Added system-wide minimum brightness curve.
The minimum brightness curve guarantess that any brightness curve
that dips below it is rejected by the system.
This prevent auto-brightness from setting the screen so dark as to
prevent the user from resetting or disabling it, and maps lux to
the absolute minimum nits that are still readable in that ambient
brightness.
Test: atest BrightnessConfigurationTest.
Fixes: 77176207
Change-Id: Ibd1e83e9b147f3849d6c907f828cbe5950c8367f
diff --git a/services/core/java/com/android/server/display/DisplayManagerService.java b/services/core/java/com/android/server/display/DisplayManagerService.java
index 93e0bd5..0f531a8 100644
--- a/services/core/java/com/android/server/display/DisplayManagerService.java
+++ b/services/core/java/com/android/server/display/DisplayManagerService.java
@@ -36,11 +36,13 @@
import android.content.pm.PackageManager;
import android.content.pm.ParceledListSlice;
import android.content.res.Resources;
+import android.content.res.TypedArray;
import android.graphics.Point;
import android.hardware.SensorManager;
import android.hardware.display.AmbientBrightnessDayStats;
import android.hardware.display.BrightnessChangeEvent;
import android.hardware.display.BrightnessConfiguration;
+import android.hardware.display.Curve;
import android.hardware.display.DisplayManagerGlobal;
import android.hardware.display.DisplayManagerInternal;
import android.hardware.display.DisplayViewport;
@@ -72,8 +74,10 @@
import android.provider.Settings;
import android.text.TextUtils;
import android.util.IntArray;
+import android.util.Pair;
import android.util.Slog;
import android.util.SparseArray;
+import android.util.Spline;
import android.view.Display;
import android.view.DisplayInfo;
import android.view.Surface;
@@ -276,6 +280,11 @@
private final Injector mInjector;
+ // The minimum brightness curve, which guarantess that any brightness curve that dips below it
+ // is rejected by the system.
+ private final Curve mMinimumBrightnessCurve;
+ private final Spline mMinimumBrightnessSpline;
+
public DisplayManagerService(Context context) {
this(context, new Injector());
}
@@ -289,8 +298,15 @@
mUiHandler = UiThread.getHandler();
mDisplayAdapterListener = new DisplayAdapterListener();
mSingleDisplayDemoMode = SystemProperties.getBoolean("persist.demo.singledisplay", false);
+ Resources resources = mContext.getResources();
mDefaultDisplayDefaultColorMode = mContext.getResources().getInteger(
com.android.internal.R.integer.config_defaultDisplayDefaultColorMode);
+ float[] lux = getFloatArray(resources.obtainTypedArray(
+ com.android.internal.R.array.config_minimumBrightnessCurveLux));
+ float[] nits = getFloatArray(resources.obtainTypedArray(
+ com.android.internal.R.array.config_minimumBrightnessCurveNits));
+ mMinimumBrightnessCurve = new Curve(lux, nits);
+ mMinimumBrightnessSpline = Spline.createSpline(lux, nits);
PowerManager pm = (PowerManager) mContext.getSystemService(Context.POWER_SERVICE);
mGlobalDisplayBrightness = pm.getDefaultScreenBrightnessSetting();
@@ -1032,9 +1048,15 @@
}
}
+ @VisibleForTesting
+ Curve getMinimumBrightnessCurveInternal() {
+ return mMinimumBrightnessCurve;
+ }
+
private void setBrightnessConfigurationForUserInternal(
@Nullable BrightnessConfiguration c, @UserIdInt int userId,
@Nullable String packageName) {
+ validateBrightnessConfiguration(c);
final int userSerial = getUserManager().getUserSerialNumber(userId);
synchronized (mSyncRoot) {
try {
@@ -1049,6 +1071,28 @@
}
}
+ @VisibleForTesting
+ void validateBrightnessConfiguration(BrightnessConfiguration config) {
+ if (config == null) {
+ return;
+ }
+ if (isBrightnessConfigurationTooDark(config)) {
+ throw new IllegalArgumentException("brightness curve is too dark");
+ }
+ }
+
+ private boolean isBrightnessConfigurationTooDark(BrightnessConfiguration config) {
+ Pair<float[], float[]> curve = config.getCurve();
+ float[] lux = curve.first;
+ float[] nits = curve.second;
+ for (int i = 0; i < lux.length; i++) {
+ if (nits[i] < mMinimumBrightnessSpline.interpolate(lux[i])) {
+ return true;
+ }
+ }
+ return false;
+ }
+
private void loadBrightnessConfiguration() {
synchronized (mSyncRoot) {
final int userSerial = getUserManager().getUserSerialNumber(mCurrentUserId);
@@ -1369,6 +1413,16 @@
}
}
+ private static float[] getFloatArray(TypedArray array) {
+ int length = array.length();
+ float[] floatArray = new float[length];
+ for (int i = 0; i < length; i++) {
+ floatArray[i] = array.getFloat(i, Float.NaN);
+ }
+ array.recycle();
+ return floatArray;
+ }
+
/**
* This is the object that everything in the display manager locks on.
* We make it an inner class within the {@link DisplayManagerService} to so that it is
@@ -1999,6 +2053,16 @@
}
}
+ @Override // Binder call
+ public Curve getMinimumBrightnessCurve() {
+ final long token = Binder.clearCallingIdentity();
+ try {
+ return getMinimumBrightnessCurveInternal();
+ } finally {
+ Binder.restoreCallingIdentity(token);
+ }
+ }
+
void setBrightness(int brightness) {
Settings.System.putIntForUser(mContext.getContentResolver(),
Settings.System.SCREEN_BRIGHTNESS, brightness, UserHandle.USER_CURRENT);