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This section is normative.

7.4.1 Overview

SMIL BasicLayout module defines a layout model for organizing mediaelements into regions on the visual rendering surface. The regions aredeclared within thelayout element inthe documenthead. Media elementsdeclare which region they are to be rendered into with theregion attribute.

Each region has a set of CSS2 compatible properties such astop,left,height,width, andbackgroundColor. These propertiesmay be declared using a syntax defined by thetype attribute of thelayout element. In this way, media layoutcan be described using the either SMIL basic layout syntax or CSS2 [[CSS2 -absolute-positioning]] syntax (note that these are not functionallyidentical). Other layout types are possible as well.

This section is informative.

An example declaration to define a region with the id "r" at location15,20 that is 100 pixels wide by 50 pixels tall using the SMIL BasicLayoutmodule is:

    <layout>      <region xml:id="r" top="15px" left="20px" width="100px" height="50px"/>    </layout>

To display a media element in the region declared above, specify theregion's id as the region attribute of the media element:

    <ref region="r" src="http://..." />

7.4.2 Elements andAttributes

This section defines the elements and attributes that make up thefunctionality in the SMIL BasicLayout module.

Theregion element

The region element controls the position, size and scaling of media objectelements that are placed within its rendering space.

The position of a region, as specified by itstop,bottom,left, andright attributes, is always relative to theparent geometry, which is defined by the parent element. For the SMILBasicLayout module, all region elements must have as their immediate parent alayout element, and the region position is defined relative to the rootwindow declared in the siblingroot-layout element. Theroot-layout element is considered tobe the logical parent of all region elements in SMIL BasicLayout. Theintrinsic size of a region is equal to the size of the logical parent'sgeometry.

When region sizes, as specified bywidth andheight attributes are declared relativewith the "%" notation, the size of a region is relative to the size of theparent geometry. Sizes declared as absolute pixel values maintain thoseabsolute values.

Conflicts between the region size and position attributeswidth,height,bottom,left,right, andtop are resolved according tothe rules for placeholder elements as detailed below. The default values ofregion position and size attributes is specified asauto. This attribute value has the same meaning herethat it does in[CSS2], when there is nodistinction drawn between replaced and non-replaced element.

A placeholder element is one which has no intrinsic width or height, butdoes have a bounding-box which has a width and height. SMIL BasicLayoutregions are placeholder elements. Placeholder elements are clipped to thebounding box.

The governing equation for the horizontal dimension is:

bbw (bounding-box-width) = left + width + right

Given that each of these three parameters may have either a value of"auto" or a defined value not "auto", then there are 8 possibilities:

*Attribute values*			*Result before clipping to the bounding box*
left	width	right	left	width	right
auto	auto	auto	0	bbw	0
auto	auto	defined	0	bbw - right	right
auto	defined	auto	0	width	bbw - width
auto	defined	defined	bbw - right - width	width	right
defined	auto	auto	left	bbw - left	0
defined	auto	defined	left	bbw - right - left	right
defined	defined	auto	left	width	bbw - left - width
defined	defined	defined	left	width	bbw - left - width

The vertical attributesheight,bottom, andtop are resolved similarly.The governing equation for the vertical dimension is:

bbh (bounding-box-height) = top + height + bottom

Given that each of these three parameters may have either a value of"auto" or a defined value not "auto", then there are 8 possibilities:

*Attribute values*			*Result before clipping to the bounding box*
top	height	bottom	top	height	bottom
auto	auto	auto	0	bbh	0
auto	auto	defined	0	bbh - bottom	bottom
auto	defined	auto	0	height	bbh - height
auto	defined	defined	bbh - bottom - height	height	bottom
defined	auto	auto	top	bbh - top	0
defined	auto	defined	top	bbh - bottom - top	bottom
defined	defined	auto	top	height	bbh - top - height
defined	defined	defined	top	height	bbh - top - height

Elementattributes

Theregion element may have thefollowing visual attributes:

backgroundColor

The use and definition of this attribute are identical to the "background-color" property in the CSS2 specification. Unlike SMIL 1.0, this module requires support forCSS2 system colors [CSS2], (Section 18.2).
This attribute specifies the background color used to fill the area of a region displaying media that is not filled by the media. The display of the background color when the region is not in use by a media element is controlled by theshowBackground attribute.
ThebackgroundColor attribute may take on the CSS valueinherit. This means that the background color will be that of the parent element. If the parent element does not have an applicable background color property, the default value depends on the language profile: if thebackground-color attribute is supported by the language profile, the default value ofbackgroundColor is inherited frombackground-color. Otherwise, the default value istransparent. The interaction of this attribute withbackgroundOpacity is discussed in theImplementation section.

background-color

Deprecated. Equivalent tobackgroundColor, which replaces this attribute. The language profile must define whether or not thebackground-color attribute is supported. The default value of thebackground-color attribute istransparent.

backgroundOpacity

This attribute defines the opacity of the background of the region. It accepts a percentage value in the range 0-100% or a number in the range 0.0-1.0, with 100% or 1.0 meaning fully opaque. If an implementation cannot support manipulation of the background opacity value, this attribute is ignored. The default value of this attribute is100%. The interaction of this attribute withbackgroundColor is discussed in theImplementation section.

bottom

The use and definition of this attribute are identical to the "bottom" property in the CSS2 specification. Attribute values can be non-negative "percentage" values, and a variation of the "length" values defined in CSS2. For "length" values, SMIL BasicLayout only supports pixel units as defined in CSS2. It allows the author to leave out the "px" unit qualifier in pixel values (the "px" qualifier is required in CSS2). Conflicts between the region size attributesbottom,left,right,top,width, andheight are resolved according to the rules for absolutely positioned, replaced elements in[CSS2]. The default value ofbottom attribute isauto.

fit

This attribute specifies the behavior if the intrinsic height and width of a visual media object differ from the values specified by the height and width attributes in theregion element. This attribute does not have a one-to-one mapping onto a CSS2 property, but may be simulated in CSS2.

This attribute may have the following values:

fill

Scale the object's height and width independently so that the content just touches all edges of the box.

hidden

Has the following effect:

If the intrinsic height (width) of the media object element is smaller than the height (width) defined in theregion element, render the object starting from the top (left) edge and fill up the remaining height (width) with the background color.
If the intrinsic height (width) of the media object element is greater than the height (width) defined in theregion element, render the object starting from the top (left) edge until the height (width) defined in theregion element is reached, and clip the parts of the object below (right of) the height (width).

meet

Scale the visual media object while preserving its aspect ratio until its height or width is equal to the value specified by the height or width attributes, while none of the content is clipped. The object's left top corner is positioned at the top-left coordinates of the box, and empty space at the right or bottom is filled up with the background color.

meetBest

The semantic of this value is identical tomeet except that the image is not scaled to greater than 100% in either dimension. This limits degradation of upwardly-scaled media content.

scroll

A scrolling mechanism should be invoked when the element's rendered contents exceed its bounds.

slice

Scale the visual media object while preserving its aspect ratio so that its height or width are equal to the value specified by the height and width attributes while some of the content may get clipped. Depending on the exact situation, either a horizontal or a vertical slice of the visual media object is displayed. Overflow width is clipped from the right of the media object. Overflow height is clipped from the bottom of the media object.

The default value offit ishidden.

Note that thefit attribute appliesto visual media once it has an intrinsic two-dimensional size, such as imagesand video. It does not apply to visual media that is rendered and adapted tovarying circumstances, such as the visual display of HTML, until itstwo-dimensional spatial dimensions have been determined, such as after anHTML page has been laid out to specific size.

height

The use and definition of this attribute are identical to the "height" property in the CSS2 specification. Attribute values follow the same restrictions and rules as the values of thebottom attribute. The intrinsic height of a region is the same as that of the parent geometry. The default value of theheight attribute isauto.

left

The use and definition of this attribute are identical to the "left" property in the CSS2 specification. Attribute values follow the same restrictions and rules as the values of the "bottom" attribute. The default value of theleft attribute isauto.

regionName

This attribute assigns a name to thisregion element that can be referred to by theregion attribute of media object elements. TheregionName attribute is not a unique identifier; multipleregionelements can share the sameregionName attribute value. This attribute does not have a default value.

right

The use and definition of this attribute are identical to the "right" property in the CSS2 specification. Attribute values follow the same restrictions and rules as the values of the "bottom" attribute. The default value ofright attribute isauto.

showBackground

This attribute controls whether thebackgroundColor of a region is shown when no media is being rendered to the region:

If the value ofshowBackground isalways, then the background color will be shown in the region when no media object is rendering into that region. If the region is part of ahierarchical sub-region layout, then any ancestor regions must also either be active or have ashowBackground value ofalways for the background color to be shown.
If the value ofshowBackground iswhenActive, then the background color will be not be shown in the region when no media object is rendering into that region. If the region is part of ahierarchical sub-region layout, then the background color will also be shown when any descendent regions are active.

The default value ofshowBackground isalways.

top

The use and definition of this attribute are identical to the "top" property in the CSS2 specification. Attribute values follow the same restrictions and rules as the values of thebottom attribute. The default value of thetop attribute isauto.

width

The use and definition of this attribute are identical to the "width" property in the CSS2 specification. Attribute values follow the same restrictions and rules as the values of thebottom attribute. The intrinsic width of a region is the same as that of the parent geometry. The default value ofwidth attribute isauto.

z-index

The use and definition of this attribute are identical to the "z-index" property in the CSS2 specification, with the following exception:

If two boxes generated by elements A and B have the same stack level, then:

If the display of an element A starts later than the display of an element B, the box of A is stacked on top of the box of B (temporal order).
Else, if the display of the elements starts at the same time, and an element A occurs later in the SMIL document text than an element B, the box of A is stacked on top of the box of B (document tree order as defined in CSS2).

A profile integrating the SMIL BasicLayout module must provide a means ofdeclaring an XML identifier onregionelements.

Elementexamples

This section is informative.

In the following example fragment, the position of a text element is setto a 5 pixel distance from the top border of the rendering window:

<smil xmlns="http://www.w3.org/ns/SMIL" version="3.0" baseProfile="Language">
  <head>
     ...
    <layout>
        ...
        <region xml:id="a" top="5" />
        ...
    </layout>
  </head>
  <body>
    ...
    <text region="a" src="text.html" dur="10s" />
    ...
  </body>
</smil>

Theroot-layout element

Theroot-layout elementdetermines the value of the layout properties of the root element, which inturn determines the size of the window in which the SMIL presentation isrendered.

If more than oneroot-layoutelement is parsed within a singlelayout element, this is an error, and thedocument should not be displayed. This does not includeroot-layout elements skipped by theuser agent (e.g. because the enclosinglayout element was skipped due to anunrecognizedtype or because atest attribute evaluated to false).

The semantics of theroot-layout element are as in SMIL1.0: the attributes of theroot-layout element determine the sizeof the top level presentation window, and the declared sibling regions arearranged within this top level window. If either theheight orwidth of theroot-layout element is not specified,the value of the attribute is implementation-dependent.

Elementattributes

backgroundColor: Defined inbackgroundColor under theregion element. Note that the effective default behavior istransparent, which implies that, by default, the implementation-dependent window background will be shown.
background-color: Deprecated. Defined inbackground-color under theregion element.
backgroundOpacity: Defined inbackgroundOpacity under theregion element.
height: Sets the height of the root element. Only length values are allowed. For "length" values, SMIL BasicLayout only supports pixel units as defined in CSS2. It allows the author to leave out the "px" unit qualifier in pixel values (the "px" qualifier is required in CSS2).
width: Sets the width of the root element. Only length values are allowed. For "length" values, SMIL BasicLayout only supports pixel units as defined in CSS2. It allows the author to leave out the "px" unit qualifier in pixel values (the "px" qualifier is required in CSS2).

Elementcontent

Theroot-layout element is anempty element. This element supports the SMIL 1.0 syntax where theroot-layout element is an emptysibling of the top levelregionelements.

Elementexamples

This section is informative.

The following example extends the fragment above with a specification oftheroot-layout element:

<smil xmlns="http://www.w3.org/ns/SMIL" version="3.0" baseProfile="Language">
  <head>
    <layout>
      <root-layout width="320" height="480" />
      <region xml:id="a" top="5" />
    </layout>
  </head>
  <body>
    <text region="a" src="text.html" dur="10s" />
  </body>
</smil>

Note that theroot-layoutelement is placed at a peer-level within thelayout section. SMIL Layout also supports anested containment model using thetopLayout element defined in theMultiWindowLayout module.

Theregion attribute

Theregion attribute is added totheref element (and its synonyms). Thetarget of this attribute will be one or more regions with aregionName declared that matches thevalue of this attribute, or a singleregion element with aregion attribute that matches this value.For processing rules, see the sectionImplementationdetails.

7.4.3 SMIL BasicLayoutImplementation and Integration

Implementation Details

SMIL BasicLayout module is consistent with the visual rendering modeldefined in CSS2, it reuses the formatting properties defined by the CSS2specification, and newly introduces thefit attribute[CSS2]. The reader is expectedto be familiar with the concepts and terms defined in CSS2.

SMIL layout regions influence the propagation of user interface events(such as a mouse click, or hyperlink activation) to underlying visibleelements. When the location of an event corresponds to the background of aregion rather than the media that is displayed in that region, aregion background color oftransparent allows user interface events to passthrough to elements lower in the display stacking order. Conversely, regionswith non-transparent background colors willcapture user interface events, not allowing the event to pass through toelements lower in the display stacking order. This behavior is separate fromthat of a language profile's ability to make use of user interface eventscaptured byregion elements.

An element that does not refer to a validregion element will display in the defaultregion. If not otherwise specified by the profile, the default region isdefined as filling and aligned to the upper-left corner of the presentationwindow. This default region takes on default values for all otherregion attributes.

Theregion attribute is applied toan element in order to specify which rendering region is assigned to theelement. The attribute refers to the abstract rendering region (either visualor acoustic) defined within the layout section of the document. Thereferenced abstract rendering region is determined by applying the followingrules, in order:

Find all elements in the layout section withregionName attributes that are assigned the same value as that of theregion attribute.
Remove the elements from this collection that are removed from the rendered presentation due to the processing ofswitch elements and test attributes.
If any elements remain, the media should be rendered in all of the referred to regions. If the implementation cannot render the media simultaneously in multiple regions, then the media should be rendered using the lexically first remaining element.
If no elements have aregionName attribute that is assigned the same value as that of the region attribute, then select the element in the layout section whose unique identifier is the value of theregion attribute.

If this process selects no rendering surface defined in the layoutsection, the values of the formatting properties of this element are definedby the default layout values, which is described in the section onintegration requirementsfor this module.

The definition ofbackgroundOpacity and the valuetransparent forbackgroundColor are independent.For example, a combination of backgroundOpacity=100% andbackgroundColor=transparent results in a transparent background.

Integration Requirements

A profile integrating the SMIL BasicLayout module must define the contentmodels for thelayout element if anyelements beyond those specified here are to be allowed as children.

A profile integrating the SMIL BasicLayout module must provide a means ofdeclaring an XML identifier onregionelements if the profile intends on referring toregion elements by XML identifier. Thisvalue is used as the argument value to theregion attribute. This is not required ifthe profile will only use theregionName method of referring to aregion element.

A profile integrating the SMIL BasicLayout module must specify whichelements have aregion attribute andany inheritance of the attribute.

If not otherwise defined by the profile, the default values of the layoutattributes listed in the SMIL layout modules will apply to presented elementsnot otherwise specifying layout semantics.

The functionality in this module builds on top of the functionality in theStructureLayout module, whichis a required prerequisite for inclusion of theBasicLayout module.

7.4.4 Document Type Definition (DTD) forthe BasicLayout Module

See the fullDTD for the SMILLayout modules.

7.5 The SMIL AudioLayout Module

7.6 The SMIL MultiWindowLayoutModule

This section is normative.

7.6.1 Overview

This section defines the functionality in the SMIL MultiWindowLayoutmodule. This level contains elements and attributes providing for creationand control of multiple top level windows on the rendering device.

In the architecture of the SMILBasicLayout module, each presentationis rendered into a single root window of a specific size/shape. The rootwindow contains all of the regions used to manage the rendering of specificmedia objects and is defined by a peer-levelroot-layout element.

The SMIL Layout specification extends the root container level with thenotion of a top-level rendering window, called atopLayout window. A SMILlayout section may support one or moretopLayout windows. The assignmentof the regions to individual top level windows allows independent placementand resizing of each top-level window, if supported by the including profileand implementation. The initial placement of the top level windows on thedisplay device and any available means of relocating the top level windows isimplementation-dependent.

The top-level windows function as rendering containers only, that is, theydo not carry temporal significance. In other words, each window does notdefine a separate timeline or any other time-container properties. There isstill a single master timeline for the SMIL presentation, no matter how manytop-level windows have been created. This is important to allowsynchronization between media displayed in separate top-level windows.

The display of top level windows can be controlled automatically by theplayer, or manually by the user of the application. If a window is closed (bythe user) while any of the elements displayed in that window are active,there is no effect on the timeline (if any) of those elements. However, aplayer may choose not to decode content as a performance improvement. Themeans provided to a user to close top level windows isimplementation-dependent.

For SMIL 1.0 compatibility, theroot-layout element will continue tosupport SMIL 1.0 layout semantics. The newtopLayout element will support theextension semantics and the improved, nested syntax.

Note also that any one region may belong to at most one top-level (orroot-level) window. Regions not declared as children of atopLayout element belong to theroot-layout window. If noroot-layout element has been declared,the region is assigned to an additional window according to the semantics intheBasicLayout module.

7.6.2 Elements andAttributes

This section defines the elements and attributes that make up the SMILMultiWindowLayout module.

ThetopLayout element

ThetopLayout elementdetermines the size of the a window in which the SMIL presentation isrendered, as well as serving as a top level window in which to place childregion elements.

MultipletopLayout elements mayappear within a singlelayoutelement, each declaring an independent top-level window.

Each instance of atopLayoutelement determines the size of a separate top-level presentation window, andthe descendant regions are arranged within this top-level window and relativeto the coordinate system of this window.

This module also provides control over whentopLayout windows open and close in apresentation. Note that the precise mapping oftopLayout windows on to the hostenvironment is implementation-dependent. It is expected that implementationswill "pop up" independent desktop windows if they can, but other means ofsupporting multiple topLayouts, such as by using frames, are allowed. Whenautomatically opening and closing windows, applications should try to complywith the WAI User Agent Guidelines[UAAG] and allow the user to choosewhether to be warned that windows are being opened and closed, and give amethod for disabling automatic opening and closing of windows.

Elementattributes

backgroundColor: Defined inbackgroundColor under theregion element. Note that the effective default behavior istransparent, which implies that, by default, the implementation-dependent window background will be shown.
backgroundOpacity: Defined inbackgroundOpacity under theregion element.
close: Specifies when the top level window should be closed. If the value ofclose isonRequest, then the top level window should not be closed automatically by the player and will only close if the user explicitly closes it via the user interface. If the value ofclose iswhenNotActive, then the top level window should close automatically when no media is being displayed in any one of the window's regions. For timed media using theSMIL timing and synchronization modules, this means when there is no media within its active duration or freeze period using any region of thetopLayout. The default value ofclose isonRequest.
height: Sets the height of the top-level window. Only length values are allowed. For "length" values, SMIL MultiWindowLayout only supports pixel units as defined in CSS2. It allows the author to leave out the "px" unit qualifier in pixel values (the "px" qualifier is required in CSS2).
open: Specifies when the top level window should be opened. If the value ofopen isonStart, then the top level window should be opened when the presentation begins, and if closed, should not be reopened automatically during the presentation. If the value ofopen iswhenActive, then, if not already open, the top level window should be opened when media is displayed in one of the window's regions. For timed media using theSMIL timing and synchronization modules, this means when there is any media within its active duration or freeze period using any region of thetopLayout. The default value ofopen isonStart.
width: Sets the width of the top-level window. Only length values are allowed. For "length" values, SMIL MultiWindowLayout only supports pixel units as defined in CSS2. It allows the author to leave out the "px" unit qualifier in pixel values (the "px" qualifier is required in CSS2).

Elementcontent

ThetopLayout element maycontain any number ofregionelements, or be empty.

Elementexamples

This section is informative.

The following example provides a restatement of theroot-layoutexample:

<smil xmlns="http://www.w3.org/ns/SMIL" version="3.0" baseProfile="Language">  <head>    <layout>      <topLayout width="320" height="480" />        <region xml:id="a" top="5" />      </topLayout/>    </layout>  </head>  <body>    <text region="a" src="text.html" dur="10s" />  </body></smil>

Multiple instances of thetopLayout element may occur within asingle layout element:

  <layout>    <topLayout xml:id="WinV" title="Video" width="320" height="240"/>      <region xml:id="pictures" title="pictures" height="100%" fit="meet"/>    </topLayout>    <topLayout xml:id="WinC" title="Captions" width="320" height="60">      <region xml:id="captions" title="caption text" top="90%" fit="meet"/>    </topLayout>  </layout>

In this example, two top-level windows are defined ("WinV" and "WinC"),and two regions are defined with one region ("pictures") assigned to WinV andthe other ("captions") to WinC. These windows may be opened and closedindependently by the presentation or by a user.

Thelayout element

The MultiWindowLayout module does not redefine the BasicLayoutlayout element. Instead, it simply extendsthe content model for that element, as described in the followingsubsection.

Elementcontent

Thelayout element defined in theSMIL BasicLayout module is extended by addingtopLayout element to the content modelof thelayout element if thetype attribute of thelayout element has the value "text/smil-basic-layout".

7.6.3 MultiWindowLayoutModule Events

This module includes two events that may be included in the integratinglanguage profile.

topLayoutOpenEvent: Raised when atopLayout window opens. This event is delivered to the associatedtopLayoutelement. If atopLayout closes and then reopens when additional media becomes active in any of its regions, this event will be raised again, and will be raised every subsequent time it reopens.
topLayoutCloseEvent: Raised when atopLayout closes for any reason. This event is delivered to the associatedtopLayoutelement. If atopLayout reopens when additional media becomes active in any of its regions, this event will be raised again if and when thetopLayout closes again, and will be raised every subsequent time it closes.

7.6.4 Implementation andIntegration Requirements for the MultiWindowLayout Module

Implementationdetails

Allowing multipletopLayoutelements within a singlelayoutelement implies support for multiple top level windows. If an implementationdoes not support multiple top level windows (because of device or processingrestrictions), only content in the first top-level window defined in thelayout will be rendered. Non-renderedobjects will still participate in all SMIL timing and schedulingoperations.

If used together with theroot-layout element, any directpeer-level regions to theroot-layout will be contained withinthe extents of the root-layout.

7.6.5 IntegrationRequirements for the MultiWindowLayout Module

The functionality in this module builds on top of the functionality in theBasicLayout module, which is arequired prerequisite for inclusion of the MultiWindowLayout module.

The language profile must specify the declarative names for binding thetopLayoutOpenEvent andtopLayoutCloseEvent events described in theMultiWindowLayoutModule Events section, as well as the bubbling behavior of the events.

7.6.6 Document Type Definition (DTD)for the MultiWindowLayout Module

See the fullDTD for the SMILLayout modules.

7.7 The SMIL SubRegionLayout Module

This section is normative.

7.7.1 Overview

The SubRegionLayout module defines two mechanisms for defining regionsthat are logically contained within a parent region (these are SMIL'ssub-regions). First, the SubRegionLayout module extends the definitionof the region element to allow for the specification of sub-regions withinthe layout section as hierarchical content of regions. Second, theSubRegionLayout module extends the attributes allowed on (media) objectreferences to allow a dynamic sub-region to be defined in-line by that objectinstance only. All values given for placement within sub-regions are definedin terms of the parent region's placement attributes. The ability to definesub-regions may be exploited for authoring convenience or when changing thelocation of a group of related regions using SMIL Animation.

This section is informative.

In the following fragment, a parent region (CaptionedVideo) isdefined that contains two hierarchical sub-regions:image andcaptions. The placement of the image and caption content is specifiedas relative to the dimensions of the parent region. This is an example of astatically-defined hierarchy of sub-regions.

  <layout>     ...     <region xml:id="CaptionedVideo" top="10px" left="20px" width="320" height="300">       <region xml:id="image" title="image content" width="100%" height="240px" fit="meet"/>       <region xml:id="captions" title="caption text" top="240px" height="60px" fit="meet"/>     </region>     ...  </layout>

A presentation using the above layout specification could also create adynamic sub-region that is defined for use by this single object:

  <body>      ...     <img xml:id="Title" region="image" top="5%" left="3" bottom="10%" right="15%"  src="TitleImage.png"/>     ...  </body>

This statement creates a sub-region with the named region "image" with thegiven extents. In the example above, the effective boundaries of thesub-region for the placement of this object are defined by declaring the top,bottom, left and right edges of the region to the values shown, and thenfilling the resulting sub-region with the specified image as directed by thefit attribute. If the size of the mediaobject being displayed is smaller than that of the resulting sub-region, thedisplay will be similar to: picture of sub-regions

The use of in-line sub-region placement is intended as a light-weightalternative to defining a large number of single-use regions. Often, thedimensions used for the sub-region will match the dimensions of the mediaobject being placed, but in all cases the values of thefit attribute will govern rendering of theobject in the sub-region. The other attributes on the media element thatwould have been applied to a referenced region are applied to the sub-regioninstead. Note that the default values for the sub-region attributes are all'auto', meaning that, by default, a sub-region is created having the samesize and position as the parent region.

The use of sub-region positioning leads to authoring convenience and SMILfile compactness, since many separate regions do not need to be defined tohandle incidental layout needs. The support for a hierarchy of sub-regionsalso allows multiple layout objects to be animated in concert by moving theparent region using SMIL Animation facilities.

7.7.2 Elements andattributes

This section defines extensions to theregion andref elements (and its synonyms) to supportsub-region functionality.

Theregion element

This module extends the definition of theregion element to include the definition ofhierarchical sub-regions.

Elementattributes

In the SubRegionLayout module, theregion element has no additional attributesbeyond that provided in the other included layout modules. However, thesemantics of thez-index attributeare extended to support hierarchical sub-regions.

z-index: This attribute is defined as in theBasicLayout module with extensions presented here.; Thez-index attribute defines the level of the region within the parent region stacking context. Elements assigned to higher level regions are rendered in front of lower level regions within the same parent region. Child regions are always placed in front of their parent region. This results in a two stage sorting of region visibility: first by parent-child containment, and then byz-index among siblings.
Just as withsimple non-hierarchical regions, the stacking order of hierarchical regions may be affected by temporal activation. A region becomes active either when media begins rendering into it, or when one of its child regions becomes active. If two sibling regions have the same z-index, the region most recently made active is in front of the other region.

Elementcontent

The SMIL SubRegionLayout module extends theregion element content model to includeregion elements.

Theref element (and its synonyms)

The SubRegionLayout module extends theref element to allow a separate, unnamedsub-region to be defined for the media object reference containing thesub-region positioning attributes.

Elementattributes

The ref element defined in the MediaObject module and its synonyms areextended to include the following positioning attributes.

top: This value uniquely identifies the position or the distance (using CSS2 pixel or non-negative percentage values) of the top edge of the sub-region relative to the top of the region. The "px" unit qualifier in pixel values may be omitted. The default value of top isauto.
bottom: This value uniquely identifies the position or the distance (using CSS2 pixel or non-negative percentage values) of the bottom edge of the sub-region relative to the bottom of the region. The "px" unit qualifier in pixel values may be omitted. The default value of bottom isauto.
height: This value uniquely identifies the position or the distance (using CSS2 pixel or non-negative percentage values) of the bottom edge of the sub-region relative to the top side of the sub-region. The "px" unit qualifier in pixel values may be omitted. The default value of height isauto.
left: This value uniquely identifies the position or the distance (using CSS2 pixel or non-negative percentage values) of the left edge of the sub-region relative to the left of the region. The "px" unit qualifier in pixel values may be omitted. The default value of left isauto.
right: This value uniquely identifies the position or the distance (using CSS2 pixel or non-negative percentage values) of the right edge of the sub-region relative to the right side of the region. The "px" unit qualifier in pixel values may be omitted. The default value of right isauto.
width: This value uniquely identifies the position or the distance (using CSS2 pixel or non-negative percentage values) of the right edge of the sub-region relative to the left side of the sub-region. The "px" unit qualifier in pixel values may be omitted. The default value of width isauto.

Conflicts between the region size attributesbottom,height,left,right,top, andwidth are resolvedaccording to the rules for placeholder elements described in the section ontheregion element.

The sub-region positioning attributes will be ignored if they are used onan element without aregion attribute(or, if supported, theregionNameattribute) that resolves to aregionelement in thelayout section.

7.7.3 SubRegionLayout ModuleEvents

This module does not define any SMIL events.

7.7.4 SubRegionLayoutImplementation and Integration

ImplementationDetails

The position of a region, as specified by itstop andleft attributes, is always relative to theparent geometry, which is defined by the parent element. For the SMILSubRegionLayout module, all hierarchical region elements must have as theirimmediate parent aregion ortopLayout element. The position of thehierarchical region is defined relative to that parent element. The intrinsicsize of a region is equal to the size of the parent geometry.

When region sizes, as specified bywidth andheight attributes are declared relativewith the "%" notation, the size of the hierarchical region is relative to thesize of the parent region. Sizes declared as absolute pixel values areabsolute values even when used with a child region.

Note that a (hierarchical) region may be defined in such a way as toextend beyond the limits of its parent. In this case the child region must beclipped to the parent boundaries.

If az-index attribute is definedon the hierarchical region, it is evaluated as a local index within that ofthe parent.

If thefit attribute and alignmentattributesregPoint andregAlign are relevant to the placementof a particular media object, the interaction is the same as described in thedefinition ofregPoint. Ifsub-region positioning attributes are used on a media object along withfit or the alignment attributesregPoint andregAlign, these attributes apply to thesub-region. In this case thefit settingon the referenced region element does not apply to the sub-region.

For both sub-region positioning and registration point use (as defined inthemodule), the value of thez-index attribute on the associatedregion is used. If media objects overlap spatially, existing rules forresolving z-index conflicts are applied.

Note that placement within the region may be defined in such a way as toextend the media object beyond the limits of the region. In this case themedia object must be clipped to the region boundaries.

If two hierarchical regions with the same z-index attribute value overlap,the existing rules forz-indexprocessing defined in theBasicLayout module are applied.Specifically, the rule concerning time priority is maintained, meaning thatin the case of a z-index conflict, the media visible in the overlap will bedetermined by the region that is rendering the media that has most recentlybegun in time. If the conflicting media began at the same time, then the ruleusing the textual order of the media elements in the SMIL document isapplied.

This section is informative.

For example:

<layout>    <root-layout width="640px" height="480px" />   <region xml:id="whole" top="0px" left="0px" width="640px"                                 height="480px" z-index="5"/>   <region xml:id="right" top="0px" left="320px" width="320px"                                height="480px" z-index="4">       <region xml:id="inset" top="140px" left="80" width="160px"                                 height="200px" z-index="6"/>       <region xml:id="inset2" top="140px" left="80" width="160px"                                 height="200px" z-index="6"/>       <region xml:id="inset3" top="140px" left="80" width="160px"                                 height="200px" z-index="7"/>   </region></layout>...<par>        <img xml:id="A" region="whole" src="imageA.jpg" dur="10s"/>        <img xml:id="B" region="inset" src="imageB.jpg" dur="10s"/></par><par>        <img xml:id="D" region="inset2" src="imageD.jpg" begin="1s" dur="10s"/>        <img xml:id="C" region="inset" src="imageC.jpg" begin="0s" dur="10s"/></par><par>        <img xml:id="E" region="inset2" src="imageE.jpg" dur="10s"/>        <img xml:id="F" region="inset3" src="imageF.jpg" dur="10s"/></par>

In the first "par", image "A" and image "B" begin at the same time. Image A will obscure image "B", even though the z-index of "inset" is greater than that of "whole". This is because the z-index of "right", which is the region containing "inset" is less than that of "whole".
In the second "par", images "C" and "D" are rendered into regions occupying the same area of the rendering surface. Image "C" will be shown for one second and then obscured by Image "D", since "D" begins after image "C". Note that lexical order is irrelevant here.
In the third "par", the z-index of region "inset" is considered when computing stacking between siblings, and therefore image "F" will be shown, but image "E" will be obscured for the entire 10 seconds that they are both active.

Integration Requirementsfor the SubRegionLayout Module

The functionality in this module builds on top of the functionality in theBasicLayout module and theMediaObject module, which are required prerequisites for inclusion of theSubRegionLayout module. If the functionality in this module is to be usedwith thetopLayout construct, theMultiWindowLayout module is aprerequisite.

7.7.5 Document Type Definition (DTD)for the SubRegionLayout Module

See the fullDTD for theSMIL Layout modules.

7.8 AlignmentLayout Module

This section is normative.

7.8.1 Overview

A registration element is an element defined within this module that isused to define a point within a region and a default object alignmentalgorithm about that point. The element may be used in a media objectelement, where it is associated with a region and an optional overridealignment algorithm. The placement values within registration elements can beeither percentages or pixels.

The use of registration points allows for consistent relative placementacross regions. As such, registration points are defined outside of anysingle region.

Registration points may be used to coordinate the placement of a set ofmedia objects that do not share the same sizes. (For example, a set of imagesmay be aligned to the center of a region.) They can also be used tocoordinate the display of images about a particular point in a region.

For authoring convenience, SMIL AlignmentLayout module provides severalpre-defined region registration points includingtopLeft,topMid,topRight,midLeft,center,midRight,bottomLeft,bottomMid, andbottomRight.

As a further convenience, SMIL AlignmentLayout module provides themediaAlign attribute, which defines acombination ofregAlign andregPoint attributes. For example, mediaobjects may be centered in any region usingmediaAlign as follows:

    <ref ... mediaAlign="center" />

If themediaAlign attributeand either (or both) of theregPoint andregAlign attributes are used together,theregPoint and/orregAlign value(s) will override thecorresponding effectiveregPoint/regAlign value(s) defined by themediaAlign value.

The default value ofregAlignfor a region istopLeft. If theregAlignattribute is used without aregPoint attribute, the alignmentoperation is relative to the upper left point of the region containing thisobject, that is, the behavior is the same as if theregPoint were to be specified astopLeft.

Rules for handling clipping of objects within regions based on theregPointandregAlign attributes are defined below.

This section is informative.

An example is given in the following code of two registration points (withid values "midPoint" and "topMargin"), one of which is defined as a relativelocation and one at a fixed pixel location, using the SMIL AlignmentLayoutsyntax:

    <layout>
      <regPoint xml:id="midPoint" top="50%" left="50%" regAlign="center" />
      <regPoint xml:id="topMargin" top="10" left="15" regAlign="topLeft" />
      <region xml:id="a" ... />
      <region xml:id="b" ... />
    </layout>

In this example, the registration point with the id value "midPoint" has adefault alignment algorithm that centers the media object about the definedpoint, while the registration point with the id value "topMargin" has adefault alignment algorithm that places the top-left point of the mediaobject at the registration point.

Various media elements could be displayed in the regions using thealignment points as follows:


    <ref region="a" src="rtsp://..." dur="2s" regPoint="midPoint" />
    <ref region="b" src="http://..." dur="2s"
                         regPoint="midPoint" regAlign="bottomRight"/>
    <ref region="a" src="http://..." dur="2s" regPoint="topMargin" />
    <ref region="b" src="http://..." dur="2s"
                         regPoint="topMargin" regAlign="center"/>

In the first example, a media object is centered in the middle ofregiona. In the second example, a media object has its bottom rightcorner centered in the middle of regionb. Similarly, in the thirdexample, a media object has its top left corner placed at a point 10,15within regiona, and in the fourth example, an object is centeredaround the point 10,15 in regionb.

The following example illustrates how images may be aligned at aparticular point in a region:

   <layout>
      <regPoint xml:id="middle" top="50%" left="50%" regAlign="center" />
      <region xml:id="a" ... />
   </layout>
   ...
   <seq>
    <ref region="a" src="rtsp://..." dur="2s" regPoint="middle"
                                        regAlign="bottomRight"/>
    <ref region="a" src="http://..." dur="2s" regPoint="middle"
                                        regAlign="bottomLeft"/>
    <ref region="a" src="http://..." dur="2s" regPoint="middle"
                                        regAlign="topLeft"/>
    <ref region="a" src="http://..." dur="2s" regPoint="middle"
                                        regAlign="topRight"/>
  </seq>

In this example, four objects are aligned over time to the middle ofregion. If any media element extends outside the bounds of a region, it willbe clipped to the region.

In the following example, media objects may be centered in any regionusing pre-defined registration and alignment points:

    <ref ... regPoint="center" regAlign="center" />

Note that registration points are global within the context of a layout,and are not tied to a particular region, but can be reused across regions. Assuch, pixel-based offsets should be used with care.

7.8.2 Elements andAttributes for the AlignmentLayout Module

This section defines the elements and attributes that make up the SMILAlignmentLayout module.

The layout element

This element extends the content model of thelayout element to support the registrationpoint functionality described in this section.

Elementcontent

If the type attribute of the layout element has the value "text/smil-basic-layout", it is extended to contain thefollowing elements:

region
root-layout
regPoint

TheregPoint element

TheregPoint element determinesthe (x, y) coordinates of a point relative to a region upper-left corner foruse in aligning elements in the document's body on regions within a visualrendering surface. AregPoint maybe defined using absolute (pixel) or relative (percentage) based values. TheregPoint functionality is notdefined and may not be used for media without intrinsic size.

For the purposes ofregPointfunctionality, media and regions are defined to be rectangular, withperpendicular sides, with the sides ordered clockwise top, right, bottom, andleft. The top side is the edge closest to the point or edge of the displaydevice considered "up".

Elementattributes

top

This value uniquely identifies the position or the distance (using CSS2 pixel or non-negative percentage values) of the registration point relative to the top of the region. The "px" unit qualifier in pixel values may be omitted. The default value of top isauto.

bottom

This value uniquely identifies the position or the distance (using CSS2 pixel or non-negative percentage values) of the registration point relative to the bottom of the region. The "px" unit qualifier in pixel values may be omitted. The default value of bottom isauto.

left

This value uniquely identifies the position or the distance (using CSS2 pixel or non-negative percentage values) of the registration point relative to the left location of the region. The "px" unit qualifier in pixel values may be omitted. The default value of left isauto.

right

This value uniquely identifies the position or the distance (using CSS2 pixel or non-negative percentage values) of the registration point relative to the right location of the region. The "px" unit qualifier in pixel values may be omitted. The default value of right isauto.

regAlign

This attribute specifies the default alignment algorithm which is associated with aregPoint relative to the media object. The value oftopLeft is the default. The following values are allowed:

topLeft: Align the top-left corner of the object with the registration point.
topMid: Align the top-middle point of the object with the registration point. The top-middle is the point offset width/2 to the right of the object top-left corner.
topRight: Align the top-right corner of the object with the registration point.
midLeft: Align the middle-left point of the object with the registration point. The middle-left is the point offset height/2 down from the object top-left corner.
center: Align the center of the object with the registration point.
midRight: Align the middle-right point of the object with the registration point. The middle-right is the point offset height/2 down from the object top-right corner.
bottomLeft: Align the bottom-left corner of the object with the registration point.
bottomMid: Align the bottom-middle point of the object with the registration point. The bottom-middle is the point offset width/2 right from the object bottom-left corner.
bottomRight: Align the bottom-right corner of the object with the registration point.

Elementcontent

None.

Theregion element

This module extends the definition of theregion element to include the definition ofdefault alignment policies for content in that region.

Elementattributes

regPoint: This attribute is identical to theregPoint attribute on media objects defined below, except that it defines a default alignment point for all media objects placed in the region. The default value for this attribute when used on theregion element istopLeft.
regAlign: This attribute is identical to theregAlign attribute on media objects defined below, except that it defines a default alignment policy for all media objects placed in the region. The default value for this attribute when used on theregion element istopLeft.
mediaAlign: This attribute is identical to themediaAlign attribute on media objects defined below, except that it defines a default combination registration point/alignment policy for all media objects placed in the region. The default value for this attribute when used on theregion element is undefined; the default behavior of this attribute is the behavior resulting from the application of theregPoint andregAlign attributes. (Note that this defines an effective default behavior oftopLeft.)
soundAlign: This attribute is identical to thesoundAlign attribute on media objects defined below, except that it defines a default 2D placement of the audio portion of a media element assigned to play within the givenregion. The default value for this attribute when used on theregion element isboth.

Element content

SMIL AlignmentLayout module does not extend theregion element content model.

Theref element (and its synonyms)

The AlignmentLayout module extends theref element to allow the positioning ofmedia content within a region based on the an alignment registration pointand an alignment policy.

Element attributes

Theref element defined in theMediaObject module is extended to include themediaAlign andregPoint attributes, both in conjunction with theregPoint element. If aregPoint attribute is missing or refersto a non-existentregPoint elementthe value of theregAlignattributes are applied to the top-left point of the region containing themedia object.

regPoint

This value uniquely identifies the registration point to be used for the placement of the object. The value should be an XML identifier of aregPoint element.

The following values are predefined registration points that do not have to be declared asregPoint elements before they are used:

topLeft: Same as using top="0%" left="0%" on the element without theregPoint attribute.
topMid: Same as using top="0%" left="50%" on the element without theregPoint attribute.
topRight: Same as using top="0%" left="100%" on the element without theregPoint attribute.
midLeft: Same as using top="50%" left="0%" on the element without theregPoint attribute.
center: Same as using top="50%" left="50%" on the element without theregPoint attribute.
midRight: Same as using top="50%" left="100%" on the element without theregPoint attribute.
bottomLeft: Same as using top="100%" left="0%" on the element without theregPoint attribute.
bottomMid: Same as using top="100%" left="50%" on the element without theregPoint attribute.
bottomRight: Same as using top="100%" left="100%" on the element without theregPoint attribute.

Note that the predefined registration points have the same meaning relative to the region as theregAlign attribute values have relative to the media. The default value is inherited from theregPoint value defined for the associatedregion. This implies a default behavior oftopLeft.

regAlign

This value uniquely identifies the registration algorithm to be used for theregPoint defined for the object, and overrides anyregAlignattribute on the referencedregPoint element. Permissible values are those defined under theregAlign attribute for theregPoint element. If used without an explicitregPoint attribute, the value is relative to the top left point of the region used by the associated media object. The default value is inherited from theregAlign value defined for the associatedregion. This implies a default behavior oftopLeft.

mediaAlign

This value uniquely identifies a short-hand notation for combining set combinations ofregAlign andregPoint attributes. Valid values are:

topLeft: Same as using theregPoint ="topLeft" andregAlign="topLeft" attributes.
topMid: Same as using theregPoint ="topMid" andregAlign="topMid" attributes.
topRight: Same as using theregPoint ="topRight" andregAlign="topRight" attributes.
midLeft: Same as using theregPoint ="midLeft" andregAlign="midLeft" attributes.
center: Same as using theregPoint ="center" andregAlign="center" attributes.
midRight: Same as using theregPoint ="midRight" andregAlign="midRight" attributes.
bottomLeft: Same as using theregPoint ="bottomLeft" andregAlign="bottomLeft" attributes.
bottomMid: Same as using theregPoint ="bottomMid" andregAlign="bottomMid" attributes.
bottomRight: Same as using theregPoint ="bottomRight" andregAlign="bottomRight" attributes.

If specified together with either (or both) of theregPoint and/orregAlign attributes, the effect values of the respective positioning attribute(s) specified bymediaAlign will be overridden by the values given forregPoint and/orregAlign. This attribute does not have a default value; the default behavior is inherited from the effective values of theregPoint andregAlign attributes.

soundAlign

Specifies the coarse 2D placement of the audio portion of a media element assigned to play within the givenregion. The default value is inherited from theregion. The following values are allowed:

both: Place the audio on both channels. If stereo or other dual-channel audio is used, the audio will be reproduced on both channels, implementation permitting.
left: Place the audio on the left channel only. If stereo audio is used, only the left source audio will be reproduced on the left audio channel, implementation permitting.
right: Place the audio on the right channel only. If stereo audio is used, only the right source audio will be reproduced on the right audio channel, implementation permitting.

Element content

SMIL AlignmentLayout module does not extend theref element content model.

7.8.3 AlignmentLayout ModuleEvents

This module does not define any SMIL events.

7.8.4 SMIL AlignmentLayoutImplementation and Integration

ImplementationDetails

If an implementation cannot support thesoundLevel attribute, it may beignored. Even when processing is ignored, the attribute must be correctlyparsed.

TheregPoint element may onlyappear as an immediate child of alayout element.

If the registration point functionality is used on a media object thatalso usessub-regionpositioning, the registration point applies to the subregion.

For registration point use, the value of thez-index attribute on the associated regionis used. If media objects overlap spatially, existing rules for resolvingz-index conflicts are applied.

Note that placement within the region may be defined in such a way as toextend the media object beyond the limits of the region. In this case themedia object must be clipped to the region boundaries.

If the registration point or alignment functionality is used on a mediaobject, the interaction between theregPoint attribute value, theregAlign attribute value, and thefit attribute value of the region in which themedia object is displayed is as follows:

fillfit value:

This depends on the value of theregAlign attribute. (Note: in all cases, the media must maintain proper alignment over theregPoint):

topLeftregAlign value:: Scale the object's height and width independently so that the content just touches the bottom and right edges of the box.
topMidregAlign value:: Scale the object's height and width independently so that the content just touches the bottom edge of the box, and the nearest (to theregPoint) of the left or right edges of the box.
topRightregAlign value:: Scale the object's height and width independently so that the content just touches the bottom and left edges of the box.
midLeftregAlign value:: Scale the object's height and width independently so that the content just touches the nearest (to theregPoint) of the top or bottom edges of the box, and touches the right edge of the box.
centerregAlign value:: Scale the object's height and width independently so that the content just touches the nearest (to theregPoint) of the top or bottom edges of the box, and touches the nearest (to theregPoint) of the left or right edges of the box.
midRightregAlign value:: Scale the object's height and width independently so that the content just touches the nearest (to theregPoint) of the top or bottom edges of the box, and touches the left edge of the box.
bottomLeftregAlign value:: Scale the object's height and width independently so that the content just touches the top and right edges of the box.
bottomMidregAlign value:: Scale the object's height and width independently so that the content just touches the top edge of the box, and the nearest (to theregPoint) of the left or right edges of the box.
bottomRightregAlign value:: Scale the object's height and width independently so that the content just touches the top and left edges of the box.

hidden fit value:

Align the media over the givenregPoint per theregAlign attribute. If the media so positioned extends past the bounds of the region, clip the excess media. If the media so positioned doesn't meet the bounds of the region, fill the remaining space with the background color of the region.

meet fit value:

This depends on the value of theregAlign attribute. Any part of the region that is not covered by the media is then filled with the region's background color. (Note: in all cases, the media must maintain proper alignment over theregPoint):

topLeftregAlign value:: Scale the visual media object's height and width while maintaining its aspect ratio so that the content just touches the right or bottom edge of the box while none of the content is clipped.
topMidregAlign value:: Scale the visual media object's height and width while maintaining its aspect ratio so that the content just touches at least one of the left, right, or bottom edges while none of the content is clipped.
topRightregAlign value:: Scale the visual media object's height and width while maintaining its aspect ratio so that the content just touches the left or bottom edge of the box while none of the content is clipped.
midLeftregAlign value:: Scale the visual media object's height and width while maintaining its aspect ratio so that the content just touches at least one of the top, right, or bottom edges while none of the content is clipped.
centerregAlign value:: Scale the visual media object's height and width while maintaining its aspect ratio so that the content just touches at least one of the top, left, right, or bottom edges while none of the content is clipped.
midRightregAlign value:: Scale the visual media object's height and width while maintaining its aspect ratio so that the content just touches at least one of the top, left, or bottom edges while none of the content is clipped.
bottomLeftregAlign value:: Scale the visual media object's height and width while maintaining its aspect ratio so that the content just touches the top or right edge of the box while none of the content is clipped.
bottomMidregAlign value:: Scale the visual media object's height and width while maintaining its aspect ratio so that the content just touches at least one of the top, left, or right edges while none of the content is clipped.
bottomRightregAlign value:: Scale the visual media object's height and width while maintaining its aspect ratio so that the content just touches the top or left edge of the box while none of the content is clipped.

meetBest fit value:

This interaction with theregAlign andregPoint attributes is identical that that of themeet fit value, with the exception that the size of the related media object is never scaled above 100%.

scroll fit value:

Align the media over the givenregPoint per theregAlign attribute. If any part of the media extends beyond the bounds of the region, a scrolling mechanism should be invoked that allows viewing of the media that is clipped beyond the bounds of the region.

slice fit value:

This depends on the value of theregAlign attribute. (Note: in all cases, the media must maintain proper alignment over theregPoint):

topLeftregAlign value:: Scale the visual media object's height and width while maintaining its aspect ratio so that the content just touches the right or bottom edge of the box, whichever requires the largest scale factor. Any content that extends beyond the bounds of the region is clipped.
topMidregAlign value:: Scale the visual media object's height and width while maintaining its aspect ratio so that the content just touches the left, right, or bottom edge of the box, whichever requires the largest scale factor. Any content that extends beyond the bounds of the region is clipped. Clipping will occur on up to two sides of the region.
topRightregAlign value:: Scale the visual media object's height and width while maintaining its aspect ratio so that the content just touches the left or bottom edge of the box, whichever requires the largest scale factor. Any content that extends beyond the bounds of the region is clipped.
midLeftregAlign value:: Scale the visual media object's height and width while maintaining its aspect ratio so that the content just touches the top, right, or bottom edge of the box, whichever requires the largest scale factor. Any content that extends beyond the bounds of the region is clipped. Clipping will occur on up to two sides of the region.
centerregAlign value:: Scale the visual media object's height and width while maintaining its aspect ratio so that the content just touches the top, left, right, or bottom edge of the box, whichever requires the largest scale factor. Any content that extends beyond the bounds of the region is clipped. Clipping will occur on up to three sides of the region.
midRightregAlign value:: Scale the visual media object's height and width while maintaining its aspect ratio so that the content just touches the top, left, or bottom edge of the box, whichever requires the largest scale factor. Any content that extends beyond the bounds of the region is clipped. Clipping will occur on up to two sides of the region.
bottomLeftregAlign value:: Scale the visual media object's height and width while maintaining its aspect ratio so that the content just touches the top or right edge of the box, whichever requires the largest scale factor. Any content that extends beyond the bounds of the region is clipped.
bottomMidregAlign value:: Scale the visual media object's height and width while maintaining its aspect ratio so that the content just touches the top, left, or right edge of the box, whichever requires the largest scale factor. Any content that extends beyond the bounds of the region is clipped. Clipping will occur on up to two sides of the region.
bottomRightregAlign value:: Scale the visual media object's height and width while maintaining its aspect ratio so that the content just touches the top or left edge of the box, whichever requires the largest scale factor. Any content that extends beyond the bounds of the region is clipped.

For example, a wide-screen video may be made to play in "letterbox" modein a region, whose width-to-height ratio is smaller, by usingregPoint ="center" andregAlign="center" and setting the region's fit value to "meet". The result is the video will touch the left andright edges of the region and will be centered vertically with the gaps aboveand below filled in with the region's background color.

IntegrationRequirements

The functionality in this module builds on top of the functionality in theBasicLayout module and theMediaObject module, which are required prerequisites for inclusion of theAlignmentLayout module.

7.8.5 Document Type Definition (DTD)for the AlignmentLayout Module

See the fullDTD for the SMILLayout modules.

7.9 BackgroundTilingLayoutModule

This section is normative.

7.9.1 Overview

The SMIL BackgroundTilingLayout module defines abackgroundImage attribute thatallows an image to be placed onto the background of a layoutregion. It also provides the samecapability for theroot-layoutand any of thetopLayoutelement(s), if supported by the language profile. This module also definesthebackgroundRepeatattribute to control tiling of the background image. These facilities areprovided as a convenience extension to SMIL's use of a background color in aregion. Although similar functionality can be defined by using a combinationof the image media object, thez-index attribute andsubregions positioning, this wouldrequire substantially more authoring effort.

The BackgroundTilingLayout module allows simple convenience tiling supportin a manner that is consistent with CSS2[CSS2]. For more complexbackground image operations such as support for animated images or non-imagebackground content, users are expected to use the standard media placementand alignment facilities available in SMIL Layout.

The opacity of the background images, whether or not tiled, is defined bythe value of thebackgroundOpacity attribute.

If abackgroundImage isdefined along with abackgroundColorattribute, the background color will be used to color any part of the background leftexposed after processing the background image.

When used with theshowBackground attribute.the background image behaves as if it were a simple background color.

7.9.2 Elementsand Attributes for the BackgroundTilingLayout Module

This section defines thebackgroundImage andbackgroundRepeat attributes thatmake up the SMIL BackgroundTilingLayout module.

Theregion Element

Theroot-layout Element

ThetopLayout Element

This module extends the attribute set for theregion,root-layout andtopLayout elements.

Elementattributes

backgroundImage

This attribute may be used to specify an image that may be placed as the background of a region.

In SMIL Layout, the image is treated as a single image frame; any behavior that is specified in the image (such as animations or multiple frames) will be ignored. The legal values for this attribute are:

<uri>

This value consists of a URI containing the location of an image to be used as a background image. If the image is larger than the background, it will be clipped as if a fit attribute of hidden was specified. If the image is smaller in either or both dimensions than the region's dimensions, it will be processed according to the value of the backgroundRepeat attribute.

none

This value indicates that no background image should be used.

inherit

This value indicates that the same background image should be used as the logical parent of this region.

The default value isnone.

backgroundRepeat

This attribute allows a repeat or tiling strategy to be specified for the background image. The legal values for this attribute are:

repeat

This value indicates that the background image should be repeated horizontally and vertically (that is, it should be tiled).

repeatX

This value indicates that the background image should be repeated horizontally only.

repeatY

This value indicates that the background image should be repeated vertically only.

noRepeat

This value indicates that the background image should not be repeated.

inherit

This value indicates that the same background repeat policy should be used as in the logical parent of this region.

The default value isrepeat.

Elementcontent

The SMIL BackgroundTilingLayout module does not extend the content model forelements integrating these attributes.

7.9.3 BackgroundTilingLayoutModule Events

This module does not define any SMIL events.

7.9.4 SMILBackgroundTilingLayout Implementation and Integration

Implementationdetails

For purposes of establishing an inheritance default value, the root-layoutelement defined in SMILBasicLayoutis considered the root of the background image inheritance tree. In thiscase, bothbackgroundImageandbackgroundRepeat may beused with theroot-layout andregion elements.

For profiles implementing the SMIL MultiWindowLayout module, eachtop-level layout element is considered to define a separate root of thebackground image inheritance tree. In this case, bothbackgroundImage andbackgroundRepeat may be used withanytopLayout elements.

IntegrationRequirements

The functionality in this module builds on top of the functionality in theBasicLayout module, which is arequired prerequisite for inclusion of the BackgroundTilingLayout module. Ifthis functionality is to be applied to multiple top-level windows, theMultiWindowLayout module must beincluded.

7.9.5 Document Type Definition(DTD) for the BackgroundTilingLayout Module

See the fullDTD for the SMILLayout modules.

Movatterモバイル変換

7.SMIL 3.0 Layout

Table of contents

7.1Summary of Changes for SMIL3.0

Thelayout element

Theregion element

Theroot-layout element

Theregion attribute

ThetopLayout element

TheregPoint element