Fix a longstanding bug in the shade pulldown trajectory.

Two parts to this:

1. We were looking at the measured height of the close view
   for a lot of our computations, which---particularly with
   recent changes that dispense with the old 3-window
   implementation---is increasingly unreliable

2. We were overestimating the minY that the panel must be
   pulled down before animation starts. It was enforced
   jankiness!

Bug: 5359178
Change-Id: Ie09b62226b7b0977527348b5527478665ece1df8

Author: dsandler

packages/SystemUI/res/layout/status_bar_expanded.xml

@@ -121,7 +121,7 @@
 
         <com.android.systemui.statusbar.phone.CloseDragHandle android:id="@+id/close"
             android:layout_width="match_parent"
-            android:layout_height="34dp"
+            android:layout_height="@dimen/close_handle_height"
             android:layout_gravity="bottom"
             android:orientation="vertical"
             >

packages/SystemUI/res/values/dimens.xml

@@ -118,4 +118,6 @@
     <!-- Diameter of outer shape drawable shown in navbar search-->
     <dimen name="navbar_search_outerring_diameter">300dip</dimen>
 
+    <!-- Height of the draggable handle at the bottom of the phone notification panel -->
+    <dimen name="close_handle_height">34dp</dimen>
 </resources>

packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java

@@ -164,6 +164,7 @@ public class PhoneStatusBar extends BaseStatusBar {
 
     // drag bar
     CloseDragHandle mCloseView;
+    private int mCloseViewHeight;
 
     // all notifications
     NotificationData mNotificationData = new NotificationData();
@@ -333,6 +334,7 @@ protected PhoneStatusBarView makeStatusBarView() {
 
         mCloseView = (CloseDragHandle)mStatusBarWindow.findViewById(R.id.close);
         mCloseView.mService = this;
+        mCloseViewHeight = res.getDimensionPixelSize(R.dimen.close_handle_height);
 
         mEdgeBorder = res.getDimensionPixelSize(R.dimen.status_bar_edge_ignore);
 
@@ -466,6 +468,10 @@ public int getStatusBarHeight() {
         return mNaturalBarHeight;
     }
 
+    private int getCloseViewHeight() {
+        return mCloseViewHeight;
+    }
+
     private View.OnClickListener mRecentsClickListener = new View.OnClickListener() {
         public void onClick(View v) {
             toggleRecentApps();
@@ -1259,7 +1265,7 @@ void incrementAnim() {
     }
 
     void doRevealAnimation() {
-        final int h = mCloseView.getHeight() + getStatusBarHeight();
+        final int h = getCloseViewHeight() + getStatusBarHeight();
         if (mAnimatingReveal && mAnimating && mAnimY < h) {
             incrementAnim();
             if (mAnimY >= h) {
@@ -1420,9 +1426,9 @@ boolean interceptTouchEvent(MotionEvent event) {
             }
         } else if (mTracking) {
             trackMovement(event);
-            final int minY = statusBarSize + mCloseView.getHeight();
+            final int minY = statusBarSize + getCloseViewHeight();
             if (action == MotionEvent.ACTION_MOVE) {
-                if (mAnimatingReveal && y < minY) {
+                if (mAnimatingReveal && (y + mViewDelta) < minY) {
                     // nothing
                 } else  {
                     mAnimatingReveal = false;
@@ -1855,6 +1861,10 @@ void updateExpandedInvisiblePosition() {
         mTrackingPosition = -mDisplayMetrics.heightPixels;
     }
 
+    static final float saturate(float a) {
+        return a < 0f ? 0f : (a > 1f ? 1f : a);
+    }
+
     void updateExpandedViewPos(int expandedPosition) {
         if (SPEW) {
             Slog.d(TAG, "updateExpandedViewPos before expandedPosition=" + expandedPosition
@@ -1905,8 +1915,9 @@ else if (expandedPosition == EXPANDED_LEAVE_ALONE) {
         }
         cropView.setLayoutParams(lp);
         // woo, special effects
-        final float frac = (float)panelh / disph;
-        final int color = ((int)(0xB0 * Math.pow(frac, 0.5))) << 24;
+        final int barh = getCloseViewHeight() + getStatusBarHeight();
+        final float frac = saturate((float)(panelh - barh) / (disph - barh));
+        final int color = ((int)(0xB0 * Math.sin(frac * 1.57f))) << 24;
         mStatusBarWindow.setBackgroundColor(color);
 
 //        Slog.d(TAG, String.format("updateExpanded: pos=%d frac=%.2f col=0x%08x", pos, frac, color));