Camera2 TextureView预览摄像头角度

要预览摄像头角度，可以通过设置TextureView的transform matrix来实现。首先，需要获取当前设备方向和相机传感器方向的差异，可以使用以下代码：

int sensorOrientation = characteristics.get(CameraCharacteristics.SENSOR_ORIENTATION);
int deviceOrientation = getWindowManager().getDefaultDisplay().getRotation();
int surfaceRotation = ORIENTATIONS.get(deviceOrientation);
int rotation = (sensorOrientation - surfaceRotation + 360) % 360;

其中，characteristics是当前相机设备的CameraCharacteristics实例，ORIENTATIONS是一个常量数组，包含了设备方向和Surface方向之间的映射关系。

接下来，根据计算出的rotation值，设置TextureView的transform matrix：

Matrix matrix = new Matrix();
RectF viewRect = new RectF(0, 0, viewWidth, viewHeight);
RectF bufferRect = new RectF(0, 0, previewSize.getHeight(), previewSize.getWidth());
float centerX = viewRect.centerX();
float centerY = viewRect.centerY();
if (rotation == Surface.ROTATION_90 || rotation == Surface.ROTATION_270) {
    bufferRect.offset(centerX - bufferRect.centerX(), centerY - bufferRect.centerY());
    matrix.setRectToRect(viewRect, bufferRect, Matrix.ScaleToFit.FILL);
    float scale = Math.max(
            (float) viewHeight / previewSize.getHeight(),
            (float) viewWidth / previewSize.getWidth());
    matrix.postScale(scale, scale, centerX, centerY);
    matrix.postRotate(90 * (rotation - 2), centerX, centerY);
} else if (rotation == Surface.ROTATION_180) {
    matrix.postRotate(180, centerX, centerY);
} 
textureView.setTransform(matrix);

上述代码中，viewWidth和viewHeight分别是TextureView的宽高，previewSize是预览尺寸。根据当前方向的不同，使用不同的变换方式设置transform matrix。最后，将变换矩阵应用到TextureView上即可。