From e63abf76782b1856c8f67ced10366900313bd923 Mon Sep 17 00:00:00 2001
From: Lucas Dupin <dupin@google.com>
Date: Mon, 2 Jul 2018 11:17:14 -0700
Subject: [PATCH] Delay brightness change

During a fingerprint wake-up, the display state changes bumping up
the display brightness. This means that the screen will flash
bright if the scrims couldn't draw and blank the screen yet.

The fix updates the state of the keyguard, waits for the frame to be
pushed to the display (can take up to 2 frames since we're using
triple buffers), when then asks PowerManager to wake-up the device.

Fixes: 80415238
Test: fp unlock with AOD on and off on devices with displays from
      multiple vendors

Change-Id: I752f9bd5ffd754166ffee7dc15960909dd3f1a81
---
 .../statusbar/phone/BiometricUnlockController.java | 33 ++++++++++++++++------
 1 file changed, 25 insertions(+), 8 deletions(-)

diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/phone/BiometricUnlockController.java b/packages/SystemUI/src/com/android/systemui/statusbar/phone/BiometricUnlockController.java
index 0b6fd1300538..2087a165b215 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/phone/BiometricUnlockController.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/phone/BiometricUnlockController.java
@@ -216,15 +216,28 @@ public class BiometricUnlockController extends KeyguardUpdateMonitorCallback {
             // until the clock and the notifications are faded out.
             mStatusBarWindowManager.setForceDozeBrightness(true);
         }
-        if (!wasDeviceInteractive) {
-            if (DEBUG_BIO_WAKELOCK) {
-                Log.i(TAG, "bio wakelock: Authenticated, waking up...");
+        // During wake and unlock, we need to draw black before waking up to avoid abrupt
+        // brightness changes due to display state transitions.
+        boolean alwaysOnEnabled = DozeParameters.getInstance(mContext).getAlwaysOn();
+        boolean delayWakeUp = mode == MODE_WAKE_AND_UNLOCK && alwaysOnEnabled;
+        Runnable wakeUp = ()-> {
+            if (!wasDeviceInteractive) {
+                if (DEBUG_BIO_WAKELOCK) {
+                    Log.i(TAG, "bio wakelock: Authenticated, waking up...");
+                }
+                mPowerManager.wakeUp(SystemClock.uptimeMillis(), "android.policy:BIOMETRIC");
+            }
+            if (delayWakeUp) {
+                mKeyguardViewMediator.onWakeAndUnlocking();
             }
-            mPowerManager.wakeUp(SystemClock.uptimeMillis(), "android.policy:BIOMETRIC");
+            Trace.beginSection("release wake-and-unlock");
+            releaseBiometricWakeLock();
+            Trace.endSection();
+        };
+
+        if (!delayWakeUp) {
+            wakeUp.run();
         }
-        Trace.beginSection("release wake-and-unlock");
-        releaseBiometricWakeLock();
-        Trace.endSection();
         switch (mMode) {
             case MODE_DISMISS_BOUNCER:
                 Trace.beginSection("MODE_DISMISS");
@@ -257,7 +270,11 @@ public class BiometricUnlockController extends KeyguardUpdateMonitorCallback {
                     mUpdateMonitor.awakenFromDream();
                 }
                 mStatusBarWindowManager.setStatusBarFocusable(false);
-                mKeyguardViewMediator.onWakeAndUnlocking();
+                if (delayWakeUp) {
+                    mHandler.postDelayed(wakeUp, 50);
+                } else {
+                    mKeyguardViewMediator.onWakeAndUnlocking();
+                }
                 if (mStatusBar.getNavigationBarView() != null) {
                     mStatusBar.getNavigationBarView().setWakeAndUnlocking(true);
                 }
-- 
2.11.0