Skip to content

Latest commit

 

History

History
516 lines (383 loc) · 19.9 KB

BottomSheet.md

File metadata and controls

516 lines (383 loc) · 19.9 KB
Raw

Bottom Sheets

Bottom sheets are surfaces containing supplementary content that are anchored to the bottom of the screen.

Example bottom sheet: modal bottom sheet

Contents

Using bottom sheets

Before you can use Material bottom sheets, you need to add a dependency to the Material Components for Android library. For more information, go to the Getting started page.

Standard bottom sheet basic usage:

<androidx.coordinatorlayout.widget.CoordinatorLayout
  ...>

  <FrameLayout
    ...
    android:id="@+id/standard_bottom_sheet"
    app:layout_behavior="com.google.android.material.bottomsheet.BottomSheetBehavior">

    <!-- Bottom sheet contents. -->

  </FrameLayout>

</androidx.coordinatorlayout.widget.CoordinatorLayout>

Modal bottom sheet basic usage:

class ModalBottomSheet : BottomSheetDialogFragment() {

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? = inflater.inflate(R.layout.modal_bottom_sheet_content, container, false)

    companion object {
        const val TAG = "ModalBottomSheet"
    }
}

class MainActivity : AppCompatActivity() {
    ...
    val modalBottomSheet = ModalBottomSheet()
    modalBottomSheet.show(supportFragmentManager, ModalBottomSheet.TAG)
    ...
}

More information on each individual section, below.

Setting behavior

There are several attributes that can be used to adjust the behavior of both standard and modal bottom sheets.

Behavior attributes can be applied to standard bottom sheets in xml by setting them on a child View set to app:layout_behavior, or programmatically:

val standardBottomSheetBehavior = BottomSheetBehavior.from(standardBottomSheet)
// Use this to programmatically apply behavior attributes

Behavior attributes can be applied to modal bottom sheets using app-level theme attributes and styles:

<style name="ModalBottomSheet" parent="Widget.Material3.BottomSheet.Modal">
  <!-- Apply attributes here -->
</style>

<style name="ModalBottomSheetDialog" parent="ThemeOverlay.Material3.BottomSheetDialog">
  <item name="bottomSheetStyle">@style/ModalBottomSheet</item>
</style>

<style name="AppTheme" parent="Theme.Material3.*">
  <item name="bottomSheetDialogTheme">@style/ModalBottomSheetDialog</item>
</style>

Or programmatically:

val modalBottomSheetBehavior = (modalBottomSheet.dialog as BottomSheetDialog).behavior
// Use this to programmatically apply behavior attributes

More information about these attributes and their default values is available in the behavior attributes section.

Retaining behavior on configuration change

In order to save and restore specific behaviors of the bottom sheet on configuration change, the following flags can be set (or combined with bitwise OR operations):

  • SAVE_PEEK_HEIGHT: app:behavior_peekHeight is preserved.
  • SAVE_HIDEABLE: app:behavior_hideable is preserved.
  • SAVE_SKIP_COLLAPSED: app:behavior_skipCollapsed is preserved.
  • SAVE_FIT_TO_CONTENTS: app:behavior_fitToContents is preserved.
  • SAVE_ALL: All aforementioned attributes are preserved.
  • SAVE_NONE: No attribute is preserved. This is the default value.

Behaviors can also be set in code:

bottomSheetBehavior.saveFlags = BottomSheetBehavior.SAVE_ALL

Or in xml using the app:behavior_saveFlags attribute.

Setting state

Standard and modal bottom sheets have the following states:

  • STATE_COLLAPSED: The bottom sheet is visible but only showing its peek height. This state is usually the 'resting position' of a bottom sheet, and should have enough height to indicate there is extra content for the user to interact with.
  • STATE_EXPANDED: The bottom sheet is visible at its maximum height and it is neither dragging nor settling (see below).
  • STATE_HALF_EXPANDED: The bottom sheet is half-expanded (only applicable if behavior_fitToContents has been set to false), and is neither dragging nor settling (see below).
  • STATE_HIDDEN: The bottom sheet is no longer visible and can only be re-shown programmatically.
  • STATE_DRAGGING: The user is actively dragging the bottom sheet up or down.
  • STATE_SETTLING: The bottom sheet is settling to a specific height after a drag/swipe gesture. This will be the peek height, expanded height, or 0, in case the user action caused the bottom sheet to hide.

You can set a state on the bottom sheet:

bottomSheetBehavior.state = BottomSheetBehavior.STATE_COLLAPSED

Note: STATE_SETTLING and STATE_DRAGGING should not be set programmatically.

Listening to state and slide changes

A BottomSheetCallback can be added to a BottomSheetBehavior:

val bottomSheetCallback = object : BottomSheetBehavior.BottomSheetCallback() {

    override fun onStateChanged(bottomSheet: View, newState: Int) {
        // Do something for new state.
    }

    override fun onSlide(bottomSheet: View, slideOffset: Float) {
        // Do something for slide offset.
    }
}

// To add the callback:
bottomSheetBehavior.addBottomSheetCallback(bottomSheetCallback)

// To remove the callback:
bottomSheetBehavior.removeBottomSheetCallback(bottomSheetCallback)

Handling insets and fullscreen

BottomSheetBehavior can automatically handle insets (such as for edge to edge) by specifying any of these to true on the view:

  • app:paddingBottomSystemWindowInsets
  • app:paddingLeftSystemWindowInsets
  • app:paddingRightSystemWindowInsets
  • app:paddingTopSystemWindowInsets

On API 21 and above the modal bottom sheet will be rendered fullscreen (edge to edge) if the navigation bar is transparent and app:enableEdgeToEdge is true. To enable edge-to-edge by default for modal bottom sheets, you can override ?attr/bottomSheetDialogTheme like the below example:

<style name="AppTheme" parent="Theme.Material3.*">
  ...
  <item name="bottomSheetDialogTheme">@style/ThemeOverlay.App.BottomSheetDialog</item>
</style>

<style name="ThemeOverlay.App.BottomSheetDialog" parent="ThemeOverlay.Material3.BottomSheetDialog">
    <item name="android:navigationBarColor" tools:ignore="NewApi">@android:color/transparent</item>
</style>

Insets can be added automatically if any of the padding attributes above are set to true in the style, either by updating the style passed to the constructor, or by updating the default style specified by the ?attr/bottomSheetDialogTheme attribute in your theme.

BottomSheetDialog will also add padding to the top when the bottom sheet slides under the status bar, to prevent content from being drawn underneath it.

Making bottom sheets accessible

The contents within a bottom sheet should follow their own accessibility guidelines, such as setting content descriptions for images.

To support dragging bottom sheets with accessibility services such as TalkBack, Voice Access, Switch Access, etc., we provide a convenient widget BottomSheetDragHandleView which will automatically receive and handle accessibility commands to expand and collapse the attached bottom sheet when the accessibility mode is enabled. To use BottomSheetDragHandleView, you can add it to the top of your bottom sheet content. It will show a customizable visual indicator for all users. See the example in the below section for how to add a drag handle to your bottom sheet.

Note: BottomSheetDragHandleView has a default min width and height of 48dp to conform to the minimum touch target requirement. So you will need to preserve at least 48dp at the top to place a drag handle.

Standard bottom sheet

Standard bottom sheets co-exist with the screen’s main UI region and allow for simultaneously viewing and interacting with both regions. They are commonly used to keep a feature or secondary content visible on screen when content in the main UI region is frequently scrolled or panned.

BottomSheetBehavior is applied to a child of CoordinatorLayout to make that child a persistent bottom sheet, which is a view that comes up from the bottom of the screen, elevated over the main content. It can be dragged vertically to expose more or less content.

API and source code:

Standard bottom sheet example

The following example shows a standard bottom sheet in its collapsed and expanded states:

Standard bottom sheet example. Collapsed on the left and expanded on the right.

BottomSheetBehavior works in tandem with CoordinatorLayout to let you display content on a bottom sheet, perform enter/exit animations, respond to dragging/swiping gestures, etc.

Apply the BottomSheetBehavior to a direct child View of CoordinatorLayout:

<androidx.coordinatorlayout.widget.CoordinatorLayout
  ...>

  <FrameLayout
    android:id="@+id/standard_bottom_sheet"
    style="@style/Widget.Material3.BottomSheet"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="com.google.android.material.bottomsheet.BottomSheetBehavior">

    <!-- Drag handle for accessibility -->
    <com.google.android.material.bottomsheet.BottomSheetDragHandleView
    android:id="@+id/drag_handle"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"/>

    <!-- Bottom sheet contents. -->
    <TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/title"
    .../>

    <TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/supporting_text"
    .../>

    <Button
    android:id="@+id/bottomsheet_button"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/action"
    .../>

    <com.google.android.material.switchmaterial.SwitchMaterial
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/switch_label"/>

  </FrameLayout>

</androidx.coordinatorlayout.widget.CoordinatorLayout>

In this example, the bottom sheet is the FrameLayout.

Modal bottom sheet

Modal bottom sheets present a set of choices while blocking interaction with the rest of the screen. They are an alternative to inline menus and simple dialogs on mobile devices, providing additional room for content, iconography, and actions.

BottomSheetDialogFragment is a thin layer on top of the regular support library Fragment that renders your fragment as a modal bottom sheet, fundamentally acting as a dialog.

Modal bottom sheets render a shadow on the content below them, to indicate that they are modal. If the content outside of the dialog is tapped, the bottom sheet is dismissed. Modal bottom sheets can be dragged vertically and dismissed by sliding them down completely.

API and source code:

Modal bottom sheet example

The following example shows a modal bottom sheet in its collapsed and expanded states:

Modal bottom sheet example. Collapsed on the left and expanded on the right.

First, subclass BottomSheetDialogFragment and overwrite onCreateView to provide a layout for the contents of the sheet (in this example, it's modal_bottom_sheet_content.xml):

class ModalBottomSheet : BottomSheetDialogFragment() {

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? = inflater.inflate(R.layout.modal_bottom_sheet_content, container, false)

    companion object {
        const val TAG = "ModalBottomSheet"
    }
}

Then, inside an AppCompatActivity, to show the bottom sheet:

val modalBottomSheet = ModalBottomSheet()
modalBottomSheet.show(supportFragmentManager, ModalBottomSheet.TAG)

BottomSheetDialogFragment is a subclass of AppCompatFragment, which means you need to use Activity.getSupportFragmentManager().

Note: Don't call setOnCancelListener or setOnDismissListener on a BottomSheetDialogFragment. You can override onCancel(DialogInterface) or onDismiss(DialogInterface) if necessary.

Anatomy and key properties

Bottom sheets have a sheet, content, and, if modal, a scrim.

Bottom sheet anatomy

  1. Sheet
  2. Content
  3. Scrim (in modal bottom sheets)

Sheet attributes

Element Attribute Related method(s) Default value
Color app:backgroundTint N/A ?attr/colorSurface
Shape app:shapeAppearance N/A ?attr/shapeAppearanceLargeComponent
Elevation android:elevation N/A 1dp
Max width android:maxWidth setMaxWidth
getMaxWidth		 640dp
Max height android:maxHeight setMaxHeight
getMaxHeight		 N/A

Behavior attributes

More info about these attributes and how to use them in the setting behavior section.

Behavior Related method(s) Default value
app:behavior_peekHeight setPeekHeight
getPeekHeight		 auto
app:behavior_hideable setHideable
isHideable		 false for standard
true for modal
app:behavior_skipCollapsed setSkipCollapsed
getSkipCollapsed		 false
app:behavior_fitToContents setFitToContents
isFitToContents		 true
app:behavior_draggable setDraggable
isDraggable		 true
app:behavior_halfExpandedRatio setHalfExpandedRatio
getHalfExpandedRatio		 0.5
app:behavior_expandedOffset setExpandedOffset
getExpandedOffset		 0dp
app:behavior_significantVelocityThreshold setSignificantVelocityThreshold
getSignificantVelocityThreshold		 500 pixels/s

To save behavior on configuration change:

Attribute Related method(s) Default value
app:behavior_saveFlags setSaveFlags
getSaveFlags		 SAVE_NONE

Styles

Element Default value
Default style (modal) @style/Widget.Material3.BottomSheet.Modal

Default style theme attribute:?attr/bottomSheetStyle

Note: The ?attr/bottomSheetStyle default style theme attribute is for modal bottom sheets only. There is no default style theme attribute for standard bottom sheets, because BottomSheetBehaviors don't have a designated associated View.

Theme overlays

Element Theme overlay
Default theme overlay ThemeOverlay.Material3.BottomSheetDialog

Default theme overlay attribute: ?attr/bottomSheetDialogTheme

See the full list of styles, attrs, and themes and theme overlays.

Theming bottom sheets

Bottom sheets support Material Theming, which can customize color and shape.

Bottom sheet theming example

API and source code:

The following example shows a bottom sheet with Material Theming, in its collapsed and expanded states.

Bottom sheet with pink background color. Collapsed on the left and expanded on the right.

Implementing bottom sheet theming

Setting the theme attribute bottomSheetDialogTheme to your custom ThemeOverlay will affect all bottom sheets.

In res/values/themes.xml:

<style name="Theme.App" parent="Theme.Material3.*">
  ...
  <item name="bottomSheetDialogTheme">@style/ThemeOverlay.App.BottomSheetDialog</item>
</style>

<style name="ThemeOverlay.App.BottomSheetDialog" parent="ThemeOverlay.Material3.BottomSheetDialog">
    <item name="bottomSheetStyle">@style/ModalBottomSheetDialog</item>
</style>

In res/values/styles.xml:

<style name="ModalBottomSheetDialog" parent="Widget.Material3.BottomSheet.Modal">
    <item name="backgroundTint">@color/shrine_pink_light</item>
    <item name="shapeAppearance">@style/ShapeAppearance.App.LargeComponent</item>
</style>

<style name="ShapeAppearance.App.LargeComponent" parent="ShapeAppearance.Material3.LargeComponent">
    <item name="cornerFamily">cut</item>
    <item name="cornerSize">24dp</item>
</style>

Note: The benefit of using a custom ThemeOverlay is that any changes to your main theme, such as updated colors, will be reflected in the bottom sheet, as long as they're not overridden in your custom theme overlay. If you use a custom Theme instead, by extending from one of the Theme.Material3.*.BottomSheetDialog variants, you will have more control over exactly what attributes are included in each, but it also means you'll have to duplicate any changes that you've made in your main theme into your custom theme.