使用Camera2和GLsurface实现相机预览
之前有用过旧版的Camera实现相机预览，可是很多东西不好控制，而且旧版的camera现在以被弃用，所以使用Camera2来进行项目的开发。
先看效果：
camera2是为连接Android相机的接口。
这里引用了管道的概念将安卓设备和摄像头之间联通起来，系统向摄像头发送Capture请求，而摄像头返回CameraMetadata。在一切建立在一个叫做CameraCaptureSession的会话中。
Camera2支持RAW输出，可以调节曝光，对焦模式，快门等。
- CameraManager：摄像头管理器，用于检测摄像头，打开系统摄像头，调用
CameraManager.getCameraCharacteristics(String)可以获取指定摄像头的相关特性 - CameraCharacteristics 摄像头的特性
- CameraDevice 摄像头，类似android.hardware.Camera也就是Camera1的Camera
- CameraCaptureSession 这个对象控制摄像头的预览或者拍照，setRepeatingRequest()开启预览，capture()拍照，CameraCaptureSession提供了StateCallback、CaptureCallback两个接口来监听CameraCaptureSession的创建和拍照过程。
- CameraRequest和CameraRequest.Builder，预览或者拍照时，都需要一个CameraRequest对象。CameraRequest表示一次捕获请求，用来对z照片的各种参数设置，比如对焦模式、曝光模式等。CameraRequest.Builder用来生成CameraRequest对象。
预览的基本思想
在这里，我使用的是OpenGL ES，用摄像头获取的图像，调用OpenGL ES的库进行绘制。
摄像头：
Camera2使用的是Surface来进行预览，这个surface包括：SurfaceView, SurfaceTexture （ Surface(SurfaceTexture)）
关于各个surface的区别可以参考：https://blog.csdn.net/jinzhuojun/article/details/44062175
主要思路
- 获得摄像头管理器
mCameraManager，mCameraManager.openCamera()来打开摄像头 - 指定要打开的摄像头，并创建
openCamera()所需要的CameraDevice.StateCallback stateCallback - 在
CameraDevice.StateCallback stateCallback中调用createPreview()，这个方法中，使用CaptureRequest.Builder创建预览需要的CameraRequest，并初始化了CameraCaptureSession - 在
CameraCaptureSession的回调中，最后调用了setRepeatingRequest(previewRequest, null, null)进行了预览
Camera代码：
public class CameraHelper {
private Context mContext;
private CameraManager mCameraManager;
private CameraDevice mCameraDevice;
private String mCameraId = null;
private boolean mFlashSupport = false;
private Surface mSurface;
private CaptureRequest.Builder mPreviewBuilder;
private android.os.Handler mMainHandler;
private android.os.Handler mChildHanlder;
private static final String TAG = "CameraHelper";
public CameraHelper(Context context, SurfaceTexture surfaceTexture){
mContext = context;
Display display = ((WindowManager)context
.getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
DisplayMetrics metrics = new DisplayMetrics();
display.getMetrics(metrics);
int screenWidth = metrics.widthPixels;
int screenHidth = metrics.heightPixels;
//设置图像像素比位4:3
surfaceTexture.
setDefaultBufferSize(4*screenWidth/3,3 * screenWidth / 4);
mSurface = new Surface(surfaceTexture);
initCamera();
}
private void initCamera(){
//得到CameraManager
mCameraManager = (CameraManager) mContext.getSystemService(Context.CAMERA_SERVICE);
try {
for(String id : mCameraManager.getCameraIdList()){
CameraCharacteristics characteristics
= mCameraManager.getCameraCharacteristics(id);
Integer front = characteristics.get(CameraCharacteristics.LENS_FACING);
mCameraId = id;
//是否支持闪光灯
Boolean available = characteristics.
get(CameraCharacteristics.FLASH_INFO_AVAILABLE);
mFlashSupport = available == null? false :available;
//启动前置摄像头
if(front!=null && front == CameraCharacteristics.LENS_FACING_FRONT){
break;
}
}
mMainHandler = new android.os.Handler(Looper.getMainLooper());
if(mCameraId!=null){
//打开摄像头
mCameraManager.openCamera(mCameraId,mStateCallback
,mMainHandler);
}
}catch (CameraAccessException e){
e.printStackTrace();
}
}
private CameraDevice.StateCallback mStateCallback = new CameraDevice.StateCallback() {
@Override
public void onOpened(@NonNull CameraDevice camera) {
mCameraDevice = camera;
//开启预览
createPreview();
}
@Override
public void onDisconnected(@NonNull CameraDevice camera) {
mCameraDevice.close();
mCameraDevice = null;
}
@Override
public void onError(@NonNull CameraDevice camera, int error) {
mCameraDevice.close();
mCameraDevice = null;
}
};
private void createPreview(){
List surfaces = new ArrayList<>();
surfaces.add(mSurface);
try {
//设置一个具有输出Surface的CaptureRequest.Builder
mPreviewBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
mPreviewBuilder.addTarget(mSurface);
//进行相机预览
mCameraDevice.createCaptureSession(surfaces,mStateCallbackSession,null);
}catch (CameraAccessException e){
e.printStackTrace();
}
}
private CameraCaptureSession.StateCallback mStateCallbackSession = new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(@NonNull CameraCaptureSession session) {
mPreviewBuilder.set(CaptureRequest.CONTROL_AF_MODE,
CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
try {
//发送请求
session.setRepeatingRequest(mPreviewBuilder.build(),
null,null);
}catch (CameraAccessException e){
e.printStackTrace();
}
}
@Override
public void onConfigureFailed(@NonNull CameraCaptureSession session) {
Log.d(TAG, "onConfigureFailed: ");
}
};
}
这里有一个点，就是surfaceTexture，这个surfaceTexture怎么得到呢？我们知道在OpenGL中，我们需要绑定纹理id，这个surfaceTextrue就是根据纹理id进行构建的，
public class RecordView extends GLSurfaceView {
private RecordRender mRender;
private Context mContext;
private float[] mStMatrix = new float[16];
private static final String TAG = "RecordView";
public RecordView(Context context) {
this(context,null);
}
public RecordView(Context context, AttributeSet attrs) {
super(context, attrs);
mContext = context;
setEGLContextClientVersion(2);
mRender = new RecordRender();
setRenderer(mRender);
}
private class RecordRender implements Renderer,SurfaceTexture.OnFrameAvailableListener{
private Photo mPhoto;
private int mTextId;
private SurfaceTexture mSurfaceTexture;
private CameraHelper mCamera;
private float[] mProjMatrix = new float[16];
@Override
public void onSurfaceCreated(GL10 gl, EGLConfig config) {
GLES20.glClearColor(1,1,1,1);
GLES20.glEnable(GLES20.GL_DEPTH_TEST);
mPhoto = new Photo();
initTextureId();//构建纹理id
mSurfaceTexture = new SurfaceTexture(mTextId);//构建用于预览的surfaceTexture
mSurfaceTexture.setOnFrameAvailableListener(this);
mCamera = new CameraHelper(mContext,mSurfaceTexture);//开启预览
}
@Override
public void onSurfaceChanged(GL10 gl, int width, int height) {
GLES20.glViewport(0,0,width,height);
}
@Override
public void onDrawFrame(GL10 gl) {
GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT|GLES20.GL_DEPTH_BUFFER_BIT);
//得到最新的图像
mSurfaceTexture.updateTexImage();
//得到图像的纹理矩阵
mSurfaceTexture.getTransformMatrix(mStMatrix);
//绘制图像
mPhoto.draw(mTextId,mStMatrix);
}
private void initTextureId(){
int[] texutes = new int[1];
GLES20.glGenTextures(1,texutes,0);
mTextId = texutes[0];
GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES,mTextId);
GLES20.glTexParameterf(GLES11Ext.GL_TEXTURE_EXTERNAL_OES,
GLES20.GL_TEXTURE_MIN_FILTER,GLES20.GL_NEAREST);//设置MIN 采样方式
GLES20.glTexParameterf(GLES11Ext.GL_TEXTURE_EXTERNAL_OES,
GLES20.GL_TEXTURE_MAG_FILTER,GLES20.GL_LINEAR);//设置MAG采样方式
GLES20.glTexParameterf(GLES11Ext.GL_TEXTURE_EXTERNAL_OES,
GLES20.GL_TEXTURE_WRAP_S,GLES20.GL_CLAMP_TO_EDGE);//设置S轴拉伸方式
GLES20.glTexParameterf(GLES11Ext.GL_TEXTURE_EXTERNAL_OES,
GLES20.GL_TEXTURE_WRAP_T,GLES20.GL_CLAMP_TO_EDGE);//设置T轴拉伸方式
}
@Override
public void onFrameAvailable(SurfaceTexture surfaceTexture) {
}
}
}
关于Photo，是我自己封装的一个类，用于定义图形的绘制坐标，纹理绑定和绘制方式。要注意的是，这里必须要使用的纹理类型是：GLES11Ext.GL_TEXTURE_EXTERNAL_OES
public class Photo {
private String mVertexShder =
"attribute vec4 aPosition;" +
"attribute vec4 aTexCoord;" +
"varying vec2 vTextureCoord;" +
"uniform mat4 uMvpMatrix;" +
"uniform mat4 uTexMatrix;" +
"void main(){" +
"gl_Position = uMvpMatrix * aPosition;" +
"vTextureCoord = (uTexMatrix * aTexCoord).xy;" +
"}";
private String mFragmentShader = "#extension GL_OES_EGL_image_external : require\n" +
"precision highp float;" +
"varying vec2 vTextureCoord;" +
"uniform samplerExternalOES uSampler;" +
"void main(){" +
"gl_FragColor = texture2D(uSampler,vTextureCoord);" +
"}";
private int maPositionHandle;
private int maTextureHandle;
private int muMvpMatrixHandle;
private int muTexMatrixHandle;
private FloatBuffer mVertexBuffer;
private FloatBuffer mTextureBuffer;
private ByteBuffer mIndexbuffer;
private int mProgram;
private int mVCount = 4;
private int mIndexCount = 6;
private float[] mMvpMatrix = new float[16];
private float[] mMMatrix = new float[16];
public Photo(){
initVertexData();
initFragmentData();
}
private void initVertexData(){
float[] vertexs = new float[]{
-1,1,0,
-1,-1,0,
1,1,0,
1,-1,0
};
ByteBuffer vbb = ByteBuffer.allocateDirect(vertexs.length*4);
vbb.order(ByteOrder.nativeOrder());
mVertexBuffer = vbb.asFloatBuffer();
mVertexBuffer.put(vertexs);
mVertexBuffer.position(0);
float[] textures = new float[]{
0,0,
0,1,
1,0,
1,1
};
ByteBuffer cbb = ByteBuffer.allocateDirect(textures.length*4);
cbb.order(ByteOrder.nativeOrder());
mTextureBuffer = cbb.asFloatBuffer();
mTextureBuffer.put(textures);
mTextureBuffer.position(0);
byte[] indexs = new byte[]{
0,1,2,
1,3,2
};
mIndexbuffer = ByteBuffer.allocateDirect(indexs.length);
mIndexbuffer.order(ByteOrder.nativeOrder());
mIndexbuffer.put(indexs);
mIndexbuffer.position(0);
}
private void initFragmentData(){
mProgram = ShaderUtil.loadProgram(mVertexShder,mFragmentShader);
maPositionHandle = GLES20.glGetAttribLocation(mProgram,"aPosition");
maTextureHandle = GLES20.glGetAttribLocation(mProgram,"aTexCoord");
muMvpMatrixHandle = GLES20.glGetUniformLocation(mProgram,"uMvpMatrix");
muTexMatrixHandle = GLES20.glGetUniformLocation(mProgram,"uTexMatrix");
}
public void draw(int textId,float[] sTMatrix){
GLES20.glUseProgram(mProgram);
GLES20.glVertexAttribPointer(maPositionHandle,3,GLES20.GL_FLOAT,
false,3*4,mVertexBuffer);
GLES20.glVertexAttribPointer(maTextureHandle,2,GLES20.GL_FLOAT,
false,2*4,mTextureBuffer);
GLES20.glEnableVertexAttribArray(maPositionHandle);
GLES20.glEnableVertexAttribArray(maTextureHandle);
if(sTMatrix!=null){
GLES20.glUniformMatrix4fv(muTexMatrixHandle,
1,false,sTMatrix,0);
}else {
GLES20.glUniformMatrix4fv(muTexMatrixHandle,
1,false,mMvpMatrix,0);
}
Matrix.setIdentityM(mMvpMatrix,0);
Matrix.rotateM(mMvpMatrix,0,180,1,0,0);
GLES20.glUniformMatrix4fv(muMvpMatrixHandle,
1,false,mMvpMatrix,0);
GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES,textId);
GLES20.glDrawElements(GLES20.GL_TRIANGLES,mIndexCount,
GLES20.GL_UNSIGNED_BYTE,mIndexbuffer);
}
}
关于OpenGL纹理绑定，可以参考：https://blog.csdn.net/qq_36391075/article/details/81564454
项目地址：https://github.com/vivianluomin/FunCamera
补充：
关于CameraCharacteristics里面的参数，主要用到的有以下几个：
- LENS_FACING：前置摄像头（LENS_FACING_FRONT）还是后置摄像头（LENS_FACING_BACK）。
- SENSOR_ORIENTATION：摄像头拍照方向。
- FLASH_INFO_AVAILABLE：是否支持闪光灯。
- CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL：获取当前设备支持的相机特性。
createCaptureRequest()方法里参数templateType代表了请求类型，请求类型一共分为六种，分别为：
- TEMPLATE_PREVIEW：创建预览的请求
- TEMPLATE_STILL_CAPTURE：创建一个适合于静态图像捕获的请求，图像质量优先于帧速率。
- TEMPLATE_RECORD：创建视频录制的请求
- TEMPLATE_VIDEO_SNAPSHOT：创建视视频录制时截屏的请求
- TEMPLATE_ZERO_SHUTTER_LAG：创建一个适用于零快门延迟的请求。在不影响预览帧率的情况下最大化图像质量。
- TEMPLATE_MANUAL：创建一个基本捕获请求，这种请求中所有的自动控制都是禁用的(自动曝光，自动白平衡、自动焦点)。
参考：https://juejin.im/post/5a33a5106fb9a04525782db5
推介一个开源视频录制项目：https://github.com/guoxiaoxing/phoenix