Definición y uso¶
El elemento <area> permite definir un ancla de contenido (un subconjunto de unidades de información del contenido de un <media> elemento) que pueden usarse en relaciones con otros objetos en una aplicación NCL.
Los anclajes de contenido pueden representar:
- porciones espaciales de imágenes: a través del atributo coords;
- porciones temporales de contenido multimedia continuo (audio, vídeo, etc.): a través de los atributos begin y end, o basándose en el número de muestras de audio o fotogramas de vídeo, hasta el primero y último atributo, que indica el inicio y el final. muestra/marco;
- porciones temporales y espaciales de videos: a través de las coords, atributos comienzo y fin; o a través del coords, primero y último atributos;
- segmentos textuales: a través de beginText, beginPosition, Atributos endText y endPosition, que definen el cadenas de inicio y fin, y su aparición en el texto respectivamente;
- una cadena que utiliza el reproductor multimedia para identificar una región de contenido (por ejemplo, una función o método en un objeto multimedia imperativo, un interfaz en un objeto de medios declarativo, como un ancla HTML, un puerto en un objeto multimedia con una aplicación NCL como contenido, etc.): a través del atributo etiqueta;
- un clip en el contenido de un objeto hipermedia declarativo: usando el *clip * atributo.
Cada elemento <media>, <context>, <body> y <switch> tiene un ancla de contenido con una región que representa todo el contenido del Nodo definido por defecto. Este ancla se llama "ancla de contenido completo". Excepto para objetos multimedia con contenido de código imperativo (por ejemplo, aquellos cuyo tipo MIME es "application/x-ncl-NCLua"), cada vez que un componente NCL se hace referencia sin especificar uno de sus anclajes, todo el contenido ancla se supone.
Sintaxis¶
| Elemento | Atributos | Contenido | Padre |
|---|---|---|---|
| <area> | id, coords, begin, end, beginText, endText, beginPosition, endPosition, primero, último, etiqueta, clip | -- | <media> |
Atributos¶
| Name | Value | Description |
|---|---|---|
| id | It may receive any string value that begins with a letter or an underscore and that only contains letters, digits, <".">, and <"_">. | The id attribute uniquely identifies the element within a document. |
| coords | A list of values of the form "left-x, top-y, right-x, bottom-y" where each value is either:
|
The coords attribute specifies the position of a rectangular area on the screen. Coordinates are relative to the top, left corner of the object content. The values are separated by commas. The order of values is "left-x", "top-y", "right-x", and "bottom-y". When the "left-x" and "right-x" are expressed as a percentage, the value is relative to the width property of the media object. When the "top-y" and "bottom-y" are expressed as a percentage, the value is relative to the height property of the media object. |
| begin | Except for the <media> element of the "application/x-ncl-time" type, the begin attribute shall be specified according with one of the following syntax:
For the <media> element of the "application/x-ncl-time" type, the begin attribute shall be specified according with the following syntax: <" If the end attribute is defined, but without an explicit definition for the begin attribute, the start of the whole media content presentation shall be considered as the anchor beginning. In the case of a media element of the "application/x-ncl-time" type, the begin attribute must always be defined and it assumes an absolute UTC value. |
The begin attribute specifies the beginning of the temporal anchor. |
| end | Same as for begin. | The end attribute specifies the end of the temporal anchor. |
| beginText | String. If the beginning of the content anchor region is not defined, the beginning of the text content is assumed. |
The beginText and beginPosition attributes specifies the beginning of the text anchor. The beginText defines a string in the text. |
| endText | String. | The endText and endPosition attributes specifies the end of the text anchor. The endText defines a string in the text. |
| beginPosition | Positive integer. The default value is 1. | The beginText and beginPosition attributes specifies the beginning of the text anchor. The beginPosition defines the occurrence of the string in the text. |
| endPosition | Positive integer. The default value is the position of the last character in string. | The endText and the endPosition attributes specifies the end of the text anchor. The endPosition defines the occurrence of the string in the text. |
| first | The first attribute shall be specified according with one of the following syntax:
If the last attribute is defined, but without an explicit definition for the first attribute, the start of the whole media content presentation shall be considered as the anchor beginning. |
-- |
| last | The last attribute shall be specified according with one of the following syntax:
If the first attribute is defined, but the last attribute is not specified, the end of the whole media content presentation shall be assumed as the anchor ending. |
-- |
| label | String. | The label attribute identifies a content region, for example, a function in an imperative media object, or an interface in a declarative media object, like an HTML anchor, or a port in a media object with an NCL application as content, etc. |
| clip | String. The value depends on the declarative hypermedia object type. For NCL media objects, the clip value is a triple <"(chainId,beginOffset,endOffset)"> that is used by the NCL media player to identify an NCL application <port> through which a temporal chain begins, and the beginning and the end time in this temporal chain. For <media> elements with NCL code content the following defaults are defined:
|
The clip identifies a stream clip in the content of a declarative hypermedia object |