一、Camera2的大致了解：
①、 CameraManager：作为整个框架的入口，用于初始化其他类；
②、CameraCharacteristics：通过CameraManager获得，可提供Camera相关参数；
③、CameraDevice：通过CameraManager获得，类似之前的Camera类，可以进行预览等操作，例如：设置显示预览的Surface。
④、CaptureRequest.Builder：通过CameraDevice获得，可以设置预览的相关配置。
⑤、CameraCaptureSession：通过CameraDevice获得，控制通过CaptureRequest.Builder进行预览。
使用流程：
CameraManager -> CameraDevice -> CaptureRequest.Builder-> CameraCaptureSession
（原文链接：https://blog.csdn.net/ccw0054/article/details/80339208）
下面是对代码的分析：
官方代码：https://github.com/android/camera-samples
以下是一个demo的代码：
private void openCamera(int width, int height) {
if (ContextCompat.checkSelfPermission(getActivity(), Manifest.permission.CAMERA)
!= PackageManager.PERMISSION_GRANTED) {
requestCameraPermission();
return;
}
setUpCameraOutputs(width, height);
Log.d("PCC","setup test");
Activity activity = getActivity();
CameraManager manager = (CameraManager) activity.getSystemService(Context.CAMERA_SERVICE);
try {
if (!mCameraOpenCloseLock.tryAcquire(2500, TimeUnit.MILLISECONDS)) {
throw new RuntimeException("Time out waiting to lock camera opening.");
}
Log.d("111","cameraid"+mCameraId);
manager.openCamera("0", mStateCallback, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
} catch (InterruptedException e) {
throw new RuntimeException("Interrupted while trying to lock camera opening.", e);
}
}
private void setUpCameraOutputs(int width, int height) {
Activity activity = getActivity();
CameraManager manager = (CameraManager) activity.getSystemService(Context.CAMERA_SERVICE);
try {
for (String cameraId : manager.getCameraIdList()) {
Log.d("PC1",cameraId);
CameraCharacteristics characteristics
= manager.getCameraCharacteristics(cameraId);
// We don't use a front facing camera in this sample.
Integer facing = characteristics.get(CameraCharacteristics.LENS_FACING);
if (facing != null && facing == CameraCharacteristics.LENS_FACING_FRONT) {
continue;
}
StreamConfigurationMap map = characteristics.get(
CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
if (map == null) {
continue;
}
// For still image captures, we use the largest available size.
Size largest = Collections.max(
Arrays.asList(map.getOutputSizes(ImageFormat.JPEG)),
new CompareSizesByArea());
// Find out if we need to swap dimension to get the preview size relative to sensor
// coordinate.
int displayRotation = activity.getWindowManager().getDefaultDisplay().getRotation();
//noinspection ConstantConditions
mSensorOrientation = characteristics.get(CameraCharacteristics.SENSOR_ORIENTATION);
boolean swappedDimensions = false;
Log.d("PC3",cameraId);
switch (displayRotation) {
case Surface.ROTATION_0:
case Surface.ROTATION_180:
if (mSensorOrientation == 90 || mSensorOrientation == 270) {
swappedDimensions = true;
}
break;
case Surface.ROTATION_90:
case Surface.ROTATION_270:
if (mSensorOrientation == 0 || mSensorOrientation == 180) {
swappedDimensions = true;
}
break;
default:
Log.e(TAG, "Display rotation is invalid: " + displayRotation);
}
Point displaySize = new Point();
activity.getWindowManager().getDefaultDisplay().getSize(displaySize);
int rotatedPreviewWidth = width;
int rotatedPreviewHeight = height;
int maxPreviewWidth = displaySize.x;
int maxPreviewHeight = displaySize.y;
if (swappedDimensions) {
rotatedPreviewWidth = height;
rotatedPreviewHeight = width;
maxPreviewWidth = displaySize.y;
maxPreviewHeight = displaySize.x;
}
if (maxPreviewWidth > MAX_PREVIEW_WIDTH) {
maxPreviewWidth = MAX_PREVIEW_WIDTH;
}
if (maxPreviewHeight > MAX_PREVIEW_HEIGHT) {
maxPreviewHeight = MAX_PREVIEW_HEIGHT;
}
// Danger, W.R.! Attempting to use too large a preview size could exceed the camera
// bus' bandwidth limitation, resulting in gorgeous previews but the storage of
// garbage capture data.
mPreviewSize = chooseOptimalSize(map.getOutputSizes(SurfaceTexture.class),
rotatedPreviewWidth, rotatedPreviewHeight, maxPreviewWidth,
maxPreviewHeight, largest);
// We fit the aspect ratio of TextureView to the size of preview we picked.
int orientation = getResources().getConfiguration().orientation;
if (orientation == Configuration.ORIENTATION_LANDSCAPE) {
autoFitTextureView.setAspectRatio(
mPreviewSize.getWidth(), mPreviewSize.getHeight());
} else {
autoFitTextureView.setAspectRatio(
mPreviewSize.getHeight(), mPreviewSize.getWidth());
}
// Check if the flash is supported.
Boolean available = characteristics.get(CameraCharacteristics.FLASH_INFO_AVAILABLE);
mFlashSupported = available == null ? false : available;
mImageReader = ImageReader.newInstance(largest.getWidth(), largest.getHeight(),
ImageFormat.YUV_420_888, /*maxImages*/5);
mCameraId = cameraId;
return;
}
} catch (CameraAccessException e) {
e.printStackTrace();
} catch (NullPointerException e) {
// Currently an NPE is thrown when the Camera2API is used but not supported on the
// device this code runs.
ErrorDialog.newInstance(getString(R.string.camera_error))
.show(getChildFragmentManager(), FRAGMENT_DIALOG);
}
}
private final CameraDevice.StateCallback mStateCallback = new CameraDevice.StateCallback() {
@Override
public void onOpened(@NonNull CameraDevice cameraDevice) {
// This method is called when the camera is opened. We start camera preview here.
mCameraOpenCloseLock.release();
mCameraDevice = cameraDevice;
//createCameraPreviewSession();
}
@Override
public void onDisconnected(@NonNull CameraDevice cameraDevice) {
mCameraOpenCloseLock.release();
cameraDevice.close();
mCameraDevice = null;
}
@Override
public void onError(@NonNull CameraDevice cameraDevice, int error) {
mCameraOpenCloseLock.release();
cameraDevice.close();
mCameraDevice = null;
Activity activity = getActivity();
if (null != activity) {
activity.finish();
}
}
};
private void createCameraPreviewSession() {
try {
mSurfaceTexture.setDefaultBufferSize(MAX_PREVIEW_WIDTH, MAX_PREVIEW_HEIGHT);
Surface surface = new Surface(mSurfaceTexture);
// This is the output Surface we need to start preview.
// We set up a CaptureRequest.Builder with the output Surface.
mPreviewRequestBuilder
= mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
mPreviewRequestBuilder.addTarget(surface);
//mPreviewRequestBuilder.addTarget(mImageReader.getSurface());
// Here, we create a CameraCaptureSession for camera preview.
mCameraDevice.createCaptureSession(Arrays.asList(surface, mImageReader.getSurface()),
new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(@NonNull CameraCaptureSession cameraCaptureSession) {
// The camera is already closed
if (null == mCameraDevice) {
return;
}
// When the session is ready, we start displaying the preview.
mCaptureSession = cameraCaptureSession;
// Auto focus should be continuous for camera preview.
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE,
CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
// Flash is automatically enabled when necessary.
setAutoFlash(mPreviewRequestBuilder);
// Finally, we start displaying the camera preview.
mPreviewRequest = mPreviewRequestBuilder.build();
try {
mCaptureSession.setRepeatingRequest(mPreviewRequest,
null, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
@Override
public void onConfigureFailed(
@NonNull CameraCaptureSession cameraCaptureSession) {
showToast("Failed");
}
}, mBackgroundHandler
);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
代码中我们可以看到openCamera这个函数首先会设置一个输出的大小以使得我们camera得到的data不被拉伸以至于造成变形，然后会 CameraManager manager = (CameraManager) activity.getSystemService(Context.CAMERA_SERVICE);获取camera的服务以启动manager.openCamera("0", mStateCallback, mBackgroundHandler)，这里的mStateCallback就对应device回调的一个状态，也是camera2特有的一个特性，告诉我们摄像头的状态。camera open之后我们需要创建一个createCameraPreviewSession活动，在这个函数我们创建的surfacetexture与纹理ID进行绑定，同时与mPreviewRequestBuilder进行通信，使得我们可以正常显示预览数据。
二、GLsurfaceview的大致了解：
GLsurfaceview作为surfaceview的补充，加入了EGL的管理（个人理解：极大的提供了一个接口，让我们方便的使用Opengl ES），一提到GLsurfaceview首先会想到render，在render中往往存在以下代码：
private GLSurfaceView.Renderer renderer=new GLSurfaceView.Renderer() {
@Override
public void onSurfaceCreated(GL10 gl10, EGLConfig eglConfig) {
}
@Override
public void onSurfaceChanged(GL10 gl10, int width, int height) {
}
@Override
public void onDrawFrame(GL10 gl10) {
}
};
render中分为onSurfaceCreated、onSurfaceChanged和onDrawFrame三大块，onSurfaceCreated中我们常常会创建一个纹理坐标和顶点坐标，而纹理中我们会使用一个纹理ID去绑定我们的surfaceTexture，这样就可以将纹理加载到我们的view中，而顶点坐标常常是用来确定顶点的颜色，以及坐标的对应。通过纹理我们可以获取到一个对象，通过顶点我们可以将我们的对象按照不同需求绘制出来！在做预览的时候，首先需要打开摄像头，也就是一中的 openCamera函数，接着我们会创建一个纹理对象（ID），创建好之后需要我们加载纹理坐标和顶点坐标，加载顶点时候，我们可以更改着色代码，对像素进行操作，这些着色语言位于raw文件下，其中包含demo所写的三种滤镜的实现。
二值：
binary.png
边缘：
edge.png
9分屏：
shared9.png
github代码：https://github.com/Frank1481906280/GlCV4Android