場(chǎng)景分析，
為了完全實(shí)現(xiàn)沉浸式效果法褥，在進(jìn)入特定的app后可以將導(dǎo)航欄移除茫叭，當(dāng)退出app后再次將導(dǎo)航欄恢復(fù)。（下面將采用發(fā)送廣播的方式來(lái)移除和恢復(fù)導(dǎo)航欄）
ps：不修改源碼的情況下半等，簡(jiǎn)單的沉浸式效果實(shí)現(xiàn)代碼如下揍愁，在ACitivy中添加即可（此種做法的缺點(diǎn)是當(dāng)界面彈出對(duì)話框時(shí)或者點(diǎn)擊的屏幕的頂部或底部邊緣，會(huì)再次出現(xiàn)導(dǎo)航欄和狀態(tài)欄）
@Override
public void onWindowFocusChanged(boolean hasFocus) {//new add
super.onWindowFocusChanged(hasFocus);
if (hasFocus && Build.VERSION.SDK_INT >= 19) {
View decorView = getWindow().getDecorView();
decorView.setSystemUiVisibility(
//hide title&navigation
View.SYSTEM_UI_FLAG_FULLSCREEN
|View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY
|View.SYSTEM_UI_FLAG_HIDE_NAVIGATION);
}
}
一杀饵、屏蔽導(dǎo)航欄虛擬按鍵（Home和RecentAPP）
我們先來(lái)分析下底部導(dǎo)航欄所處的控件,
所見(jiàn)即所得莽囤，既然是虛擬按鍵，必定有相對(duì)應(yīng)的View切距，要么是xml的布局文件朽缎，要么是自定義View，基于此思路谜悟，打開(kāi)AS中的Tools菜單下Android-->Android Device Monitor-->Hierarchy View ,不會(huì)用的童鞋可以自己參考這篇Hierarchy View话肖，這里就不再寫了。
我們發(fā)現(xiàn)Home按鍵對(duì)應(yīng)的id為 @+id/home, 有了id我們就已經(jīng)成功的揪出它了葡幸，接下來(lái)通過(guò)搜索命令
grep -nr 命令
通過(guò)搜索最筒，我們發(fā)現(xiàn)了Home按鍵的 源碼位置
frameworks\base\packages\SystemUI\res\layout-sw600dp\navigation_bar.xml
frameworks\base\packages\SystemUI\res\layout\navigation_bar.xml
<!--2018-10-13 cczheng set home KeyButton visibility invisible-->
<com.android.systemui.statusbar.policy.KeyButtonView android:id="@+id/home"
android:layout_width="162dp" android:paddingStart="42dp" android:paddingEnd="42dp"
android:layout_height="match_parent"
android:src="@drawable/ic_sysbar_home"
android:scaleType="centerInside"
systemui:keyCode="3"
systemui:keyRepeat="true"
android:layout_weight="0"
android:contentDescription="@string/accessibility_home"
android:visibility="invisible"
/>
<!--2018-10-13 cczheng set recent KeyButton visibility invisible-->
<com.android.systemui.statusbar.policy.KeyButtonView android:id="@+id/recent_apps"
android:layout_width="162dp" android:paddingStart="42dp" android:paddingEnd="42dp"
android:layout_height="match_parent"
android:src="@drawable/ic_sysbar_recent"
android:scaleType="centerInside"
android:layout_weight="0"
android:contentDescription="@string/accessibility_recent"
android:visibility="invisible"
/>
此處說(shuō)下為什么用invisible，而不用gone, 如果使用gone蔚叨，剩下的按鍵將自動(dòng)居中床蜘，這并不是我們想要的效果，當(dāng)你以為按照上面的代碼屏蔽后就可以安心的交差了缅叠，那你真是too young too simple了悄泥。
繼續(xù)搜索 R.id.home,我們接下來(lái)查找在java代碼中的引用虏冻，找到位置
frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarView.java
public View getBackButton() {
ImageView view = (ImageView) mCurrentView.findViewById(R.id.back);
view.setImageDrawable(mNavBarPlugin.getBackImage(view.getDrawable()));
return view;
}
很明顯通過(guò)getBackButton()方法能獲取到該View肤粱，就能對(duì)View進(jìn)行操作，繼續(xù)查看調(diào)用getBackButton()的地方
找到當(dāng)前類中
public void setDisabledFlags(int disabledFlags, boolean force) {
if (!force && mDisabledFlags == disabledFlags) return;
mDisabledFlags = disabledFlags;
...
getBackButton().setVisibility(disableBack ? View.INVISIBLE : View.VISIBLE);
getHomeButton().setVisibility(disableHome ? View.INVISIBLE : View.VISIBLE);
getRecentsButton().setVisibility(disableRecent ? View.INVISIBLE : View.VISIBLE);
//2018-10-13 cczheng add recent KeyButton visibility invisible
getHomeButton().setVisibility(View.INVISIBLE);
getRecentsButton().setVisibility(View.INVISIBLE);
//2018-10-13 cczheng add recent KeyButton visibility invisible
...
}
另外一處位于
frameworks\base\packages\SystemUI\src\com\android\systemui\statusbar\phone\PhoneStatusBar.java
private void prepareNavigationBarView() {
mNavigationBarView.reorient();
mNavigationBarView.getRecentsButton().setOnClickListener(mRecentsClickListener);
mNavigationBarView.getRecentsButton().setOnTouchListener(mRecentsPreloadOnTouchListener);
mNavigationBarView.getRecentsButton().setLongClickable(true);
mNavigationBarView.getRecentsButton().setOnLongClickListener(mLongPressBackRecentsListener);
mNavigationBarView.getBackButton().setLongClickable(true);
mNavigationBarView.getBackButton().setOnLongClickListener(mLongPressBackRecentsListener);
mNavigationBarView.getHomeButton().setOnTouchListener(mHomeActionListener);
mNavigationBarView.getHomeButton().setOnLongClickListener(mLongPressHomeListener);
mAssistManager.onConfigurationChanged();
//2018-10-13 cczheng set recent KeyButton visibility invisible
mNavigationBarView.getHomeButton().setVisibility(View.INVISIBLE);
mNavigationBarView.getRecentsButton().setVisibility(View.INVISIBLE);
//2018-10-13 cczheng set recent KeyButton visibility invisible
....
}
ok厨相，大功告成领曼，重新mm，編譯替換SystemUI.apk重啟查看效果蛮穿。
二庶骄、動(dòng)態(tài)顯示和隱藏NavigationBar
文章開(kāi)頭提到將以廣播的方式來(lái)實(shí)現(xiàn)動(dòng)態(tài)顯示和隱藏NavigationBar這一功能，那么我們改從哪里入手呢践磅？細(xì)心的你可能已經(jīng)發(fā)現(xiàn)了上面的一個(gè)方法单刁，prepareNavigationBarView()在PhoneStatusBar.java中，從方法名字就能猜到它和NavigationBar的加載有關(guān)府适。查找prepareNavigationBarView()引用
// For small-screen devices (read: phones) that lack hardware navigation buttons
private void addNavigationBar() {
if (DEBUG) Log.v(TAG, "addNavigationBar: about to add " + mNavigationBarView);
if (mNavigationBarView == null) return;
prepareNavigationBarView();
mWindowManager.addView(mNavigationBarView, getNavigationBarLayoutParams());
}
private void repositionNavigationBar() {
if (mNavigationBarView == null || !mNavigationBarView.isAttachedToWindow()) return;
prepareNavigationBarView();
mWindowManager.updateViewLayout(mNavigationBarView, getNavigationBarLayoutParams());
}
共有兩處引用羔飞，很明顯找對(duì)地方了肺樟，在addNavigationBar()中，核心方法是通過(guò)mWindowManager.addView()添加的逻淌∶床看到這你應(yīng)該明白了，導(dǎo)航欄其實(shí)就是一個(gè)在window最底部添加的View卡儒，既然有addView田柔，對(duì)應(yīng)就有removeView，查找源碼中并未發(fā)現(xiàn)提供了removeView方法骨望∮脖看來(lái)需要我們自己來(lái)實(shí)現(xiàn)這個(gè)方法。
PS:如果想實(shí)現(xiàn)屏蔽整個(gè)NavigationBar的效果擎鸠，可直接將addNavigationBar()方法注釋
@Override
public void start() {
mDisplay = ((WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE))
.getDefaultDisplay();
updateDisplaySize();
mScrimSrcModeEnabled = mContext.getResources().getBoolean(
R.bool.config_status_bar_scrim_behind_use_src);
super.start(); // calls createAndAddWindows()
mMediaSessionManager
= (MediaSessionManager) mContext.getSystemService(Context.MEDIA_SESSION_SERVICE);
// TODO: use MediaSessionManager.SessionListener to hook us up to future updates
// in session state
//"anotation this can hide navigationbar" 注釋此處的addNavigationBar即可
addNavigationBar();
// Lastly, call to the icon policy to install/update all the icons.
mIconPolicy = new PhoneStatusBarPolicy(mContext, mCastController, mHotspotController,
mUserInfoController, mBluetoothController);
mIconPolicy.setCurrentUserSetup(mUserSetup);
mSettingsObserver.onChange(false); // set up
}
完整的通過(guò)廣播動(dòng)態(tài)顯示和隱藏NavigationBar的代碼如下所示：
////2018-10-13 cczheng hide or show navigationbat by broadcast
private NotifyChangeNavigationBarBroadcast mNotifyChangeNavigationBarBroadcast;
private static final String SHOW_NAVIGATION = "cc.intent.systemui.shownavigation";
private static final String HIDE_NAVIGATION = "cc.intent.systemui.hidenavigation";
@Override
public void start() {
mDisplay = ((WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE))
.getDefaultDisplay();
updateDisplaySize();
mScrimSrcModeEnabled = mContext.getResources().getBoolean(
R.bool.config_status_bar_scrim_behind_use_src);
....
//2018-10-13 cczheng hide or show navigationbat by broadcast
mNotifyChangeNavigationBarBroadcast = new NotifyChangeNavigationBarBroadcast();
IntentFilter mfilter = new IntentFilter();
mfilter.addAction(HIDE_NAVIGATION);
mfilter.addAction(SHOW_NAVIGATION);
mContext.registerReceiver(mNotifyChangeNavigationBarBroadcast, mfilter);
}
private void prepareNavigationBarView() {
mNavigationBarView.reorient();
mNavigationBarView.getRecentsButton().setOnClickListener(mRecentsClickListener);
mNavigationBarView.getRecentsButton().setOnTouchListener(mRecentsPreloadOnTouchListener);
mNavigationBarView.getRecentsButton().setLongClickable(true);
mNavigationBarView.getRecentsButton().setOnLongClickListener(mLongPressBackRecentsListener);
mNavigationBarView.getBackButton().setLongClickable(true);
.....
//2018-10-13 cczheng hide or show navigationbat by broadcast start
if (!isNavigationShow) {
int newVal = mSystemUiVisibility;
mSystemUiVisibility = View.SYSTEM_UI_FLAG_VISIBLE;
setSystemUiVisibility(newVal, /*SYSTEM_UI_VISIBILITY_MASK*/Color.TRANSPARENT);
int hints = mNavigationIconHints;
mNavigationIconHints = 0;
setNavigationIconHints(hints);
topAppWindowChanged(mShowMenu);
}
//2018-10-13 cczheng hide or show navigationbat by broadcast end
}
//2018-10-13 cczheng hide or show navigationbat by broadcast start
private static boolean isNavigationShow = true ;
class NotifyChangeNavigationBarBroadcast extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
Log.i(TAG, "NotifyChangeNavigationBarBroadcast: action =" + action);
if (HIDE_NAVIGATION.equals(action)) {
isNavigationShow = false;
hideNavigationBar();
}else if (SHOW_NAVIGATION.equals(action)) {
if (isNavigationShow) return;
showNavigationBar();
}
}
};
private void showNavigationBar() {
mNavigationBarView =(NavigationBarView) View.inflate(mContext, R.layout.navigation_bar, null);
mNavigationBarView.setBar(this);
addNavigationBar();
isNavigationShow = true;
// mNavigationBarView.setBackgroundColor(Color.TRANSPARENT);
}
private void hideNavigationBar() {
Log.d(TAG, "hideNavigationBar: about to remove" + mNavigationBarView);
if (mNavigationBarView == null) return;
mWindowManager.removeView(mNavigationBarView);
mNavigationBarView = null;
}
//2018-10-13 cczheng hide or show navigationbat by broadcast end
ok, 動(dòng)態(tài)顯示和隱藏NavigationBar的功能也搞定了摆屯。
三、總結(jié)
Hierarchy View是一個(gè)非常好用的利器糠亩，不僅是對(duì)源碼分析查找虐骑，當(dāng)你要查看借鑒別人的app時(shí)也會(huì)是一個(gè)非常好用的扳手。So赎线，多研究研究吧廷没。
下一篇將介紹在不修改源碼的情況下，通過(guò)兩種方式實(shí)現(xiàn)加載loading對(duì)話框的功能(不退出沉浸式效果)
