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解析Android 8.1平台SystemUI 导航栏加载流程

  2021-04-02 我要评论

需求

基于MTK8163 8.1平台定制导航栏部分在左边增加音量减右边增加音量加

思路

需求开始做之前一定要研读SystemUI Navigation模块的代码流程!!!不要直接去网上copy别人改的需求代码盲改的话很容易出现问题然而无从解决。网上有老平台(8.0-)的讲解System UI的导航栏模块的博客自行搜索。8.0对System UI还是做了不少细节上的改动代码改动体现上也比较多但是总体基本流程并没变。

源码阅读可以沿着一条线索去跟代码不要过分在乎代码细节!例如我客制化这个需求可以跟着导航栏的返回(back)桌面(home)最近任务(recent)中的一个功能跟代码流程大体知道比如recen这个view是哪个方法调哪个方法最终加载出来加载的关键代码在哪点击事件怎么生成而不在意里面的具体逻辑判断等等。

代码流程

1.SystemUI\src\com\android\systemui\statusbar\phone\StatusBar.java;

从状态栏入口开始看。

protected void makeStatusBarView() {
  final Context context = mContext;
  updateDisplaySize(); // populates mDisplayMetrics
  updateResources();
  updateTheme();
  ...
  ...
   try {
    boolean showNav = mWindowManagerService.hasNavigationBar();
    if (DEBUG) Log.v(TAG, "hasNavigationBar=" + showNav);
    if (showNav) {
      createNavigationBar();//创建导航栏
    }
  } catch (RemoteException ex) {
  }
}

2.进入 createNavigationBar 方法发现主要是用 NavigationBarFragment 来管理.

protected void createNavigationBar() {
  mNavigationBarView = NavigationBarFragment.create(mContext, (tag, fragment) -> {
    mNavigationBar = (NavigationBarFragment) fragment;
    if (mLightBarController != null) {
      mNavigationBar.setLightBarController(mLightBarController);
    }
    mNavigationBar.setCurrentSysuiVisibility(mSystemUiVisibility);
  });
}

3.看 NavigationBarFragment 的create方法终于知道是WindowManager去addView了导航栏的布局最终add了fragment的onCreateView加载的布局。(其实SystemUI所有的模块都是WindowManager来加载View)

public static View create(Context context, FragmentListener listener) {
  WindowManager.LayoutParams lp = new WindowManager.LayoutParams(
      LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT,
      WindowManager.LayoutParams.TYPE_NAVIGATION_BAR,
      WindowManager.LayoutParams.FLAG_TOUCHABLE_WHEN_WAKING
          | WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
          | WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL
          | WindowManager.LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH
          | WindowManager.LayoutParams.FLAG_SPLIT_TOUCH
          | WindowManager.LayoutParams.FLAG_SLIPPERY,
      PixelFormat.TRANSLUCENT);
  lp.token = new Binder();
  lp.setTitle("NavigationBar");
  lp.windowAnimations = 0;
  View navigationBarView = LayoutInflater.from(context).inflate(
      R.layout.navigation_bar_window, null);
  if (DEBUG) Log.v(TAG, "addNavigationBar: about to add " + navigationBarView);
  if (navigationBarView == null) return null;
  context.getSystemService(WindowManager.class).addView(navigationBarView, lp);
  FragmentHostManager fragmentHost = FragmentHostManager.get(navigationBarView);
  NavigationBarFragment fragment = new NavigationBarFragment();
  fragmentHost.getFragmentManager().beginTransaction()
      .replace(R.id.navigation_bar_frame, fragment, TAG) //注意!fragment里onCreateView加载的布局是add到这个Window属性的view里的。
      .commit();
  fragmentHost.addTagListener(TAG, listener);
  return navigationBarView;
 }
}

4.SystemUI\res\layout\navigation_bar_window.xml;

来看WindowManager加载的这个view的布局:navigation_bar_window.xml发现根布局是自定义的view类NavigationBarFrame.(其实SystemUI以及其他系统应用如Launcher,都是这种自定义view的方式好多逻辑处理也都是在自定义view里不能忽略)

<com.android.systemui.statusbar.phone.NavigationBarFrame
  xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:systemui="http://schemas.android.com/apk/res-auto"
  android:id="@+id/navigation_bar_frame"
  android:layout_height="match_parent"
  android:layout_width="match_parent"> 

</com.android.systemui.statusbar.phone.NavigationBarFrame>

5.SystemUI\src\com\android\systemui\statusbar\phone\NavigationBarFrame.java;

我们进入NavigationBarFrame类。发现类里并不是我们的预期就是一个FrameLayout对DeadZone功能下的touch事件做了手脚不管了。

6.再回来看看NavigationBarFragment的生命周期呢。onCreateView()里导航栏的真正的rootView。

@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container,
    Bundle savedInstanceState) {
  return inflater.inflate(R.layout.navigation_bar, container, false);
}

进入导航栏的真正根布局:navigation_bar.xml好吧又是自定义viewNavigationBarView 和 NavigationBarInflaterView 都要仔细研读。

<com.android.systemui.statusbar.phone.NavigationBarView
  xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:systemui="http://schemas.android.com/apk/res-auto"
  android:layout_height="match_parent"
  android:layout_width="match_parent"
android:background="@drawable/system_bar_background">
<com.android.systemui.statusbar.phone.NavigationBarInflaterView
    android:id="@+id/navigation_inflater"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

</com.android.systemui.statusbar.phone.NavigationBarView>

7.SystemUI\src\com\android\systemui\statusbar\phone\NavigationBarInflaterView.java;继承自FrameLayout

先看构造方法因为加载xml布局首先走的是初始化

public NavigationBarInflaterView(Context context, AttributeSet attrs) {
  super(context, attrs);
  createInflaters();//根据屏幕旋转角度创建子view(单个back home or recent)的父布局
  Display display = ((WindowManager)
      context.getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
  Mode displayMode = display.getMode();
  isRot0Landscape = displayMode.getPhysicalWidth() > displayMode.getPhysicalHeight();
}
private void inflateChildren() {
  removeAllViews();
  mRot0 = (FrameLayout) mLayoutInflater.inflate(R.layout.navigation_layout, this, false);
  mRot0.setId(R.id.rot0);
  addView(mRot0);
  mRot90 = (FrameLayout) mLayoutInflater.inflate(R.layout.navigation_layout_rot90, this, false);
  mRot90.setId(R.id.rot90);
  addView(mRot90);
  updateAlternativeOrder();
}

再看onFinishInflate()方法这是view的生命周期每个view被inflate之后都会回调。

@Override
protected void onFinishInflate() {
  super.onFinishInflate();
  inflateChildren();//进去看无关紧要 忽略
  clearViews();//进去看无关紧要 忽略
  inflateLayout(getDefaultLayout());//关键方法:加载了 back.home.recent三个按钮的layout
}

看inflateLayout():里面的newLayout参数很重要!!!根据上一个方法看到getDefaultLayout()他return了一个在xml写死的字符串。再看inflateLayout方法他解析分割了xml里配置的字符串并传给了inflateButtons方法

protected void inflateLayout(String newLayout) {
  mCurrentLayout = newLayout;
  if (newLayout == null) {
    newLayout = getDefaultLayout();
  }
  String[] sets = newLayout.split(GRAVITY_SEPARATOR, 3);//根据“;”号分割成长度为3的数组
  String[] start = sets[0].split(BUTTON_SEPARATOR);//根据“”号分割包含 left[.5W]和back[1WC]
  String[] center = sets[1].split(BUTTON_SEPARATOR);//包含home
  String[] end = sets[2].split(BUTTON_SEPARATOR);//包含recent[1WC]和right[.5W]
  // Inflate these in start to end order or accessibility traversal will be messed up.
  inflateButtons(start, mRot0.findViewById(R.id.ends_group), isRot0Landscape, true);
  inflateButtons(start, mRot90.findViewById(R.id.ends_group), !isRot0Landscape, true);
  inflateButtons(center, mRot0.findViewById(R.id.center_group), isRot0Landscape, false);
  inflateButtons(center, mRot90.findViewById(R.id.center_group), !isRot0Landscape, false);
  addGravitySpacer(mRot0.findViewById(R.id.ends_group));
  addGravitySpacer(mRot90.findViewById(R.id.ends_group));
  inflateButtons(end, mRot0.findViewById(R.id.ends_group), isRot0Landscape, false);
  inflateButtons(end, mRot90.findViewById(R.id.ends_group), !isRot0Landscape, false);
}
  protected String getDefaultLayout() {
  return mContext.getString(R.string.config_navBarLayout);
}

SystemUI\res\values\config.xml

 <!-- Nav bar button default ordering/layout -->
<string name="config_navBarLayout" translatable="false">left[.5W],back[1WC];home;recent[1WC],right[.5W]</string>

再看inflateButtons()方法遍历加载inflateButton:

private void inflateButtons(String[] buttons, ViewGroup parent, boolean landscape,
    boolean start) {
  for (int i = 0; i < buttons.length; i++) {
    inflateButton(buttons[i], parent, landscape, start);
  }
}
@Nullable
protected View inflateButton(String buttonSpec, ViewGroup parent, boolean landscape,
    boolean start) {
  LayoutInflater inflater = landscape ? mLandscapeInflater : mLayoutInflater;
  View v = createView(buttonSpec, parent, inflater);//创建view
  if (v == null) return null;
  v = applySize(v, buttonSpec, landscape, start);
  parent.addView(v);//addView到父布局
  addToDispatchers(v);
  View lastView = landscape ? mLastLandscape : mLastPortrait;
  View accessibilityView = v;
  if (v instanceof ReverseFrameLayout) {
    accessibilityView = ((ReverseFrameLayout) v).getChildAt(0);
  }
  if (lastView != null) {
    accessibilityView.setAccessibilityTraversalAfter(lastView.getId());
  }
  if (landscape) {
    mLastLandscape = accessibilityView;
  } else {
    mLastPortrait = accessibilityView;
  }
  return v;
}

我们来看createView()方法:以home按键为例加载了home的button,其实是加载了 R.layout.home 的layout布局

private View createView(String buttonSpec, ViewGroup parent, LayoutInflater inflater) {
  View v = null;
  ...
  ...
  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 (MENU_IME.equals(button)) {
    v = inflater.inflate(R.layout.menu_ime, parent, false);
  } else if (NAVSPACE.equals(button)) {
    v = inflater.inflate(R.layout.nav_key_space, parent, false);
  } else if (CLIPBOARD.equals(button)) {
    v = inflater.inflate(R.layout.clipboard, parent, false);
  } 
  ...
  ...
  return v;
}
//SystemUI\res\layout\home.xml 
//这里布局里没有src显示home的icon,肯定是在代码里设置了
//这里也是自定义view:KeyButtonView
<com.android.systemui.statusbar.policy.KeyButtonView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:systemui="http://schemas.android.com/apk/res-auto"
android:id="@+id/home"
android:layout_width="@dimen/navigation_key_width"//引用了dimens.xml里的navigation_key_width
android:layout_height="match_parent"
android:layout_weight="0"
systemui:keyCode="3"//systemui自定义的属性
android:scaleType="fitCenter"
android:contentDescription="@string/accessibility_home"
android:paddingTop="@dimen/home_padding"
android:paddingBottom="@dimen/home_padding"
android:paddingStart="@dimen/navigation_key_padding"
android:paddingEnd="@dimen/navigation_key_padding"/>

8.SystemUI\src\com\android\systemui\statusbar\policy\KeyButtonView.java

先来看KeyButtonView的构造方法:我们之前xml的systemui:keyCode=”3”方法在这里获取。再来看Touch事件通过sendEvent()方法可以看出back等view的点击touch事件不是自己处理的而是交由系统以实体按键(keycode)的形式处理的.

当然KeyButtonView类还处理了支持长按的button,按键的响声等这里忽略。

至此导航栏按键事件我们梳理完毕。

public KeyButtonView(Context context, AttributeSet attrs, int defStyle) {
  super(context, attrs);
  TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.KeyButtonView,
      defStyle, 0);
  mCode = a.getInteger(R.styleable.KeyButtonView_keyCode, 0);
  mSupportsLongpress = a.getBoolean(R.styleable.KeyButtonView_keyRepeat, true);
  mPlaySounds = a.getBoolean(R.styleable.KeyButtonView_playSound, true);
  TypedValue value = new TypedValue();
  if (a.getValue(R.styleable.KeyButtonView_android_contentDescription, value)) {
    mContentDescriptionRes = value.resourceId;
  }
  a.recycle();
  setClickable(true);
  mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
  mAudioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
  mRipple = new KeyButtonRipple(context, this);
  setBackground(mRipple);
}
...
...
public boolean onTouchEvent(MotionEvent ev) {
  ...
  switch (action) {
    case MotionEvent.ACTION_DOWN:
      mDownTime = SystemClock.uptimeMillis();
      mLongClicked = false;
      setPressed(true);
      if (mCode != 0) {
        sendEvent(KeyEvent.ACTION_DOWN, 0, mDownTime);//关键方法
      } else {
        // Provide the same haptic feedback that the system offers for virtual keys.
        performHapticFeedback(HapticFeedbackConstants.VIRTUAL_KEY);
      }
      playSoundEffect(SoundEffectConstants.CLICK);
      removeCallbacks(mCheckLongPress);
      postDelayed(mCheckLongPress, ViewConfiguration.getLongPressTimeout());
      break;
    ...
    ...
  }
  return true;
}
void sendEvent(int action, int flags, long when) {
  mMetricsLogger.write(new LogMaker(MetricsEvent.ACTION_NAV_BUTTON_EVENT)
      .setType(MetricsEvent.TYPE_ACTION)
      .setSubtype(mCode)
      .addTaggedData(MetricsEvent.FIELD_NAV_ACTION, action)
      .addTaggedData(MetricsEvent.FIELD_FLAGS, flags));
  final int repeatCount = (flags & KeyEvent.FLAG_LONG_PRESS) != 0 ? 1 : 0;
  //这里根据mCode new了一个KeyEvent事件通过injectInputEvent使事件生效。
  final KeyEvent ev = new KeyEvent(mDownTime, when, action, mCode, repeatCount,
      0, KeyCharacterMap.VIRTUAL_KEYBOARD, 0,
      flags | KeyEvent.FLAG_FROM_SYSTEM | KeyEvent.FLAG_VIRTUAL_HARD_KEY,
      InputDevice.SOURCE_KEYBOARD);
  InputManager.getInstance().injectInputEvent(ev,
      InputManager.INJECT_INPUT_EVENT_MODE_ASYNC);
}

9.还遗留一个问题:设置图片的icon到底在哪?我们之前一直阅读的是NavigationBarInflaterView根据布局我们还有一个类没有看NavigationBarView.java

SystemUI\src\com\android\systemui\statusbar\phone\NavigationBarView.java;

进入NavigationBarView类里找到构造方法。

public NavigationBarView(Context context, AttributeSet attrs) {
  super(context, attrs);
  mDisplay = ((WindowManager) context.getSystemService(
      Context.WINDOW_SERVICE)).getDefaultDisplay();
  ...
  ...
  updateIcons(context, Configuration.EMPTY, mConfiguration);//关键方法
  mBarTransitions = new NavigationBarTransitions(this);
  //mButtonDispatchers 是维护这些home back recent图标view的管理类会传递到他的child,NavigationBarInflaterView类中
  mButtonDispatchers.put(R.id.back, new ButtonDispatcher(R.id.back));
  mButtonDispatchers.put(R.id.home, new ButtonDispatcher(R.id.home));
  mButtonDispatchers.put(R.id.recent_apps, new ButtonDispatcher(R.id.recent_apps));
  mButtonDispatchers.put(R.id.menu, new ButtonDispatcher(R.id.menu));
  mButtonDispatchers.put(R.id.ime_switcher, new ButtonDispatcher(R.id.ime_switcher));
  mButtonDispatchers.put(R.id.accessibility_button,new ButtonDispatcher(R.id.accessibility_button));
}
 private void updateIcons(Context ctx, Configuration oldConfig, Configuration newConfig) {
    ...
    iconLight = mNavBarPlugin.getHomeImage(
                  ctx.getDrawable(R.drawable.ic_sysbar_home));
    iconDark = mNavBarPlugin.getHomeImage(
                  ctx.getDrawable(R.drawable.ic_sysbar_home_dark));
    //mHomeDefaultIcon = getDrawable(ctx,
    //    R.drawable.ic_sysbar_home, R.drawable.ic_sysbar_home_dark);
    mHomeDefaultIcon = getDrawable(iconLight,iconDark);
    //亮色的icon资源
    iconLight = mNavBarPlugin.getRecentImage(
                  ctx.getDrawable(R.drawable.ic_sysbar_recent));
    //暗色的icon资源
    iconDark = mNavBarPlugin.getRecentImage(
                  ctx.getDrawable(R.drawable.ic_sysbar_recent_dark));
    //mRecentIcon = getDrawable(ctx,
    //    R.drawable.ic_sysbar_recent, R.drawable.ic_sysbar_recent_dark);
    mRecentIcon = getDrawable(iconLight,iconDark);
    mMenuIcon = getDrawable(ctx, R.drawable.ic_sysbar_menu,
                  R.drawable.ic_sysbar_menu_dark);
    ...
    ...

}

10.从第10可以看到以recent为例在初始化时得到了mRecentIcon的资源再看谁调用了了mRecentIcon就可知道即反推看调用流程。

private void updateRecentsIcon() {
  getRecentsButton().setImageDrawable(mDockedStackExists ? mDockedIcon : mRecentIcon);
  mBarTransitions.reapplyDarkIntensity();
}

updateRecentsIcon这个方法设置了recent图片的资源再看谁调用了updateRecentsIcon方法:onConfigurationChanged屏幕旋转会重新设置资源图片

@Override
protected void onConfigurationChanged(Configuration newConfig) {
  super.onConfigurationChanged(newConfig);
  boolean uiCarModeChanged = updateCarMode(newConfig);
  updateTaskSwitchHelper();
  updateIcons(getContext(), mConfiguration, newConfig);
  updateRecentsIcon();
  if (uiCarModeChanged || mConfiguration.densityDpi != newConfig.densityDpi
      || mConfiguration.getLayoutDirection() != newConfig.getLayoutDirection()) {
    // If car mode or density changes, we need to reset the icons.
    setNavigationIconHints(mNavigationIconHints, true);
  }
  mConfiguration.updateFrom(newConfig);
}
public void setNavigationIconHints(int hints, boolean force) {
  ...
  ...
  mNavigationIconHints = hints;
  // We have to replace or restore the back and home button icons when exiting or entering
  // carmode, respectively. Recents are not available in CarMode in nav bar so change
  // to recent icon is not required.
  KeyButtonDrawable backIcon = (backAlt)
      ? getBackIconWithAlt(mUseCarModeUi, mVertical)
      : getBackIcon(mUseCarModeUi, mVertical);
  getBackButton().setImageDrawable(backIcon);
  updateRecentsIcon();
  ...
  ...
}

reorient()也调用了setNavigationIconHints()方法:

public void reorient() {
  updateCurrentView();
  ...
  setNavigationIconHints(mNavigationIconHints, true);
  getHomeButton().setVertical(mVertical);
}

再朝上推最终追溯到NavigationBarFragment的onConfigurationChanged()方法 和 NavigationBarView的onAttachedToWindow()和onSizeChanged()方法。也就是说在NavigationBarView导航栏这个布局加载的时候就会设置图片资源和长度改变屏幕旋转都有可能引起重新设置

至此SystemUI的虚拟导航栏模块代码流程结束。

总结

  1. 创建一个window属性的父view
  2. 通过读取解析xml里config的配置addView需要的icon,或者调换顺序
  3. src图片资源通过代码设置亮色和暗色
  4. touch事件以keycode方式交由系统处理

以上所述是小编给大家介绍的Android 8.1平台SystemUI 导航栏加载流程希望对大家有所帮助如果大家有任何疑问请给我留言小编会及时回复大家的。在此也非常感谢大家对网站的支持!
如果你觉得本文对你有帮助欢迎转载烦请注明出处谢谢!

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