Android导航栏音量调节

音量调节"/>

Android导航栏音量调节

导航栏音量加减其实质是模拟实体按键

android系统定义了音量up和down的keyevent,如下：
./core/java/android/view/KeyEvent.java

    /** Key code constant: Volume Up key.* Adjusts the speaker volume up. */public static final int KEYCODE_VOLUME_UP       = 24;                                                                                         /** Key code constant: Volume Down key.* Adjusts the speaker volume down. */public static final int KEYCODE_VOLUME_DOWN     = 25;

事件被触发的代码如下：
./services/core/java/com/android/server/policy/PhoneWindowManager.java

        int flags = AudioManager.FLAG_SHOW_UI | AudioManager.FLAG_PLAY_SOUND| AudioManager.FLAG_FROM_KEY;String pkgName = mContext.getOpPackageName();switch (keyCode) {case KeyEvent.KEYCODE_VOLUME_UP:   try {getAudioService().adjustSuggestedStreamVolume(AudioManager.ADJUST_RAISE,AudioManager.USE_DEFAULT_STREAM_TYPE, flags, pkgName, TAG);} catch (Exception e) {Log.e(TAG, "Error dispatching volume up in dispatchTvAudioEvent.", e);}break;case KeyEvent.KEYCODE_VOLUME_DOWN: try {getAudioService().adjustSuggestedStreamVolume(AudioManager.ADJUST_LOWER,AudioManager.USE_DEFAULT_STREAM_TYPE, flags, pkgName, TAG);} catch (Exception e) {Log.e(TAG, "Error dispatching volume down in dispatchTvAudioEvent.", e);}break;

最终通过AudioService去设置音量大小

因此在导航栏创建虚拟音量键时，需要在xml中加上keyCode值，如下

<com.android.systemui.statusbar.policy.KeyButtonViewxmlns:android=""xmlns:systemui=""android:id="@+id/volume_up"android:layout_width="@dimen/navigation_key_width"android:layout_height="match_parent"android:layout_weight="0"systemui:keyCode="24"android:scaleType="center"android:contentDescription="@string/accessibility_home"android:paddingStart="@dimen/navigation_key_padding"android:paddingEnd="@dimen/navigation_key_padding"/>

<com.android.systemui.statusbar.policy.KeyButtonViewxmlns:android=""xmlns:systemui=""android:id="@+id/volume_down"android:layout_width="@dimen/navigation_key_width"android:layout_height="match_parent"android:layout_weight="0"systemui:keyCode="25"android:scaleType="center"android:contentDescription="@string/accessibility_home"android:paddingStart="@dimen/navigation_key_padding"android:paddingEnd="@dimen/navigation_key_padding"/>