SystemUI之NavigationBar导航栏

布局结构

navigation_bar_window.xml à navigation_bar.xml

[NavigationBarFrame [NavigationBarView [NavigationBarInflaterView ] ] ]

View结构图：

二、代码控制流程

2.1、NavigationBar创建及View添加

StatusBar.java:

        start() à createAndAddWindows(result) à makeStatusBarView(result) à createNavigationBar(result) à mNavigationBarController.createNavigationBars(……)

protected void makeStatusBarView(@Nullable RegisterStatusBarResult result) {
createNavigationBar(result);
……
inflateStatusBarWindow();
}

protected void createNavigationBar(@Nullable RegisterStatusBarResult result) {
mNavigationBarController.createNavigationBars(true /* includeDefaultDisplay */, result);
}

NavigationBarController.java:

               createNavigationBars(……) à createNavigationBar(……) à

navBar. createView (……)

void createNavigationBar(Display display, Bundle savedState, RegisterStatusBarResult result) {
……
……
NavigationBar navBar = new NavigationBar(context,
mWindowManager,
……
mUserTracker);
mNavigationBars.put(displayId, navBar);
View navigationBarView = navBar.createView(savedState);
……
}

NavigationBar.java(Contains logic for a navigation bar view):

public View createView(Bundle savedState) {
WindowManager.LayoutParams lp = new WindowManager.LayoutParams(
WindowManager.LayoutParams.MATCH_PARENT,
WindowManager.LayoutParams.MATCH_PARENT,
WindowManager.LayoutParams.TYPE_NAVIGATION_BAR,
……
PixelFormat.TRANSLUCENT);
lp.token = new Binder();
……
lp.setTrustedOverlay();
NavigationBarFrame frame = (NavigationBarFrame) LayoutInflater.from(mContext).inflate(
R.layout.navigation_bar_window, null);
View barView = LayoutInflater.from(frame.getContext()).inflate(
R.layout.navigation_bar, frame);
barView.addOnAttachStateChangeListener(this);
mNavigationBarView = barView.findViewById(R.id.navigation_bar_view);
mContext.getSystemService(WindowManager.class).addView(frame, lp)
mContentResolver.registerContentObserver(
Settings.Secure.getUriFor(Settings.Secure.ASSISTANT),
false /* notifyForDescendants */, mAssistContentObserver, UserHandle.USER_ALL);
……
return barView;
}

备注 : 导航栏的具体位置在框架DisplayPolicy中根据方向等因素确定:

services\core\java\com\android\server\wm\DisplayPolicy.java

private int layoutNavigationBar(DisplayFrames displayFrames, Rect contentFrame) {
……
final int rotation = displayFrames.mRotation;
final int displayHeight = displayFrames.mDisplayHeight;
final int displayWidth = displayFrames.mDisplayWidth;
final int navBarPosition = navigationBarPosition(displayWidth, displayHeight, rotation);
……
if (navBarPosition == NAV_BAR_BOTTOM) {
navigationFrame.top = Math.min(cutoutSafeUnrestricted.bottom, navigationFrame.bottom)
- getNavigationBarFrameHeight(rotation, uiMode);
} else if (navBarPosition == NAV_BAR_RIGHT) {
// Landscape screen; nav bar goes to the right.
navigationFrame.left = Math.min(cutoutSafeUnrestricted.right, navigationFrame.right)
- getNavigationBarWidth(rotation, uiMode);
} else if (navBarPosition == NAV_BAR_LEFT) {
// Seascape screen; nav bar goes to the left.
navigationFrame.right = Math.max(cutoutSafeUnrestricted.left, navigationFrame.left)
+ getNavigationBarWidth(rotation, uiMode);
}
……
return navBarPosition;
}

通过上述代码

1、使用navigation_bar_window和navigation_bar填充布局

2、创建NavigationBarFrame 并且添加到windowManager中

2.2、导航栏图标加载及事件逻辑

2.2.1、布局文件添加

navigation_bar_window.xml：

     NavigationBarFrame，对DeadZone功能下的touch事件做了处理。

navigation_bar.xml：

<com.android.systemui.navigationbar.NavigationBarView
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/navigation_bar_view"
android:layout_height="match_parent"
android:layout_width="match_parent"
android:clipChildren="false"
android:clipToPadding="false"
android:background="@drawable/system_bar_background">
<com.android.systemui.navigationbar.NavigationBarInflaterView
android:id="@+id/navigation_inflater"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:clipChildren="false"
android:clipToPadding="false" />
</com.android.systemui.navigationbar.NavigationBarView>

NavigationBarInflaterView:

protected void onFinishInflate() {
super.onFinishInflate();
inflateChildren(); //载导航栏布局文件
clearViews();
inflateLayout(getDefaultLayout());
}

private void inflateChildren() {
removeAllViews();
mHorizontal = (FrameLayout) mLayoutInflater.inflate(R.layout.navigation_layout,
this /* root */, false /* attachToRoot */);
addView(mHorizontal); //载导0度航栏布局文件
mVertical = (FrameLayout) mLayoutInflater.inflate(R.layout.navigation_layout_vertical,
this /* root */, false /* attachToRoot */);
addView(mVertical); //载导90度航栏布局文件
updateAlternativeOrder();
}

protected void inflateLayout(String newLayout) {
……
inflateButtons(start, mHorizontal.findViewById(R.id.ends_group),
false /* landscape */, true /* start */);
inflateButtons(start, mVertical.findViewById(R.id.ends_group),
true /* landscape */, true /* start */);
inflateButtons(center, mHorizontal.findViewById(R.id.center_group),
false /* landscape */, false /* start */);
inflateButtons(center, mVertical.findViewById(R.id.center_group),
true /* landscape */, false /* start */);
addGravitySpacer(mHorizontal.findViewById(R.id.ends_group));
addGravitySpacer(mVertical.findViewById(R.id.ends_group));
inflateButtons(end, mHorizontal.findViewById(R.id.ends_group),
false /* landscape */, false /* start */);
inflateButtons(end, mVertical.findViewById(R.id.ends_group),
true /* landscape */, false /* start */);
updateButtonDispatchersCurrentView();
}

protected View inflateButton(String buttonSpec, ViewGroup parent, boolean landscape, boolean start) {
LayoutInflater inflater = landscape ? mLandscapeInflater : mLayoutInflater;
View v = createView(buttonSpec, parent, inflater);
……
v = applySize(v, buttonSpec, landscape, start);
parent.addView(v);
……
return v;
}

View createView(String buttonSpec, ViewGroup parent, LayoutInflater inflater) {
View v = null;
String button = extractButton(buttonSpec);
if (LEFT.equals(button)) {
button = extractButton(NAVSPACE);
} else if (RIGHT.equals(button)) {
button = extractButton(MENU_IME_ROTATE);
}
if (HOME.equals(button)) {
v = inflater.inflate(R.layout.home, parent, false);
} else if (BACK.equals(button)) {
v = inflater.inflate(R.layout.back, parent, false);
} else if (RECENT.equals(button)) {
v = inflater.inflate(R.layout.recent_apps, parent, false);
} else if
……
return v;
}

1、getDefaultLayout决定导航栏显示哪些控件。

一般情况下是home，recent，back这三个键，如果需要加其他的就在这配置，同时在createView添加对应的布局文件。

2、createView方法创建对应的布局文件，并且添加到导航栏中。

2.2.2、资源文件添加、点击触摸事件

1、NavigationBarView.java(图标资源文件加载)

        reloadNavIcons( ) à updateIcons(Configuration.EMPTY) à

2、NavigationBar.java(事件处理)

     prepareNavigationBarView()

private void prepareNavigationBarView() {
mNavigationBarView.reorient();
ButtonDispatcher recentsButton = mNavigationBarView.getRecentsButton();
recentsButton.setOnClickListener(this::onRecentsClick);
recentsButton.setOnTouchListener(this::onRecentsTouch);
ButtonDispatcher homeButton = mNavigationBarView.getHomeButton();
homeButton.setOnTouchListener(this::onHomeTouch);
reconfigureHomeLongClick();
ButtonDispatcher accessibilityButton = mNavigationBarView.getAccessibilityButton();
accessibilityButton.setOnClickListener(this::onAccessibilityClick);
accessibilityButton.setOnLongClickListener(this::onAccessibilityLongClick);
updateAccessibilityServicesState(mAccessibilityManager);
ButtonDispatcher imeSwitcherButton = mNavigationBarView.getImeSwitchButton();
imeSwitcherButton.setOnClickListener(this::onImeSwitcherClick);
updateScreenPinningGestures();
}

参考链接:

SystemUI虚拟导航键加载流

SystemUI之NavigationBar