bug 描述：来电铃声响起后，来电页面隔个2~4秒才起来

解决思路

把原有响铃逻辑稍微延后，等到页面起来后再通知铃声播放。

响铃实际在 Telecomm 中，这个简单

要判断页面是否在前台这个有点挑战，一开始没啥思路，后来分析 log 找到了很明显的地方 DecorView

V/PhoneWindow: DecorView setVisiblity: visibility = 4, Parent = android.view.ViewRootImpl@b9781c9, this = DecorView@383b0ce[LiveWallpaperActivity] V/PhoneWindow: DecorView setVisiblity: visibility = 0, Parent = android.view.ViewRootImpl@b9781c9, this = DecorView@383b0ce[LiveWallpaperActivity] V/PhoneWindow: DecorView setVisiblity: visibility = 0, Parent = android.view.ViewRootImpl@a138a1d, this = DecorView@f98de06[Settings$WallpaperSettingsActivity] V/PhoneWindow: DecorView setVisiblity: visibility = 4, Parent = android.view.ViewRootImpl@bcb3e0a, this = DecorView@d2e335f[MainActivity] V/PhoneWindow: DecorView setVisiblity: visibility = 4, Parent = android.view.ViewRootImpl@b9781c9, this = DecorView@383b0ce[LiveWallpaperActivity]

每一个页面(activity) 的根布局为 DecorView，从上面 log 看到在 0/visible 和 4/invisible 之间不断切换,那基本上就可以从这里下手

frameworks\base\core\java\com\android\internal\policy\DecorView.java

    @Override
    public void setVisibility(int visibility) {
        super.setVisibility(visibility);
        String packageName = this.getContext().getPackageName();
		/*if (ViewDebugManager.DEBUG_USER) {
			Log.v("PhoneWindow", "DecorView setVisiblity: visibility = " + visibility
            + ", Parent = " + getParent() + ", this = " + this + " packageName="+packageName);
		}*/
        if ("com.android.dialer".equals(packageName)
		 || "com.google.dialer".equals(packageName)) {
            getContext().sendBroadcast(new android.content.Intent("com.android.action.activityChange")
                .putExtra("visibility", visibility));
        }
    }

通知已经发出，接下来去 Telecomm 中接收处理响铃

vendor\mediatek\proprietary\packages\services\Telecomm\src\com\android\server\telecom\Ringer.java

import android.content.BroadcastReceiver;
import android.content.Intent;
import android.content.IntentFilter;

    public Ringer(
            InCallTonePlayer.Factory playerFactory,
            Context context,
            SystemSettingsUtil systemSettingsUtil,
            AsyncRingtonePlayer asyncRingtonePlayer,
            RingtoneFactory ringtoneFactory,
            Vibrator vibrator,
            VibrationEffectProxy vibrationEffectProxy,
            InCallController inCallController) {

        mIsHapticPlaybackSupportedByDevice =
                mSystemSettingsUtil.isHapticPlaybackSupported(mContext);
				
	   //add
	   android.util.Log.d("Ringer", "Initializes the Ringer"); 
       mContext.registerReceiver(new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                 int visibility = intent.getIntExtra("visibility", 4);
                 if (visibility == 0) {
                    if (!justRingOnce) {
                        justRingOnce = true;
                        startRinging(foregroundCall, isHfpDeviceAttached, true);
                    }
                 }else {
                     justRingOnce = false;
                 }
            }
        }, new IntentFilter("com.android.action.activityChange"));
       //end

    }
	//add
    Call foregroundCall;
    boolean isHfpDeviceAttached;
    boolean justRingOnce;

    public boolean startRinging(Call foregroundCall, boolean isHfpDeviceAttached) {
	    this.foregroundCall = foregroundCall;
        this.isHfpDeviceAttached = isHfpDeviceAttached;
		return false;
	}
	//end
	
	public boolean startRinging(Call foregroundCall, boolean isHfpDeviceAttached, boolean newFun) {
        if (foregroundCall == null) {
            /// M: ALPS03787956 Fix wtf log warning. @{
            /// Hand up the call immediately when ringing. Then the foreground call will
            /// change to null, but call audio is start ringing at the same time.
            /// Log.wtf will occur in this case.
            /// Solution:
            /// Call audio can handle this case, so change Log.wtf to Log.i here.
            Log.i(this, "startRinging called with null foreground call.");
            /// @}
            return false;
        }