CameraView/docs/_posts/2018-12-20-previews.md

layout	title	subtitle	description	category	order	date	disqus
page	Engine and previews	Camera engine and preview implementations	Camera engine and preview implementations	docs	6	2018-12-20 21:58:16	1

Engine

CameraView can interact with the camera sensor through the old Android interface typically referred as CAMERA1, and more recently, also through the more modern interface called CAMERA2, for API level 21 (Lollipop).

Being more recent, the latter received less testing and feedback. As such, to enable it, you are required to also set the experimental flag on: app:cameraExperimental="true". On devices older than Lollipop, the engine will always be Engine.CAMERA1.

Engine	API Level	Info
Engine.CAMERA1	All	Highly tested and reliable. Currently supports the full set of features.
Engine.CAMERA2	API 21+	Experimental, but will be the key focus for the future. New controls might be available only for this engine.

Previews

CameraView supports different types of previews, configurable either through the cameraPreview XML attribute or programmatically with the Preview control class.

All previews are supported in all conditions, regardless, for example, of the Engine that you choose.

This parameter defaults to the OpenGL GL_SURFACE and it is highly recommended that you do not change this to use all the features available. However, experienced user might prefer a different solution.

Preview	Backed by	Info
Preview.SURFACE	A SurfaceView	Can be good for battery, but will not work well with dynamic layout changes and similar things. No support for video snapshots.
Preview.TEXTURE	A TextureView	Better. Requires hardware acceleration. No support for video snapshots.
Preview.GL_SURFACE	A GLSurfaceView	Recommended. Supports video snapshots. Might support GL real time filters in the future.

The GL surface, as an extra benefit, has a much more efficient way of capturing picture snapshots, that avoids OOM errors, rotating the image on the fly, reading EXIF, and other horrible things belonging to v1. These picture snapshots will also work while taking videos.

XML Attributes

<com.otaliastudios.cameraview.CameraView
    app:cameraEngine="camera1|camera2"
    app:cameraPreview="surface|texture|glSurface"/>

Related APIs

The preview method should only be called once and if the CameraView was never added to a window, for example if you just created it programmatically. Otherwise, it has no effect.

The engine method should only be called when the CameraView is closed. Otherwise, it has no effect.

Method	Description
setPreview(Preview)	Sets the preview implementation.
setEngine(Engine)	Sets the engine implementation.