Indicador de carga
Muestra que hay en curso una espera breve de duración desconocida, en línea o sobre el contenido.
- Categoría
- Comunicación
- Tokens
comp.loading-indicator- Nivel
- Base
- Web
tanrei-loading-indicatorschedule - SwiftUI
TanreiLoadingIndicatorschedule - Jetpack Compose
TanreiLoadingIndicatorschedule - Flutter
TanreiLoadingIndicatorschedule - React Native
LoadingIndicatorschedule
Generado a partir de docs/status/status.json, specs/loading-indicator.spec.json
Una especificación revisada, que aún no está en todas las plataformas
Esta página describe el indicador de carga tal como lo define ahora la especificación: espera antes de mostrarse y luego entra. El componente web ya lo hace, y también las demostraciones, que aparecen después del retardo. SwiftUI, Compose, Flutter y React Native están marcados arriba como rezagados: hasta que se pongan al día, dibujan y exponen el indicador en cuanto se inserta, y no admiten las tres propiedades nuevas, así que sus ejemplos de más abajo muestran solo lo que ofrecen.
En línea y con contenedor
<section aria-busy="true">
<tanrei-loading-indicator label="Cargando mensajes"></tanrei-loading-indicator>
</section>
<!-- Con contenedor: sobre un círculo elevado propio, encima del contenido. -->
<tanrei-loading-indicator contained size="large" label="Actualizando"></tanrei-loading-indicator>
<!-- Un botón ocupado responde a la pulsación de inmediato: sin retardo. -->
<tanrei-loading-indicator size="small" show-delay="0" label="Guardando"></tanrei-loading-indicator>
<!-- Otro ritmo para un solo indicador: espera más y luego entra creciendo. -->
<tanrei-loading-indicator show-delay="600" entrance="grow" label="Cargando el informe"></tanrei-loading-indicator>
<script type="module">
import '@tanrei/web/components/loading-indicator';
</script>import { LoadingIndicator } from '@tanrei/react';
<section aria-busy={loading}>
{loading ? <LoadingIndicator label="Cargando mensajes" /> : <MessageList />}
</section>
<LoadingIndicator contained size="large" label="Actualizando" />
<LoadingIndicator size="small" showDelay={0} label="Guardando" />
<LoadingIndicator showDelay={600} entrance="grow" label="Cargando el informe" />import Tanrei
TanreiLoadingIndicator("Cargando mensajes")
// Encima del contenido, sobre su propio contenedor elevado.
TanreiLoadingIndicator("Actualizando", size: .large, contained: true)import io.github.chnotchy.tanrei.components.TanreiContainedLoadingIndicator
import io.github.chnotchy.tanrei.components.TanreiLoadingIndicator
import io.github.chnotchy.tanrei.tokens.TanreiLoadingIndicatorSize
TanreiLoadingIndicator(contentDescription = "Cargando mensajes")
// La forma con contenedor es un segundo composable con los mismos parámetros.
TanreiContainedLoadingIndicator(contentDescription = "Actualizando", size = TanreiLoadingIndicatorSize.Large)import 'package:tanrei/tanrei.dart';
const TanreiLoadingIndicator(semanticsLabel: 'Cargando mensajes');
const TanreiLoadingIndicator(
semanticsLabel: 'Actualizando',
size: TanreiLoadingIndicatorSize.large,
contained: true,
);import { LoadingIndicator } from '@tanrei/react-native';
<LoadingIndicator accessibilityLabel="Cargando mensajes" />
<LoadingIndicator accessibilityLabel="Actualizando" size="large" contained />Tamaños, en línea y con contenedor
Anatomía
Anatomía
small, tal como lo dibuja el paquete web.| Parte | Descripción |
|---|---|
1 indicator | The moving mark: an arc a quarter of a circle long that turns. It has no track, because there is no value to read. |
2 container · opcional | A filled, raised circle behind the indicator, drawn only when contained, so the indicator can be seen over content. |
Medidas
Medidas
| Longitud | Token | Valor (px) |
|---|---|---|
indicator size | tanrei.comp.loading-indicator.indicator.size.small | 16 |
small, tal como lo dibuja el paquete web.Propiedades
| Propiedad | Tipo | Valor predeterminado | Descripción |
|---|---|---|---|
size | small | medium | large | "medium" | The indicator's box (16 / 24 / 40): small replaces an icon in a control, medium sits next to text, large fills an empty section. Contained, the container is 24 / 32 / 48. A design system may add values. |
contained | boolean | false | Draws the indicator on a raised container of its own, for places where it floats over content (pull to refresh, over an image or a list). |
label | string | "" | The accessible name: what is loading ("Loading messages"). Required: a moving mark alone is not a name. |
showDelay | number | null | How long, in milliseconds, this indicator waits from the moment it is inserted before it is drawn and exposed to assistive technology; 0 shows it as it is inserted. Null takes comp.loading-indicator.motion.show-delay, the system's answer for every indicator. Set it only where one indicator needs another pace than the rest (a wait the product knows is never instant, a busy button that should answer the press at once). |
entrance | auto | fade | grow | "auto" | How this indicator enters once its show delay has passed: fade eases it in, grow eases it in while it grows from its center. Auto takes comp.loading-indicator.motion.entrance, the system's answer for every indicator. Under reduced motion grow enters as fade (LDG-13). |
enterDuration | number | null | How long, in milliseconds, this indicator's entrance lasts; 0 shows it whole at once. Null takes comp.loading-indicator.motion.enter-duration. |
Estados
Comportamiento
Requisitos en formato EARS. Cada implementación de plataforma se prueba contra estos identificadores. El texto de los requisitos se muestra tal como está en la especificación, en inglés.
| ID | Requisito |
|---|---|
LDG-1 | THE loading indicator SHALL draw, inside a comp.loading-indicator.indicator.size.medium square for medium (and so on for each size), an arc a quarter of the circle long with round caps and a stroke of comp.loading-indicator.indicator.thickness.medium for medium (and so on), whose outer edge touches the square, and SHALL turn it clockwise once per comp.loading-indicator.motion.cycle-duration at constant speed (sys.motion.easing.linear); it SHALL draw no track. |
LDG-2 | WHILE contained is false THE loading indicator SHALL take exactly its indicator square, draw no container, and draw the arc in comp.loading-indicator.indicator.color. |
LDG-3 | WHILE contained is true THE loading indicator SHALL draw a container of comp.loading-indicator.container.size.medium for medium (and so on for each size) with corners of comp.loading-indicator.container.shape, filled with comp.loading-indicator.contained.container.color and raised by comp.loading-indicator.contained.container.elevation, center the indicator in it, and draw the arc in comp.loading-indicator.contained.indicator.color. |
LDG-4 | WHERE reduced motion is requested THE loading indicator SHALL NOT turn: it SHALL draw the whole circle at the indicator's size and stroke and ease its opacity from 1 to 0 and back to 1 once per comp.loading-indicator.motion.cycle-duration with sys.motion.easing.standard; a container, when contained, SHALL stay still and opaque. |
LDG-5 | WHILE the loading indicator is shown (LDG-12) THE loading indicator SHALL expose the progressbar role to assistive technology with label as its name, no current value, and the platform's busy or indeterminate state. |
LDG-6 | THE loading indicator SHALL NOT be focusable and SHALL NOT announce itself when it appears or disappears; the region being loaded is marked busy, and its completion announced, by the product. |
LDG-7 | WHILE the loading indicator is not visible (scrolled out of view, in a hidden view, or in an app in the background) THE loading indicator SHALL NOT run its animation, and SHALL resume it when it becomes visible. |
LDG-8 | WHERE the layout direction is right-to-left THE loading indicator SHALL NOT be mirrored: it turns clockwise in every direction. |
LDG-9 | WHEN size names a value that the active design system does not have THE loading indicator SHALL render with the default value's tokens, and in debug builds report the unknown value. |
LDG-10 | WHILE label is empty THE loading indicator SHALL still render, and in debug builds report that it has no accessible name. |
LDG-11 | WHEN the loading indicator is inserted into a view THE loading indicator SHALL wait for its show delay (LDG-14) before it is shown, and WHILE it waits SHALL draw nothing (no indicator, no container, no shadow), SHALL run no animation, SHALL be absent from the accessibility tree (no role, no name, no busy state), and SHALL still take the box it takes when shown (LDG-2, LDG-3), so that nothing around it moves when it appears; a show delay of 0 SHALL show it as it is inserted. |
LDG-12 | WHEN its show delay ends THE loading indicator SHALL be shown: it SHALL expose itself as LDG-5 says, without announcing itself (LDG-6), start its entrance (LDG-13), and start the turn of LDG-1, or the pulse of LDG-4, at the beginning of a cycle. |
LDG-13 | WHEN the loading indicator is shown THE loading indicator SHALL enter over its enter duration (LDG-14) with comp.loading-indicator.motion.enter-easing, as its entrance names: fade SHALL ease the opacity of the whole component (the indicator and, when contained, the container and its shadow) from 0 to 1, and grow SHALL ease the opacity the same way while scaling the whole component from nothing to its full size about its center, on the same curve over the same time. The entrance SHALL be drawn only: the box SHALL keep its full size throughout, and the entrance SHALL run to its end whether or not the indicator is visible (LDG-7 pauses the cycle, not the entrance). An enter duration of 0 SHALL show the indicator whole at once. WHERE reduced motion is requested THE loading indicator SHALL NOT scale: grow SHALL enter as fade, and on a platform whose reduced-motion setting removes every animation (Android's) the indicator SHALL appear at once. |
LDG-14 | THE loading indicator SHALL take its show delay from showDelay and its enter duration from enterDuration, each a number of milliseconds used as given (the motion dial does not scale it), and its kind of entrance from entrance. WHILE showDelay or enterDuration is null THE loading indicator SHALL use comp.loading-indicator.motion.show-delay or comp.loading-indicator.motion.enter-duration in its place, and WHILE entrance is auto it SHALL use comp.loading-indicator.motion.entrance; IF showDelay or enterDuration is negative or not a finite number, or entrance names a kind the indicator does not know, THE loading indicator SHALL use the token likewise and in debug builds report the value it ignored. |
LDG-15 | THE loading indicator SHALL treat its show delay as a waiting time, not motion: WHERE motion is reduced it SHALL keep it, on every platform, including one whose reduced-motion setting removes every animation; and it SHALL keep counting it while the indicator cannot be seen (scrolled out of view, in a hidden view), because the delay measures the wait, not what is seen. |
LDG-16 | WHEN the loading indicator is removed before its show delay ends THE loading indicator SHALL have drawn, exposed and announced nothing, and WHEN it is removed while shown, during its entrance included, it SHALL disappear at once. WHEN it is inserted again THE loading indicator SHALL wait its whole show delay again; hiding it without removing it (a hidden ancestor, scrolling) SHALL neither restart nor pause the delay (LDG-15). WHEN showDelay, entrance or enterDuration changes while the delay or the entrance is running THE loading indicator SHALL finish the running one as it started and use the new value from its next insertion. |
LDG-17 | THE loading indicator SHALL take its layout direction from where it is used — the direction of the nearest ancestor that sets one, and the platform's own where none does — and SHALL have no direction setting of its own; WHEN that direction changes while the loading indicator is shown THE loading indicator SHALL draw itself for the new direction at once, without a motion of its own, keeping its place in its cycle. |
LDG-18 | WHERE the platform has ARIA attributes (the web), the host carries its progressbar role (LDG-5) itself, so what the product writes on it is not moved, but for a name: WHILE label is not empty THE loading indicator SHALL hold the product's aria-label and aria-labelledby on that host as their data-aria- twins, so that label is its whole name although the platform gives aria-labelledby the precedence, and WHEN label is emptied SHALL give them back as they were written; WHILE label is empty a name the product gives so — aria-label, or aria-labelledby naming an element — SHALL be its name and SHALL NOT be reported as having none in debug builds (LDG-10). WHILE it waits to be shown (LDG-11) it has no role, and SHALL hold them as well, so that nothing names an element with no role, and give them back when it is shown. WHEN the product removes one, or its data-aria- twin, or sets the ARIA property that reflects it (ariaLabel, ariaLabelledByElements) to null, THE loading indicator SHALL take it away. |
Correspondencia de nombres por plataforma
Paridad no significa API idénticas. Cada plataforma expresa el mismo contrato con su propio estilo.
| Especificación | Web | SwiftUI | Jetpack Compose | Flutter | React Native |
|---|---|---|---|---|---|
| Componente | tanrei-loading-indicator | TanreiLoadingIndicator | TanreiLoadingIndicator | TanreiLoadingIndicator | LoadingIndicator |
size · Propiedad | size | size | size | size | size |
contained · Propiedad | contained | contained | TanreiContainedLoadingIndicator | contained | contained |
label · Propiedad | label | label | contentDescription | semanticsLabel | accessibilityLabel |
showDelay · Propiedad | showDelay | showDelay | showDelayMillis | showDelay | showDelay |
entrance · Propiedad | entrance | entrance | entrance | entrance | entrance |
enterDuration · Propiedad | enterDuration | enterDuration | enterDurationMillis | enterDuration | enterDuration |
| Notas | The host carries role="progressbar", aria-label and aria-busy="true" once shown, and no aria-value attributes; during the show delay it carries none of them and is aria-hidden="true", and its parts are visibility: hidden while the host keeps its size (LDG-11). The delay starts in connectedCallback and is cancelled in disconnectedCallback, so moving the element within the document starts a new delay; hiding it with hidden or CSS does not (LDG-16) — insert and remove it with the wait. showDelay and enterDuration are number properties in milliseconds, null by default, set by the show-delay and enter-duration attributes; an attribute that is empty or does not parse as a finite number is not a number (LDG-14), so show-delay="" takes the token and does not show at once. entrance is a string property and attribute, auto by default; auto reads --tanrei-comp-loading-indicator-motion-entrance from the cascade, which carries the choice's name. The arc turns with a CSS animation that @media (prefers-reduced-motion: reduce) replaces, and pauses while the element is not intersecting the viewport. Snapshot harness: each fixture is rendered with show-delay="0" and enter-duration="0" (LDG-11). | Lagging: ships the earlier spec, drawn and exposed as it is inserted, with no delay or entrance; owes LDG-5's revision and LDG-11 to LDG-16. The target: TanreiLoadingIndicator(_ label:, size:, contained:, showDelay: Duration? = nil, entrance: TanreiLoadingEntrance? = nil, enterDuration: Duration? = nil); a Duration carries its own unit (.milliseconds(300)), nil takes the token (nil is also entrance's auto), and a negative one takes the token and is reported in debug builds. The delay is a .task bound to the view's identity (cancelled when the view leaves the hierarchy), and the view is .accessibilityHidden(true) and at zero opacity until it ends, keeping its frame. Reduced motion is accessibilityReduceMotion from the environment. Snapshot harness: renders each fixture with showDelay: .zero and enterDuration: .zero. | Lagging: ships the earlier spec, drawn and exposed as it is inserted, with no delay or entrance; owes LDG-5's revision and LDG-11 to LDG-16. The target adds showDelayMillis: Long? = null, entrance: TanreiLoadingEntrance? = null (null is auto) and enterDurationMillis: Long? = null to both composables, named in milliseconds as ViewConfiguration.longPressTimeoutMillis is; null takes the token, a negative value takes the token and is reported in debug builds. The delay is a coroutine delay in a LaunchedEffect started when the indicator enters the composition, not an animation, so the animator duration scale of 0 (Android's reduced motion) does not remove it (LDG-15); until it ends the layout keeps its size, draws nothing, and its semantics are cleared. Compose idiom, as Material's LoadingIndicator and ContainedLoadingIndicator: contained is a second composable, TanreiContainedLoadingIndicator, with the same parameters, not a flag. Snapshot harness: renders each fixture with showDelayMillis = 0 and enterDurationMillis = 0. | Lagging: ships the earlier spec, drawn and exposed as it is inserted, with no delay or entrance; owes LDG-5's revision and LDG-11 to LDG-16. The target adds showDelay, entrance (a TanreiLoadingEntrance?, null is auto) and enterDuration, the times as Duration?: null takes the token, a negative one takes the token and is reported in debug builds. The delay is a Timer started in initState and cancelled in dispose; until it ends the child keeps its size, paints nothing and is wrapped in ExcludeSemantics. semanticsLabel as Flutter's progress indicators name it. Reduced motion is MediaQuery.disableAnimationsOf(context); the turning animation stops with TickerMode, which covers hidden routes, and the timer does not. Snapshot harness: a golden of each fixture with showDelay: Duration.zero and enterDuration: Duration.zero. | Lagging: ships the earlier spec, drawn and exposed as it is inserted, with no delay or entrance; owes LDG-5's revision and LDG-11 to LDG-16. The target: showDelay and enterDuration are numbers of milliseconds, as Pressable's delayLongPress is; undefined or null takes the token, and a negative or non-finite number takes the token and is reported in development builds; entrance is 'auto' | 'fade' | 'grow', 'auto' by default. The delay is a timer set when the component mounts and cleared when it unmounts; until it ends the view keeps its size at zero opacity with accessibilityElementsHidden and importantForAccessibility="no-hide-descendants", and once shown it takes accessibilityRole="progressbar" with accessibilityState={{ busy: true }}. Reduced motion from AccessibilityInfo.isReduceMotionEnabled(). Not React Native's ActivityIndicator, which draws the platform's own spinner and cannot follow the tokens. Snapshot harness: renders each fixture with showDelay={0} and enterDuration={0}. |
Tokens
| Token | Alias de | Valor resuelto (claro) |
|---|---|---|
--tanrei-comp-loading-indicator-contained-container-color | sys.color.surface-container-lowest | |
--tanrei-comp-loading-indicator-contained-container-elevation | sys.elevation.level2 | 0px 0px 0px 1px rgb(0 0 0 / 0.08), 0px 1px 2px 0px rgb(0 0 0 / 0.04) |
--tanrei-comp-loading-indicator-contained-indicator-color | sys.color.on-surface-variant | |
--tanrei-comp-loading-indicator-container-shape | sys.shape.corner.full | 9999px |
--tanrei-comp-loading-indicator-container-size-large | — | 48px |
--tanrei-comp-loading-indicator-container-size-medium | — | 32px |
--tanrei-comp-loading-indicator-container-size-small | — | 24px |
--tanrei-comp-loading-indicator-indicator-color | sys.color.on-surface-variant | |
--tanrei-comp-loading-indicator-indicator-size-large | — | 40px |
--tanrei-comp-loading-indicator-indicator-size-medium | — | 24px |
--tanrei-comp-loading-indicator-indicator-size-small | — | 16px |
--tanrei-comp-loading-indicator-indicator-thickness-large | sys.border.thick | 2px |
--tanrei-comp-loading-indicator-indicator-thickness-medium | sys.border.thick | 2px |
--tanrei-comp-loading-indicator-indicator-thickness-small | sys.border.thick | 2px |
--tanrei-comp-loading-indicator-motion-cycle-duration | sys.motion.duration.extra-long4 | 1000ms |
--tanrei-comp-loading-indicator-motion-enter-duration | sys.motion.role.state.large | 250ms |
--tanrei-comp-loading-indicator-motion-enter-easing | sys.motion.easing.enter | cubic-bezier(0.2, 0, 0, 1) |
--tanrei-comp-loading-indicator-motion-entrance | — | 0 |
--tanrei-comp-loading-indicator-motion-show-delay | sys.motion.role.show-delay | 300ms |
Fixtures
Representaciones canónicas. Todas las plataformas capturan cada fixture con el mismo identificador para poder comparar los resultados.
size: small (2)
small
size: small label: Loading contained-small
size: small contained: true label: Loading size: medium (2)
medium
label: Loading contained-medium
contained: true label: Loading size: large (2)
large
size: large label: Loading contained-large
size: large contained: true label: Loading Generado a partir de specs/loading-indicator.spec.json, tokens/comp/loading-indicator.tokens.json, design/tokens/
Usa un indicador de carga para una espera breve cuya duración no puedes conocer: una lista que obtiene su página siguiente, un control que guarda, una vista previa que se está generando. Dice que algo está ocurriendo y nada sobre cuánto va a tardar.
Cuando la espera pueda durar más de unos segundos, o cuando puedas medir cuánto ha avanzado, usa en su lugar un indicador de progreso. Un valor, aunque sea aproximado, hace más llevadera una espera larga.
| Tamaño | Indicador / contenedor en el sistema predeterminado | Úsalo para |
|---|---|---|
| Small | 16 / 24 | En lugar de un icono dentro de un control, como un botón que está guardando. |
| Medium | 24 / 32 | Junto a una línea de texto. Es el valor predeterminado. |
| Large | 40 / 48 | Una sección vacía o una vista entera que espera su contenido. |
La forma con contenedor dibuja el indicador sobre un círculo elevado propio. Úsala donde el indicador flota sobre el contenido, como al tirar para actualizar o encima de una imagen o de una lista, para que siga viéndose sea lo que sea lo que haya detrás. Donde se apoya sobre una superficie lisa, déjalo en línea.
Una espera que termina en un instante no debería mostrar nada. Por eso el indicador espera antes de mostrarse: 300 ms en el sistema predeterminado, contados desde el momento en que se inserta. Después aparece con un fundido. Una espera más corta que el retardo nunca muestra una marca que se enciende y se apaga. Durante el retardo el indicador ya ocupa su tamaño completo, así que nada de lo que tiene al lado se mueve cuando aparece.
Inserta el indicador cuando empiece la espera y quítalo cuando termine. El retardo cuenta desde la inserción: un indicador que se oculta y se vuelve a mostrar sin quitarlo no espera otra vez, y uno que se inserta de nuevo vuelve a esperar el retardo entero.
El sistema decide el retardo y la entrada de todos los indicadores. Defínelos en un indicador solo cuando necesite un ritmo distinto:
showDelayes la espera en milisegundos.0muestra el indicador en cuanto se inserta, para un botón ocupado que debe responder a la pulsación de inmediato.entranceesfadeogrow. Con grow, el indicador aparece con un fundido mientras crece desde su centro.auto, el valor predeterminado, toma la elección del sistema.enterDurationes la duración de la entrada en milisegundos.0muestra el indicador entero de una vez.
Un valor que definas se usa tal como lo das: el dial de movimiento no lo escala. Deja una propiedad sin definir para tomar el valor del sistema.
- Dale una etiqueta que diga qué se está cargando: «Cargando mensajes», no «Cargando». Si se muestra una leyenda a su lado, usa las mismas palabras.
- Ponlo donde aparecerá el contenido, para que la persona mire al lugar correcto cuando llegue.
- Cuando sustituya a un icono dentro de un control, conserva el tamaño del control, para que nada se mueva a su alrededor.
- Deja el retardo en manos del sistema salvo que un indicador necesite otro ritmo.
- No lo uses para una espera que puedes medir, ni para una que pueda alargarse. Usa un indicador de progreso.
- No muestres varios indicadores para una misma espera. Basta con uno por cada región que se está cargando.
- No lo pongas sobre una pantalla entera cuando solo se está cargando una parte. Mantén utilizable el resto.
- No le des color para decir que algo ha ido mal. Detenlo y muestra un mensaje.
- No dejes un indicador en su sitio ocultándolo entre una espera y otra. Quítalo, para que la siguiente espera inicie un retardo nuevo.
- Rol
progressbar- Etiquetado
- label is the accessible name. The indicator has no value: once shown, it is exposed as a progressbar in the platform's busy (indeterminate) state, never as a status message; during its show delay it is not exposed at all (LDG-11).
- Objetivo mínimo
- El área de pulsación cumple el tamaño mínimo de objetivo aunque el tamaño visual sea menor. minimum 32px · pointer 44px · spacing 8px · touch 48px
Teclado
| Teclas | Acción |
|---|
Notas
- Not interactive: the indicator takes no input and is never focusable (LDG-6), so the minimum target holds without extending anything.
- comp.loading-indicator.indicator.color must stay at least 3:1 against the surface behind it, and comp.loading-indicator.contained.indicator.color against comp.loading-indicator.contained.container.color (non-text contrast): the moving mark is the only sign that something is happening.
- Text size does not change the indicator: it is not text. Where it replaces an icon in a control, the control keeps its size.
- A product marks the region it loads as busy (aria-busy on the web) and says when the content has arrived; a wait that may exceed a few seconds, or whose length can be measured, belongs to the progress indicator.
- A wait shorter than the show delay shows and exposes nothing (LDG-11): no mark that flashes for a sighted person, and no progressbar that appears and vanishes for a screen-reader user. The product's own busy marking of the region does not wait for the delay; aria-busy and its equivalents announce nothing by themselves.
- Reduced motion replaces the turning arc with an opacity pulse of at most one per second (LDG-4), below the three-per-second flash threshold, and turns a grow entrance into a fade (LDG-13). The show delay is kept: it is a wait, not motion (LDG-15).
Generado a partir de specs/loading-indicator.spec.json, tokens/sys/measure.tokens.json
- Una vez mostrado, expone el rol de barra de progreso en el estado ocupado de la plataforma, con la etiqueta como nombre y sin valor. Flutter todavía no tiene rol de barra de progreso ni estado ocupado, así que ahí expone la etiqueta.
- Durante su retardo de aparición no está en el árbol de accesibilidad: sin rol, sin nombre, sin estado ocupado. Una espera demasiado corta para verse tampoco se oye.
- Nunca puede recibir el foco, y no se anuncia a sí mismo cuando aparece ni cuando desaparece.
- Cuando se pide reducir movimiento, el arco deja de girar y, en su lugar, un círculo completo hace pulsar suavemente su opacidad, como mucho una vez por segundo; un contenedor se queda quieto. Una entrada grow se convierte en un fundido. El retardo de aparición se conserva: es una espera, no movimiento.
- Su animación se detiene mientras no se puede ver (en todas partes cuando la aplicación está en segundo plano, y cuando queda desplazado fuera de la vista o en una pantalla oculta donde la plataforma puede saberlo) y se reanuda cuando se puede.
- Una etiqueta vacía se notifica en las compilaciones de depuración.
- Marca como ocupada la región que se está cargando mientras se carga (
aria-busyen la web), desde el inicio de la espera, sin aguardar al retardo del indicador, y di cuándo ha llegado el contenido: con un mensaje en una región activa (live region), o llevando el foco al contenido nuevo cuando la persona lo haya pedido. - Si cambias los colores, mantén el color del indicador con un contraste de al menos 3:1 frente a la superficie que tiene detrás, y el color del indicador con contenedor frente a su contenedor. La marca en movimiento es la única señal de que algo está ocurriendo.