Android SystemUI源代码分析和修改

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1.在导航栏中添加音量加减button

一些Android音量调节button。或者从保护实体按键的角度考虑，就须要在导航栏的虚拟按键中加入音量加减调节按键。

效果例如以下图所看到的：

实现步骤例如以下：

1.首先在SystemUI中加入音量加减的资源文件。路径例如以下：

frameworks/base/packages/SystemUI/res/

将图片放入相应的drawable目录，包含音量+。和音量-，见上图。

2.改动导航栏的布局文件。路径：

frameworks/base/packages/SystemUI/res/

在相应的layout目录中找到navigation_bar.xml文件进行改动：

在返回键前面加入“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"

                />

音量减的布局例如以下。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”加入到“近期应用”之后，近期应用的布局：

<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.接着改动代码逻辑，文件路径：

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

在private void prepareNavigationBarView() {……}函数中加入显示音量加减的代码：

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

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

相应的函数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

中加入监听函数：

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);

                    }

            }

    }