在片段中创建相机预览

Question

>我整天都在互联网上搜索，但我没有找到任何可以解决我的问题的东西：如何在应用程序运行时获得相机预览？我认为这并不难，但我是一个初学者，我真的无法达到这一点。我使用的代码如下：

public class CameraConnectionFragment extends Fragment {
private static final Logger LOGGER = new Logger();
/**
* The camera preview size will be chosen to be the smallest frame by pixel  size capable of
* containing a DESIRED_SIZE x DESIRED_SIZE square.
*/
private static final int MINIMUM_PREVIEW_SIZE = 320;
/**
* Conversion from screen rotation to JPEG orientation.
*/
private static final SparseIntArray ORIENTATIONS = new SparseIntArray();
private static final String FRAGMENT_DIALOG = "dialog";
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);
}

/**
* {@link android.view.TextureView.SurfaceTextureListener} handles several  lifecycle events on a
* {@link TextureView}.
*/
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,   Bundle savedInstanceState) {
View view =  inflater.inflate(R.layout.camera_connection_fragment, container, false);
Button capture = (Button) view.findViewById(R.id.button);
Button preview = (Button) view.findViewById(R.id.button2);
preview.setOnClickListener(new View.OnClickListener() {

public void onClick(View v) {
//I WANT TO INSERT THE CODE FOR THE CAMERA PREVIEW HERE.
}
});
capture.setOnClickListener(new View.OnClickListener() {

public void onClick(View v) {
try {
captureSession.capture(previewRequest, captureCallback, backgroundHandler);
}
catch (final CameraAccessException e) {
LOGGER.e(e, "Exception!");
}
}
});
return view;
}

XML 文件camera_connection_fragment如下：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent">
<org.tensorflow.demo.AutoFitTextureView
android:id="@+id/texture"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true" />
<org.tensorflow.demo.RecognitionScoreView
android:id="@+id/results"
android:layout_width="match_parent"
android:layout_height="198dp"
android:layout_alignParentTop="true" />
<org.tensorflow.demo.OverlayView
android:id="@+id/debug_overlay"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true" />
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentStart="true"
android:layout_marginBottom="21dp"
android:layout_marginStart="12dp"
android:text="Capture" />
<Button
android:id="@+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentEnd="true"
android:layout_alignTop="@+id/button"
android:layout_marginEnd="35dp"
android:text="Preview" />
<SurfaceView
android:id="@+id/surfaceView2"
android:layout_width="wrap_content"
android:layout_height="67dp"
android:layout_alignBottom="@+id/button"
android:layout_alignParentStart="true"
android:layout_marginStart="134dp" />

</RelativeLayout>

我想将相机预览的代码放在

preview.setOnClickListener(new View.OnClickListener() {

public void onClick(View v) {
//I WANT TO INSERT THE CODE FOR THE CAMERA PREVIEW HERE.
}
});

你对我应该如何做到这一点有任何想法吗？

Answer 1

我相信将其作为答案发布更容易。从 API 23 开始，您需要在运行时请求权限。因此，如果您计划以设备 23 及更高版本为目标，则需要添加运行时权限检查以及清单权限。

至于预览，你需要查看方法createCameraPreviewSession，更准确地说是onConfigured回调：

mCameraDevice.createCaptureSession(Arrays.asList(surface, mImageReader.getSurface()),
new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(@NonNull CameraCaptureSession cameraCaptureSession) {
// The camera is already closed
if (null == mCameraDevice) {
return;
}
// When the session is ready, we start displaying the preview.
mCaptureSession = cameraCaptureSession;
try {
// Auto focus should be continuous for camera preview.
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE,
CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
// Flash is automatically enabled when necessary.
setAutoFlash(mPreviewRequestBuilder);
// Finally, we start displaying the camera preview.
mPreviewRequest = mPreviewRequestBuilder.build();
mCaptureSession.setRepeatingRequest(mPreviewRequest,
mCaptureCallback, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
@Override
public void onConfigureFailed(
@NonNull CameraCaptureSession cameraCaptureSession) {
showToast("Failed");
}
}, null
);

如您所见，mPreviewRequest和mPreviewRequestBuilder用于设置预览。

编辑：

因此，Camera2BasicFragment只是一个托管Surface和相机的Fragment，因此当您运行应用程序时，您可以直接看到预览。据我了解，您想要的是预览前有一个进入屏幕。

为了方便起见，您可以构建您的应用程序，以便您的CameraConnectionFragment可以充当入口屏幕(您将在其中有一个按钮来启动预览(，然后导致预览片段。

预览片段将被Camera2BasicFragment您可以从存储库中复制。因此，在您的onClick方法中，您将执行一个片段事务，该事务将引导您Camera2BasicFragment。