Android 觸控提示音
阿新 • • 發佈：2019-01-03
近期任務，涉及Android觸控提示音。
首先，定位原始碼目標。很顯然的，在原生的設定的聲音功能頁裡面就包含了觸控音的開關。
那麼我們找到對應的java程式碼，SoundSettings.java
package com.android.settings;
import java.util.List;
public class SoundSettings extends SettingsPreferenceFragment implements
Preference.OnPreferenceChangeListener {
可以看到 這是個PreferenceFragment的子類。（這裡的SettingsPreferenceFragment是繼承PreferenceFragment）。那麼找到它對應的xml檔案。
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ContentResolver resolver = getContentResolver();
int activePhoneType = TelephonyManager.getDefault().getCurrentPhoneType();
mAudioManager = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
addPreferencesFromResource(R.xml.sound_settings);
常識性的，它在onCreate裡面，找到addPreferencesFromResource,然後檢視sound_settings的xml檔案。
這裡我通過查詢中文string資原始檔，標示了xml檔案的一些item的title。
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"
android:title="@string/sound_settings"
android:key="sound_settings"
xmlns:settings OK，接著我們在SoundSettings裡面搜尋關鍵字: sound_effects
private static final String KEY_SOUND_EFFECTS = "sound_effects";
接著搜尋：KEY_SOUND_EFFECTS
// 觸控提示音相關
mSoundEffects = (CheckBoxPreference) findPreference(KEY_SOUND_EFFECTS);
mSoundEffects.setPersistent(false);
mSoundEffects.setChecked(Settings.System.getInt(resolver,
Settings.System.SOUND_EFFECTS_ENABLED, 1) != 0); @Override
public boolean onPreferenceTreeClick(PreferenceScreen preferenceScreen, Preference preference) {
if (preference == mVibrateWhenRinging) {
Settings.System.putInt(getContentResolver(), Settings.System.VIBRATE_WHEN_RINGING,
mVibrateWhenRinging.isChecked() ? 1 : 0);
} else if (preference == mDtmfTone) {
Settings.System.putInt(getContentResolver(), Settings.System.DTMF_TONE_WHEN_DIALING,
mDtmfTone.isChecked() ? 1 : 0);
} else if (preference == mSoundEffects) {
if (mSoundEffects.isChecked()) {
mAudioManager.loadSoundEffects();
} else {
mAudioManager.unloadSoundEffects();
}
Settings.System.putInt(getContentResolver(), Settings.System.SOUND_EFFECTS_ENABLED,
mSoundEffects.isChecked() ? 1 : 0);
}這裡我們很容易的看清楚它的例項和點選監聽，都是通過修改系統配置來進行操作的，那麼這玩意到底在哪裡整呢？
首先，觸控提示音，是對所有的view的點選時間都會有觸發效果，那麼我們看看View.java的類。
View.java有將近2萬行，想研究的徹底很明顯是不現實，或者說，不輕鬆的。那麼我們搜素SOUND_EFFECTS_ENABLED 這個關鍵字
/**
* View flag indicating whether this view should have sound effects enabled
* for events such as clicking and touching.
*/
public static final int SOUND_EFFECTS_ENABLED = 0x08000000;看註釋，意思是是否啟動聲音效果。
/**
* Set whether this view should have sound effects enabled for events such as
* clicking and touching.
*
* <p>You may wish to disable sound effects for a view if you already play sounds,
* for instance, a dial key that plays dtmf tones.
*
* @param soundEffectsEnabled whether sound effects are enabled for this view.
* @see #isSoundEffectsEnabled()
* @see #playSoundEffect(int)
* @attr ref android.R.styleable#View_soundEffectsEnabled
*/
public void setSoundEffectsEnabled(boolean soundEffectsEnabled) {
setFlags(soundEffectsEnabled ? SOUND_EFFECTS_ENABLED: 0, SOUND_EFFECTS_ENABLED);
}
/**
* @return whether this view should have sound effects enabled for events such as
* clicking and touching.
*
* @see #setSoundEffectsEnabled(boolean)
* @see #playSoundEffect(int)
* @attr ref android.R.styleable#View_soundEffectsEnabled
*/
@ViewDebug.ExportedProperty
public boolean isSoundEffectsEnabled() {
return SOUND_EFFECTS_ENABLED == (mViewFlags & SOUND_EFFECTS_ENABLED);
}看到這2個方法我就有底了。很明顯，我們要檢視isSoundEffectsEnabled的呼叫關係。
/**
* Play a sound effect for this view.
*
* <p>The framework will play sound effects for some built in actions, such as
* clicking, but you may wish to play these effects in your widget,
* for instance, for internal navigation.
*
* <p>The sound effect will only be played if sound effects are enabled by the user, and
* {@link #isSoundEffectsEnabled()} is true.
*
* @param soundConstant One of the constants defined in {@link SoundEffectConstants}
*/
public void playSoundEffect(int soundConstant) {
if (mAttachInfo == null || mAttachInfo.mRootCallbacks == null || !isSoundEffectsEnabled()) {
return;
}
mAttachInfo.mRootCallbacks.playSoundEffect(soundConstant);
}接著我們看誰呼叫了它，找到在AudioServeice.java中
/** @see AudioManager#playSoundEffect(int) */
public void playSoundEffect(int effectType) {
playSoundEffectVolume(effectType, -1.0f);
}
/** @see AudioManager#playSoundEffect(int, float) */
public void playSoundEffectVolume(int effectType, float volume) {
sendMsg(mAudioHandler, MSG_PLAY_SOUND_EFFECT, SENDMSG_QUEUE,
effectType, (int) (volume * 1000), null, 0);
}寫到這裡，就是完了。接下來的需要，也就是對觸控音的資原始檔的修改，它的位置在framework/base/data/sounds/effects 資料夾下。（同時這個資料夾的ogg下面也有一個相同的檔案，這個我還不清楚）Effect_Tick.ogg。
對應的是在Android system/media/audio/ui Effect_Tick.ogg的檔案。
想要修改它的話，可以在編譯room的時候替換了它，或者push 一個新的同名檔案。