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Fix Android display metrics refresh on density changes #57295

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19a6ac7
Fix Android display metrics refresh on density changes
nikhilpakhloo Jun 20, 2026
778e936
Fixes:ReactHostImpl and ReactInstanceManager so the display metrics r…
nikhilpakhloo Jun 23, 2026
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26 changes: 26 additions & 0 deletions ...ages/react-native/ReactAndroid/src/main/java/com/facebook/react/ReactInstanceManager.java
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Original file line number Diff line number Diff line change
Expand Up @@ -72,13 +72,16 @@
import com.facebook.react.devsupport.interfaces.PackagerStatusCallback;
import com.facebook.react.devsupport.interfaces.PausedInDebuggerOverlayManager;
import com.facebook.react.devsupport.interfaces.RedBoxHandler;
import com.facebook.react.fabric.FabricUIManager;
import com.facebook.react.interfaces.TaskInterface;
import com.facebook.react.internal.AndroidChoreographerProvider;
import com.facebook.react.internal.ChoreographerProvider;
import com.facebook.react.internal.featureflags.ReactNativeFeatureFlags;
import com.facebook.react.modules.appearance.AppearanceModule;
import com.facebook.react.modules.core.DefaultHardwareBackBtnHandler;
import com.facebook.react.modules.core.DeviceEventManagerModule;
import com.facebook.react.modules.core.ReactChoreographer;
import com.facebook.react.modules.deviceinfo.DeviceInfoModule;
import com.facebook.react.packagerconnection.RequestHandler;
import com.facebook.react.uimanager.DisplayMetricsHolder;
import com.facebook.react.uimanager.ReactRoot;
Expand Down Expand Up @@ -859,6 +862,29 @@ public void onConfigurationChanged(Context updatedContext, @Nullable Configurati

ReactContext currentReactContext = getCurrentReactContext();
if (currentReactContext != null) {
if (ReactNativeFeatureFlags.enableFontScaleChangesUpdatingLayout()) {
boolean didDisplayMetricsChange =
DisplayMetricsHolder.updateDisplayMetricsIfChanged(updatedContext);
if (didDisplayMetricsChange) {
@Nullable UIManager uiManager = UIManagerHelper.getUIManager(currentReactContext, FABRIC);
if (uiManager instanceof FabricUIManager) {
((FabricUIManager) uiManager).updateDisplayMetricDensity();
}

synchronized (mAttachedReactRoots) {
for (ReactRoot reactRoot : mAttachedReactRoots) {
reactRoot.getRootViewGroup().requestLayout();
}
}

DeviceInfoModule deviceInfoModule =
currentReactContext.getNativeModule(DeviceInfoModule.class);
if (deviceInfoModule != null) {
deviceInfoModule.emitUpdateDimensionsEvent();
}
}
}

AppearanceModule appearanceModule =
currentReactContext.getNativeModule(AppearanceModule.class);

Expand Down
6 changes: 3 additions & 3 deletions packages/react-native/ReactAndroid/src/main/java/com/facebook/react/ReactRootView.java
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Original file line number Diff line number Diff line change
Expand Up @@ -137,7 +137,7 @@ private void init() {
setClipChildren(false);

if (ReactNativeFeatureFlags.enableFontScaleChangesUpdatingLayout()) {
DisplayMetricsHolder.initDisplayMetrics(getContext().getApplicationContext());
DisplayMetricsHolder.initDisplayMetrics(getContext());
}
}

Expand Down Expand Up @@ -916,7 +916,7 @@ private class CustomGlobalLayoutListener implements ViewTreeObserver.OnGlobalLay
private int mDeviceRotation = 0;

/* package */ CustomGlobalLayoutListener() {
DisplayMetricsHolder.initDisplayMetricsIfNotInitialized(getContext().getApplicationContext());
DisplayMetricsHolder.initDisplayMetricsIfNotInitialized(getContext());
mVisibleViewArea = new Rect();
}

Expand Down Expand Up @@ -991,7 +991,7 @@ private void checkForDeviceOrientationChanges() {
return;
}
mDeviceRotation = rotation;
DisplayMetricsHolder.initDisplayMetrics(getContext().getApplicationContext());
DisplayMetricsHolder.initDisplayMetrics(getContext());
emitOrientationChanged(rotation);
}

Expand Down
7 changes: 7 additions & 0 deletions ...es/react-native/ReactAndroid/src/main/java/com/facebook/react/fabric/FabricUIManager.java
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Original file line number Diff line number Diff line change
Expand Up @@ -361,6 +361,7 @@ public <T extends View> int startSurface(
UiThreadUtil.isOnUiThread() ? RootViewUtil.getViewportOffset(rootView) : new Point(0, 0);

Assertions.assertNotNull(mBinding, "Binding in FabricUIManager is null");
mBinding.setPixelDensity(context.getResources().getDisplayMetrics().density);
mBinding.startSurfaceWithConstraints(
rootTag,
moduleName,
Expand Down Expand Up @@ -1033,6 +1034,12 @@ void setBinding(FabricUIManagerBinding binding) {
mBinding = binding;
}

public void updateDisplayMetricDensity() {
if (mBinding != null) {
mBinding.setPixelDensity(PixelUtil.getDisplayMetricDensity());
}
}

/**
* Updates the layout metrics of the root view based on the Measure specs received by parameters.
*/
Expand Down
12 changes: 6 additions & 6 deletions packages/react-native/ReactAndroid/src/main/java/com/facebook/react/runtime/ReactHostImpl.kt
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Expand Up @@ -62,12 +62,12 @@ import com.facebook.react.internal.featureflags.ReactNativeNewArchitectureFeatur
import com.facebook.react.modules.appearance.AppearanceModule
import com.facebook.react.modules.core.DefaultHardwareBackBtnHandler
import com.facebook.react.modules.core.DeviceEventManagerModule
import com.facebook.react.modules.deviceinfo.DeviceInfoModule
import com.facebook.react.modules.systeminfo.AndroidInfoHelpers
import com.facebook.react.runtime.internal.bolts.Task
import com.facebook.react.runtime.internal.bolts.TaskCompletionSource
import com.facebook.react.turbomodule.core.interfaces.CallInvokerHolder
import com.facebook.react.uimanager.DisplayMetricsHolder
import com.facebook.react.uimanager.PixelUtil
import com.facebook.react.uimanager.events.BlackHoleEventDispatcher
import com.facebook.react.uimanager.events.EventDispatcher
import com.facebook.react.views.imagehelper.ResourceDrawableIdHelper
Expand Down Expand Up @@ -737,14 +737,14 @@ public class ReactHostImpl(
val currentReactContext = this.currentReactContext
if (currentReactContext != null) {
if (ReactNativeFeatureFlags.enableFontScaleChangesUpdatingLayout()) {
val previousFontScale = PixelUtil.toPixelFromSP(1.0)
DisplayMetricsHolder.initDisplayMetrics(currentReactContext)
val newFontScale = PixelUtil.toPixelFromSP(1.0)

if (previousFontScale != newFontScale) {
val didDisplayMetricsChange = DisplayMetricsHolder.updateDisplayMetricsIfChanged(context)

@fabriziocucci fabriziocucci Jun 24, 2026 •
edited
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Thanks for gating both ReactHostImpl and ReactInstanceManager on enableFontScaleChangesUpdatingLayout(). That covers the consistency point.

One thing I noticed on the new arch path: setPixelDensity seems to be the only thing that sets the Fabric pixel density and it looks global (no surfaceId). The relayout here goes through setConstraints, which seems to carry width/height/offset/RTL but no scale factor. A relayout alone might not refresh the density. Old arch ReactInstanceManager pushes the new density via updateDisplayMetricDensity() but I don't see ReactHostImpl (or anything else in runtime/) doing the same. So on new arch a density change seems like it might relayout with a stale C++ pixel density, which would keep sp -> px wrong.

I might be missing something here. The test plan also doesn't seem to cover a device run. Did you get a chance to check the density actually updates on new arch (bridgeless)? If not, it seems like ReactHostImpl may also need to call updateDisplayMetricDensity().

if (didDisplayMetricsChange) {
synchronized(attachedSurfaces) {
attachedSurfaces.forEach { surface -> surface.view?.requestLayout() }
}

val deviceInfoModule = currentReactContext.getNativeModule(DeviceInfoModule::class.java)
deviceInfoModule?.emitUpdateDimensionsEvent()
}
}

Expand Down
25 changes: 24 additions & 1 deletion ...ct-native/ReactAndroid/src/main/java/com/facebook/react/uimanager/DisplayMetricsHolder.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -50,6 +50,29 @@ public object DisplayMetricsHolder {
@SuppressLint("DeprecatedMethod") // for Android Lint
@Suppress("DEPRECATION") // for Kotlin compiler
public fun initDisplayMetrics(context: Context) {
screenDisplayMetrics = getDisplayMetrics(context)
}

@JvmStatic
@SuppressLint("DeprecatedMethod") // for Android Lint
@Suppress("DEPRECATION") // for Kotlin compiler
public fun updateDisplayMetricsIfChanged(context: Context): Boolean {
val oldMetrics = screenDisplayMetrics
val newMetrics = getDisplayMetrics(context)
val didChange =
oldMetrics == null ||
oldMetrics.widthPixels != newMetrics.widthPixels ||
oldMetrics.heightPixels != newMetrics.heightPixels ||
oldMetrics.density != newMetrics.density ||
oldMetrics.scaledDensity != newMetrics.scaledDensity ||
oldMetrics.densityDpi != newMetrics.densityDpi
screenDisplayMetrics = newMetrics
return didChange
}

@SuppressLint("DeprecatedMethod") // for Android Lint
@Suppress("DEPRECATION") // for Kotlin compiler
private fun getDisplayMetrics(context: Context): DisplayMetrics {
val displayMetrics = context.resources.displayMetrics
val screenDisplayMetrics = DisplayMetrics()
screenDisplayMetrics.setTo(displayMetrics)
Expand All @@ -65,7 +88,7 @@ public object DisplayMetricsHolder {
// physical display metrics without the system font scale setting.
// This is needed for proper text scaling when fontScale < 1.0
screenDisplayMetrics.scaledDensity = displayMetrics.scaledDensity
DisplayMetricsHolder.screenDisplayMetrics = screenDisplayMetrics
return screenDisplayMetrics
}

internal fun getStatusBarHeightPx(activity: Activity?): Int {
Expand Down
55 changes: 55 additions & 0 deletions ...ative/ReactAndroid/src/test/java/com/facebook/react/uimanager/DisplayMetricsHolderTest.kt
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Expand Up @@ -80,6 +80,61 @@ class DisplayMetricsHolderTest {
assertThat(DisplayMetricsHolder.getScreenDisplayMetrics()).isNotNull()
}

@Test
fun updateDisplayMetricsIfChanged_returnsTrueAndUpdatesMetricsWhenMetricsChange() {
val originalMetrics = DisplayMetrics().apply {
density = 2.0f
scaledDensity = 2.0f
widthPixels = 1000
heightPixels = 2000
densityDpi = DisplayMetrics.DENSITY_XHIGH
}
val updatedMetrics = DisplayMetrics().apply {
density = 1.5f
scaledDensity = 1.5f
widthPixels = 1200
heightPixels = 1800
densityDpi = DisplayMetrics.DENSITY_HIGH
}
val mockContext: Context = mock()
val mockResources: android.content.res.Resources = mock()

DisplayMetricsHolder.setScreenDisplayMetrics(originalMetrics)
whenever(mockContext.resources).thenReturn(mockResources)
whenever(mockResources.displayMetrics).thenReturn(updatedMetrics)
whenever(mockContext.getSystemService(Context.WINDOW_SERVICE))
.thenThrow(IllegalStateException("non-visual context"))

val didChange = DisplayMetricsHolder.updateDisplayMetricsIfChanged(mockContext)

assertThat(didChange).isTrue()
assertThat(DisplayMetricsHolder.getScreenDisplayMetrics().density).isEqualTo(1.5f)
assertThat(DisplayMetricsHolder.getScreenDisplayMetrics().scaledDensity).isEqualTo(1.5f)
}

@Test
fun updateDisplayMetricsIfChanged_returnsFalseWhenMetricsMatch() {
val metrics = DisplayMetrics().apply {
density = 2.0f
scaledDensity = 2.0f
widthPixels = 1000
heightPixels = 2000
densityDpi = DisplayMetrics.DENSITY_XHIGH
}
val mockContext: Context = mock()
val mockResources: android.content.res.Resources = mock()

DisplayMetricsHolder.setScreenDisplayMetrics(DisplayMetrics().apply { setTo(metrics) })
whenever(mockContext.resources).thenReturn(mockResources)
whenever(mockResources.displayMetrics).thenReturn(metrics)
whenever(mockContext.getSystemService(Context.WINDOW_SERVICE))
.thenThrow(IllegalStateException("non-visual context"))

val didChange = DisplayMetricsHolder.updateDisplayMetricsIfChanged(mockContext)

assertThat(didChange).isFalse()
}

@Test
fun initDisplayMetricsIfNotInitialized_onlyInitializesOnce() {
DisplayMetricsHolder.initDisplayMetricsIfNotInitialized(context)
Expand Down
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