From 95b804ad4f0c0be174285b62cb010ad697a451ef Mon Sep 17 00:00:00 2001
From: Stevie Kideckel <kideckel@google.com>
Date: Tue, 8 Jun 2021 11:14:38 +0000
Subject: [PATCH] Stop using TIME_TICK broadcast in TextClock

This gets called even when the view is not visible, which is bad for
performance. I've adapted the existing tick framework to handle ticking
for minutes when there aren't seconds in the format.

I verified the correct behavior with sample apps with and without
seconds in the format, including across DST time changes.

Fix: 190467448
Test: locally with sample apps
Change-Id: I75fed5c9d162b5361c31fe22d057a007db0ce75c
---
 core/java/android/widget/TextClock.java | 40 +++++++++++++++----------
 1 file changed, 24 insertions(+), 16 deletions(-)

diff --git a/core/java/android/widget/TextClock.java b/core/java/android/widget/TextClock.java
index b1485ef27de54..e48afb2a3cc8b 100644
--- a/core/java/android/widget/TextClock.java
+++ b/core/java/android/widget/TextClock.java
@@ -34,7 +34,6 @@ import android.icu.text.DateTimePatternGenerator;
 import android.net.Uri;
 import android.os.Build;
 import android.os.Handler;
-import android.os.SystemClock;
 import android.os.UserHandle;
 import android.provider.Settings;
 import android.text.format.DateFormat;
@@ -45,6 +44,10 @@ import android.view.inspector.InspectableProperty;
 
 import com.android.internal.R;
 
+import java.time.Duration;
+import java.time.Instant;
+import java.time.ZoneId;
+import java.time.ZonedDateTime;
 import java.util.Calendar;
 import java.util.TimeZone;
 
@@ -185,18 +188,29 @@ public class TextClock extends TextView {
 
     private final Runnable mTicker = new Runnable() {
         public void run() {
-            if (mStopTicking) {
+            removeCallbacks(this);
+            if (mStopTicking || !mShouldRunTicker) {
                 return; // Test disabled the clock ticks
             }
             onTimeChanged();
 
-            long now = SystemClock.uptimeMillis();
-            long next = now + (1000 - now % 1000);
+            Instant now = mTime.toInstant();
+            ZoneId zone = mTime.getTimeZone().toZoneId();
 
-            Handler handler = getHandler();
-            if (handler != null) {
-                handler.postAtTime(mTicker, next);
+            ZonedDateTime nextTick;
+            if (mHasSeconds) {
+                nextTick = now.atZone(zone).plusSeconds(1).withNano(0);
+            } else {
+                nextTick = now.atZone(zone).plusMinutes(1).withSecond(0).withNano(0);
             }
+
+            long millisUntilNextTick = Duration.between(now, nextTick.toInstant()).toMillis();
+            if (millisUntilNextTick <= 0) {
+                // This should never happen, but if it does, then tick again in a second.
+                millisUntilNextTick = 1000;
+            }
+
+            postDelayed(this, millisUntilNextTick);
         }
     };
 
@@ -519,8 +533,7 @@ public class TextClock extends TextView {
         mHasSeconds = DateFormat.hasSeconds(mFormat);
 
         if (mShouldRunTicker && hadSeconds != mHasSeconds) {
-            if (hadSeconds) getHandler().removeCallbacks(mTicker);
-            else mTicker.run();
+            mTicker.run();
         }
     }
 
@@ -557,14 +570,10 @@ public class TextClock extends TextView {
 
         if (!mShouldRunTicker && isVisible) {
             mShouldRunTicker = true;
-            if (mHasSeconds) {
-                mTicker.run();
-            } else {
-                onTimeChanged();
-            }
+            mTicker.run();
         } else if (mShouldRunTicker && !isVisible) {
             mShouldRunTicker = false;
-            getHandler().removeCallbacks(mTicker);
+            removeCallbacks(mTicker);
         }
     }
 
@@ -592,7 +601,6 @@ public class TextClock extends TextView {
     private void registerReceiver() {
         final IntentFilter filter = new IntentFilter();
 
-        filter.addAction(Intent.ACTION_TIME_TICK);
         filter.addAction(Intent.ACTION_TIME_CHANGED);
         filter.addAction(Intent.ACTION_TIMEZONE_CHANGED);