Android2.2平台上支持多camera（三）
5、ICameraService.h文件
Framework/base/include/camera/ICameraService.h是CameraService对外的接口文件。
首先增加了三个宏定义，如下：
class ICameraService : public IInterface
{
public:
enum {
GET_NUMBER_OF_CAMERAS = IBinder::FIRST_CALL_TRANSACTION,
GET_CAMERA_INFO,
CONNECT,
SET_CAMERA_ID
};
GET_NUMBER_OF_CAMERAS，GET_CAMERA_INFO和SET_CAMERA_ID对应于那三个函数接口。
接下来，定义了三个纯虚函数，CODE如下：
public:
DECLARE_META_INTERFACE(CameraService);
virtual int32_t getNumberOfCameras() = 0;
virtual status_t getCameraInfo(int cameraId,
struct CameraInfo* cameraInfo) = 0;
virtual int32_t setCameraId(int cameraId) = 0;
virtual sp<ICamera> connect(const sp<ICameraClient>& cameraClient) = 0;
};
6、ICameraService.cpp文件
Framework/base/libs/camera/ICameraService.cpp是对ICameraService.h文件的实现。
它对下面三个函数进行了定义：
// get number of cameras available
virtual int32_t getNumberOfCameras()
{
Parcel data, reply;
data.writeInterfaceToken(ICameraService::getInterfaceDescriptor());
remote()->transact(BnCameraService::GET_NUMBER_OF_CAMERAS, data, &reply);
return reply.readInt32();
}
// get information about a camera
virtual status_t getCameraInfo(int cameraId,
struct CameraInfo* cameraInfo) {
Parcel data, reply;
data.writeInterfaceToken(ICameraService::getInterfaceDescriptor());
data.writeInt32(cameraId);
remote()->transact(BnCameraService::GET_CAMERA_INFO, data, &reply);
cameraInfo->facing = reply.readInt32();
cameraInfo->orientation = reply.readInt32();
return reply.readInt32();
}
virtual int32_t setCameraId(int cameraId)
{
Parcel data, reply;
data.writeInterfaceToken(ICameraService::getInterfaceDescriptor());
data.writeInt32(cameraId);
remote()->transact(BnCameraService::SET_CAMERA_ID, data, &reply);
return reply.readInt32();
}
然后又在函数BnCameraService::onTransact()中做了修改：
status_t BnCameraService::onTransact(
uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags)
{
switch(code) {
case GET_NUMBER_OF_CAMERAS: {
CHECK_INTERFACE(ICameraService, data, reply);
reply->writeInt32(getNumberOfCameras());
return NO_ERROR;
} break;
case GET_CAMERA_INFO: {
CHECK_INTERFACE(ICameraService, data, reply);
CameraInfo cameraInfo;
memset(&cameraInfo, 0, sizeof(cameraInfo));
status_t result = getCameraInfo(data.readInt32(), &cameraInfo);
reply->writeInt32(cameraInfo.facing);
reply->writeInt32(cameraInfo.orientation);
reply->writeInt32(result);
return NO_ERROR;
} break;
case SET_CAMERA_ID: {
CHECK_INTERFACE(ICameraService, data, reply);
reply->writeInt32(setCameraId(data.readInt32()));
return NO_ERROR;
} break;
case CONNECT: {
CHECK_INTERFACE(ICameraService, data, reply);
sp<ICameraClient> cameraClient = interface_cast<ICameraClient>(data.readStrongBinder());
sp<ICamera> camera = connect(cameraClient);
reply->writeStrongBinder(camera->asBinder());
return NO_ERROR;
} break;
default:
return BBinder::onTransact(code, data, reply, flags);
}
}
这里通过Binder与CameraService.cpp进行通信。下面介绍CameraService相关的文件。
7、CameraService.h文件
Frameworks/base/camera/libcameraservice/CameraService.h中定义了如下三个接口函数：
virtual int32_t getNumberOfCameras();
virtual status_t getCameraInfo(int cameraId,
struct CameraInfo* cameraInfo);
virtual int32_t setCameraId(int cameraId);
其具体实现在CameraService.cpp中。
8、CameraService.cpp
frameworks/base/camera/libcameraservice/CameraService.cpp调用Camera HAL层的接口，对CameraService.h中的三个新增接口做了实现。其CODE如下：
int32_t CameraService::getNumberOfCameras() {
return HAL_getNumberOfCameras();
}
status_t CameraService::getCameraInfo(int cameraId,
struct CameraInfo* cameraInfo) {
int mNumberOfCameras = HAL_getNumberOfCameras();
if (cameraId < 0 || cameraId >= mNumberOfCameras) {
return BAD_VALUE;
}
HAL_getCameraInfo(cameraId, cameraInfo);
return OK;
}
int32_t CameraService::setCameraId(int cameraId) {
return HAL_setCameraId(cameraId);
}
下面我们将介绍Camera HAL层对多Camera的支持。（待续）