CameraAppFramework流程之OpenCamera

最新推荐文章于 2024-11-11 12:25:24 发布

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最新推荐文章于 2024-11-11 12:25:24 发布 · 509 阅读

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CC 4.0 BY-SA版权

文章标签：

#java #android #android studio

本文深入探讨Android相机应用框架，重点在于如何通过CameraManager打开相机，并详细解析Camera2Client、CameraDeviceClient及Camera3Device在CameraManager.OpenCamera过程中的作用。同时，介绍了CameraDevice.StateCallback的相关回调机制。

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APP 到 Framework 阶段

CameraManager.java

谷歌将CameraManager定义为一个系统服务，通过 Context.getService 来获取(Context.CAMERA_SERVICE)，主要用于检测以及打开系统相机，通过 OpenCamera 方法来打开相机；此外，还定义了 getCameraCharacteristics 方法来获取当前 Camera 设备支持的属性信息，该属性信息通过 CameraCharacteristics 来表示，其中包括了图像数据的大小以及帧率等信息

manager.openCamera(cameraId, callback, handler);

openCamera(@NonNull String cameraId,
            @NonNull final CameraDevice.StateCallback callback, @Nullable Handler handler)
openCameraForUid(cameraId, callback, CameraDeviceImpl.checkAndWrapHandler(handler),
                USE_CALLING_UID);
openCameraForUid(cameraId, callback, executor, clientUid, /*oomScoreOffset*/0);

openCameraDeviceUserAsync(cameraId, callback, executor, clientUid, oomScoreOffset){
    
    ICameraDeviceUser cameraUser = null;
    
    android.hardware.camera2.implCameraDeviceImpl deviceImpl = new     android.hardware.camera2.impl.CameraDeviceImpl(
        cameraId, callback, executor, characteristics, physicalIdsToChars, mContext.getApplicationInfo().targetSdkVersion, mContext)
    
    ICameraService cameraService = CameraManagerGlobal.get().getCameraService();
    

    //这一步开始去链接设备
    cameraUser = cameraService.connectDevice(callbacks, cameraId, mContext.getOpPackageName(), mContext.getAttributionTag(), uid, oomScoreOffset， mContext.getApplicationInfo().targetSdkVersion)
    
    deviceImpl.setRemoteDevice(cameraUser)
    return deviceImpl
};

CaneraService.cpp

Status CameraService::connectDevice(const sp<hardware::camera2::ICameraDeviceCallbacks>& cameraCb, const String16& cameraId, const String16& clientPackageName, int clientUid){
    sp<CameraDeviceClient> client = nullptr;
    ret = connectHelper<hardware::camera2::ICameraDeviceCallBacks, CameraDeviceClient>(cameraCb, id,/*api1CameraId*/ -1, CAMERA_HAL_API_VERSION_UNSPECIFIED, clientPackageName, /*legacyMode*/ false, /*shimUpdateOnly*/ false, /*out*/ client);
}

Status CameraService::connectHelper(const sp<CALLBACK>& cameraCb, const String8& cameraId, int api1CameraId, int halVersion, const String16& clientPackageName, int clientUid, int clientPid, apiLevel effectiveApiLevel, bool legacyMode, bool shimUpdateOnly, /*out*/ sp<CLIENT>& device){
        
    ALOGI("CameraService::connect call (PI