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.

Summary