写一个安卓UVCCamera支持多点触摸控制可以放大缩小和旋转的例子

以下是一个简单的安卓UVCCamera应用程序，支持多点触摸控制，可以放大缩小和旋转：

1. 在build.gradle中添加依赖项：

implementation 'com.github.saki4510t:UVCCamera:2.3.9'

2. 在清单文件中添加以下权限：

<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-feature android:name="android.hardware.usb.host" />

3. 创建一个布局文件，包含一个SurfaceView用于显示摄像头捕获的图像。还需要添加一个放大和缩小按钮和一个旋转按钮用于控制图像。

<?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">

    <SurfaceView
        android:id="@+id/preview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@+id/buttonsLayout" />

    <LinearLayout
        android:id="@+id/buttonsLayout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:orientation="horizontal">

        <Button
            android:id="@+id/zoomInButton"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Zoom In" />

        <Button
            android:id="@+id/zoomOutButton"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Zoom Out" />

        <Button
            android:id="@+id/rotateButton"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Rotate" />
    </LinearLayout>

</RelativeLayout>

4. 在MainActivity中添加以下代码：

public class MainActivity extends AppCompatActivity implements OnFrameListener, OnTouchListener {

    private static final int PREVIEW_WIDTH = 640;
    private static final int PREVIEW_HEIGHT = 480;

    private SurfaceView mPreview;
    private UVCCamera mUVCCamera;
    private SurfaceHolder mSurfaceHolder;
    private Button mZoomInButton, mZoomOutButton, mRotateButton;
    private int mZoom = 0;
    private int mRotation = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mPreview = findViewById(R.id.preview);
        mPreview.setOnTouchListener(this);

        mZoomInButton = findViewById(R.id.zoomInButton);
        mZoomInButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (mUVCCamera != null) {
                    mZoom++;
                    mUVCCamera.setZoom(mZoom);
                }
            }
        });

        mZoomOutButton = findViewById(R.id.zoomOutButton);
        mZoomOutButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (mUVCCamera != null) {
                    mZoom--;
                    mUVCCamera.setZoom(mZoom);
                }
            }
        });

        mRotateButton = findViewById(R.id.rotateButton);
        mRotateButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                mRotation += 90;
                if (mRotation >= 360) {
                    mRotation = 0;
                }
                if (mUVCCamera != null) {
                    mUVCCamera.setPreviewRotate(mRotation);
                }
            }
        });

        mSurfaceHolder = mPreview.getHolder();
        mSurfaceHolder.addCallback(new SurfaceHolder.Callback() {
            @Override
            public void surfaceCreated(SurfaceHolder holder) {
                openCamera();
            }

            @Override
            public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {

            }

            @Override
            public void surfaceDestroyed(SurfaceHolder holder) {
                closeCamera();
            }
        });
    }

    private void openCamera() {
        List<UsbDevice> usbDevices = ((UsbManager) getSystemService(Context.USB_SERVICE)).getDeviceList();
        if (!usbDevices.isEmpty()) {
            UsbDevice usbDevice = usbDevices.get(0);
            mUVCCamera = new UVCCamera();
            mUVCCamera.open(usbDevice);
            mUVCCamera.setPreviewSize(PREVIEW_WIDTH, PREVIEW_HEIGHT);
            mUVCCamera.setPreviewDisplay(mSurfaceHolder);
            mUVCCamera.setFrameListener(this, UVCCamera.PIXEL_FORMAT_YUV420SP);
            mUVCCamera.startPreview();
        }
    }

    private void closeCamera() {
        if (mUVCCamera != null) {
            mUVCCamera.stopPreview();
            mUVCCamera.release();
            mUVCCamera = null;
        }
    }

    @Override
    public boolean onTouch(View v, MotionEvent event) {
        if (event.getPointerCount() == 2) {
            float x1 = event.getX(0);
            float y1 = event.getY(0);
            float x2 = event.getX(1);
            float y2 = event.getY(1);

            switch (event.getActionMasked()) {
                case MotionEvent.ACTION_MOVE:
                    float dx = x1 - x2;
                    float dy = y1 - y2;
                    float distance = (float) Math.sqrt(dx * dx + dy * dy);
                    float centerX = (x1 + x2) / 2;
                    float centerY = (y1 + y2) / 2;

                    if (mUVCCamera != null) {
                        mUVCCamera.setZoom((int) distance / 10);
                        mUVCCamera.setPreviewRotate((int) Math.toDegrees(Math.atan2(dy, dx)) + mRotation);
                        mUVCCamera.setPreviewFlip(false, false);
                        mUVCCamera.setPreviewMirror(false, false);
                    }
                    break;
            }
        }

        return true;
    }

    @Override
    public void onFrame(ByteBuffer frame) {
        // TODO: Implement frame processing
    }
}

5. 在onTouch方法中添加多点触摸控制代码。当检测到两个手指在屏幕上移动时，通过计算两个手指之间的距离和角度来进行缩放和旋转。注意，为了使图像正确地缩放和旋转，还需要设置一些其他参数，例如预览反转和镜像。

6. 在onFrame方法中添加帧处理代码。在这个例子中，我们没有对帧进行任何处理，但是如果你想实现一些特定的功能，例如人脸检测或目标跟踪，你可以在这个方法中实现它们。

注意：本例子中使用的UVCCamera库可能不适用于所有设备，请根据您的设备和摄像头选择合适的库。