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85 lines
3.7 KiB
Markdown
85 lines
3.7 KiB
Markdown
<!--docs:
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title: "Bottom Sheets"
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layout: detail
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section: components
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excerpt: "Bottom sheets slide up from the bottom of the screen to reveal more content."
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iconId: bottom_sheet
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path: /catalog/bottom-sheet-behavior/
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-->
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# Bottom Sheets
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<!--{: .article__asset.article__asset--screenshot }-->
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`BottomSheetBehavior` is applied to a child of
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[CoordinatorLayout](CoordinatorLayout.md)
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to make that child a **persistent bottom sheet**.
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Persistent bottom sheets are views that come up from the bottom of the
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screen, elevated over the main content. They can be dragged vertically to
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expose more or less of their content.
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Note: If you want to use Bottom Sheets that are modal (dialogs), use
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[BottomSheetDialogFragment](BottomSheetDialogFragment.md).
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## Design & API Documentation
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- [Material Design guidelines: Bottom Sheets](https://material.io/guidelines/components/bottom-sheets.html#bottom-sheets-persistent-bottom-sheets)
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<!--{: .icon-list-item.icon-list-item--spec }-->
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- [Class definition](https://github.com/material-components/material-components-android/tree/master/lib/src/android/support/design/widget/BottomSheetBehavior.java)
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<!--{: .icon-list-item.icon-list-item--link }-->
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- [Class overview](https://developer.android.com/reference/android/support/design/widget/BottomSheetBehavior.html)
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<!--{: .icon-list-item.icon-list-item--link }-->
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<!--{: .icon-list }-->
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## Usage
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`BottomSheetBehavior` works in tandem with CoordinatorLayout to let you display
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content on a Bottom sheet (a layer on top of the main content), perform
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enter/exit animations, respond to dragging/swiping gestures, etc.
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Bottom sheets have 5 states:
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- `STATE_COLLAPSED`: The bottom sheet is visible but only showing its peek
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height. This state is usually the 'resting position' of a Bottom Sheet. The
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peek height is chosen by the developer and should be enough to indicate
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there is extra content, allow the user to trigger an action or expand the
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bottom sheet.
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- `STATE_EXPANDED`: The bottom sheet is visible and its maximum height and it
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is neither dragging or settling (see below).
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- `STATE_DRAGGING`: The user is actively dragging the bottom sheet up or down.
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- `STATE_SETTLING`: The bottom sheet is settling to specific height after a
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drag/swipe gesture. This will be the peek height, expanded height, or
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0, in case the user action caused the bottom sheet to hide.
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- `STATE_HIDDEN`: The bottom sheet is no longer visible.
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If you're already using CoordinatorLayout for your activity, adding a bottom
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sheet is trivial:
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1. Add any View as a direct child of CoordinatorLayout.
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2. Apply the behavior by adding the following xml attribute
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`app:layout_behavior="android.support.design.widget.BottomSheetBehavior"`
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3. Set the desired behavior flags
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- `app:behavior_hideable` whether this bottom sheet can be hidden by
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dragging it down.
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- `app:behavior_peekHeight` the peek height for the collapsed state.
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- `app:behavior_skipCollapsed` if the bottom sheet is hideable, and this
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is set to true, it does not have a collapsed state.
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To programatically control the bottom sheet you can call the `setState` method
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on the `BottomSheetBehavior`. A common pattern is setting a peek height and
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setting the state to collapsed to make it visible to the user:
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```java
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bottomSheetBehavior.setPeekHeight(300);
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bottomSheetBehavior.setState(BottomSheetBehavior.STATE_COLLAPSED);
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```
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## Related Concepts
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Using [BottomSheetDialogFragment](BottomSheetDialogFragment.md) provides a
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similar UI and interactions as `BottomSheetBehavior`, however
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BottomSheetDialogFragment does not require CoordinatorLayout and creates a modal
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bottom sheet (essentially a dialog).
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