client side.
19.3 Speaking properties: ’speak’
’speak’
Value:
normal | none | spell-out | inherit
Initial:
normal
Applies to:
all elements
Inherited:
yes
Percentages: N/A
Media:
aural
This property specifies whether text will be rendered aurally and if so, in what
manner (somewhat analogous to the ’display’ property). The possible values are:
none
Suppresses aural rendering so that the element requires no time to render.
Note, however, that descendants may override this value and will be spoken.
(To be sure to suppress rendering of an element and its descendants, use
the ’display’ property).
normal
Uses language-dependent pronunciation rules for rendering an element and
its children.
spell-out
Spells the text one letter at a time (useful for acronyms and abbreviations). [ Pobierz całość w formacie PDF ]

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