This section is informative.

The purpose of including text content functionality into SMIL 3.0 is toallow authors to define small amounts of lightly-formatted text containingembedded temporal markup within the context of a SMIL presentation. Such textmay be used for labels within a presentation or for incidental captions orforeign-language subtitles. Users who wish to use large amounts of structuredtext (with or without temporal markup) should consider the use of smilText asan text media object, or the use of objects encoded in formats such as XHTMLor the "Distribution Format Exchange Profile" (DFXP) of Timed Text[DFXP].

All versions of SMIL have had support for thetext element, which is defined as an alias ofthe generic SMILref media referenceelement. A typical use of the text element is:

    <text region="Title" src="Headline.html" dur="10s" >

Users new to SMIL are often surprised that the text element does not havea content model -- that is, an ability to specify the content text along withthe element, such as in:

    <text region="Title" dur="10s" >       Willemijn's 11th Birthday Party    </text>

More advanced users of SMIL found that they were able to insert in-linetext content into the SMIL file using a data URL, such as:

    <text src="data:,Willemijn's%2011th%20Birthday%20Party"           region="Title" dur="10s" >

However, the strict syntax of this approach, plus the limited stylingoptions available, make it a less-than-optimal way of including incidentaltext content into a SMIL presentation. A more author-friendly approach totext inclusion was a requirement for SMIL 3.0.

The implementation of SMIL on a wide range of devices, from set-top boxesand mobile devices to conventional desktop computers, means that care neededto be taken in defining the complexity of the smilText modules. Themotivation of the SMIL's in-line text facility was not to provide completesupport for all types of text, but to provide a balance between authoringconvenience and player complexity. smilText was also designed todifferentiate text styling from general layout and positioning so thatsmilText could be used efficiently with SMIL Layout. Both of thesemotivations, plus the desire to define a media facility that could be usedacross all of SMIL's implementation platforms, has resulted in a simple textspecification that meet many of the requirements for incidental text within aSMIL document.

smilText has been designed as a functional subset of the W3C Timed TextDistribution Format Exchange Profile (DFXP) of TimedText. While usersfamiliar with DFXP will recognize the functionality included in thisspecification, the differences in temporal and layout specifications betweenSMIL and DFXP have resulted in a slightly different syntax in the twolanguages. The SYMM working group has striven to minimize these differences.A complete list of differences between smilText and DFXP is presented inAppendix A.

This attribute defines an absolute time, relative to the beginning of the parentsmilText element, when the associatedtev orclear element becomes active. Within a single element, absolute begin times are expected to be specified in temporal order. If this is not the case, the associatedtev orclear element becomes active as soon as the previous fragment is activated.
The attribute value is a semi-colon separated list of begin-values.

For in-line use of smilText, the values of the begin attribute are:

begin-value : ( clock-value | ed-value )

Defines the element's begin time.

Clock-value

Describes the element begin as a non-negative offset from the start of the element's smilText container. The offset is measured in parent simple time.

event-value : ( Id-value "." )? ( event-ref? ) ( ( "+" )Clock-value )?

Describes an event and an optional offset that determine the element begin. The element begin is defined relative to the time that the event is raised. Events may be any event defined for the host language in accordance with[DOM2Events]. These may include user-interface events, event-triggers transmitted via a network, etc. When using smilText, only event-based timing is supported. The use of offsets based on scheduled activation of other elements is not supported. All support for event timing is optional and not required. If event timing cannot be supported, the associated time will be ignored.

When used as an external container format, the attribute value is a single clock valued, defined as follows:

begin-value : clock-value

Defines the element's begin time.

Clock-value

Describes the element begin as a non-negative offset from the start of the element's smilText container. The offset is measured in parent simple time.

Thenext attribute defines a relative start time, relative to the effective begin time of the parentsmilText element, or the most recently activatedtev orclear element within the parent.
The attribute value is a single clock value.

Clock-value

Defines a time marker relative to the effective start time of the preceding temporal marker The offset is measured in parent simple time.

ThetextWrapOption attribute specifies whether text content that is larger than the effective space available on one line in a region wraps. Given the complexities of general support for line breaking in different languages, smilText only guarantees implementation-dependent, best effort support for determining appropriate line break points.

Values:

wrap (default)

Text is wrapped across lines within a region: content that extends beyond the logical boundary of the rendering region will be displayed across multiple lines or columns.

noWrap

Text is not wrapped across lines within a region: content that extends beyond the logical boundary of the rendering region will be truncated in an implementation-dependent manner.

inherit

The effective value is used, as defined by the initial value or an override value.

The initial value is set towrap.

Unless otherwise defined by the profile integrating this attribute, it may be used on thesmilText element or as a default on theregion element.

This section is informative.

Since smilText is expected to be supported by a wide range of rendering agents, the behavior associated with text wrapping is defined to be best-effort. In general, rendering agents are encouraged to support text wrapping as defined by DFXP[DFXP].

Thexml:space attribute specifies how whitespace and linefeeds are processed.

Values:

default (default)

Whitespace is collapsed according to the semantics defined byXML 1.1, ([XML11] section 2.10).

As with DFXP, smilText processing with an effective value forxml:space ofdefault must occur as if the following XSL 1.1[XSL11] properties were specified:

• suppress-at-line-break="auto"

• linefeed-treatment="treat-as-space"

• white-space-collapse="true"

• white-space-treatment="ignore-if-surrounding-linefeed"

preserve

Whitespace is preserved according to the semantics defined byXML 1.1, ([XML11], section 2.10).

As with DFXP, smilText processing with an effective value forxml:space ofpreserve must occur as if the following XSL 1.1[XSL11] properties were specified:

• suppress-at-line-break="retain"

• linefeed-treatment="preserve"

• white-space-collapse="false"

• white-space-treatment="preserve"

This attribute may be used on thesmilText element or as a default on theregion element. In general, smilText does not add white space into a text string unless explicitly authored.

This section is informative.

In-Line Use of smilText

ThesmilText element provides atemporal wrapper for in-line text:

    <smilText>       Hello world!    </smilText>

ThesmilText element is theequivalent of allowing a data URL that contains text content, such as:<ref src="data:,Hello%20world!" ... > . Notethat since this example does not define explicit temporal markup on thesmilText element, the intrinsic duration will be zero seconds. The fillsemantics of the embedding SMIL content will determine the visual persistenceof the content.

In this simple form, the text will be rendered based on the default layoutproperties defined for the user agent. If SMIL Layout is used, the defaultbehavior is that a dynamic region will be defined that contains the textcontent of the element. All styling information -- including font, font size,font style and font color -- will be determined by the SMIL player.

If the SMIL Layout BasicLayout module is also supported by the profileimplementing this module, the rendering extent and the clipping behavior ofthe text rendered in a SMIL region will be determined by the effective valueof SMIL's layout attributes.

<smil ...> <head>   ...   <layout>     ...     <region xml:id="Title" top="5px" left="10%" width="80%" height="30px" />     ...   </layout>  </head>  <body>   ...    <smilText region="Title" dur="10s">       Hello World!    </smilText>   ...  </body></smil>

This is equivalent to specifying:<refregion="Title" src="data:,Hello%20world!" ... >. In both cases, theproperties associated with the region namedTitle will be used whenpositioning the text.

If the rendering space for the content of the smilText element is greaterhorizontal extent of one line, the effective value of thetextWrapOption attribute willdetermine whether content will be clipped or wrapped:

<smil ...> <head>     ...     <region xml:id="Title" top="5px" left="10%" width="80%" height="30px"           textWrapOption="wrap"/>     ...  </head>  <body>   ...    <smilText region="Title" dur="10s">       Willemijn's 11th Birthday Party was held six weeks late. (Again!)    </smilText>   ...  </body></smil>

Line breaks within smilText content may be forced by using thebr element within text content:

   ...    <smilText region="Title" dur="10s">       Willemijn's 11th Birthday Party<br/>was held six weeks late.<br/>(Again!)    </smilText>   ...  </body></smil>

The following fragment illustrates use of temporal markers with a smilTextelement that contains an explicit duration:

 <smil ...>  <head>     ...    <layout>     <root-layout width="400" height="300"/>      <region xml:id="Contents" top="5px" left="10%" width="80%" height="300"/>    </layout>   </head>   <body>      ...        <smilText xml:id="TS01" region="Contents" dur="6s">           Willemijn's 11th Birthday Party           <tev xml:id="TS02" next="2s"/>           was held six weeks late.           <clear xml:id="TS03" begin="4s"/>           (Again!)        </smilText>         ...   </body> </smil>

The smilText element TS01 is active for 6s. All activity occurs withinthis time period, even if the timing definition within the smilText objectextends beyond the 6s time limit. If SMIL Layout is used (as in this case),the fill attribute will determine the visual persistence of the text contentif its internal timing was shorter than that of the smilText object.

The initial content that is rendered is the stringWillemijn's 11thBirthday Party. At 2s after the start of the TS01 container, thefragment with id TS02 gets rendered. In this case, the contentwas heldsix weeks late. is displayed along with the previous contents of thesmilText element. (The exact display depends on the size of the renderingregion and the setting of the textWrapOption attribute.)

At 4s after the start of the parent smilText container, the fragment withthe id TS03 is displayed. The use of the clear element causes the displayarea to be erased before the new text is displayed. Note that since a beginattribute is used instead of the next attribute, the activation time of thisfragment is relative to the containing smilText container instead of relativeto TS02.

The following fragment is similar to the previous example, except that itillustrates use of temporal markers with a smilText element that does notcontain an explicit duration (and in which the duration is dependent on theintrinsic duration of the smilText content):

 <smil ...>  <head>     ...    <layout>     <root-layout width="400" height="300"/>      <region xml:id="Contents" top="5px" left="10%" width="80%" height="300"/>    </layout>   </head>   <body>      ...        <smilText xml:id="TS04" region="Contents">           Willemijn's 11th Birthday Party           <tev xml:id="TS05" next="2s"/>           was held six weeks late.           <clear xml:id="TS06" begin="4s"/>           (Again!)        </smilText>         ...   </body> </smil>

The smilText element TS04 is active for a duration that is determined byits content. All activity occurs within this time period. Note that in thisexample, this may lead to an unexpected result.

The initial content that is rendered is the stringWillemijn's 11thBirthday Party. At 2s after the start of the TS05 container, thefragment with id TS02 gets rendered. In this case, the contentwas heldsix weeks late. is displayed along with the previous contents of thesmilText element.

At 4s after the start of the parent smilText container, the fragment withthe id TS06 is displayed. The use of the clear element causes the displayarea to be erased before the new text is displayed. All of the text that isdefined to be rendered at this instance is placed into the region, but afterthis the smilText element ends: no additional timing markup has been providedto extend its intrinsic duration. Thefill semantics associated withthe smilText element will determine the visual persistence of the content, ifany.

The following example is used to illustrate smilText behavior when usedwith event-based timing:

      ...    <par>        <smilText xml:id="TS11" region="Contents" dur="6s">           Willemijn's 11th Birthday Party           <tev xml:id="TS12" next="2s"/>           was held six weeks late.           <clear xml:id="TS13" begin="TS14.beginEvent"/>           (Again!)        </smilText>        <audio xml:id="TS14" begin="4.5s" src="gongAudio.mp3">    </par>      ...

In this example, elements TS11 and TS12 act as TS01 and TS02 in theexample earlier in this section. Coincident with the start of TS12, thepotential active period for TS13 begins. Anytime between 2s after TS11 andthe end of the smilText element, TS13 will begin if the "gong.beginEvent" isactivated. In this example, the activation happens at 4.5 after the start ofthe par element containing both the smilText and audio object.

The following example illustrates the interaction of timing rules withinsmilText:

      ...        <smilText xml:id="TS31" region="Contents" dur="10s">           fragment 1,           <tev xml:id="TS32" next="2s"/>           fragment 2,           <clear xml:id="TS33" begin="1s"/>           fragment 3,           <clear xml:id="TS34" begin="XXX.beginEvent"/>           fragment 4,           <clear xml:id="TS35" next="5s"/>           fragment 5,           <clear xml:id="TS36" begin="8s"/>           fragment 6.        </smilText>      ...

The TS31 smilText element starts, and 'fragment 1,' is rendered. Then, 2slater, TS32 is appended to the displayed text. At the same time, TS33 isappended to the display: it has an absolute begin time of 1s after the startof TS31, but its temporal scope only becomes active once TS32 has displayed.(The begin time is still absolute, so the fragment is displayed immediately.)TS34 comes into temporal scope at 2s (that is, at the effective begin time ofits predecessor), so the associated fragment will be displayed if the eventis triggered between 2s and 10s in the presentation. TS35 is displayed 5safter the effective start of TS34 (assuming the parent smilText container isstill active). The effective begin time of TS36 will depend on a number offactors: if the TS35 fragment starts before an absolute 8s, TS36 will waituntil 8s. If it starts later (but before the end of the smilText container),the fragment will start immediately.

External Use of smilText

It is possible to define an external file with timed text content usingsmilText semantics. The capabilities of such an external use are defined inthe SmilText profile. A full SMIL rendering agent is not required to renderthe smilText content.

The following example shows an external encoding of smilText content:

                  <smil xmlns="http://www.w3.org/ns/smil" version="3.0" baseProfile="smilText"              height="50" width="30" dur="6s">         <body>           Willemijn's 11th Birthday Party           <tev xml:id="TS12" next="2s"/>           was held six weeks late.           <clear xml:id="TS13" begin="TS14.beginEvent"/>           (Again!)         </body>        </smil>

The external file (which in this example we assume is named"external.smil"), may be referenced by any smilText-complaint renderingagent. If that rendering agent is a SMIL 3.0 player, then the followingreference to the text file may be used:

     ...     <par>        <textstream src="external.smil" dur="10s" width="40" region="Contents" >        <audio xml:id="TS14" begin="4.5s" src="gongAudio.mp3">     </par>     ...

In this example, the source smilText file is defined as proscribed by theSmilText profile. It contains a namespace declaration for smil plus thesmilText base profile definition, as well as default values for height, widthand duration. The SMIL fragment shown next illustrates a <par>containing an audio object and atextstream object that references thesmilText encoding. The SMIL-based reference overrides the width specificationgiven in the smilText source file. The smilText duration is treated as theintrinsic duration of the object; the duration is extended in the SMIL filein a manner similar to the reference of a video object.

ThetextAlign attribute provides a hint on how text should be aligned within the region referenced by the smilText element, based on the primary writing direction defined by thetextWritingMode attribute.textAlign attribute may be used on thesmilText anddiv elements or as a default on theregion andtextStyle elements. It is supported on a best-effort basis. The semantics of this attribute are a subset of those defined inXSL 1.1, ([XSL11], section 7.16.9).

Values:

start

The text is aligned on the starting edge of the rendering region based on the primary writing direction defined by thetextWritingMode attribute. For example, it will be left-aligned in the region if the primary writing mode is left-to-right, and it will be right-aligned in the region if the primary writing mode is right-to-left.

end

The text is aligned on the ending edge of the rendering region based on the primary writing direction defined by thetextWritingMode attribute. For example, it will be right-aligned in the region if the primary writing mode is left-to-right, and it will be left-aligned in the region if the primary writing mode is right-to-left.

left

If the primary writing direction is either left-to-right or right-to-left, the text is left-aligned in the region. It is ignored otherwise.

right

If the primary writing direction is either left-to-right or right-to-left, the text is right-aligned in the region. It is ignored otherwise.

center

If the primary writing direction is either left-to-right or right-to-left, the text is center-aligned in the region. It is ignored otherwise.

inherit (default)

The effective value is used, as defined by the initial value or an override value.

The initial value for this attribute isstart.

This section is informative.

Because of the implementation complexities of arbitrary text placement, not all text renderers may support all of the alignment operations specified by this attribute. If the selected attribute value is not supported, a renderer may substitute a player-dependent behavior.

ThetextBackgroundColor attribute is identical to the "background-color" property in theXSL 1.1, ([XSL11], section 7.8.2) specification. As such, support for CSS2 system colors is required. This attribute specifies the background color used to fill the area around text content that falls within a player-defined bounding box. This attribute may be used on thesmilText,div,p orspan elements, or as a default on theregion andtextStyle elements.

Values:

CSS2 color specification

The textBackgroundColor attribute may take on the CSS valueinherit. This means that the background color used for text will be that of the backgroundColor attribute defined for the region specified by the parent text element.

If no color has been specified, the default istransparent.

ThetextColor attribute is identical to the "color" property in theXSL 1.1, ([XSL11], section 7.18.1) specification. As such, support for CSS2 system colors is required. This attribute specifies the color used to render text content in the region specified by the parent text element. This attribute may be used on thesmilText,div,p orspan elements, or as a default on theregion andtextStyle elements.

Values:

CSS2 color specification

The textColor attribute may take on the CSS valueinherit. This means that the color used for text will be that of the color attribute defined for the region specified by the parent text element.

If no color has been specified, the default is implementation dependent.

ThetextDirection attribute provides a hint on the desired horizontal direction of text within aspan. The specified direction may be overridden by the font based on the Unicode Bidirectional algorithm. This attribute is supported on a best-effort basis. The semantics defined inXSL 1.1, ([XSL11], section 7.29.1) are available, plus two attributes that allow default unicode-BIDI behavior to be overriden. Unlike XSL 1.1 and DFXP, smilText only supports this functionality within aspan element or as a default on thetextStyle element. For block-level control of text direction, see thetextWritingMode attribute.

Values:

ltr

Text is written in a left-to-right direction, unless overridden by font unicode-BIDI processing.

rtl

The text is written in a right-to-left direction, unless overridden by font unicode-BIDI processing.

ltro

Text is written in a left-to-right direction, and any font unicode-BIDI processing is explicitly overridden.

rtlo

The text is written in a right-to-left direction, and any font unicode-BIDI processing is explicitly overridden.

inherit (default)

The effective value is used, as defined by the initial value or an override value.

The initial value for this attribute isltr.

This section is informative.

Because of the implementation complexities of arbitrary text placement, not all text renderers may support all of the direction operations specified by this attribute. If the selected attribute value cannot supported, a renderer may substitute a player-dependent behavior.

In XSL and DFXP, two attributes are used to control direction and unicode-BIDI override. Given the lightweight nature of smilText, basic override behavior is supported within the textDirection attribute.

This attribute defines the family of font used to render text. An ordered list of specific font names and/or a generic family name may be supplied. The resolution of a generic family name to a specific font instance is not defined by this specification, but may be defined by a profile implementing this module. The sansSerif and serif fonts are expected to be proportional. SeeXSL 1.1, ([XSL11], section 7.9.2) for font family details. This attribute may be used on thesmilText,div,p orspan elements, or as a default on theregion andtextStyle elements.

Values:

font-list:

a prioritized, comma-separated list of font names, optionally including one or more of the generic font identifiersmonospace,sansSerif, and/orserif.

inherit: (default)

The effective value is used, as defined by the initial value or an override value.

The initial value for this attribute issansSerif. If an unrecognized or unsupported textFontFamily is specified,monospace will be expected.

This attribute defines the size of the font to be used. In order to reduce implementation burden and to provide scalability across device classes, only absolute and relative sizes (as defined inXSL 1.1, ([XSL11], section 7.9.4) are supported by smilText. This attribute may be used on thesmilText,div,p orspan elements, or as a default on theregion andtextStyle elements.

Values:

length

absolute-size

absolute-size represents a set of absolute font sizes, maintained by the SMIL player (and possible influenced by the player user agent). Expected absolute sizes are: [ xx-small | x-small | small | medium | large | x-large | xx-large ]. As recommended in XSL 1.1, it is expected that each of the absolute sizes will differ by a factor of 1.2. The default absolute size is medium.

relative-size

relative-size represents a relative increase or reduction in the absolute font size value. Expected values are: [ larger | smaller ]. Effective font sizes larger absolute-size xx-large or smaller than the absolute-size xx-small will not be supported.

inherit (default)

The effective value is used, as defined by the initial value or an override value.

The initial value for this attribute ismedium. If a specified size cannot be support, implementations are expected to provide a best-effort substitute size.

This attribute defines the style (italic, oblique, reverseOblique or normal) of the text displayed. If the specified style is not available, a style ofnormal will be used. This attribute may be used on thesmilText,div,p orspan elements, or as a default on theregion andtextStyle elements. Of the values defined inXSL 1.1, ([XSL11], section 7.9.7), only the options defined in the following list will be supported by smilText.

Values:

normal

italic

oblique

reverseOblique

inherit (default)

The effective value is used, as defined by the initial value or an override value.

The initial value for this attribute isnormal. If a particular style cannot be support, implementations may provide an implementation-dependent alternative style.

This attribute defines the weight (bold or regular) of text displayed. If the specified weight is not available, a weight ofnormal will be used. This attribute may be used on thesmilText,div,p orspan elements, or as a default on theregion andtextStyle elements. Of the values defined inXSL 1.1, ([XSL11], section 7.9.9), only the options defined in the following list will be supported by smilText.

Values:

normal

The normal font weight for the font family selected is used.

bold

The bold font weight for the font family selected is used.

inherit (default)

The effective value is used, as defined by the initial value or an override value.

The initial value for this attribute isnormal. If a particular weight cannot be support, implementations may provide an implementation-dependent alternative weight.

The attribute defines the manner in which each temporal fragment within asmilText element is added to the rendering area. This attribute may be used on thesmilText element or as a default on theregion andtextStyle elements.

Values:

append

The new fragment is added to any existing content in the rendering area. The new content is appended to the text at the logical end of the display without the introduction of any additional white space.

replace

New content replaces any existing content in the rendering area. The new content becomes the only content within the display.

inherit (default)

The effective value is used, as defined by the initial value or an override value.

The initial value for this attribute isappend.

This section is informative.

The textStyling module extends the single default value of append defined by the BasicText module with replace and inherit. Note that the textMotion module further extends this attribute with values that specify how text movement is controlled.

The attribute provides a hint on where content is initially placed in a rendering area, both as an initial string and after aclear operation. The placement is defined in terms of the secondary writing direction, as defined by thetextWritingMode attribute. ThetextPlace attribute may be used on thesmilText element or as a default on theregion andtextStyle elements.

Values:

start

New content in an empty region is placed first at the starting edge of the secondary writing direction, and then flowed in the secondary writing direction as text is wrapped or explicitbr elements are used. For example, if the secondary writing direction is top-to-bottom, the content will initially be placed at the top of the region.

center

New content in an empty region is placed first at the center of the secondary writing direction, and then flowed in the secondary writing direction as text is wrapped or explicitbr elements are used. For example, if the secondary writing direction is top-to-bottom, the content will initially be placed at the vertical center of the region.

end

New content in an empty region is placed first at the ending edge of the secondary writing direction, and then flowed in the secondary writing direction as text is wrapped or explicitbr elements are used. For example, if the secondary writing direction is top-to-bottom, the content will initially be placed at the bottom of the region.

inherit (default)

The effective value is used, as defined by the initial value or an override value.

The initial value for this attribute isstart.

This section is informative.

If no text motion attributes have been defined, any text that is explicitly or implicitly placed beyond the ending boundary of the region will not be displayed. As a consequence, if the valueend is used without motion, only one line of content will be visible.

The attribute references a text style set defined using the textStyle element in the document head. This attribute may be used on thesmilText,div,p orspan elements, or as a default on theregion element.

Values:

IDREF

The ID of a textStyle definition. If the IDREF specified as a value does not refer to a valid textStyle set definition, this attribute is ignored.

The textStyle attribute will be applied only to the content within the scope of the element to which it is applied.

ThetextWritingMode attribute provides a hint on the desired primary and secondary writing directions of text added to a region. It is supported on a best-effort basis. The semantics defined inXSL 1.1, ([XSL11], section 7.29.7) are available, with the restriction that only the subset provided below may be available. This attribute may be used on thesmilText,div orp elements, or as a default on theregion andtextStyle elements. When used with thediv orp elements, implementations may limit the allowable the override behavior to the opposite of the primary writing direction. The specified behavior may be overridden by the Unicode BIDI algorithm. Within ap, the direction of text and unicode-BIDI processing may be overridden by thetextDirection attribute.

Values:lr-tb | rl-tb | tb-rl | tb-lr | lr | rl | inherit

lr-tb

The primary writing direction of text is a left-to-right progression and the secondary writing direction is a top-to-bottom progression.

rl-tb

The primary writing direction of text is a right-to-left progression and the secondary writing direction is a top-to-bottom progression.

tb-lr

The primary writing direction of text is a top-to-bottom progression and the secondary writing direction is a left-to-right progression.

tb-rl

The primary writing direction of text is a top-to-bottom progression and the secondary writing direction is a right-to-left progression.

lr

A shortcut forlr-tb.

rl

A shortcut forrl-tb.

inherit (default)

The effective value is used, as defined by the initial value or an override value.

The initial value for this attribute islr-tb.

This section is informative.

Because of the implementation complexities of arbitrary text placement, not all text renderers may support all of the alignment operations specified by this attribute. A given profile may further restrict the available values. If the selected attribute value is not supported, a renderer may substitute a player-dependent behavior. At a minimum,lr-tb may be expected.

Implementations may define default behavior if adiv orp element attempts to override both the primary and secondary writing directions (such as changing from lr-tb to tb-lr). Additionally, changes to the primary writing direction may be ingored if the text mode is set tocrawl, and changes to the secondary writing direction may be ignored if the text mode is set toscroll, as defined within theTextMotion module.

Note that only the subset of XSL 1.1's writing-mode attribute supported by DFXP are adopted by smilText. In smilText, the XSL naming conventions for the writing modes are adopted.

This section is informative.

The following example provides an indication of the use of smilText withina profile that provides support for theTextStyling module (such as the SMIL 3.0Language profile).

00 <smil ...>01  <head>     ...02    <textStyling>03      <textStyle xml:id="HeadlineStyle" textFontFamily="serif" textFontSize="12px"              textFontWeight="bold" textFontStyle="italic"                       textWrapOption="noWrap" textColor="blue" textBackgroundColor="white" />04    </textStyling>05    <layout>         ...06      <region xml:id="Title" top="5px" left="10%" width="80%" height="25px"             textStyle="HeadlineStyle" />07      <region xml:id="Captions" top="215px" left="10%" width="80%" height="35px"           textFontFamily="serif" textColor="orange"  backgroundColor="blue"/>08      <region xml:id="Slides" top="10px" left="5%" width="90%" height="200px" />09    </layout>10   </head>11   <body>      ...12    <par>13     <smilText region="Title" textFontFamily="sansSerif" fill="freeze">14        Willemijn's 11th Birthday Party15     </smilText>16     <seq>17       <par>18         <img region="slides" src="p001.jpg" begin="1s" dur="9s"/>19         <audio ... src="yip.mp3" begin="woof.tevEvent"/>20         <smilText region="Captions" textAlign="start" dur="8s">21              Shortly <span textFontStyle="italic">before</span> dawn ...22              <tev next="1.5s"/>23              <div textAlign="center" textColor="green">24              just as the clock began25              </div>26              <br/>27              to chime six times...28              <tev begin="4s"/>29              our trusty dog Gretchen30              <tev xml:id="woof" begin="3s"/>31              barked. 32         </smilText>33       </par>         ...34       <par>35         <img region="Slides" src="p128.jpg" dur="7s"/>36         <text region="Captions" src="c128.html" dur="7s"/>37       </par>38     </seq>39     <audio ... src="Commentary.mp3" />40    </par>41   </body>42 </smil>

In this example, one text style is defined (on line 03) and three layoutregions are defined, one of which (on line 06) references a style definitionwith local overrides, and another of which (on line 07) uses mostly defaultstyle. In the body of the presentation, a parallel container is defined thatcontains a text title (on line 13); most of the styling attributes aredefined on the region via the text style attribute. Later in thepresentation, a sequence of images are defined that are each accompanied byone or more text captions. The text definition on line 13 illustrates thattext, like images, has no inherit duration, but that by using the SMIL fillattribute, the content of the smilText element remains visible until the endof the parent time container (in this case, the par that is defined on line12). The three smilText fragments that accompany the image defined on line 18illustrate that the in-line text object may use the standard SMIL timingattributes, plus several new attributes to explicitly control text placementand styling. A tevEvent will be generated by a text fragment and used tocontrol some other portion of the presentation, as is shown in line 30'striggering of the sound on line 19. Finally, the text element on line 36illustrates that it is possible to mix in-line and external text in a singledocument.

ThetextMode is extended to support three values for motion-based text presentation of asmilText object. These values may be used on the smilText element or as a default on theregion andtextStyle elements.

Values:

crawl

This value causes text to move as a single line against the primary writing direction (as defined by thetextWritingMode attribute). The initial position of the text in the primary writing direction will be determined by thetextAlign attribute, unless overridden by thetextConceal attribute. The position of the text in the secondary writing direction will be determined by thetextPlace attribute. All line breaks, either implicit or explicit, will be ignored. The speed of movement, in pixels per second, is determined by thetextRate attribute. If present, thetev/clear elements may be used to specify incremental appearance of content within a crawling string.

scroll

This value causes text to move smoothly against the secondary writing direction (as defined by thetextWritingMode attribute). The alignment of the text in the primary writing direction will be determined by thetextAlign attribute. The initial position of the text in the secondary writing direction is defined by thetextPlace attribute, unless overridden by thetextConceal attribute. All line breaks, either implicit or explicit, will be respected. The speed of movement, in pixels per second, is determined by thetextRate attribute. Unless otherwise specified by thetextRate attribute, thetev/clear elements may be used to specify incremental presentation of content within a scrolling string.

jump

This value causes text to jump against the secondary writing direction (as defined by thetextWritingMode attribute) by line within the region when the current line fills (or after an explicitbr). The alignment of the text in the primary writing direction will be determined by thetextAlign attribute. The initial position of the text in the secondary writing direction is defined by thetextPlace attribute, unless overridden by thetextConceal attribute. All line breaks, either implicit or explicit, will be respected. The number of line jumped is determined by thetextRate attribute. Thetev/clear elements may be used to specify incremental presentation of content within a jumping block.

The default value for this attribute is given in thetextMode definition in theTextStyling module.

The textMode will be applied to all text displayed in the region.

This section is informative.

Given the complexities of supporting text motion, it is expected that motion in all primary and secondary modes may not be available. At a minimum, motion should be supported with an effective text writing mode of lr-tb.

ThetextConceal attribute specifies the initial and ending positioning content as a result of a textMode setting ofcrawl,scroll orjump. This attribute may be specified on the smilText element or as a default on theregion andtextStyle elements.

Values:

none:

Text initially will be rendered at the starting point in the region defined by thetextPlace andtextAlign attributes, and will finish at the terminating placement determined by the normal processing of the content. No leading or trailing space will be added.

initial:

Text initially will be rendered at a starting point that is just outside the region and enter the region once the simple duration begins. Text will finish at the terminating placement determined by the normal processing of the content. This has the visual effect that leading spaces will be added to the content. IftextMode is set tocrawl, thetextAlign attribute will be ignored. IftextMode is set toscroll orjump, thetextPlace attribute will be ignored.
This setting will extend the intrinsic duration of the content to support the rendering of leading spaces.

final:

Text initially will be rendered at the starting point in the region defined by thetextPlace andtextAlign attributes. At the conclusion of normal processing of the content, any content left in the rendering region will be crawled, scrolled or jumped out of view. This has the visual effect that trailing spaces will be added to the content.
This setting will extend the intrinsic duration of the content to support the rendering of trailing spaces.

both:

Theinitial andfinal behavior described for this attribute are both applied to the text.
This setting will extend the intrinsic duration of the content to support the rendering of leading and trailing spaces.

inherit: (default)

The effective value is used, as defined by the initial value or an override value.

The initial value for this attribute isnone.

This section is informative.

Given the complexities of supporting text motion and recalculating the intrinsic duration, only best-effort support for all textConceal modes can be expected.

ThetextRate specifies the rate of motion of smilText elements that have thecrawl,scroll orjump values defined for thetextMode attribute. This attribute may be specified on the smilText element or as a default on theregion andtextStyle elements.

Values:

auto (default):

The interpretation of this value depends on the effective motion mode of text. When used with thecrawl orscroll text modes, this value specifies that the rendering system should determine the appropriate rate of movement (in pixels per second) to display the entire content of the smilText element (including any extra spacing required for processing the textConceal attribute) within its simple duration. All timing markup on tev/clear elements to be ignored and no activation events will be generated from within the smilText element. If the simple duration is not known, implementations may make an informed guess or provide a default rate. When used with thejump text mode, this value specifies that a single line in the secondary writing direction is jumped when an explicit or implicit line break is generated. There is no further impact on temporal processing of the text. When used with all other text modes, this attribute is ignored.

CSS2 pixel value:

The interpretation of this value depends on the effective motion mode of text. When used with thecrawl orscroll text modes, this value defines a non-negative integer representing a pixel movement rate in pixels per second. The "px" unit qualifier in pixel values may be omitted. When used with thejump text mode, this value will be interpreted as a non-negative integer and the "px" qualifier, if present, will be ignored. When used with all other text modes, this attribute is ignored.

non-negative integer:

The interpretation of this value depends on the effective motion mode of text. When used with thecrawl orscroll text modes, this value will be interpreted as a CSS2 pixel value without the "px" qualifier. When used with thejump text mode, this value defines the number of lines to jump when adding new content. When used with any other text mode, this attribute is ignored.

Implementations may use simple algorithms to determine the rate of motion,either based on a fixed pixel movement value per update cycle or as a defaultvalue.

Looping behavior of crawling, scrolling or jumping text may be specifiedusing standard SMIL repeat semantics on the smilText element.

This section is informative.

The text motion rendering behavior of within this module has been designedto be relatively simple to implement and stay consistent with other forms ofscrollable/crawlable text. The following example illustrates the use of theattributes and attribute values defined in this section.

 <smil ...>  <head>     ...    <layout>        ...      <region xml:id="Contents" top="5px" left="10%" width="80%" height="300px"             textMode="crawl" textRate="20px" />    </layout>   </head>   <body>      ...        <smilText xml:id="TS21" region="Contents" textAlign="right">           Willemijn's 11th Birthday Party           <tev begin="5s"/>           was held six weeks late.           <tev next="5s"/>           (Again!)        </smilText>         ...   </body> </smil>

This example displays a crawling text string that is initially aligned atthe right of the display. The text crawls across the screen in a directionthat is opposite to the (in this case default) textWritingMode ofleft-to-right. Initially, only the first fragment is visible. After 5seconds, the entire portion of the second fragment is made visible; note thata portion may be initially clipped from view. After another 5 seconds, thefinal fragment is added to the text display.