The principle and application of the Camera View framework in the Java class library

The Camera View framework is an important view framework in the Java class library that can easily handle camera operation and image capture.This article will introduce the principles and applications of the Camera View framework, and provide examples of Java code. 1. The principle of Camera View framework The Camera View framework is implemented based on the Camera class of the Android system.It provides a set of APIs for managing camera hardware and image capture, including the function of the camera's opening, closure, preview image display, image capture and processing. The main principle of the Camera View framework is to obtain the image data of each frame of the camera through the camera preview.When the application calls the preview of the Camera View framework, the framework will pass it to the application for processing after each frame image data is ready.Applications can choose to process directly on the preview data, or save it as an image file. To achieve this function, the Camera View framework first needs to obtain the access of the camera hardware.In the Androidmanifest.xml file, you need to declare the camera access, such as: <uses-permission android:name="android.permission.CAMERA" /> Then, in the application of the Activity class, the object of the Camera View framework needs to be instantly manifested, and the camera is opened and closed in the life cycle method.For example: private CameraView mCameraView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mCameraView = findViewById(R.id.camera_view); mCameraView.setCameraCallback(mCameraCallback); } @Override protected void onResume() { super.onResume(); mCameraView.startCamera(); } @Override protected void onPause() { super.onPause(); mCameraView.stopCamera(); } In the above code, the CameraView object is a custom view defined in the layout file to display the camera preview image.McAmeracallback is a customized callback interface for processing camera preview data. 2. Application of Camera View framework The Camera View framework is widely used in applications that require camera operation and image capture, such as camera applications and scanning QR code applications. For example, the following code demonstrates how to use the Camera View framework to take photos: private CameraView.CameraCallback mCameraCallback = new CameraView.CameraCallback() { @Override public void onPreviewFrame(byte[] data, Camera camera) { // Process camera preview data } @Override public void onPictureTaken(byte[] data, Camera camera) { // Process photos data } }; private void takePhoto() { mCameraView.takePicture(); } @Override public void onPictureTaken(byte[] data) { // Process photos data } In the above code, McAmeracallback implements CameraView's callback interface for processing camera preview data and shooting data.The takephoto () method is used to trigger the camera operation. The Camera View framework can also be used with other image processing libraries, such as OpenCV, GPUIMAGE, etc., to achieve richer image processing functions.It can be converted to Bitmap by converting preview data into Bitmap in the Cameraview callback method, and then use other image processing libraries to process the image. Summarize: The Camera View framework is a view framework that facilitates camera operation and image capture in the Java class library.It is based on the Camera class of the Android system and obtains the image data of each frame of the camera through the camera preview.The Camera View framework is widely used and can be used for camera applications and scanning QR code applications.It can be used with other image processing libraries to achieve richer image processing function.