https://blog.csdn.net/garment1991/article/details/50437546
三个虚拟按键的设置是在framework层中。
先查看三个按键的布局的初始化:
位置 frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java:
protected PhoneStatusBarView makeStatusBarView() {
if (showNav) {
mNavigationBarView =
(NavigationBarView) View.inflate(context, R.layout.navigation_bar, null);
mNavigationBarView.setDisabledFlags(mDisabled);
mNavigationBarView.setBar(this);
mNavigationBarView.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
checkUserAutohide(v, event);
return false;
}});
}
}
位置 frameworks/base/packages/SystemUI/res/layout/navigation_bar.xml:
<com.android.systemui.statusbar.phone.NavigationBarView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:systemui="http://schemas.android.com/apk/res/com.android.systemui"
android:layout_height="match_parent"
android:layout_width="match_parent"
android:background="@drawable/system_bar_background"
>
xxx
xx
</>
<!--
-->
其中,android:background="@drawable/system_bar_background"该属性用于设置布局的背景(个人尝试修改该属性,貌似没有起作用)
@drawable/system_bar_background,背景图片就是一种颜色
位置:frameworks/base/packages/SystemUI/res/values/colors.xml
<drawable name="system_bar_background">@color/system_bar_background_opaque</drawable>
<color name="system_bar_background_opaque">#77000000</color>
进入NavigationBarView的源码中查看:
位置:frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarView.java
public NavigationBarView(Context context, AttributeSet attrs) {
super(context, attrs);
mDisplay = ((WindowManager)context.getSystemService(
Context.WINDOW_SERVICE)).getDefaultDisplay();
final Resources res = mContext.getResources();
mBarSize = res.getDimensionPixelSize(R.dimen.navigation_bar_size);
mVertical = false;
mShowMenu = false;
mDelegateHelper = new DelegateViewHelper(this);
getIcons(res);
mBarTransitions = new NavigationBarTransitions(this);
mCameraDisabledByDpm = isCameraDisabledByDpm();
watchForDevicePolicyChanges();
}
其中,mBarTransitions = new NavigationBarTransitions(this)中实例化了一个大用于布局的过渡的实例,按键布局作为参数传递到该类中,查看NavigationBarTransitions类的源码:
位置:frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarTransitions.java
public NavigationBarTransitions(NavigationBarView view) {
super(view, R.drawable.nav_background);
mView = view;
mBarService = IStatusBarService.Stub.asInterface(
ServiceManager.getService(Context.STATUS_BAR_SERVICE));
}
看super(view, R.drawable.nav_background)代码,可以知道该类的构造函数调用了其父类的构造函数,其中,NavigationBarView实例和一个图片的Id作为参数传到该类的父类的构造函数中,进入NavigationBarTransitions类的父类,查看代码:
位置:frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/BarTransitions.java
public BarTransitions(View view, int gradientResourceId) {
mTag = "BarTransitions." + view.getClass().getSimpleName();
mView = view;
mBarBackground = new BarBackgroundDrawable(mView.getContext(), gradientResourceId);
if (HIGH_END) {
Log.i("Garment27", "BarTransitions---HIGH_END");
mView.setBackground(mBarBackground);
}
}
从其构造函数可以看到,mView.setBackground(mBarBackground)这段代码就是把传入的图片设置成为按键布局的背景(在Launcher3中,该图片是一张透明的图片,所以得到的背景是透明的)
尝试把mView.setBackground(mBarBackground)这段代码屏蔽了,然后按键布局就只显示<color name="system_bar_background_opaque">#77000000</color>中定义的颜色,
上面的statusbar和下面的虚拟按键布局的背景设置是共用一套的背景,是因为两个布局都是有一个过渡类,大家都是继承BarTransitions类。