Android SystemUI在导航栏添加音量加减按钮

有些Android设备没有实体的音量调节按钮，或者从保护实体按键的角度考虑，就需要在导航栏的虚拟按键中添加音量加减调节按键。

效果如下图所示：

实现过程如下：

1.首先在SystemUI中添加音量加减的资源文件，路径如下：

frameworks/base/packages/SystemUI/res/

将图片放入对应的drawable文件夹，包括音量+，和音量-，见上图。

2.修改导航栏的布局文件，路径：

frameworks/base/packages/SystemUI/res/

在对应的layout文件夹中找到navigation_bar.xml文件进行修改：

在返回键前面添加“音量减”，返回键的布局：

 <com.android.systemui.statusbar.policy.KeyButtonView android:id="@+id/back"
                 android:layout_width="128dp" android:paddingStart="25dp" android:paddingEnd="25dp"
                 android:layout_height="match_parent"
                 android:src="@drawable/ic_sysbar_back"
                 systemui:keyCode="4"
                 android:layout_weight="0"
                 systemui:glowBackground="@drawable/ic_sysbar_highlight"
                 android:contentDescription="@string/accessibility_back"
                 />

音量减的布局如下，这里先把Visibility定义为Gone，然后在代码中控制是否显示：

 <com.android.systemui.statusbar.policy.KeyButtonView android:id="@+id/sub"
                 android:src="@drawable/sub_normal"
                 android:layout_width="@dimen/navigation_key_width"
                 android:layout_height="match_parent"
                 android:layout_weight="0"
                 systemui:keyCode="302"
                 systemui:glowBackground="@drawable/ic_sysbar_highlight"
                 android:visibility="gone"/>

“音量加”添加到“最近应用”之后，最近应用的布局：

 <com.android.systemui.statusbar.policy.KeyButtonView android:id="@+id/recent_apps"
                 android:layout_width="128dp" android:paddingStart="25dp" android:paddingEnd="25dp"
                 android:layout_height="match_parent"
                 android:src="@drawable/ic_sysbar_recent"
                 android:layout_weight="0"
                 systemui:glowBackground="@drawable/ic_sysbar_highlight"
                 android:contentDescription="@string/accessibility_recent"
                 />

音量加的布局：

 <com.android.systemui.statusbar.policy.KeyButtonView android:id="@+id/add"
                 android:src="@drawable/add_normal"
                 android:layout_width="@dimen/navigation_key_width"
                 android:layout_height="match_parent"
                 android:layout_weight="0"
                 systemui:keyCode="301"
                 systemui:glowBackground="@drawable/ic_sysbar_highlight"
                 android:visibility="gone"/>

3.接着修改代码逻辑，文件路径：

frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java

在private void prepareNavigationBarView() {……}函数中添加显示音量加减的代码：

 mNavigationBarView.getAddVolume().setVisibility(View.VISIBLE);
         mNavigationBarView.getSubVolume().setVisibility(View.VISIBLE);

对应的函数getAddVolume()和getAddVolume()要在

frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarView.java

中实现：

 public View getAddVolume(){
        return mCurrentView.findViewById(R.id.add);
     }

     public View getSubVolume(){
         return mCurrentView.findViewById(R.id.sub);
     }

最后就是功能实现了，在

frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java

中添加监听函数：

 private View.OnTouchListener mAddVolumeOnTouchListener = new View.OnTouchListener() {
       public boolean onTouch(View v, MotionEvent ev) {
       final int action = ev.getAction();
                 switch(action) {
                 case MotionEvent.ACTION_DOWN:
                    is_down = true;
                    Adjust_Volume(true);
                    maddHandler.postDelayed(maddRun, ADJUST_VOLUME_DELAY * 2);
                    break;
                 case MotionEvent.ACTION_MOVE:
                    is_down = true;
                    maddHandler.postDelayed(maddRun, ADJUST_VOLUME_DELAY * 2);
     //             maddHandler.removeCallbacks(maddRun);
                    break;
                 case MotionEvent.ACTION_UP:
                    is_down = false;
                    maddHandler.removeCallbacks(maddRun);
                    break;

          }
          return true;
       }
     };


     private View.OnTouchListener mSubVolumeOnTouchListener = new View.OnTouchListener() {
            public boolean onTouch(View v, MotionEvent ev) {
            final int action = ev.getAction();
             int x, y;
             //int mCode = ev.getAction();

                 switch (action) {
                 case MotionEvent.ACTION_DOWN:
                   is_down = true;
                   Adjust_Volume(false);
                   msubHandler.postDelayed(msubRun, ADJUST_VOLUME_DELAY * 2);
                   break;
                 case MotionEvent.ACTION_MOVE:

                   is_down = true;
                   msubHandler.postDelayed(msubRun, ADJUST_VOLUME_DELAY * 2);
                   //msubHandler.removeCallbacks(msubRun);
                   break;
                 case MotionEvent.ACTION_UP:
                   is_down = false;
                   msubHandler.removeCallbacks(msubRun);
                   break;
             }
             return true;
         }
     };

     public void Adjust_Volume(boolean opition){
             AudioManager audioManager = (AudioManager)mContext.getSystemService(Context.AUDIO_SERVICE);
             if (audioManager != null) {
                 //
                  // Adjust the volume in on key down since it is more
                  // responsive to the user.
                  //
                     if(opition){
                             audioManager.adjustSuggestedStreamVolume(
                             AudioManager.ADJUST_RAISE,
                            AudioManager.USE_DEFAULT_STREAM_TYPE,
                            AudioManager.FLAG_SHOW_UI | AudioManager.FLAG_REMOVE_SOUND_AND_VIBRATE);
                     }else{
                             audioManager.adjustSuggestedStreamVolume(
                          AudioManager.ADJUST_LOWER,
                         AudioManager.USE_DEFAULT_STREAM_TYPE,
                         AudioManager.FLAG_SHOW_UI | AudioManager.FLAG_REMOVE_SOUND_AND_VIBRATE);
                     }
             }
     }