java - 在 Android 中使用相机

Question

我正在尝试构建一个 Android 应用程序，它仅使用相机来拍照，而无需启动默认相机应用程序。换句话说，我想制作一个自定义相机应用程序。我可以使用 Camera 硬件对象类来完成此操作，但是这已被弃用，我想使用camerax的一些新功能，而不必担心代码在一段时间后无法工作。我也阅读了相机API文档，但仍然不清楚如何使用相机。有没有非常简单的分步教程或指南可以帮助我？谢谢，

Answer 1

您可以查看我的示例，了解如何使用 AndroidX 库和 TextureView 进行相机自定义。

https://github.com/icerrate/Custom-Camera-App

首先，定义您的布局。这是我的 activity_main.xml 文件:

<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextureView
        android:id="@+id/view_finder"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent" />

    <com.google.android.material.floatingactionbutton.FloatingActionButton
        android:id="@+id/take_photo"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        android:layout_margin="@dimen/horizontal_margin"
        app:layout_constraintStart_toStartOf="parent"
        android:src="@drawable/ic_camera"/>

</androidx.constraintlayout.widget.ConstraintLayout>

请记住，TextureView 将接收相机预览，并且 float 操作按钮用作“拍照”按钮。

然后添加您的MainActivity.java 文件:

public class MainActivity extends AppCompatActivity implements LifecycleOwner {

    private static final int RC_PERMISSIONS = 100;

    private TextureView viewFinder;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                WindowManager.LayoutParams.FLAG_FULLSCREEN);
        setContentView(R.layout.activity_main);

        viewFinder = findViewById(R.id.view_finder);
        FloatingActionButton takePhotoFab = findViewById(R.id.take_photo);

        //Check permissions
        if (allPermissionGranted()) {
            viewFinder.post(new Runnable() {
                @Override
                public void run() {
                    startCamera();
                }
            });
        } else {
            ActivityCompat.requestPermissions(this,
                    new String[] {Manifest.permission.CAMERA}, RC_PERMISSIONS);
        }

        takePhotoFab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                takePhoto();
            }
        });
    }

    private void startCamera() {
        Point screenSize = getScreenSize();
        int width = screenSize.x;
        int height = screenSize.y;

        //Get real aspect ratio
        DisplayMetrics displayMetrics = new DisplayMetrics();
        Display display = getWindowManager().getDefaultDisplay();
        display.getRealMetrics(displayMetrics);
        Rational rational = new Rational(displayMetrics.widthPixels, displayMetrics.heightPixels);

        //Build the camera preview
        PreviewConfig build = new PreviewConfig.Builder()
                .setTargetAspectRatio(rational)
                .setTargetResolution(new Size(width,height))
                .build();
        Preview preview = new Preview(build);

        preview.setOnPreviewOutputUpdateListener(new Preview.OnPreviewOutputUpdateListener() {
            @Override
            public void onUpdated(Preview.PreviewOutput output) {
                ViewGroup group = (ViewGroup) viewFinder.getParent();
                group.removeView(viewFinder);
                group.addView(viewFinder, 0);

                viewFinder.setSurfaceTexture(output.getSurfaceTexture());
            }
        });

        CameraX.bindToLifecycle(this, preview);
    }

    private void takePhoto() {
        Toast.makeText(this, "Shot!",
                Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode == RC_PERMISSIONS) {
            if (allPermissionGranted()) {
                viewFinder.post(new Runnable() {
                    @Override
                    public void run() {
                        startCamera();
                    }
                });
            } else {
                Toast.makeText(this, "Permission not granted",
                        Toast.LENGTH_SHORT).show();
                finish();
            }
        }
    }

    private boolean allPermissionGranted() {
        return ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) == PackageManager.PERMISSION_GRANTED;
    }

    private Point getScreenSize() {
        Display display = getWindowManager(). getDefaultDisplay();
        Point size = new Point();
        display.getSize(size);
        return size;
    }
}

在此类中，您可以在 PreviewConfig.Builder() 的帮助下将相机预览发送到 TextureView，并将其绑定(bind)到 Activity 生命周期，使用CameraX.bindToLifeCycle()

此外，不要忘记将相机权限添加到 list 中并考虑运行时权限。

屏幕截图: Custom Camera preview

希望这对您有帮助!