在相机预览textureView界面添加对焦的小圆圈

您可以在TextureView上绘制一个小圆圈来表示对焦区域。以下是一些示例代码，您可以将其添加到您的项目中：

1. 在XML布局文件中添加TextureView：

<TextureView
    android:id="@+id/textureView"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

2. 在相机预览过程中，获取TextureView的宽度和高度：

private int mTextureViewWidth;
private int mTextureViewHeight;

private void setUpCameraOutputs() {
    // ...

    // 获取TextureView的宽度和高度
    mTextureViewWidth = mTextureView.getWidth();
    mTextureViewHeight = mTextureView.getHeight();

    // ...
}

3. 在onTouchEvent()方法中，获取用户触摸的坐标，并将其转换为相对于TextureView的坐标：

@Override
public boolean onTouchEvent(MotionEvent event) {
    switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            // 获取用户触摸的坐标
            float x = event.getX();
            float y = event.getY();

            // 将坐标转换为相对于TextureView的坐标
            float touchX = (x / mTextureViewWidth) * 2000 - 1000;
            float touchY = (y / mTextureViewHeight) * 2000 - 1000;

            // 设置相机对焦区域
            Rect rect = new Rect((int) touchX - 50, (int) touchY - 50, (int) touchX + 50, (int) touchY + 50);
            mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_REGIONS, new MeteringRectangle[]{new MeteringRectangle(rect, MeteringRectangle.METERING_WEIGHT_MAX)});
            mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_REGIONS, new MeteringRectangle[]{new MeteringRectangle(rect, MeteringRectangle.METERING_WEIGHT_MAX)});
            mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_AUTO);
            mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER, CameraMetadata.CONTROL_AF_TRIGGER_START);
            try {
                mCaptureSession.setRepeatingRequest(mPreviewRequestBuilder.build(), mCaptureCallback, mHandler);
            } catch (CameraAccessException e) {
                e.printStackTrace();
            }
            break;
    }
    return true;
}

4. 在onDraw()方法中，绘制小圆圈：

private void drawFocusCircle(Canvas canvas, float x, float y) {
    Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
    paint.setColor(Color.WHITE);
    paint.setStyle(Paint.Style.STROKE);
    paint.setStrokeWidth(2);

    canvas.drawCircle(x, y, 50, paint);
}

@Override
public void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    drawFocusCircle(canvas, mTextureViewWidth / 2, mTextureViewHeight / 2);
}

这将在TextureView中心绘制一个白色的小圆圈，表示对焦区域。您可以根据需要修改代码，以适应您的应用程序。