通过camera2接口强制焦距定值的方法如下:
getSystemService(Context.CAMERA_SERVICE)
获取CameraManager实例。getCameraIdList()
方法获取所有相机设备的ID列表,并选择需要操作的相机设备ID。openCamera(String cameraId, CameraDevice.StateCallback callback, Handler handler)
方法打开相机设备。在回调函数中,可以获取到CameraDevice实例。createCaptureRequest(int templateType)
方法创建CaptureRequest.Builder实例。templateType参数可以选择不同的模板类型,例如TEMPLATE_PREVIEW、TEMPLATE_STILL_CAPTURE等。set(CaptureRequest.LENS_FOCUS_DISTANCE, focusDistance)
方法设置焦距参数。其中,focusDistance为焦距的具体数值,单位为米。build()
方法创建CaptureRequest实例。setRepeatingRequest(CaptureRequest request, CameraCaptureSession.CaptureCallback callback, Handler handler)
方法设置CaptureRequest参数,并开始预览或拍摄。完整的代码示例如下:
import android.Manifest;
import android.content.Context;
import android.content.pm.PackageManager;
import android.hardware.camera2.CameraAccessException;
import android.hardware.camera2.CameraCaptureSession;
import android.hardware.camera2.CameraCharacteristics;
import android.hardware.camera2.CameraDevice;
import android.hardware.camera2.CameraManager;
import android.hardware.camera2.CaptureRequest;
import android.os.Bundle;
import android.os.Handler;
import android.os.HandlerThread;
import android.util.Log;
import android.view.Surface;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import java.util.Arrays;
public class MainActivity extends AppCompatActivity implements SurfaceHolder.Callback {
private static final String TAG = "Camera2Example";
private static final int REQUEST_CAMERA_PERMISSION = 200;
private SurfaceView surfaceView;
private Button captureButton;
private CameraManager cameraManager;
private String cameraId;
private CameraDevice cameraDevice;
private CameraCaptureSession cameraCaptureSession;
private CaptureRequest.Builder captureRequestBuilder;
private HandlerThread backgroundThread;
private Handler backgroundHandler;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
surfaceView = findViewById(R.id.surfaceView);
captureButton = findViewById(R.id.captureButton);
surfaceView.getHolder().addCallback(this);
captureButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
try {
setFocusDistance(2.0f); // 设置焦距为2.0米
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
});
}
@Override
protected void onResume() {
super.onResume();
startBackgroundThread();
if (surfaceView.isAvailable()) {
openCamera();
} else {
surfaceView.getHolder().addCallback(this);
}
}
@Override
protected void onPause() {
closeCamera();
stopBackgroundThread();
super.onPause();
}
@Override
public void surfaceCreated(@NonNull SurfaceHolder holder) {
// Surface已创建,打开相机
openCamera();
}
@Override
public void surfaceChanged(@NonNull SurfaceHolder holder, int format, int width, int height) {
// Surface发生变化,重新配置相机预览
configureTransform(width, height);
}
@Override
public void surfaceDestroyed(@NonNull SurfaceHolder holder) {
// Surface已销毁,关闭相机
closeCamera();
}
private void startBackgroundThread() {
backgroundThread = new HandlerThread("CameraBackground");
backgroundThread.start();
backgroundHandler = new Handler(backgroundThread.getLooper());
}
private void stopBackgroundThread() {
backgroundThread.quitSafely();
try {
backgroundThread.join();
backgroundThread = null;
backgroundHandler = null;
} catch (InterruptedException e) {
e.printStackTrace();
}
}
private void openCamera() {
cameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
try {
cameraId = cameraManager.getCameraIdList()[0]; // 获取第一个相机设备ID
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA}, REQUEST_CAMERA_PERMISSION);
return;
}
cameraManager.openCamera(cameraId, cameraStateCallback, backgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
private void closeCamera() {
if (cameraCaptureSession != null) {
cameraCaptureSession.close();
cameraCaptureSession = null;
}
if (cameraDevice != null) {
cameraDevice.close();
cameraDevice = null;
}
}
private void createCameraPreviewSession() {
try {
Surface surface = surfaceView.getHolder().getSurface();
captureRequestBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
captureRequestBuilder.addTarget(surface);
cameraDevice.createCaptureSession(Arrays.asList(surface), cameraCaptureSessionStateCallback, backgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
private void setFocusDistance(float focusDistance) throws CameraAccessException {
if (captureRequestBuilder != null) {
captureRequestBuilder.set(CaptureRequest.LENS_FOCUS_DISTANCE, focusDistance);
cameraCaptureSession.setRepeatingRequest(captureRequestBuilder.build(), null, backgroundHandler);
}
}
private void configureTransform(int viewWidth, int viewHeight) {
if (null == surfaceView || null == cameraCharacteristics) {
return;
}
int rotation = getWindowManager().getDefaultDisplay().getRotation();
Matrix matrix = new Matrix();
RectF viewRect = new RectF(0, 0, viewWidth, viewHeight);
RectF bufferRect = new RectF(0, 0, previewSize.getHeight(), previewSize.getWidth());
float centerX = viewRect.centerX();
float centerY = viewRect.centerY();
if (Surface.ROTATION_90 == rotation || Surface.ROTATION_270 == rotation) {
bufferRect.offset(centerX - bufferRect.centerX(), centerY - bufferRect.centerY());
matrix.setRectToRect(viewRect, bufferRect, Matrix.ScaleToFit.FILL);
float scale = Math.max(
(float) viewHeight / previewSize.getHeight(),
(float) viewWidth / previewSize.getWidth());
matrix.postScale(scale, scale, centerX, centerY);
matrix.postRotate(90 * (rotation - 2), centerX, centerY);
} else if (Surface.ROTATION_180 == rotation) {
matrix.postRotate(180, centerX, centerY);
}
surfaceView.setTransform(matrix);
}
private final CameraDevice.StateCallback cameraStateCallback = new CameraDevice.StateCallback() {
@Override
public void onOpened(@NonNull CameraDevice camera) {
cameraDevice = camera;
createCameraPreviewSession();
}
@Override
public void onDisconnected(@NonNull CameraDevice camera) {
camera.close();
cameraDevice = null;
}
@Override
public void onError(@NonNull CameraDevice camera, int error) {
camera.close();
cameraDevice = null;
}
};
private final CameraCaptureSession.StateCallback cameraCaptureSessionStateCallback = new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(@NonNull CameraCaptureSession session) {
cameraCaptureSession = session;
try {
captureRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
cameraCaptureSession.setRepeatingRequest(captureRequestBuilder.build(), null, backgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
@Override
public void onConfigureFailed(@NonNull CameraCaptureSession session) {
Log.e(TAG, "Camera capture session configuration failed");
}
};
}
这段代码演示了如何通过camera2接口强制焦距定值。首先,在setFocusDistance(float focusDistance)
方法中,通过captureRequestBuilder.set(CaptureRequest.LENS_FOCUS_DISTANCE, focusDistance)
设置焦距参数。然后,在cameraCaptureSession.setRepeatingRequest(captureRequestBuilder.build(), null, backgroundHandler)
方法中应用该参数,并开始预览或拍摄。
请注意,以上代码仅为示例,实际应用中需要根据具体需求进行适当修改和完善。
推荐的腾讯云相关产品:腾讯云人工智能服务(https://cloud.tencent.com/product/ai)
领取专属 10元无门槛券
手把手带您无忧上云