- - Example of a Heads-up notification (incoming phone call, high priority) coming in on top of an - immersive app -
-The notification system allows users to keep informed about relevant and timely -events in your app, such as new chat messages from a friend or a calendar event. -Think of notifications as a news channel that alerts the user to important events as -they happen or a log that chronicles events while the user is not paying attention - -and one that is synced as appropriate across all their Android devices.
- -In L, notifications receive an important structural visual and functional update:
- -This section goes over basic parts of a notification and how they can -appear on different types of devices.
- -At a minimum, all notifications consist of a base layout, including:
- -Notifications created with Notification.Builder for versions of Android earlier
-than L will look and work the same in L, with only minor stylistic changes that the system handles
-for you.
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-- Base layout of a handheld notification and the same notification on Wear, - with a user photo and a notification icon -
-You have the option to provide more details on notifications. You can use this to show the first -few lines of a message or show a larger image preview. This provides the user with additional -context, and - in some cases - may allow the user to read a message in its entirety. The user can -pinch-zoom or perform a single-finger glide in order to toggle between compact and expanded layouts. - For single event notifications, Android provides three expanded layout templates (text, inbox, and - image) for you to re-use in your application. The following images show you how they look on - handhelds and wearables.
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-Android has supported optional actions that are displayed at the bottom of the notification, as -far back as Jelly Bean. With actions, users can handle the most common tasks for a particular -notification from within the notification shade without having to open the originating application. -This speeds up interaction and, in conjunction with "swipe-to-dismiss", helps users to streamline -their notification triaging experience.
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-Be judicious with how many actions you include with a notification. The more -actions you include, the more cognitive complexity you create. Limit yourself to the fewest number -of actions possible by only including the most imminently important and meaningful ones.
- -Good candidates for actions on notifications are actions that:
- -Avoid actions that are:
- -You can specify a maximum of three actions, each consisting of an action icon and an action name. - Adding actions to a simple base layout will make the notification expandable, even if the - notification doesn't have an expanded layout. Since actions are only shown for expanded - notifications and are otherwise hidden, you must make sure that any action a user can invoke from - a notification is available from within the associated application as well.
- -Additionally, notifications and their actions are bridged over to Wear devices by default. -Developers have control to control which notifications from bridging from the phone to the watch -and vice versa. And developers can control which actions bridge as well. If your app includes -actions that can't be accomplished with a single tap, either hide these actions on your Wear -notification or consider hooking them up to a Wear app to allow the user to finish the action on -their watch.
- -Notifications that should be bridged
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-Don't bridge
- -Actions to bridge
- -Actions not to bridge
- -Unique actions to define for Wear
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- - Example of a Heads-up notification (incoming phone call, high priority) coming in on top of an - immersive app -
-When notifications with priority set to High (see right) arrives, it is presented to users for a -short period of time on the device with an expanded layout with its actions exposed.
-After this period of time, it retreats back to the Notification shade. If a notification is -flagged as High or Max or a full-screen takeover, it gets a HUN in L.
- -Good examples of Heads-up notifications
- -For notifications of items sent by another person (such as a message or status update), include -that person's image using setLargeIcon. Also attach information about the person to the -notification's metadata (see EXTRA_PEOPLE).
- -Your notification's main icon will still be shown, so the user can associate it with the icon -visible in the status bar.
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-- Notification that shows the person who triggered it and the content they are sending you -
- - -When the user touches the body of a notification (outside of the action buttons), open your app -to the place where the user can view and act upon the data referenced in the notification. In most -cases this will be the detail view of a single data item such as a message, but it might also be a -summary view if the notification is stacked (see Stacked notifications below) and -references multiple items. If in any of those cases the user is taken to a hierarchy level below -your app's top-level, insert navigation into your app's back stack to allow them to navigate to -your app's top level using the system back button. For more information, see the chapter on -System-to-app navigation in the Navigation -design pattern.
- -Starting with Jelly Bean, Android supported a priority flag for notifications. It allows you to -influence where your notification will appear in comparison to other notifications and help to make -sure that users always see their most important notifications first. You can choose from the -following priority levels when posting a notification:
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- Use for critical and urgent notifications that alert the user to a condition that is -time-critical or needs to be resolved before they can continue with a particular task. - |
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- Use high priority notifications primarily for important communication, such as message or chat -events with content that is particularly interesting for the user. High priority notifications will get the Heads-Up Notification display starting in L. - |
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- The default priority. Keep all notifications that don't fall into any of the other categories at -this priority level. - |
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- Use for notifications that you still want the user to be informed about, but that rate low in -urgency. LOW notifications will tend to show up at the bottom of the list, which makes them a good -choice for things like pubic/undirected social updates: the user has asked to be notified about -them, but they should never take precedence over urgent or direct communication. - |
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- Contextual/background information (e.g. weather information, contextual location information). -Minimum priority notifications will not show in the status bar. The user will only discover them -when they expand the notification shade. - |
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Default, High, and Max priority are interruptive priority levels and risk interrupting the user -from what they are doing. This should not be taken lightly, so these levels should be reserved -for notifications that:
- -Notifications set to LOW and MIN can still be very valuable for the
-user. Many if not most notifications just don't need to command the user's immediate attention, or
-vibrate the user's wrist, yet contain information that they will find valuable when they choose to
-look for notifications. Criteria for LOW and MIN priority notifications:
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-If your notification falls into one of the predefined categories (see below), assign it -accordingly. Aspects of the system UI such as the notification shade (or any other notification -listener) may use this information to make ranking and filtering decisions.
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- Incoming call (voice or video) or similar synchronous communication request - |
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- A specific, timely recommendation for a single thing. For example, a news app might want to -recommend a news story it believes the user will want to read next. - |
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If your app creates a notification while another of the same type is still pending, avoid -creating an altogether new notification object. Instead, turn it into a summary notification for -the app.
- -A summary notification builds a summary description and allows the user to understand how many -notifications of a particular kind are pending.
- -Don't
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-You can provide more detail about the individual notifications that make up a - summary by using the expanded digest layout. This allows users to gain a better sense of which - notifications are pending and if they are interesting enough to be read in detail within the - associated app.
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- - Expanded and contracted notification that is a summary (using InboxStyle) -
-Users should always be in control of notifications. Allow the user to disable your app's -notifications or change their alert properties, such as alert sound and whether to use vibration, -by adding a notification settings item to your application settings.
- -By glancing at the notification area, the user should be able to discern what kinds of -notifications are currently pending.
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-Look at the notification icons Android apps already provide and create notification icons for - your app that are sufficiently distinct in appearance.
- -Do
-Use the proper notification icon - style for small icons, and the Material Light - action bar icon style for your action - icons. Do not place any additional alpha (dimming or fading) into your small icons and action - icons; they can have anti-aliased edges, but because L uses these icons as masks (that is, only - the alpha channel is used), the image should generally be drawn at full opacity.
-Do
-Keep your icons visually simple and avoid excessive detail that is hard to discern.
- -Don't
- -Use color to distinguish your app from others. Notification icons should only be a white-on-transparent background image.
- - -Many Android devices contain a notification LED, which is used to keep the user informed about
-events while the screen is off. Notifications with a priority level of MAX, HIGH, or DEFAULT should
-cause the LED to glow, while those with lower priority (LOW and MIN) should not.
The user's control over notifications should extend to the LED. When you use DEFAULT_LIGHTS, the -LED will glow with a white color. Your notifications shouldn't use a different color unless the -user has explicitly customized it.
- -To create an app that users love, it is important to design your notifications carefully. -Notifications embody your app's voice, and contribute to your app's personality. Unwanted or -unimportant notifications can annoy the user or make them resent how much attention the app wants -from them, so use notifications judiciously.
- -To create an application that people enjoy using, it's important to recognize that the user's
-attention and focus is a resource that must be protected. While Android's notification system has
-been designed to minimize the impact of notifications on the user's attention, it is nonetheless
-still important to be aware of the fact that notifications are interrupting the user's task flow.
-As you plan your notifications, ask yourself if they are important enough to warrant an interruption. If you are unsure, allow the user to opt into a notification using your apps notification settings or adjust
-the notifications priority flag to LOW or MIN to avoid distracting the user while they are doing
-something else.
- - Time sensitive notification examples -
- -While well behaved apps generally only speak when spoken to, there are some limited cases where an app actually should interrupt the user with an unprompted notification.
- -Notifications should be used primarily for time sensitive events, and especially - if these synchronous events involve other people. For instance, an incoming chat - is a real time and synchronous form of communication: there is another user actively waiting on you - to respond. Calendar events are another good example of when to use a notification and grab the - user's attention, because the event is imminent, and calendar events often involve other people.
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-There are however many other cases where notifications should not be used:
- -Notifications are indicated by icons in the status bar and can be accessed by opening the -notification drawer.
- -Touching a notification opens the associated app to detailed content matching the notification. -Swiping left or right on a notification removes it from the list.
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- - Ongoing notification due to music playback -
-Ongoing notifications keep users informed about an ongoing process in the background. -For example, music players announce the currently playing track in the notification system and -continue to do so until the user stops the playback. They can also be used to show the user -feedback for longer tasks like downloading a file, or encoding a video. Ongoing notifications -cannot be manually removed from the notification drawer.
- -The L lockscreen doesn't show transport controls for RCC (RemoteControlClient)s anymore. But the -lockscreen does show notifications, so each app's playback notification is now the primary -way for users to control playback from a locked state. This gives apps more control over which -buttons to show and in what way, while providing a consistent experience for the user whether on -the lockscreen or unlocked.
- -Your app should not create a dialog or toast if it is not currently on screen. Dialogs and Toasts - should only be displayed as the immediate response to the user taking an action inside of your app. -For further guidance on the use of dialogs and toasts, refer to -Confirming & Acknowledging.
- -Notifications are "news" and so they are essentially shown in reverse-chronological order, with -special consideration given to the app's stated notification priority.
- -In L, notifications are now a key part of the lockscreen, and are featured prominently every -time the device display comes on. Because space on the lockscreen is tight, it is more important -than ever to identify the most urgent or relevant notifications.
- -Therefore, L has a more sophisticated sorting algorithm for notifications, taking into account:
- -EXTRA_PEOPLE, and in
- particular whether those are starred contacts.To best take advantage of this sorting, developers should focus on the user experience they want -to create rather than aiming for any particular spot on the list.
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- Gmail notifications are default priority, so they - normally sort below messages from an instant messaging app like Hangouts, but Gmail will get a - temporary bump when new messages come in. -
- - -Starting in L, notifications are visible on the lockscreen, and so we must consider the user's -privacy. Notifications often contain sensitive information, and we must take care when showing it to -anyone who picks up the device and turns on the display.
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- - Notifications on the lockscreen followed by the Pattern Unlock when the user attempts to unlock the phone. -
-When setting up a secure lockscreen, the user can choose to conceal sensitive details from atop the secure lockscreen. In this case the SystemUI considers the notification's visibility level to figure out what can safely be shown.
- To control the visibility level, call
-Notification.Builder.setVisibility() and specify one of these values:
Notification.VISIBILITY_PUBLIC. Shows the notification's full content.
- This is the system default if visibility is left unspecified.Notification.VISIBILITY_PRIVATE. The lockscreen will reveal basic information about the existence of this notification, including its icon and the name of the app that posted it. The rest of the notification's details, however, are not displayed.
- Notification.publicVersion field.
- VISIBILITY_PRIVATE, but the publicVersion could still contain useful information like "3 new messages" without any other identifying details.
- Notification.VISIBILITY_SECRET. Shows only the most minimal information, excluding even the notification's icon.Android offers a rich user experience that's optimized for apps running on large screen - devices, such as high-definition televisions. Apps on TV offer new opportunities to - delight your users from the comfort of their couch.
- -This guide helps you build apps for TV devices, including:
- -Prepare your app for its big screen debut!
- -- Get Started > -
- diff --git a/docs/html/preview/tv/ui/index.jd b/docs/html/preview/tv/ui/index.jd deleted file mode 100644 index c861ec233dcb2..0000000000000 --- a/docs/html/preview/tv/ui/index.jd +++ /dev/null @@ -1,40 +0,0 @@ -page.title=User Interfaces for TV - -@jd:body - - -- Building an effective and engaging user interface for TV devices requires a firm understanding of what works well - in the context of a living room. Imagine a large screen that can be seen by many people at the - same time, controlled with a few buttons by users with limited attention, and you start to see the - challenges and opportunities of building an app for TV. Building apps for this environment - requires a different approach and different tools.
- -This section discusses how to build a living room experience with your app, including - implementation instructions and creating user interface widgets built for TV. Also check out - Design for TV for information and inspiration - on creating engaging user interfaces for TV devices.
- -