2、菜单的创建
在文件Packages/apps/camera/src/com/android/camera/Camera.java中，函数onCreateOptionsMenu()用来创建Camera系统的菜单。其具体定义如下：
@Override
public boolean onCreateOptionsMenu(Menu menu) {
super.onCreateOptionsMenu(menu);
if (mIsImageCaptureIntent) {
// No options menu for attach mode.
return false;
} else {
addBaseMenuItems(menu);
}
return true;
}
在非Video Camera模式下，mIsImageCaptureIntent为true，此处将不做任何处理。当mIsImageCaptureIntent为false时，即Video Camera模式下，将调用函数addBaseMenuItems()来创建Video Camera的菜单。Picture大小的菜单不会出现在Video Camera模式下，所以就不对addBaseMenuItems()函数分析了。
既然这里没有创建Camera模式下的菜单，那Camera模式下的菜单在哪里创建的了？我们接着分析。
在Camera.java文件中定义了类MainHandler，它里面只有一个成员函数handleMessage()，它用来处理Camera应用程序中的message。
类MainHandler的定义如下：
/**
* This Handler is used to post message back onto the main thread of the
* application
*/
private class MainHandler extends Handler {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case RESTART_PREVIEW: {
restartPreview();
if (mJpegPictureCallbackTime != 0) {
long now = System.currentTimeMillis();
mJpegCallbackFinishTime = now - mJpegPictureCallbackTime;
Log.v(TAG, "mJpegCallbackFinishTime = "
+ mJpegCallbackFinishTime + "ms");
mJpegPictureCallbackTime = 0;
}
break;
}
case CLEAR_SCREEN_DELAY: {
getWindow().clearFlags(
WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
break;
}
case FIRST_TIME_INIT: {
initializeFirstTime();
break;
}
case SET_CAMERA_PARAMETERS_WHEN_IDLE: {
setCameraParametersWhenIdle(0);
break;
}
}
}
Message FIRST_TIME_INIT应该在类Camera初始化时就会被处理，我是这样猜的，只是还没有找到具体的code。initializeFirstTime()的实现如下所示：
// Snapshots can only be taken after this is called. It should be called
// once only. We could have done these things in onCreate() but we want to
// make preview screen appear as soon as possible.
private void initializeFirstTime() {
……
mFirstTimeInitialized = true;
changeHeadUpDisplayState();
addIdleHandler();
}
在函数的结束部位有一个函数changeHeadUpDisplayState()，它的定义如下：
private void changeHeadUpDisplayState() {
// If the camera resumes behind the lock screen, the orientation
// will be portrait. That causes OOM when we try to allocation GPU
// memory for the GLSurfaceView again when the orientation changes. So,
// we delayed initialization of HeadUpDisplay until the orientation
// becomes landscape.
Configuration config = getResources().getConfiguration();
if (config.orientation == Configuration.ORIENTATION_LANDSCAPE
&& !mPausing && mFirstTimeInitialized) {
if (mGLRootView == null) initializeHeadUpDisplay();
} else if (mGLRootView != null) {
finalizeHeadUpDisplay();
}
}
此时mFirstTimeInitialized已经为true，当其他条件也满足时将进入函数initializeHeadUpDisplay()，它的具体定义为：
private void initializeHeadUpDisplay() {
FrameLayout frame = (FrameLayout) findViewById(R.id.frame);
mGLRootView = new GLRootView(this);
frame.addView(mGLRootView);
mHeadUpDisplay = new CameraHeadUpDisplay(this);
CameraSettings settings = new CameraSettings(this, mInitialParams);
mHeadUpDisplay.initialize(this,
settings.getPreferenceGroup(R.xml.camera_preferences));
mHeadUpDisplay.setListener(new MyHeadUpDisplayListener());
mHeadUpDisplay.setOrientation(mLastOrientation);
if (mParameters.isZoomSupported()) {
……
}
updateSceneModeInHud();
mGLRootView.setContentPane(mHeadUpDisplay);
}
语句mHeadUpDisplay.initialize(this, settings.getPreferenceGroup(R.xml.camera_preferences));中的R.xml.camera_preferences指的就是camera_preference.xml资源文件。
接下来我们将对settings.getPreferenceGroup()，mHeadUpDisplay.initialize()和MyHeadUpDisplayListener做以介绍。
函数settings.getPreferenceGroup()定义在文件Packages/apps/camera/src/com/android/camera/CameraSetting.java中。其具体定义为：
public PreferenceGroup getPreferenceGroup(int preferenceRes) {
PreferenceInflater inflater = new PreferenceInflater(mContext);
PreferenceGroup group =
(PreferenceGroup) inflater.inflate(preferenceRes);
initPreference(group);
return group;
}
函数inflater.inflate(preferenceRes)将camera_preference.xml文件中的菜单信息存储到PreferenceGroup中。接着函数initPreference()对这些信息做了处理，其定义为：
private void initPreference(PreferenceGroup group) {
ListPreference videoQuality = group.findPreference(KEY_VIDEO_QUALITY);
ListPreference pictureSize = group.findPreference(KEY_PICTURE_SIZE);
ListPreference whiteBalance = group.findPreference(KEY_WHITE_BALANCE);
……
// Since the screen could be loaded from different resources, we need
// to check if the preference is available here
if (videoQuality != null) {
// Modify video duration settings.
// The first entry is for MMS video duration, and we need to fill
// in the device-dependent value (in seconds).
CharSequence[] entries = videoQuality.getEntries();
CharSequence[] values = videoQuality.getEntryValues();
for (int i = 0; i < entries.length; ++i) {
if (VIDEO_QUALITY_MMS.equals(values[i])) {
entries[i] = entries[i].toString().replace(
"30", Integer.toString(MMS_VIDEO_DURATION));
break;
}
}
}
// Filter out unsupported settings / options
if (pictureSize != null) {
filterUnsupportedOptions(group, pictureSize, sizeListToStringList(
mParameters.getSupportedPictureSizes()));
}
if (whiteBalance != null) {
filterUnsupportedOptions(group,
whiteBalance, mParameters.getSupportedWhiteBalance());
}
……
}
其中，宏定义KEY_PICTURE_SIZE定义在文件
Packages/apps/camera/src/com/android/camera/CameraSetting.java中，具体定义为：
public static final String KEY_PICTURE_SIZE = "pref_camera_picturesize_key";
该值与camera_preference.xml中的KEY值匹配。语句ListPreference pictureSize = group.findPreference(KEY_PICTURE_SIZE);将picture的大小信息存储在了结构体ListPreference pictureSize中。
语句
if (pictureSize != null) {
filterUnsupportedOptions(group, pictureSize, sizeListToStringList(
mParameters.getSupportedPictureSizes()));
}
mParameters.getSupportedPictureSizes()获取了硬件Camera所支持的picture大小信息，我在Camera HAL层的实现中，在函数initDefaultParameters()中设置了硬件所支持的picture大小。CODE如下：
CameraParameters p;
p.set(“picture-size-values”, “1600x1200,1024x768,640x480”);
函数filterUnsupportedOptions()会将Camera应用和硬件支持的picture大小中两者匹配的大小存储在group中。
函数mHeadUpDisplay.initialize()定义在文件
Packages/apps/camera/src/com/android/camera/ui/HeadUpDisplay.java中，其具体定义为：
public void initialize(Context context, PreferenceGroup preferenceGroup) {
mPreferenceGroup = preferenceGroup;
mSharedPrefs = PreferenceManager.getDefaultSharedPreferences(context);
mSharedPrefs.registerOnSharedPreferenceChangeListener(
mSharedPreferenceChangeListener);
initializeIndicatorBar(context, preferenceGroup);
}
其中函数initializeIndicatorBar()定义如下：
protected void initializeIndicatorBar(
Context context, PreferenceGroup group) {
mIndicatorBar = new IndicatorBar();
mIndicatorBar.setBackground(new NinePatchTexture(
context, R.drawable.ic_viewfinder_iconbar));
mIndicatorBar.setHighlight(new NinePatchTexture(
context, R.drawable.ic_viewfinder_iconbar_highlight));
addComponent(mIndicatorBar);
mIndicatorBar.setOnItemSelectedListener(new IndicatorBarListener());
}
函数addComponent()将group中的picture大小添加到了菜单中。至此，菜单的创建就告一段落。下面我们介绍一下菜单的事件。
（待续）
