Don't trigger full relayout if DateTimeView doesn't change

Right now, when an update is triggered, DateTimeView will trigger a full
relayout of its parents because it always calls setText, even if it
doesn't change the contents (later down the line, TextView will call
requestLayout() for wrap_content, even if size didn't change).

Checking if the content actually changed avoids that extra layout pass
which avoids needless relayouts in e.g. SystemUI Notifications.

Bug:220712538

Test: atest DateTimeView (new test failed before fix / passes after fix)

Change-Id: Ib391d6715136b64b98f0bda3b3d4a3f991809c89

core/java/android/widget/DateTimeView.java

@@ -32,6 +32,7 @@ import android.content.res.TypedArray;
 import android.database.ContentObserver;
 import android.os.Build;
 import android.os.Handler;
+import android.text.TextUtils;
 import android.util.AttributeSet;
 import android.util.PluralsMessageFormatter;
 import android.view.accessibility.AccessibilityNodeInfo;
@@ -230,7 +231,7 @@ public class DateTimeView extends TextView {
 
         // Set the text
         String text = format.format(new Date(time));
-        setText(text);
+        maybeSetText(text);
 
         // Schedule the next update
         if (display == SHOW_TIME) {
@@ -258,7 +259,7 @@ public class DateTimeView extends TextView {
         boolean past = (now >= mTimeMillis);
         String result;
         if (duration < MINUTE_IN_MILLIS) {
-            setText(mNowText);
+            maybeSetText(mNowText);
             mUpdateTimeMillis = mTimeMillis + MINUTE_IN_MILLIS + 1;
             return;
         } else if (duration < HOUR_IN_MILLIS) {
@@ -308,7 +309,19 @@ public class DateTimeView extends TextView {
                 mUpdateTimeMillis = mTimeMillis - millisIncrease * count + 1;
             }
         }
-        setText(result);
+        maybeSetText(result);
+    }
+
+    /**
+     * Sets text only if the text has actually changed. This prevents needles relayouts of this
+     * view when set to wrap_content.
+     */
+    private void maybeSetText(String text) {
+        if (TextUtils.equals(getText(), text)) {
+            return;
+        }
+
+        setText(text);
     }
 
     /**

core/tests/coretests/src/android/widget/DateTimeViewTest.java

@@ -16,14 +16,20 @@
 
 package android.widget;
 
+import android.view.View;
+import android.view.ViewGroup;
+
 import androidx.test.InstrumentationRegistry;
 import androidx.test.annotation.UiThreadTest;
 import androidx.test.filters.SmallTest;
 import androidx.test.runner.AndroidJUnit4;
 
+import org.junit.Assert;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
+import java.time.Duration;
+
 @RunWith(AndroidJUnit4.class)
 @SmallTest
 public class DateTimeViewTest {
@@ -39,7 +45,33 @@ public class DateTimeViewTest {
         dateTimeView.detachedFromWindow();
     }
 
+    @UiThreadTest
+    @Test
+    public void noChangeInRelativeText_doesNotTriggerRelayout() {
+        // Week in the future is chosen because it'll result in a stable string during this test
+        // run. This should be improved once the class is refactored to be more testable in
+        // respect of clock retrieval.
+        final long weekInTheFuture = System.currentTimeMillis() + Duration.ofDays(7).toMillis();
+        final TestDateTimeView dateTimeView = new TestDateTimeView();
+        dateTimeView.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT,
+                ViewGroup.LayoutParams.WRAP_CONTENT));
+        dateTimeView.setShowRelativeTime(true);
+        dateTimeView.setTime(weekInTheFuture);
+        // View needs to be measured to request layout, skipping this would make this test pass
+        // always.
+        dateTimeView.measure(View.MeasureSpec.makeMeasureSpec(200, View.MeasureSpec.UNSPECIFIED),
+                View.MeasureSpec.makeMeasureSpec(100, View.MeasureSpec.UNSPECIFIED));
+        dateTimeView.reset();
+
+        // This should not change the text content and thus no relayout is expected.
+        dateTimeView.setTime(weekInTheFuture + 1000);
+
+        Assert.assertFalse(dateTimeView.wasLayoutRequested());
+    }
+
     private static class TestDateTimeView extends DateTimeView {
+        private boolean mRequestedLayout = false;
+
         TestDateTimeView() {
             super(InstrumentationRegistry.getContext());
         }
@@ -51,5 +83,18 @@ public class DateTimeViewTest {
         void detachedFromWindow() {
             super.onDetachedFromWindow();
         }
+
+        public void requestLayout() {
+            super.requestLayout();
+            mRequestedLayout = true;
+        }
+
+        public boolean wasLayoutRequested() {
+            return mRequestedLayout;
+        }
+
+        public void reset() {
+            mRequestedLayout = false;
+        }
     }
 }