Initialise the brightness value with Float.NaN in PersistentDataStore

If there is no DisplayState, and it gets initialised because of any
other field, for instance refresh-rate, the brightness gets initialised
by 0. Since 0 is a permissible value for brightness, is causes issues by
changing the brightness to 0.

Bug: 259517441
Test: atest PersistentDataStoreTest
Change-Id: I532afc9e9d437199922f83f3c4440127a86a88f5

2 files changed, 43 insertions, 3 deletions

diff --git a/services/core/java/com/android/server/display/PersistentDataStore.java b/services/core/java/com/android/server/display/PersistentDataStore.java
index a11f1721a4b9..73131a1dc220 100644
--- a/services/core/java/com/android/server/display/PersistentDataStore.java
+++ b/services/core/java/com/android/server/display/PersistentDataStore.java
@@ -619,7 +619,7 @@ final class PersistentDataStore {
 
     private static final class DisplayState {
         private int mColorMode;
-        private float mBrightness;
+        private float mBrightness = Float.NaN;
         private int mWidth;
         private int mHeight;
         private float mRefreshRate;
@@ -700,7 +700,11 @@ final class PersistentDataStore {
                         break;
                     case TAG_BRIGHTNESS_VALUE:
                         String brightness = parser.nextText();
-                        mBrightness = Float.parseFloat(brightness);
+                        try {
+                            mBrightness = Float.parseFloat(brightness);
+                        } catch (NumberFormatException e) {
+                            mBrightness = Float.NaN;
+                        }
                         break;
                     case TAG_BRIGHTNESS_CONFIGURATIONS:
                         mDisplayBrightnessConfigurations.loadFromXml(parser);
@@ -727,7 +731,9 @@ final class PersistentDataStore {
             serializer.endTag(null, TAG_COLOR_MODE);
 
             serializer.startTag(null, TAG_BRIGHTNESS_VALUE);
-            serializer.text(Float.toString(mBrightness));
+            if (!Float.isNaN(mBrightness)) {
+                serializer.text(Float.toString(mBrightness));
+            }
             serializer.endTag(null, TAG_BRIGHTNESS_VALUE);
 
             serializer.startTag(null, TAG_BRIGHTNESS_CONFIGURATIONS);
diff --git a/services/tests/servicestests/src/com/android/server/display/PersistentDataStoreTest.java b/services/tests/servicestests/src/com/android/server/display/PersistentDataStoreTest.java
index 3b0a22f80c30..35a677e0f816 100644
--- a/services/tests/servicestests/src/com/android/server/display/PersistentDataStoreTest.java
+++ b/services/tests/servicestests/src/com/android/server/display/PersistentDataStoreTest.java
@@ -344,6 +344,40 @@ public class PersistentDataStoreTest {
         assertEquals(85.3f, newDataStore.getUserPreferredRefreshRate(testDisplayDevice), 0.1f);
     }
 
+    @Test
+    public void testBrightnessInitialisesWithInvalidFloat() {
+        final String uniqueDisplayId = "test:123";
+        DisplayDevice testDisplayDevice = new DisplayDevice(null, null, uniqueDisplayId, null) {
+            @Override
+            public boolean hasStableUniqueId() {
+                return true;
+            }
+
+            @Override
+            public DisplayDeviceInfo getDisplayDeviceInfoLocked() {
+                return null;
+            }
+        };
+
+        // Set any value which initialises Display state
+        float refreshRate = 85.3f;
+        mDataStore.loadIfNeeded();
+        mDataStore.setUserPreferredRefreshRate(testDisplayDevice, refreshRate);
+
+        final ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        mInjector.setWriteStream(baos);
+        mDataStore.saveIfNeeded();
+        mTestLooper.dispatchAll();
+        assertTrue(mInjector.wasWriteSuccessful());
+        TestInjector newInjector = new TestInjector();
+        PersistentDataStore newDataStore = new PersistentDataStore(newInjector);
+        ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());
+        newInjector.setReadStream(bais);
+        newDataStore.loadIfNeeded();
+        assertTrue(Float.isNaN(mDataStore.getBrightness(testDisplayDevice)));
+    }
+
+
     public class TestInjector extends PersistentDataStore.Injector {
         private InputStream mReadStream;
         private OutputStream mWriteStream;