Android camera: CameraServiceProxy

最新推荐文章于 2025-06-20 09:13:49 发布

原创最新推荐文章于 2025-06-20 09:13:49 发布 · 1.9k 阅读

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本文深入解析了CameraServiceProxy服务的工作原理及其在Android系统中的实现细节。CameraServiceProxy作为system_server与media_server之间的桥梁，负责处理摄像头状态更新等关键任务。

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CameraServiceProxy　service的实现

frameworks/base/services/core/java/com/android/server/camera/CameraServiceProxy.java

/**
 * CameraServiceProxy is the system_server analog to the camera service running in mediaserver.
 *
 * @hide
 */
public class CameraServiceProxy extends SystemService

{

   public static final String CAMERA_SERVICE_PROXY_BINDER_NAME = "media.camera.proxy";

    private final ICameraServiceProxy.Stub mCameraServiceProxy = new ICameraServiceProxy.Stub() {
        @Override
        public void pingForUserUpdate() {
            notifySwitchWithRetries(30);
        }

        @Override
        public void notifyCameraState(String cameraId, int newCameraState) {
            String state = cameraStateToString(newCameraState);
            if (DEBUG) Slog.v(TAG, "Camera " + cameraId + " state now " + state);

            updateActivityCount(cameraId, newCameraState);
        }
    };

    @Override
    public void onStart() {
        mUserManager = UserManager.get(mContext);

        IntentFilter filter = new IntentFilter();
        filter.addAction(Intent.ACTION_USER_ADDED);
        filter.addAction(Intent.ACTION_USER_REMOVED);
        filter.addAction(Intent.ACTION_USER_INFO_CHANGED);
        filter.addAction(Intent.ACTION_MANAGED_PROFILE_ADDED);
        filter.addAction(Intent.ACTION_MANAGED_PROFILE_REMOVED);
        mContext.registerReceiver(mIntentReceiver, filter);

        publishBinderService(CAMERA_SERVICE_PROXY_BINDER_NAME, mCameraServiceProxy);
    }

}

怎样使用该service

frameworks/av/services/camera/libcameraservice/CameraService.cpp

void CameraService::updateProxyDeviceState(ICameraServiceProxy::CameraState newState,
        const String8& cameraId) {
    sp<ICameraServiceProxy> proxyBinder = getCameraServiceProxy();
    if (proxyBinder == nullptr) return;
    String16 id(cameraId);
    proxyBinder->notifyCameraState(id, newState);
}

sp<ICameraServiceProxy> CameraService::getCameraServiceProxy() {

    sp<ICameraServiceProxy> proxyBinder = nullptr;
    sp<IServiceManager> sm = defaultServiceManager();
    // Use checkService because cameraserver normally starts before the
    // system server and the proxy service. So the long timeout that getService
    // has before giving up is inappropriate.
    sp<IBinder> binder = sm->checkService(String16("media.camera.proxy"));
    if (binder != nullptr) {
        proxyBinder = interface_cast<ICameraServiceProxy>(binder);
    }
    return proxyBinder;
}

template <typename TClientBase>
void Camera2ClientBase<TClientBase>::notifyShutter(const CaptureResultExtras& resultExtras,
                                                   nsecs_t timestamp) {
    (void)resultExtras;
    (void)timestamp;

    if (!mDeviceActive) {
        getCameraService()->updateProxyDeviceState(
            hardware::ICameraServiceProxy::CAMERA_STATE_ACTIVE, TClientBase::mCameraIdStr,
            TClientBase::mCameraFacing, TClientBase::mClientPackageName);
    }
    mDeviceActive = true;

    ALOGV("%s: Shutter notification for request id %" PRId32 " at time %" PRId64,
            __FUNCTION__, resultExtras.requestId, timestamp);
}