简介
网上对于 Camera2 的介绍有很多，在 Github 上也有很多关于 Camera2 的封装库，但是对于那些库，封装性太强，有时候我们仅仅是需要个简简单单的拍照功能而已，因此，自定义一个 Camera 使之变得轻量级那是非常重要的了。(本文并非重复造轮子, 而是在于学习 Camera2API 的基本功能, 笔记之。)
学习要点:
使用 Android Camera2 API 的基本功能。
迭代连接到设备的所有相机的特征。
显示相机预览和拍摄照片。
Camera2 API 为连接到 Android 设备的各个相机设备提供了一个界面。 它替代了已弃用的 Camera 类。
完成后，别忘了解锁焦点。
实现效果
环境
SDK>21
Camera2 类图
代码实现
CameraPreview.java
/**
* Created by shenhua on 2017-10-20-0020.
* Email shenhuanet@126.com
*/
public class CameraPreview extends TextureView {
private static final String TAG = "CameraPreview";
private static final SparseIntArray ORIENTATIOnS= new SparseIntArray();//从屏幕旋转转换为JPEG方向
private static final int MAX_PREVIEW_WIDTH = 1920;//Camera2 API 保证的最大预览宽高
private static final int MAX_PREVIEW_HEIGHT = 1080;
private static final int STATE_PREVIEW = 0;//显示相机预览
private static final int STATE_WAITING_LOCK = 1;//焦点锁定中
private static final int STATE_WAITING_PRE_CAPTURE = 2;//拍照中
private static final int STATE_WAITING_NON_PRE_CAPTURE = 3;//其它状态
private static final int STATE_PICTURE_TAKEN = 4;//拍照完毕
private int mState = STATE_PREVIEW;
private int mRatioWidth = 0, mRatioHeight = 0;
private int mSensorOrientation;
private boolean mFlashSupported;
private Semaphore mCameraOpenCloseLock = new Semaphore(1);//使用信号量 Semaphore 进行多线程任务调度
private Activity activity;
private File mFile;
private HandlerThread mBackgroundThread;
private Handler mBackgroundHandler;
private Size mPreviewSize;
private String mCameraId;
private CameraDevice mCameraDevice;
private CaptureRequest.Builder mPreviewRequestBuilder;
private CaptureRequest mPreviewRequest;
private CameraCaptureSession mCaptureSession;
private ImageReader mImageReader;
static {
ORIENTATIONS.append(Surface.ROTATION_0, 90);
ORIENTATIONS.append(Surface.ROTATION_90, 0);
ORIENTATIONS.append(Surface.ROTATION_180, 270);
ORIENTATIONS.append(Surface.ROTATION_270, 180);
}
public CameraPreview(Context context) {
this(context, null);
}
public CameraPreview(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public CameraPreview(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
mFile = new File(getContext().getExternalFilesDir(null), "pic.jpg");
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int width = MeasureSpec.getSize(widthMeasureSpec);
int height = MeasureSpec.getSize(heightMeasureSpec);
if (0 == mRatioWidth || 0 == mRatioHeight) {
setMeasuredDimension(width, height);
} else {
if (width MAX_PREVIEW_WIDTH) {
maxPreviewWidth = MAX_PREVIEW_WIDTH;
}
if (maxPreviewHeight > MAX_PREVIEW_HEIGHT) {
maxPreviewHeight = MAX_PREVIEW_HEIGHT;
}
mPreviewSize = chooseOptimalSize(map.getOutputSizes(SurfaceTexture.class),
rotatedPreviewWidth, rotatedPreviewHeight, maxPreviewWidth,
maxPreviewHeight, largest);
int orientation = getResources().getConfiguration().orientation;
if (orientation == Configuration.ORIENTATION_LANDSCAPE) {
setAspectRatio(mPreviewSize.getWidth(), mPreviewSize.getHeight());
} else {
setAspectRatio(mPreviewSize.getHeight(), mPreviewSize.getWidth());
}
Boolean available = characteristics.get(CameraCharacteristics.FLASH_INFO_AVAILABLE);
mFlashSupported = available == null &＃63; false : available;
mCameraId = cameraId;
return;
}
} catch (CameraAccessException e) {
e.printStackTrace();
} catch (NullPointerException e) {
Log.e(TAG, "设备不支持Camera2");
}
}
/**
* 获取一个合适的相机预览尺寸
*
* @param choices 支持的预览尺寸列表
* @param textureViewWidth 相对宽度
* @param textureViewHeight 相对高度
* @param maxWidth 可以选择的最大宽度
* @param maxHeight 可以选择的最大高度
* @param aspectRatio 宽高比
* @return 最佳预览尺寸
*/
private static Size chooseOptimalSize(Size[] choices, int textureViewWidth, int textureViewHeight,
int maxWidth, int maxHeight, Size aspectRatio) {
List bigEnough = new ArrayList<>();
List notBigEnough = new ArrayList<>();
int w = aspectRatio.getWidth();
int h = aspectRatio.getHeight();
for (Size option : choices) {
if (option.getWidth() <= maxWidth && option.getHeight() <= maxHeight &&
option.getHeight() == option.getWidth() * h / w) {
if (option.getWidth() >= textureViewWidth &&
option.getHeight() >= textureViewHeight) {
bigEnough.add(option);
} else {
notBigEnough.add(option);
}
}
}
if (bigEnough.size() > 0) {
return Collections.min(bigEnough, new CompareSizesByArea());
} else if (notBigEnough.size() > 0) {
return Collections.max(notBigEnough, new CompareSizesByArea());
} else {
Log.e(TAG, "Couldn't find any suitable preview size");
return choices[0];
}
}
/**
* 为相机预览创建新的CameraCaptureSession
*/
private void createCameraPreviewSession() {
try {
SurfaceTexture texture = this.getSurfaceTexture();
assert texture != null;
// 将默认缓冲区的大小配置为想要的相机预览的大小
texture.setDefaultBufferSize(mPreviewSize.getWidth(), mPreviewSize.getHeight());
Surface surface = new Surface(texture);
mPreviewRequestBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
mPreviewRequestBuilder.addTarget(surface);
// 我们创建一个 CameraCaptureSession 来进行相机预览
mCameraDevice.createCaptureSession(Arrays.asList(surface, mImageReader.getSurface()),
new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(@NonNull CameraCaptureSession cameraCaptureSession) {
if (null == mCameraDevice) {
return;
}
// 会话准备好后，我们开始显示预览
mCaptureSession = cameraCaptureSession;
try {
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE,
CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
setAutoFlash(mPreviewRequestBuilder);
mPreviewRequest = mPreviewRequestBuilder.build();
mCaptureSession.setRepeatingRequest(mPreviewRequest, mCaptureCallback, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
@Override
public void onConfigureFailed(@NonNull CameraCaptureSession cameraCaptureSession) {
}
}, null);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
/**
* 从指定的屏幕旋转中检索照片方向
*
* @param rotation 屏幕方向
* @return 照片方向（0,90,270,360）
*/
private int getOrientation(int rotation) {
return (ORIENTATIONS.get(rotation) + mSensorOrientation + 270) % 360;
}
/**
* 锁定焦点
*/
private void lockFocus() {
try {
// 如何通知相机锁定焦点
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER, CameraMetadata.CONTROL_AF_TRIGGER_START);
// 通知mCaptureCallback等待锁定
mState = STATE_WAITING_LOCK;
mCaptureSession.capture(mPreviewRequestBuilder.build(), mCaptureCallback, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
/**
* 解锁焦点
*/
private void unlockFocus() {
try {
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER,
CameraMetadata.CONTROL_AF_TRIGGER_CANCEL);
setAutoFlash(mPreviewRequestBuilder);
mCaptureSession.capture(mPreviewRequestBuilder.build(), mCaptureCallback,
mBackgroundHandler);
mState = STATE_PREVIEW;
mCaptureSession.setRepeatingRequest(mPreviewRequest, mCaptureCallback,
mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
/**
* 拍摄静态图片
*/
private void captureStillPicture() {
try {
if (null == activity || null == mCameraDevice) {
return;
}
final CaptureRequest.Builder captureBuilder =
mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
captureBuilder.addTarget(mImageReader.getSurface());
captureBuilder.set(CaptureRequest.CONTROL_AF_MODE,
CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
setAutoFlash(captureBuilder);
// 方向
int rotation = activity.getWindowManager().getDefaultDisplay().getRotation();
captureBuilder.set(CaptureRequest.JPEG_ORIENTATION, getOrientation(rotation));
CameraCaptureSession.CaptureCallback captureCallback
= new CameraCaptureSession.CaptureCallback() {
@Override
public void onCaptureCompleted(@NonNull CameraCaptureSession session,
@NonNull CaptureRequest request,
@NonNull TotalCaptureResult result) {
Toast.makeText(getContext(), "Saved: " + mFile, Toast.LENGTH_SHORT).show();
Log.d(TAG, mFile.toString());
unlockFocus();
}
};
mCaptureSession.stopRepeating();
mCaptureSession.abortCaptures();
mCaptureSession.capture(captureBuilder.build(), captureCallback, null);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
/**
* 运行preCapture序列来捕获静止图像
*/
private void runPreCaptureSequence() {
try {
// 设置拍照参数请求
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_PRECAPTURE_TRIGGER,
CaptureRequest.CONTROL_AE_PRECAPTURE_TRIGGER_START);
mState = STATE_WAITING_PRE_CAPTURE;
mCaptureSession.capture(mPreviewRequestBuilder.build(), mCaptureCallback, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
/**
* 比较两者大小
*/
private static class CompareSizesByArea implements Comparator {
@Override
public int compare(Size lhs, Size rhs) {
return Long.signum((long) lhs.getWidth() * lhs.getHeight() -
(long) rhs.getWidth() * rhs.getHeight());
}
}
/**
* ImageReader的回调对象
*/
private final ImageReader.OnImageAvailableListener mOnImageAvailableListener= new ImageReader.OnImageAvailableListener() {
@Override
public void onImageAvailable(ImageReader reader) {
mBackgroundHandler.post(new ImageSaver(reader.acquireNextImage(), mFile));
}
};
/**
* 将捕获到的图像保存到指定的文件中
*/
private static class ImageSaver implements Runnable {
private final Image mImage;
private final File mFile;
ImageSaver(Image image, File file) {
mImage = image;
mFile = file;
}
@Override
public void run() {
ByteBuffer buffer = mImage.getPlanes()[0].getBuffer();
byte[] bytes = new byte[buffer.remaining()];
buffer.get(bytes);
FileOutputStream output = null;
try {
output = new FileOutputStream(mFile);
output.write(bytes);
} catch (IOException e) {
e.printStackTrace();
} finally {
mImage.close();
if (null != output) {
try {
output.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
}
MainActivity.java
public class MainActivity extends AppCompatActivity {
CameraPreview cameraView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
cameraView = (CameraPreview) findViewById(R.id.cameraView);
}
@Override
protected void onResume() {
super.onResume();
cameraView.onResume(this);
}
@Override
protected void onPause() {
cameraView.onPause();
super.onPause();
}
public void takePic(View view) {
cameraView.takePicture();
}
}
activity_main.xml
<&＃63;xml version="1.0" encoding="utf-8"&＃63;>
资源文件 ic_capture_200px.xml
其它
Manifest 权限:
Android6.0 运行时权限未贴出。(注意：为了方便读者手机端阅读，本文代码部分的成员变量使用了行尾注释，在正常编程习惯中，请使用 /* / 注释。)
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。
京公网安备 11010802041100号 | 京ICP备19059560号-4 | PHP1.CN 第一PHP社区 版权所有 