写出一个TextureView放大缩小旋转的例子并处理闪屏问题

这里有一个使用TextureView放大缩小旋转的例子，并处理了闪屏问题。

public class TextureViewActivity extends AppCompatActivity implements TextureView.SurfaceTextureListener {

    private static final String TAG = "TextureViewActivity";
    private TextureView mTextureView;
    private float mLastX, mLastY;
    private int mRotation;
    private boolean mIsEnlarged;

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

        mTextureView = findViewById(R.id.textureView);
        mTextureView.setSurfaceTextureListener(this);
        mTextureView.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                switch (event.getAction()) {
                    case MotionEvent.ACTION_DOWN:
                        mLastX = event.getX();
                        mLastY = event.getY();
                        break;
                    case MotionEvent.ACTION_MOVE:
                        float offsetX = event.getX() - mLastX;
                        float offsetY = event.getY() - mLastY;
                        if (Math.abs(offsetX) > Math.abs(offsetY)) {
                            rotateTextureView(offsetX);
                        } else {
                            scaleTextureView(offsetY);
                        }
                        mLastX = event.getX();
                        mLastY = event.getY();
                        break;
                }
                return true;
            }
        });
    }

    private void rotateTextureView(float offsetX) {
        mRotation -= offsetX / 10;
        if (mRotation < 0) {
            mRotation += 360;
        } else if (mRotation >= 360) {
            mRotation -= 360;
        }
        mTextureView.setRotation(mRotation);
    }

    private void scaleTextureView(float offsetY) {
        float scaleY = mTextureView.getScaleY();
        scaleY += offsetY / 1000;
        if (scaleY < 0.1f) {
            scaleY = 0.1f;
        } else if (scaleY > 2.0f) {
            scaleY = 2.0f;
        }
        mTextureView.setScaleX(scaleY);
        mTextureView.setScaleY(scaleY);
        if (scaleY > 1.0f) {
            mIsEnlarged = true;
        } else {
            mIsEnlarged = false;
        }
    }

    @Override
    public void onSurfaceTextureAvailable(SurfaceTexture surface, int width, int height) {
        Log.d(TAG, "onSurfaceTextureAvailable");
        Canvas canvas = mTextureView.lockCanvas();
        if (canvas != null) {
            canvas.drawColor(Color.BLACK);
            mTextureView.unlockCanvasAndPost(canvas);
        }
    }

    @Override
    public void onSurfaceTextureSizeChanged(SurfaceTexture surface, int width, int height) {
        Log.d(TAG, "onSurfaceTextureSizeChanged");
        Canvas canvas = mTextureView.lockCanvas();
        if (canvas != null) {
            canvas.drawColor(Color.BLACK);
            mTextureView.unlockCanvasAndPost(canvas);
        }
    }

    @Override
    public boolean onSurfaceTextureDestroyed(SurfaceTexture surface) {
        Log.d(TAG, "onSurfaceTextureDestroyed");
        return true;
    }

    @Override
    public void onSurfaceTextureUpdated(SurfaceTexture surface) {
        Log.d(TAG, "onSurfaceTextureUpdated");
        if (!mIsEnlarged) {
            Canvas canvas = mTextureView.lockCanvas();
            if (canvas != null) {
                canvas.drawColor(Color.BLACK);
                mTextureView.unlockCanvasAndPost(canvas);
            }
        }
    }
}

在这个例子中，我们使用`TextureView`展示视频画面，并通过手势实现了放大缩小和旋转功能，同时还处理了闪屏问题。

在`onCreate()`方法中，我们首先设置了`TextureView`的`SurfaceTextureListener`和`OnTouchListener`，其中`SurfaceTextureListener`用于监听`SurfaceTexture`的创建、大小改变和销毁，而`OnTouchListener`用于监听用户手势操作。

在`onTouch()`方法中，我们根据手势的横向偏移量来旋转`TextureView`，根据手势的纵向偏移量来缩放`TextureView`。由于`TextureView`的缩放会导致视图出现闪屏，因此我们在缩小到原始大小时重新绘制`TextureView`，避免了闪屏问题。

在`onSurfaceTextureAvailable()`和`onSurfaceTextureSizeChanged()`方法中，我们在`TextureView`上绘制了一个黑色背景，以避免闪屏问题。

在`onSurfaceTextureDestroyed()`方法中，我们返回`true`，表示要销毁`SurfaceTexture`，这样就可以在`onSurfaceTextureUpdated()`方法中重新绘制`TextureView`，避免了闪屏问题。

需要注意的是，为了避免闪屏问题，我们在缩小到原始大小时重新绘制了`TextureView`，这可能会影响性能。因此，如果你需要高性能的应用程序，可以考虑使用OpenGL ES来绘制视频画面，这样可以更好地处理缩放和旋转，而且不会出现闪屏问题。