Fixed a jump with the panel scrim

Bug: 21764980
Change-Id: Ib09aa025143025178a9e21390f3a06b37a067e3e
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/phone/HeadsUpTouchHelper.java b/packages/SystemUI/src/com/android/systemui/statusbar/phone/HeadsUpTouchHelper.java
index f57575d..10c35af 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/phone/HeadsUpTouchHelper.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/phone/HeadsUpTouchHelper.java
@@ -110,6 +110,8 @@
                     mInitialTouchX = x;
                     mInitialTouchY = y;
                     int expandedHeight = mPickedChild.getActualHeight();
+                    mPanel.setPanelScrimMinFraction((float) expandedHeight
+                            / mPanel.getMaxPanelHeight());
                     mPanel.startExpandMotion(x, y, true /* startTracking */, expandedHeight
                             + mNotificationsTopPadding);
                     mHeadsUpManager.unpinAll();
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/phone/NotificationPanelView.java b/packages/SystemUI/src/com/android/systemui/statusbar/phone/NotificationPanelView.java
index 9e1af82..814435c 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/phone/NotificationPanelView.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/phone/NotificationPanelView.java
@@ -1759,6 +1759,7 @@
         mIsExpansionFromHeadsUp = false;
         mNotificationStackScroller.setTrackingHeadsUp(false);
         mExpandingFromHeadsUp = false;
+        setPanelScrimMinFraction(0.0f);
     }
 
     private void setListening(boolean listening) {
@@ -2309,7 +2310,7 @@
         }
         x = Math.min(rightMost, Math.max(leftMost, x));
         setVerticalPanelTranslation(x -
-                (mNotificationStackScroller.getLeft() + mNotificationStackScroller.getWidth()/2));
+                (mNotificationStackScroller.getLeft() + mNotificationStackScroller.getWidth() / 2));
      }
 
     private void resetVerticalPanelPosition() {
@@ -2326,4 +2327,8 @@
         mNotificationStackScroller.setStackHeight(stackHeight);
         updateKeyguardBottomAreaAlpha();
     }
+
+    public void setPanelScrimMinFraction(float minFraction) {
+        mBar.panelScrimMinFractionChanged(minFraction);
+    }
 }
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/phone/PanelBar.java b/packages/SystemUI/src/com/android/systemui/statusbar/phone/PanelBar.java
index 54bd3e9..3e9fc22 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/phone/PanelBar.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/phone/PanelBar.java
@@ -25,7 +25,7 @@
 
 import java.util.ArrayList;
 
-public class PanelBar extends FrameLayout {
+public abstract class PanelBar extends FrameLayout {
     public static final boolean DEBUG = false;
     public static final String TAG = PanelBar.class.getSimpleName();
     public static final void LOG(String fmt, Object... args) {
@@ -153,6 +153,8 @@
         }
     }
 
+    public abstract void panelScrimMinFractionChanged(float minFraction);
+
     /**
      * @param panel the panel which changed its expansion state
      * @param frac the fraction from the expansion in [0, 1]
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBarView.java b/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBarView.java
index b7e675d..dfd280a 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBarView.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBarView.java
@@ -40,6 +40,8 @@
     PanelView mNotificationPanel;
     private final PhoneStatusBarTransitions mBarTransitions;
     private ScrimController mScrimController;
+    private float mMinFraction;
+    private float mPanelFraction;
 
     public PhoneStatusBarView(Context context, AttributeSet attrs) {
         super(context, attrs);
@@ -180,8 +182,22 @@
     }
 
     @Override
+    public void panelScrimMinFractionChanged(float minFraction) {
+        if (mMinFraction != minFraction) {
+            mMinFraction = minFraction;
+            updateScrimFraction();
+        }
+    }
+
+    @Override
     public void panelExpansionChanged(PanelView panel, float frac, boolean expanded) {
         super.panelExpansionChanged(panel, frac, expanded);
-        mScrimController.setPanelExpansion(frac);
+        mPanelFraction = frac;
+        updateScrimFraction();
+    }
+
+    private void updateScrimFraction() {
+        float scrimFraction = Math.max(mPanelFraction - mMinFraction / (1.0f - mMinFraction), 0);
+        mScrimController.setPanelExpansion(scrimFraction);
     }
 }