PreviewView

public final class PreviewView
extends FrameLayout

java.lang.Object
   ↳ android.view.View
     ↳ android.view.ViewGroup
       ↳ android.widget.FrameLayout
         ↳ androidx.camera.view.PreviewView


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 View.INVISIBLE or View.GONE) on top of it. When the SurfaceView is attached to the display window, it calls ViewParent.requestTransparentRegion(View) 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 ViewParent.requestTransparentRegion(View) 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.

Summary

Nested classes

enum PreviewView.ImplementationMode

The implementation mode of a PreviewView

enum PreviewView.ScaleType

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

enum PreviewView.StreamState

Definitions for the preview stream state. 

Inherited constants

Inherited fields

Public constructors

PreviewView(Context context)
PreviewView(Context context, AttributeSet attrs)
PreviewView(Context context, AttributeSet attrs, int defStyleAttr)
PreviewView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes)

Public methods

Bitmap getBitmap()

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