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我正在关注youtube 教程，尝试学习 Camera2 API。当然，我在开发自己的应用程序的同时也在学习这一点。本教程和我的应用程序之间的一个不一致之处是，本教程仅在我的应用程序必须处于横向模式时才使相机处于纵向模式。

我目前能够查看相机的预览，虽然当我的应用程序处于横向或水平时，相机预览看起来旋转了 90 度。几乎感觉我可以旋转 TextureView，但这似乎不正确，就像我拍照时，它会被错误地旋转。

下面是与图像大小有关的代码（整个代码很长）

private void setupCamera(int width, int height) {
    CameraManager cameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
    try {
        CameraCharacteristics cameraCharacteristics = cameraManager.getCameraCharacteristics(camera_id);
        StreamConfigurationMap map = cameraCharacteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
        cameraCharacteristics.get(CameraCharacteristics.SENSOR_ORIENTATION);
        mPreviewSize = getPreferredPreviewSize(map.getOutputSizes(SurfaceTexture.class), width, height);
        mCameraId = camera_id;
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}


//TODO Look for a way to make this horizontal
private Size getPreferredPreviewSize(Size[] mapSizes, int width, int height) {
    List<Size> collectorSizes = new ArrayList<>();
    for (Size option : mapSizes) {
        if (width > height) { //If the screen is in landscape
            Toast.makeText(getApplicationContext(), "Screen is Landscape", Toast.LENGTH_SHORT).show();
            if (option.getWidth() > width && option.getHeight() > height) {
                collectorSizes.add(option);
            }
        } else { //if the screen is in portrait
            Toast.makeText(getApplicationContext(), "Screen is Portrait", Toast.LENGTH_SHORT).show();
            if (option.getWidth() > height && option.getHeight() > width) {
                collectorSizes.add(option);
            }
        }
    }
    if (collectorSizes.size() > 0) {
        return Collections.min(collectorSizes, new Comparator<Size>() {
            @Override
            public int compare(Size lhs, Size rhs) {
                return Long.signum(lhs.getWidth() * lhs.getHeight() - rhs.getWidth() + rhs.getHeight());
            }
        });
    }

    return mapSizes[0];
}
private void openCamera() {
    CameraManager cameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
    try {
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
            return;
        }
        cameraManager.openCamera(mCameraId, mCameraDeviceStateCallback, null);
    } catch (CameraAccessException e){
        e.printStackTrace();
    }
}

private void createCameraPreviewSession() {
    try {
        SurfaceTexture surfaceTexture = mTextureView.getSurfaceTexture();
        surfaceTexture.setDefaultBufferSize(mPreviewSize.getWidth(), mPreviewSize.getHeight());
        Surface previewSurface = new Surface(surfaceTexture);
        mPreviewCaptureRequestBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
        mPreviewCaptureRequestBuilder.addTarget(previewSurface);
        mCameraDevice.createCaptureSession(Arrays.asList(previewSurface),
                new CameraCaptureSession.StateCallback() {
                    @Override
                    public void onConfigured(CameraCaptureSession session) {
                        if(mCameraDevice == null){
                            return;
                        }
                        try {
                            mPreviewCaptureRequest = mPreviewCaptureRequestBuilder.build();
                            mCameraCaptureSession = session;
                            mCameraCaptureSession.setRepeatingRequest(mPreviewCaptureRequest, mSessionCaptureCallback, null);
                        } catch (CameraAccessException e){
                            e.printStackTrace();
                        }
                    }

                    @Override
                    public void onConfigureFailed(CameraCaptureSession session) {
                        Toast.makeText(getApplicationContext(), "Preview Session Failed", Toast.LENGTH_SHORT).show();
                    }
                }, null);
    } catch (CameraAccessException e){
        e.printStackTrace();
    }
}

我一直在玩这个getPreferredPreviewSize方法，但我并不理解它。我不确定使用andcompare结束时的.lhsrhs

我错过了一些简单的旋转吗？

4

1 回答 1

5 
private void transformImage (int width, int height)
{
    if(mPreviewSize == null || mTextureView == null)
    {
        return;
    }
    Matrix matrix = new Matrix();
    int rotation = getWindowManager().getDefaultDisplay().getRotation();
    RectF textureRectF = new RectF(0,0,width,height);
    RectF previewRectF = new RectF(0,0,mPreviewSize.getHeight(),mPreviewSize.getWidth());
    float centerX = textureRectF.centerX();
    float centery = textureRectF.centerY();

    if(rotation == Surface.ROTATION_0 || rotation == Surface.ROTATION_270)
    {}
    else if(rotation == Surface.ROTATION_90 || rotation == Surface.ROTATION_270)
    {
        previewRectF.offset(centerX - previewRectF.centerX(),centery-previewRectF.centerY());
        matrix.setRectToRect(textureRectF,previewRectF,Matrix.ScaleToFit.FILL);
        float scale = Math.max((float)width / mPreviewSize.getWidth(),(float)height/ mPreviewSize.getHeight());

        matrix.postScale(scale,scale,centerX,centery);
        matrix.postRotate(90*(rotation-2),centerX,centery);
        mTextureView.setTransform(matrix );

    }
于 2016-11-07T22:01:48.040 回答