本篇内容介绍了“怎么用Android Camera实现最简单的预览框显示”的有关知识，在实际案例的操作过程中，不少人都会遇到这样的困境，接下来就让小编带领大家学习一下如何处理这些情况吧！希望大家仔细阅读，能够学有所成！
Android要预览Camer2界面比Camera1稍微复杂一点，但是也是不难的，下面是简单的预览相关代码。
1、首先要再AndroidManifest.xml中添加权限
<uses-permission android:name="android.permission.CAMERA"/>
2、创建一个xml包含控件TextureView
比如activity_main.xml：
<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent"> <TextureView android:id="@+id/textureView" android:layout_width="match_parent" android:layout_height="match_parent" /> <Button android:id="@+id/btnStop" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_margin="0.8dp" android:text="stop preview" android:layout_alignParentBottom="true" android:layout_alignParentEnd="true"/> <Button android:id="@+id/btnStart" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_margin="0.8dp" android:text="start preview" android:layout_alignParentBottom="true" android:layout_toStartOf="@id/btnStop"/> </RelativeLayout>
3、在Activity创建使用 CamaerManager
(1)使用 CamaerManager.openCamera(),传入监听openState状态
(2)在openState状态里面执行预览界面即可
(3)关闭预览框的时候释放一下对象就行
比如下面的MainActivity2.java代码：
package com.lwz.camera;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import android.Manifest;
import android.content.Context;
import android.content.pm.PackageManager;
import android.graphics.SurfaceTexture;
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.CaptureFailure;
import android.hardware.camera2.CaptureRequest;
import android.hardware.camera2.CaptureResult;
import android.hardware.camera2.TotalCaptureResult;
import android.hardware.camera2.params.StreamConfigurationMap;
import android.os.Bundle;
import android.util.Log;
import android.util.Size;
import android.view.Surface;
import android.view.TextureView;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.content.ContextCompat;
/**
* 本类使用Camera2使用简单相机
*/
public class MainActivity2 extends AppCompatActivity implements View.OnClickListener {
private static final String TAG = "Camera2Test";
private static final int REQUEST_CAMERA_PERMISSION = 80;
private TextureView mTextureView;
private Button mBtnStart;
private Button mBtnStop;
private CameraManager mCameraManager;
private CameraDevice mCameraDevice;
private String mCameraId = "0";
private Size previewSize; // 用于设置预览的宽高
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.e(TAG, "onCreate！");
setContentView(R.layout.activity_main);
initData();
intiView();
initEvent();
}
private void intiView() {
mTextureView = (TextureView) findViewById(R.id.textureView);
mBtnStart = (Button) findViewById(R.id.btnStart);
mBtnStop = (Button) findViewById(R.id.btnStop);
}
private void initData() {
mCameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
if (mCameraManager == null) {
Toast.makeText(this, "获取不到CameraService对象！", Toast.LENGTH_LONG).show();
finish();
}
}
private void initEvent() {
mBtnStart.setOnClickListener(this);
mBtnStop.setOnClickListener(this);
// 对预览View的状态监听
mTextureView.setSurfaceTextureListener(new TextureView.SurfaceTextureListener() {
@Override
public void onSurfaceTextureAvailable(@NonNull SurfaceTexture surface, int width, int height) {
Log.i(TAG, "onSurfaceTextureAvailable width = " + width + ",height = " + height);
//1、当SurefaceTexture可用的时候，设置相机参数并打开相机
initCamera();
}
@Override
public void onSurfaceTextureSizeChanged(@NonNull SurfaceTexture surface, int width, int height) {
Log.i(TAG, "onSurfaceTextureSizeChanged width = " + width + ",height = " + height);
}
@Override
public boolean onSurfaceTextureDestroyed(@NonNull SurfaceTexture surface) {
Log.i(TAG, "onSurfaceTextureDestroyed！");
return false;
}
@Override
public void onSurfaceTextureUpdated(@NonNull SurfaceTexture surface) {
//正常预览的时候，会一直打印
//Log.i(TAG, "onSurfaceTextureUpdated！");
}
});
}
private void initCamera() {
Log.i(TAG, "initCamera");
// 2.配置前置相机，获取尺寸及id
getCameraIdAndPreviewSizeByFacing(CameraCharacteristics.LENS_FACING_FRONT); // 0为前置摄像头,Camera api1里面定义0为后置
// 3.打开相机
openCamera();
}
/*获取cameraId及相机预览的最佳尺寸*/
private void getCameraIdAndPreviewSizeByFacing(int lensFacingFront) {
Log.i(TAG, "getCameraIdAndPreviewSizeByFacing");
try {
String[] cameraIdList = mCameraManager.getCameraIdList(); //如果设备节点不可用，会阻塞在这里
Log.i(TAG, "getCameraIdAndPreviewSizeByFacing cameraIdList = " + Arrays.toString(cameraIdList));
for (String cameraId : cameraIdList) {
CameraCharacteristics cameraCharacteristics = mCameraManager.getCameraCharacteristics(cameraId);
int deviceLevel = cameraCharacteristics.get(CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL); //硬件与api2的契合度，0-4
Log.i(TAG, "deviceLevel = " + deviceLevel);
int facing = cameraCharacteristics.get(CameraCharacteristics.LENS_FACING);
if (facing != lensFacingFront) {
continue;
}
StreamConfigurationMap streamConfigurationMap = cameraCharacteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
Size[] outputSizes = streamConfigurationMap.getOutputSizes(SurfaceTexture.class);
mCameraId = cameraId;
previewSize = setOptimalPreviewSize(outputSizes, mTextureView.getMeasuredWidth(), mTextureView.getMeasuredHeight());
Log.i(TAG, "最佳预览尺寸（w-h）：" + previewSize.getWidth() + "-" + previewSize.getHeight() + ",相机id：" + mCameraId);
}
} catch (CameraAccessException e) {
Log.e(TAG, "getCameraIdAndPreviewSizeByFacing error = " + e.getMessage());
}
}
/**
* 打开相机，预览是在回调里面执行的。
*/
private void openCamera() {
try {
// 4.权限检查
if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA)
!= PackageManager.PERMISSION_GRANTED) {
requestCameraPermission();
return;
}
// 5.真正打开相机
Log.i(TAG, "openCamera");
mCameraManager.openCamera(mCameraId, mStateCallback, null);
} catch (CameraAccessException e) {
Log.e(TAG, "openCamera error = " + e.getMessage());
}
}
//请求相机权限
private void requestCameraPermission() {
requestPermissions(new String[]{Manifest.permission.CAMERA}, REQUEST_CAMERA_PERMISSION);
}
/**
* 根据相机可用的预览尺寸和用户给定的TextureView的显示尺寸选择最接近的预览尺寸
*/
private Size setOptimalPreviewSize(Size[] sizes, int previewViewWidth, int previewViewHeight) {
List<Size> bigEnoughSizes = new ArrayList<>();
List<Size> notBigEnoughSizes = new ArrayList<>();
for (Size size : sizes) {
if (size.getWidth() >= previewViewWidth && size.getHeight() >= previewViewHeight) {
bigEnoughSizes.add(size);
} else {
notBigEnoughSizes.add(size);
}
}
if (bigEnoughSizes.size() > 0) {
return Collections.min(bigEnoughSizes, new Comparator<Size>() {
@Override
public int compare(Size lhs, Size rhs) {
return Long.signum((long) lhs.getWidth() * lhs.getHeight() -
(long) rhs.getWidth() * rhs.getHeight());
}
});
} else if (notBigEnoughSizes.size() > 0) {
return Collections.max(notBigEnoughSizes, new Comparator<Size>() {
@Override
public int compare(Size lhs, Size rhs) {
return Long.signum((long) lhs.getWidth() * lhs.getHeight() -
(long) rhs.getWidth() * rhs.getHeight());
}
});
} else {
Log.e(TAG, "未找到合适的预览尺寸");
return sizes[0];
}
}
//关闭相机，释放对象
private void releaseCamera() {
if (mCameraDevice != null) {
mCameraDevice.close();
mCameraDevice = null;
}
}
/**
* 相机状态监听对象
*/
private final CameraDevice.StateCallback mStateCallback = new CameraDevice.StateCallback() {
@Override
public void onOpened(CameraDevice camera) {
Log.i(TAG, "StateCallback！ onOpened");
mCameraDevice = camera; // 打开成功，保存代表相机的CameraDevice实例
SurfaceTexture surfaceTexture = mTextureView.getSurfaceTexture();
surfaceTexture.setDefaultBufferSize(mTextureView.getWidth(), mTextureView.getHeight());
Surface surface = new Surface(surfaceTexture);
ArrayList<Surface> previewList = new ArrayList<>();
previewList.add(surface);
try {
// 6.将TextureView的surface传递给CameraDevice
mCameraDevice.createCaptureSession(previewList, new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(@NonNull CameraCaptureSession session) {
try {
CaptureRequest.Builder builder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
builder.addTarget(surface); // 必须设置才能正常预览
CaptureRequest captureRequest = builder.build();
// 7.CameraCaptureSession与CaptureRequest绑定（这是最后一步，已可显示相机预览）
session.setRepeatingRequest(captureRequest, mSessionCaptureCallback, null);
} catch (CameraAccessException e) {
Log.e(TAG, "createCaptureRequest error = " + e.getMessage());
}
}
@Override
public void onConfigureFailed(@NonNull CameraCaptureSession session) {
Log.e(TAG, "onConfigureFailed");
}
}, null);
} catch (CameraAccessException e) {
Log.e(TAG, "createCaptureSession error = " + e.getMessage());
}
}
@Override
public void onDisconnected(@NonNull CameraDevice camera) {
Log.e(TAG, "StateCallback！ onDisconnected camera.getId() = " + camera.getId());
releaseCamera();
}
@Override
public void onError(@NonNull CameraDevice camera, int error) {
Log.e(TAG, "StateCallback camera.getId() = " + camera.getId() + " , error = " + error);
releaseCamera();
}
};
//预览情况回调
private CameraCaptureSession.CaptureCallback mSessionCaptureCallback = new CameraCaptureSession.CaptureCallback() {
@Override
public void onCaptureStarted(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, long timestamp, long frameNumber) {
super.onCaptureStarted(session, request, timestamp, frameNumber);
// 正常预览会一直刷新
//Log.i(TAG, "mSessionCaptureCallback onCaptureStarted frameNumber =" + frameNumber);
}
@Override
public void onCaptureProgressed(CameraCaptureSession session, CaptureRequest request, CaptureResult partialResult) {
super.onCaptureProgressed(session, request, partialResult);
Log.i(TAG, "mSessionCaptureCallback onCaptureProgressed request =" + request);
}
@Override
public void onCaptureFailed(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull CaptureFailure failure) {
super.onCaptureFailed(session, request, failure);
Log.e(TAG, "mSessionCaptureCallback onCaptureFailed request =" + request);
}
@Override
public void onCaptureCompleted(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull TotalCaptureResult result) {
super.onCaptureCompleted(session, request, result);
// 正常预览时会一直刷新
//Log.i(TAG, "mSessionCaptureCallback onCaptureCompleted request =" + request);
}
};
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.btnStart:
Log.i(TAG, "btnStart！");
openCamera();
break;
case R.id.btnStop:
Log.i(TAG, "btnStop！");
releaseCamera();
break;
default:
}
}
@Override
protected void onDestroy() {
super.onDestroy();
releaseCamera();
}
}Camera1的使用更简单，但是Camera1新增功能会少一点。
Camaera1的简单使用：Android Camera1实现预览框显示
“怎么用Android Camera实现最简单的预览框显示”的内容就介绍到这里了，感谢大家的阅读。如果想了解更多行业相关的知识可以关注亿速云网站，小编将为大家输出更多高质量的实用文章！
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