基于android4.4的camera的各个文件功能梳理

最新推荐文章于 2024-07-03 18:57:31 发布

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本文详细阐述了Android系统中相机管理的核心组件AndroidCameraManagerImpl的实现方式，以及其在CameraManagerFactory、CameraHolder和CameraUtil类中的应用。通过解析这些类的方法调用流程，揭示了如何在不同场景下创建、打开和操作Android设备的相机，为开发者提供了一个全面的指南。

第一:AndroidCameraManagerImpl,实现了接口:CameraManager,内部实习的class图表结构如下:

第二:该class在CameraManagerFactory这个工厂类中被new,从而创建一个camera的线程,该工厂类在CameraHolder调用,用于创建一个camera的设备实例:

f (mMockCameraInfo == null) {
mCameraDevice = CameraManagerFactory
.getAndroidCameraManager().cameraOpen(handler, cameraId, cb);

}

第三:cameraholder类主要的作用是"The class is used to hold an {@code android.hardware.Camera} instance."内部定义的class图标显示如下:

第四:该类定义的open在CameraUtil类中引用:

public static CameraManager.CameraProxy openCamera(
Activity activity, final int cameraId,
Handler handler, final CameraManager.CameraOpenErrorCallback cb) {
try {
throwIfCameraDisabled(activity);
return CameraHolder.instance().open(handler, cameraId, cb);
} catch (CameraDisabledException ex) {
handler.post(new Runnable() {
@Override
public void run() {
cb.onCameraDisabled(cameraId);
}
});
}
return null;
}

第五:CameraUtil的opencamera在PhotoModule中被引用:

private boolean prepareCamera() {
// We need to check whether the activity is paused before long
// operations to ensure that onPause() can be done ASAP.
Log.v(TAG, "Open camera device.");
mCameraDevice = CameraUtil.openCamera(
mActivity, mCameraId, mHandler,
mActivity.getCameraOpenErrorCallback());
if (mCameraDevice == null) {
Log.e(TAG, "Failed to open camera:" + mCameraId);
return false;
}
mParameters = mCameraDevice.getParameters();

initializeCapabilities();
if (mFocusManager == null) initializeFocusManager();
setCameraParameters(UPDATE_PARAM_ALL);
mHandler.sendEmptyMessage(CAMERA_OPEN_DONE);
mCameraPreviewParamsReady = true;
startPreview();
mOnResumeTime = SystemClock.uptimeMillis();
checkDisplayRotation();
return true;
}

photomodule类定义的class图表如下:

prepareCamera被调用于：

private void onResumeTasks() {
Log.v(TAG, "Executing onResumeTasks.");
if (mOpenCameraFail || mCameraDisabled) return;

mJpegPictureCallbackTime = 0;
mZoomValue = 0;
resetExposureCompensation();
if (!prepareCamera()) {
// Camera failure.
return;
}

。。。。。。

}

public void onResumeAfterSuper() {
// Add delay on resume from lock screen only, in order to to speed up
// the onResume --> onPause --> onResume cycle from lock screen.
// Don't do always because letting go of thread can cause delay.
String action = mActivity.getIntent().getAction();
if (MediaStore.INTENT_ACTION_STILL_IMAGE_CAMERA.equals(action)
|| MediaStore.INTENT_ACTION_STILL_IMAGE_CAMERA_SECURE.equals(action)) {
Log.v(TAG, "On resume, from lock screen.");
// Note: onPauseAfterSuper() will delete this runnable, so we will
// at most have 1 copy queued up.
mHandler.postDelayed(new Runnable() {
public void run() {
onResumeTasks();
}
}, ON_RESUME_TASKS_DELAY_MSEC);
} else {
Log.v(TAG, "On resume.");
onResumeTasks();
}
}

onResumeAfterSuper被调用于：

CameraActivity的

public voidonResume() {
// TODO: Handle this in OrientationManager.
// Auto-rotate off
if (Settings.System.getInt(getContentResolver(),
Settings.System.ACCELEROMETER_ROTATION, 0) == 0) {
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED);
mAutoRotateScreen = false;
} else {
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_FULL_SENSOR);
mAutoRotateScreen = true;
}

UsageStatistics.onEvent(UsageStatistics.COMPONENT_CAMERA,
UsageStatistics.ACTION_FOREGROUNDED, this.getClass().getSimpleName());

mOrientationListener.enable();
mCurrentModule.onResumeBeforeSuper();
super.onResume();
mCurrentModule.onResumeAfterSuper();