Fix issue #6603152: User-adjustable autobrightness broken?

Two issues:
- The new brightness was not being applied when switching out
  of auto-brightness mode.
- We were resetting to the last brightness level when switching
  modes.  This is because at that point we read the current
  brightness setting, but that isn't changed as the user adjusts
  only when the final value is committed.  To fix this, we have
  a new local variable keeping track of the last brightness value
  we have shown and use that when we haven't committed the
  brightness to settings.

Change-Id: I7cc02c9f90128eacec427587a3f6b8f25ede4bd3

src/com/android/settings/BrightnessPreference.java

@@ -47,6 +47,8 @@ public class BrightnessPreference extends SeekBarDialogPreference implements
     private boolean mAutomaticAvailable;
     private boolean mAutomaticMode;
 
+    private int mCurBrightness = -1;
+
     private boolean mRestoredOldState;
 
     // Backlight range is from 0 - 255. Need to make sure that user
@@ -60,6 +62,7 @@ public class BrightnessPreference extends SeekBarDialogPreference implements
     private ContentObserver mBrightnessObserver = new ContentObserver(new Handler()) {
         @Override
         public void onChange(boolean selfChange) {
+            mCurBrightness = -1;
             onBrightnessChanged();
         }
     };
@@ -135,6 +138,7 @@ public class BrightnessPreference extends SeekBarDialogPreference implements
                 : Settings.System.SCREEN_BRIGHTNESS_MODE_MANUAL);
         mSeekBar.setProgress(getBrightness());
         mSeekBar.setEnabled(!mAutomaticMode);
+        setBrightness(mSeekBar.getProgress(), false);
     }
 
     private int getBrightness() {
@@ -145,8 +149,12 @@ public class BrightnessPreference extends SeekBarDialogPreference implements
                     Settings.System.SCREEN_AUTO_BRIGHTNESS_ADJ, 0);
             brightness = (brightness+1)/2;
         } else {
-            brightness = Settings.System.getInt(getContext().getContentResolver(),
-                    Settings.System.SCREEN_BRIGHTNESS, 100);
+            if (mCurBrightness < 0) {
+                brightness = Settings.System.getInt(getContext().getContentResolver(),
+                        Settings.System.SCREEN_BRIGHTNESS, 100);
+            } else {
+                brightness = mCurBrightness;
+            }
             brightness = (brightness - mScreenBrightnessDim)
                     / (MAXIMUM_BACKLIGHT - mScreenBrightnessDim);
         }
@@ -199,6 +207,7 @@ public class BrightnessPreference extends SeekBarDialogPreference implements
         }
         setBrightness(mOldBrightness, false);
         mRestoredOldState = true;
+        mCurBrightness = -1;
     }
 
     private void setBrightness(int brightness, boolean write) {
@@ -229,9 +238,12 @@ public class BrightnessPreference extends SeekBarDialogPreference implements
                     power.setBacklightBrightness(brightness);
                 }
                 if (write) {
+                    mCurBrightness = -1;
                     final ContentResolver resolver = getContext().getContentResolver();
                     Settings.System.putInt(resolver,
                             Settings.System.SCREEN_BRIGHTNESS, brightness);
+                } else {
+                    mCurBrightness = brightness;
                 }
             } catch (RemoteException doe) {
             }
@@ -255,6 +267,7 @@ public class BrightnessPreference extends SeekBarDialogPreference implements
         myState.progress = mSeekBar.getProgress();
         myState.oldAutomatic = mOldAutomatic == 1;
         myState.oldProgress = mOldBrightness;
+        myState.curBrightness = mCurBrightness;
 
         // Restore the old state when the activity or dialog is being paused
         restoreOldState();
@@ -275,6 +288,7 @@ public class BrightnessPreference extends SeekBarDialogPreference implements
         mOldAutomatic = myState.oldAutomatic ? 1 : 0;
         setMode(myState.automatic ? 1 : 0);
         setBrightness(myState.progress, false);
+        mCurBrightness = myState.curBrightness;
     }
 
     private static class SavedState extends BaseSavedState {
@@ -283,6 +297,7 @@ public class BrightnessPreference extends SeekBarDialogPreference implements
         boolean oldAutomatic;
         int progress;
         int oldProgress;
+        int curBrightness;
 
         public SavedState(Parcel source) {
             super(source);
@@ -290,6 +305,7 @@ public class BrightnessPreference extends SeekBarDialogPreference implements
             progress = source.readInt();
             oldAutomatic = source.readInt() == 1;
             oldProgress = source.readInt();
+            curBrightness = source.readInt();
         }
 
         @Override
@@ -299,6 +315,7 @@ public class BrightnessPreference extends SeekBarDialogPreference implements
             dest.writeInt(progress);
             dest.writeInt(oldAutomatic ? 1 : 0);
             dest.writeInt(oldProgress);
+            dest.writeInt(curBrightness);
         }
 
         public SavedState(Parcelable superState) {