Android Camera进程间通信类总结

我们直达camera模块的代码根据层次可以分为下面几层，开发者直接接触的是Camera api的部分，Camera api会通过Binder IPC方式调用到Camera服务部分，但是这部分代码实在繁杂，需要将这部分IPC联系的方式总结一些，方便后来人方便的学习这一块的内容。

Camera api部分：
frameworks/base/core/java/android/hardware/camera2

Camera JNI部分：
frameworks/base/core/jni/android_hardware_Camera.cpp
编译选项在目录下的Android.bp
make libandroid_runtime -j1

Camera UI库部分：
frameworks/av/camera/
编译选项在目录下的Android.bp
make libcamera_client -j1

Camera服务部分：
frameworks/av/services/camera/libcameraservice/
编译选项在目录下的Android.mk
make libcameraservice -j1

Camera HAL部分：
hardware/qcom/camera/

首先大家关注一下这个代码路径：frameworks/av/camera/aidl/ 这里是和cameraservice端交互的桥梁。

image.png

cameraservice端的代码在frameworks/av/services/camera/libcameraservice/下面。

image.png

1.ICameraDeviceUser.aidl

这个aidl文件会自动生成：
./out/soong/.intermediates/frameworks/av/camera/libcamera_client/android_arm_armv7-a-neon_core_shared_platform/gen/aidl/android/hardware/camera2/ICameraDeviceUser.h

#ifndef AIDL_GENERATED_ANDROID_HARDWARE_CAMERA2_I_CAMERA_DEVICE_USER_H_
#define AIDL_GENERATED_ANDROID_HARDWARE_CAMERA2_I_CAMERA_DEVICE_USER_H_

#include <binder/IBinder.h>
#include <binder/IInterface.h>
#include <binder/Status.h>
#include <camera/CameraMetadata.h>
#include <camera/camera2/CaptureRequest.h>
#include <camera/camera2/OutputConfiguration.h>
#include <camera/camera2/SubmitInfo.h>
#include <cstdint>
#include <gui/view/Surface.h>
#include <utils/StrongPointer.h>
#include <vector>

namespace android {

namespace hardware {

namespace camera2 {

class ICameraDeviceUser : public ::android::IInterface {
public:
  DECLARE_META_INTERFACE(CameraDeviceUser)
  enum  : int32_t {
    NO_IN_FLIGHT_REPEATING_FRAMES = -1,
    NORMAL_MODE = 0,
    CONSTRAINED_HIGH_SPEED_MODE = 1,
    VENDOR_MODE_START = 32768,
    TEMPLATE_PREVIEW = 1,
    TEMPLATE_STILL_CAPTURE = 2,
    TEMPLATE_RECORD = 3,
    TEMPLATE_VIDEO_SNAPSHOT = 4,
    TEMPLATE_ZERO_SHUTTER_LAG = 5,
    TEMPLATE_MANUAL = 6,
  };
  virtual ::android::binder::Status disconnect() = 0;
  virtual ::android::binder::Status submitRequest(const ::android::hardware::camera2::CaptureRequest& request, bool streaming, ::android::hardware::camera2::utils::SubmitInfo* _aidl_return) = 0;
  virtual ::android::binder::Status submitRequestList(const ::std::vector<::android::hardware::camera2::CaptureRequest>& requestList, bool streaming, ::android::hardware::camera2::utils::SubmitInfo* _aidl_return) = 0;
  virtual ::android::binder::Status cancelRequest(int32_t requestId, int64_t* _aidl_return) = 0;
  virtual ::android::binder::Status beginConfigure() = 0;
  virtual ::android::binder::Status endConfigure(int32_t operatingMode, const ::android::hardware::camera2::impl::CameraMetadataNative& sessionParams) = 0;
  virtual ::android::binder::Status deleteStream(int32_t streamId) = 0;
  virtual ::android::binder::Status createStream(const ::android::hardware::camera2::params::OutputConfiguration& outputConfiguration, int32_t* _aidl_return) = 0;
  virtual ::android::binder::Status createInputStream(int32_t width, int32_t height, int32_t format, int32_t* _aidl_return) = 0;
  virtual ::android::binder::Status getInputSurface(::android::view::Surface* _aidl_return) = 0;
  virtual ::android::binder::Status createDefaultRequest(int32_t templateId, ::android::hardware::camera2::impl::CameraMetadataNative* _aidl_return) = 0;
  virtual ::android::binder::Status getCameraInfo(::android::hardware::camera2::impl::CameraMetadataNative* _aidl_return) = 0;
  virtual ::android::binder::Status waitUntilIdle() = 0;
  virtual ::android::binder::Status flush(int64_t* _aidl_return) = 0;
  virtual ::android::binder::Status prepare(int32_t streamId) = 0;
  virtual ::android::binder::Status tearDown(int32_t streamId) = 0;
  virtual ::android::binder::Status prepare2(int32_t maxCount, int32_t streamId) = 0;
  virtual ::android::binder::Status updateOutputConfiguration(int32_t streamId, const ::android::hardware::camera2::params::OutputConfiguration& outputConfiguration) = 0;
  virtual ::android::binder::Status finalizeOutputConfigurations(int32_t streamId, const ::android::hardware::camera2::params::OutputConfiguration& outputConfiguration) = 0;
  enum Call {
    DISCONNECT = ::android::IBinder::FIRST_CALL_TRANSACTION + 0,
    SUBMITREQUEST = ::android::IBinder::FIRST_CALL_TRANSACTION + 1,
    SUBMITREQUESTLIST = ::android::IBinder::FIRST_CALL_TRANSACTION + 2,
    CANCELREQUEST = ::android::IBinder::FIRST_CALL_TRANSACTION + 3,
    BEGINCONFIGURE = ::android::IBinder::FIRST_CALL_TRANSACTION + 4,
    ENDCONFIGURE = ::android::IBinder::FIRST_CALL_TRANSACTION + 5,
    DELETESTREAM = ::android::IBinder::FIRST_CALL_TRANSACTION + 6,
    CREATESTREAM = ::android::IBinder::FIRST_CALL_TRANSACTION + 7,
    CREATEINPUTSTREAM = ::android::IBinder::FIRST_CALL_TRANSACTION + 8,
    GETINPUTSURFACE = ::android::IBinder::FIRST_CALL_TRANSACTION + 9,
    CREATEDEFAULTREQUEST = ::android::IBinder::FIRST_CALL_TRANSACTION + 10,
    GETCAMERAINFO = ::android::IBinder::FIRST_CALL_TRANSACTION + 11,
    WAITUNTILIDLE = ::android::IBinder::FIRST_CALL_TRANSACTION + 12,
    FLUSH = ::android::IBinder::FIRST_CALL_TRANSACTION + 13,
    PREPARE = ::android::IBinder::FIRST_CALL_TRANSACTION + 14,
    TEARDOWN = ::android::IBinder::FIRST_CALL_TRANSACTION + 15,
    PREPARE2 = ::android::IBinder::FIRST_CALL_TRANSACTION + 16,
    UPDATEOUTPUTCONFIGURATION = ::android::IBinder::FIRST_CALL_TRANSACTION + 17,
    FINALIZEOUTPUTCONFIGURATIONS = ::android::IBinder::FIRST_CALL_TRANSACTION + 18,
  };
};  // class ICameraDeviceUser

class ICameraDeviceUserDefault : public ICameraDeviceUser {
public:
  ::android::IBinder* onAsBinder() override;
  ::android::binder::Status disconnect() override;
  ::android::binder::Status submitRequest(const ::android::hardware::camera2::CaptureRequest& request, bool streaming, ::android::hardware::camera2::utils::SubmitInfo* _aidl_return) override;
  ::android::binder::Status submitRequestList(const ::std::vector<::android::hardware::camera2::CaptureRequest>& requestList, bool streaming, ::android::hardware::camera2::utils::SubmitInfo* _aidl_return) override;
  ::android::binder::Status cancelRequest(int32_t requestId, int64_t* _aidl_return) override;
  ::android::binder::Status beginConfigure() override;
  ::android::binder::Status endConfigure(int32_t operatingMode, const ::android::hardware::camera2::impl::CameraMetadataNative& sessionParams) override;
  ::android::binder::Status deleteStream(int32_t streamId) override;
  ::android::binder::Status createStream(const ::android::hardware::camera2::params::OutputConfiguration& outputConfiguration, int32_t* _aidl_return) override;
  ::android::binder::Status createInputStream(int32_t width, int32_t height, int32_t format, int32_t* _aidl_return) override;
  ::android::binder::Status getInputSurface(::android::view::Surface* _aidl_return) override;
  ::android::binder::Status createDefaultRequest(int32_t templateId, ::android::hardware::camera2::impl::CameraMetadataNative* _aidl_return) override;
  ::android::binder::Status getCameraInfo(::android::hardware::camera2::impl::CameraMetadataNative* _aidl_return) override;
  ::android::binder::Status waitUntilIdle() override;
  ::android::binder::Status flush(int64_t* _aidl_return) override;
  ::android::binder::Status prepare(int32_t streamId) override;
  ::android::binder::Status tearDown(int32_t streamId) override;
  ::android::binder::Status prepare2(int32_t maxCount, int32_t streamId) override;
  ::android::binder::Status updateOutputConfiguration(int32_t streamId, const ::android::hardware::camera2::params::OutputConfiguration& outputConfiguration) override;
  ::android::binder::Status finalizeOutputConfigurations(int32_t streamId, const ::android::hardware::camera2::params::OutputConfiguration& outputConfiguration) override;

};

}  // namespace camera2

}  // namespace hardware

}  // namespace android

#endif  // AIDL_GENERATED_ANDROID_HARDWARE_CAMERA2_I_CAMERA_DEVICE_USER_H_

./out/soong/.intermediates/frameworks/av/camera/libcamera_client/android_arm_armv7-a-neon_core_shared_platform/gen/aidl/android/hardware/camera2/BnCameraDeviceUser.h继承了ICameraDeviceUser.h

#ifndef AIDL_GENERATED_ANDROID_HARDWARE_CAMERA2_BN_CAMERA_DEVICE_USER_H_
#define AIDL_GENERATED_ANDROID_HARDWARE_CAMERA2_BN_CAMERA_DEVICE_USER_H_

#include <binder/IInterface.h>
#include <android/hardware/camera2/ICameraDeviceUser.h>

namespace android {

namespace hardware {

namespace camera2 {

class BnCameraDeviceUser : public ::android::BnInterface<ICameraDeviceUser> {
public:
  ::android::status_t onTransact(uint32_t _aidl_code, const ::android::Parcel& _aidl_data, ::android::Parcel* _aidl_reply, uint32_t _aidl_flags = 0) override;
};  // class BnCameraDeviceUser

}  // namespace camera2

}  // namespace hardware

}  // namespace android

#endif  // AIDL_GENERATED_ANDROID_HARDWARE_CAMERA2_BN_CAMERA_DEVICE_USER_H_

./frameworks/av/services/camera/libcameraservice/api2/CameraDeviceClient.h中又发现了继承BnCameraDeviceUser.h的代码。

struct CameraDeviceClientBase :
         public CameraService::BasicClient,
         public hardware::camera2::BnCameraDeviceUser
{
    typedef hardware::camera2::ICameraDeviceCallbacks TCamCallbacks;

    const sp<hardware::camera2::ICameraDeviceCallbacks>& getRemoteCallback() {
        return mRemoteCallback;
    }

protected:
    CameraDeviceClientBase(const sp<CameraService>& cameraService,
            const sp<hardware::camera2::ICameraDeviceCallbacks>& remoteCallback,
            const String16& clientPackageName,
            const String8& cameraId,
            int api1CameraId,
            int cameraFacing,
            int clientPid,
            uid_t clientUid,
            int servicePid);

    sp<hardware::camera2::ICameraDeviceCallbacks> mRemoteCallback;
};

class CameraDeviceClient :
        public Camera2ClientBase<CameraDeviceClientBase>,
        public camera2::FrameProcessorBase::FilteredListener
{
//......
}

这个IPC调用时为了操作底层的Camera Device，获取camera device重要信息，并操作Camera Device，提供了int createStream(in OutputConfiguration outputConfiguration);来创建captute session机制，Surface getInputSurface();来返回相应的输入流。

2.ICameraDeviceCallbacks.aidl

./out/soong/.intermediates/frameworks/av/camera/libcamera_client/android_arm_armv7-a-neon_core_shared_platform/gen/aidl/android/hardware/camera2/ICameraDeviceCallbacks.h
| |
| |
./out/soong/.intermediates/frameworks/av/camera/libcamera_client/android_arm_armv7-a-neon_core_shared_platform/gen/aidl/android/hardware/camera2/BnCameraDeviceCallbacks.h
| |
| |
frameworks/av/camera/ndk/impl/ACameraDevice.h

    // Callbacks from camera service
    class ServiceCallback : public hardware::camera2::BnCameraDeviceCallbacks {
      public:
        explicit ServiceCallback(CameraDevice* device) : mDevice(device) {}
        binder::Status onDeviceError(int32_t errorCode,
                           const CaptureResultExtras& resultExtras) override;
        binder::Status onDeviceIdle() override;
        binder::Status onCaptureStarted(const CaptureResultExtras& resultExtras,
                              int64_t timestamp) override;
        binder::Status onResultReceived(const CameraMetadata& metadata,
                              const CaptureResultExtras& resultExtras,
                              const std::vector<PhysicalCaptureResultInfo>& physicalResultInfos) override;
        binder::Status onPrepared(int streamId) override;
        binder::Status onRequestQueueEmpty() override;
        binder::Status onRepeatingRequestError(int64_t lastFrameNumber,
                int32_t stoppedSequenceId) override;
      private:
        const wp<CameraDevice> mDevice;
    };

这是获取当前Camera Device状态的回调，在操作camera device之前需要判断当前的camera是否可用。

3.ICameraService.aidl

./out/soong/.intermediates/frameworks/av/camera/libcamera_client/android_arm_armv7-a-neon_core_shared_platform/gen/aidl/android/hardware/ICameraService.h
| |
| |
./out/soong/.intermediates/frameworks/av/camera/libcamera_client/android_arm_armv7-a-neon_core_shared_platform/gen/aidl/android/hardware/BnCameraService.h
| |
| |
frameworks/av/services/camera/libcameraservice/CameraService.h

class CameraService :
    public BinderService<CameraService>,
    public virtual ::android::hardware::BnCameraService,
    public virtual IBinder::DeathRecipient,
    public virtual CameraProviderManager::StatusListener
{
//......
}

这个Camera Service的主类，用户进程中操作camera核心功能：connectDevice、设置闪光灯等等操作都是通过IPC调用camera service实现的。

4.ICameraServiceProxy.aidl

./out/soong/.intermediates/frameworks/av/camera/libcamera_client/android_arm_armv7-a-neon_core_shared_platform/gen/aidl/android/hardware/ICameraServiceProxy.h
| |
| |
./out/soong/.intermediates/frameworks/av/camera/libcamera_client/android_arm_armv7-a-neon_core_shared_platform/gen/aidl/android/hardware/BnCameraServiceProxy.h
| |
| |
frameworks/base/services/core/java/com/android/server/camera/CameraServiceProxy.java

    private final ICameraServiceProxy.Stub mCameraServiceProxy = new ICameraServiceProxy.Stub() {
        @Override
        public void pingForUserUpdate() {
            if (Binder.getCallingUid() != Process.CAMERASERVER_UID) {
                Slog.e(TAG, "Calling UID: " + Binder.getCallingUid() + " doesn't match expected " +
                        " camera service UID!");
                return;
            }
            notifySwitchWithRetries(30);
        }

        @Override
        public void notifyCameraState(String cameraId, int newCameraState, int facing,
                String clientName, int apiLevel) {
            if (Binder.getCallingUid() != Process.CAMERASERVER_UID) {
                Slog.e(TAG, "Calling UID: " + Binder.getCallingUid() + " doesn't match expected " +
                        " camera service UID!");
                return;
            }
            String state = cameraStateToString(newCameraState);
            String facingStr = cameraFacingToString(facing);
            if (DEBUG) Slog.v(TAG, "Camera " + cameraId + " facing " + facingStr + " state now " +
                    state + " for client " + clientName + " API Level " + apiLevel);

            updateActivityCount(cameraId, newCameraState, facing, clientName, apiLevel);
        }
    };

5.ICameraServiceListener.aidl

./out/soong/.intermediates/frameworks/av/camera/libcamera_client/android_arm_armv7-a-neon_core_shared_platform/gen/aidl/android/hardware/ICameraServiceListener.h
| |
| |
./out/soong/.intermediates/frameworks/av/camera/libcamera_client/android_arm_armv7-a-neon_core_shared_platform/gen/aidl/android/hardware/BnCameraServiceListener.h
| |
| |
frameworks/base/core/java/android/hardware/camera2/CameraManager.java

    private static final class CameraManagerGlobal extends ICameraServiceListener.Stub
            implements IBinder.DeathRecipient {
    }

6.其他aidl文件

其他的aidl文件都是IPC间传输的Parcelable类型的数据，例如CaptureRequest.aidl就是IPC中相机捕获请求的数据，CameraInfo.aidl就是IPC中 camera数据的集合。

作者：木子一秋
链接：https://www.jianshu.com/p/2eb683037379
来源：简书
简书著作权归作者所有，任何形式的转载都请联系作者获得授权并注明出处。

posted @ 2019-05-10 10:30 zzzxzzz 阅读(416) 评论(0) 收藏举报

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