PreviewView


public final class PreviewView extends FrameLayout


Custom View that displays the camera feed for CameraX's Preview use case.

This class manages the preview Surface's lifecycle. It internally uses either a TextureView or SurfaceView to display the camera feed, and applies required transformations on them to correctly display the preview, this involves correcting their aspect ratio, scale and rotation.

If PreviewView uses a SurfaceView to display the preview stream, be careful when overlapping a View that's initially not visible (either INVISIBLE or GONE) on top of it. When the SurfaceView is attached to the display window, it calls requestTransparentRegion which requests a computation of the transparent regions on the display. At this point, the View isn't visible, causing the overlapped region between the SurfaceView and the View to be considered transparent. Later if the View becomes visible, it will not be displayed on top of SurfaceView. A way around this is to call requestTransparentRegion right after making the View visible, or initially hiding the View by setting its opacity to 0, then setting it to 1.0F to show it.

There are some limitations of transition animations to SurfaceView and TextureView, which applies to PreviewView as well.

See also
Limitations

Summary

Nested types

The implementation mode of a PreviewView.

Options for scaling the preview vis-à-vis its container PreviewView.

Definitions for the preview stream state.

Public constructors

@UiThread
PreviewView(
    @NonNull Context context,
    @Nullable AttributeSet attrs,
    int defStyleAttr
)
@UiThread
PreviewView(
    @NonNull Context context,
    @Nullable AttributeSet attrs,
    int defStyleAttr,
    int defStyleRes
)

Public methods

@Nullable Bitmap

Returns a Bitmap representation of the content displayed on the PreviewView, or null if the camera preview hasn't started yet.

@Nullable CameraController

Get the CameraController.

@NonNull PreviewView.ImplementationMode

Returns the ImplementationMode.

@NonNull MeteringPointFactory

Gets the MeteringPointFactory for the camera currently connected to the PreviewView, if any.

@Nullable OutputTransform

Gets the OutputTransform associated with the PreviewView.

@NonNull LiveData<PreviewView.StreamState>

Gets a LiveData for the preview StreamState.

@NonNull PreviewView.ScaleType

Returns the ScaleType currently applied to the preview.

@Nullable ImageCapture.ScreenFlash

Returns an ImageCapture.ScreenFlash implementation based on the Window instance set via setScreenFlashWindow.

@Nullable Matrix

Gets the transformation matrix from camera sensor to PreviewView.

@NonNull Preview.SurfaceProvider

Gets a Preview.SurfaceProvider to be used with setSurfaceProvider.

@Nullable ViewPort

Gets a ViewPort based on the current status of PreviewView.

@Nullable ViewPort
@UiThread
getViewPort(int targetRotation)

Gets a ViewPort with custom target rotation.

boolean
boolean
void

Sets the CameraController.

void

Sets the ImplementationMode for the PreviewView.

void

Applies a ScaleType to the preview.

void

Sets the color of the top overlay view during screen flash.

void

Sets a Window instance for subsequent photo capture requests with FLASH_MODE_SCREEN set.

Protected methods

void
void

Inherited Constants

From android.view.View
static final int
static final int
static final int
static final int
static final int
static final int
static final Property<ViewFloat>
static final int
static final String
AUTOFILL_HINT_CREDIT_CARD_EXPIRATION_DATE = "creditCardExpirationDate"
static final String
AUTOFILL_HINT_CREDIT_CARD_EXPIRATION_DAY = "creditCardExpirationDay"
static final String
AUTOFILL_HINT_CREDIT_CARD_EXPIRATION_MONTH = "creditCardExpirationMonth"
static final String
AUTOFILL_HINT_CREDIT_CARD_EXPIRATION_YEAR = "creditCardExpirationYear"
static final String
static final String
AUTOFILL_HINT_CREDIT_CARD_SECURITY_CODE = "creditCardSecurityCode"
static final String
static final String
static final String
static final String
static final String
static final String
static final String
static final int
static final int
static final int
static final int
static final int
static final int
static final int
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static final int
static final int
static final int
static final int
static final int

This field is deprecated.

static final int

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static final int

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static final int[]
static final int[]
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static final int[]
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static final int[]
static final int[]
static final int
static final int
static final int
static final int
static final int
static final int
static final int[]
static final int[]
static final int[]
static final int[]
static final int
static final int
static final int
static final int
static final int
static final int
static final int
GONE = 8
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
KEEP_SCREEN_ON = 67108864
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
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static final int
NO_ID = -1
static final int
static final int
static final int
static final int[]
static final int[]
static final int[]
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static final int[]
static final int[]
static final int[]
static final int[]
static final int[]
static final int[]
static final int[]
static final int[]
static final int[]
static final int[]
static final int[]
static final int[]
static final Property<ViewFloat>
static final Property<ViewFloat>
static final Property<ViewFloat>
static final Property<ViewFloat>
static final Property<ViewFloat>
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int[]
static final int[]
static final int
static final int

This field is deprecated.

static final int

This field is deprecated.

static final int

This field is deprecated.

static final int

This field is deprecated.

static final int

This field is deprecated.

static final int

This field is deprecated.

static final int

This field is deprecated.

static final int

This field is deprecated.

static final int

This field is deprecated.

static final int

This field is deprecated.

static final int

This field is deprecated.

static final int

This field is deprecated.

static final int

This field is deprecated.

static final int

This field is deprecated.

static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final int
static final Property<ViewFloat>
static final Property<ViewFloat>
static final Property<ViewFloat>
static final String
VIEW_LOG_TAG = "View"
static final int
static final int[]
static final Property<ViewFloat>
static final Property<ViewFloat>
static final Property<ViewFloat>
From android.view.ViewGroup
static final int
static final int
static final int
static final int
static final int
static final int
static final int

This field is deprecated.

static final int

This field is deprecated.

static final int

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static final int

This field is deprecated.

Inherited methods

From android.widget.FrameLayout
boolean
FrameLayout.LayoutParams
FrameLayout.LayoutParams
CharSequence
boolean

This method is deprecated.

boolean
void
onLayout(boolean changed, int left, int top, int right, int bottom)
void
onMeasure(int widthMeasureSpec, int heightMeasureSpec)
void
setForegroundGravity(int foregroundGravity)
void
setMeasureAllChildren(boolean measureAll)
boolean
From android.view.View
void
void
void
ViewPropertyAnimator
void
void
boolean
void
void

This method is deprecated.

void
boolean
boolean
boolean
boolean
boolean
canScrollHorizontally(int direction)
boolean
canScrollVertically(int direction)
final void
void
final void
boolean
void
void
static int
combineMeasuredStates(int curState, int newState)
int
int
int
void
WindowInsets
int
int
int
AccessibilityNodeInfo
void
void

This method is deprecated.

boolean
boolean
dispatchNestedFling(float velocityX, float velocityY, boolean consumed)
boolean
dispatchNestedPreFling(float velocityX, float velocityY)
boolean
dispatchNestedPrePerformAccessibilityAction(
    int action,
    Bundle arguments
)
boolean
dispatchNestedPreScroll(
    int dx,
    int dy,
    int[] consumed,
    int[] offsetInWindow
)
boolean
dispatchNestedScroll(
    int dxConsumed,
    int dyConsumed,
    int dxUnconsumed,
    int dyUnconsumed,
    int[] offsetInWindow
)
boolean
void
draw(Canvas canvas)
void
drawableHotspotChanged(float x, float y)
final OnBackInvokedDispatcher
final T
<T extends View> findViewById(int id)
final T
<T extends View> findViewWithTag(Object tag)
boolean

This method is deprecated.

void
forceHasOverlappingRendering(boolean hasOverlappingRendering)
void
void
generateDisplayHash(
    String hashAlgorithm,
    Rect bounds,
    Executor executor,
    DisplayHashResultCallback callback
)
static int
View.AccessibilityDelegate
int
AccessibilityNodeProvider
CharSequence
int
int
String
String
float
Animation
Matrix
IBinder
int[]
Map<IntegerInteger>
String[]
final AutofillId
int
AutofillValue
Drawable
BlendMode
ColorStateList
PorterDuff.Mode
int
final int
float
int
float
Rect
boolean
final boolean
final ContentCaptureSession
CharSequence
final Context
ContextMenu.ContextMenuInfo
final boolean
static int
getDefaultSize(int size, int measureSpec)
Display
final int[]
Bitmap

This method is deprecated.

int

This method is deprecated.

int

This method is deprecated.

void
long
float
int
boolean
boolean
int
ArrayList<View>
getFocusables(int direction)
void
Drawable
int
BlendMode
ColorStateList
PorterDuff.Mode
boolean
getGlobalVisibleRect(Rect r, Point globalOffset)
Handler
float
float
float
float
Runnable
final boolean
final int
void
getHitRect(Rect outRect)
int
int
Drawable
Drawable
int
int
int
int
boolean
KeyEvent.DispatcherState
int
int
int
ViewGroup.LayoutParams
final int
float
int
final boolean
void
getLocationInSurface(int[] location)
void
getLocationInWindow(int[] outLocation)
void
getLocationOnScreen(int[] outLocation)
Matrix
final int
final int
final int
final int
final int
int
int
int
int
int
int
int
int
View.OnFocusChangeListener
int
ViewOutlineProvider
int
int
ViewOverlay
int
int