Made stack scroller animation and apply logic reusable

Change-Id: I5d513dfc91b2a041ccefaa65074a64d1f211ec4a

7 files changed, 396 insertions, 289 deletions

diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java b/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java
index b14a70d..3bdc250 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java
@@ -161,7 +161,7 @@ import com.android.systemui.statusbar.policy.UserSwitcherController;
 import com.android.systemui.statusbar.policy.ZenModeController;
 import com.android.systemui.statusbar.stack.NotificationStackScrollLayout;
 import com.android.systemui.statusbar.stack.NotificationStackScrollLayout.OnChildLocationsChangedListener;
-import com.android.systemui.statusbar.stack.StackScrollState.ViewState;
+import com.android.systemui.statusbar.stack.StackViewState;
 import com.android.systemui.volume.VolumeComponent;
 
 import java.io.FileDescriptor;
@@ -444,10 +444,10 @@ public class PhoneStatusBar extends BaseStatusBar implements DemoMode,
     // Fingerprint (as computed by getLoggingFingerprint() of the last logged state.
     private int mLastLoggedStateFingerprint;
 
-    private static final int VISIBLE_LOCATIONS = ViewState.LOCATION_FIRST_CARD
-            | ViewState.LOCATION_TOP_STACK_PEEKING
-            | ViewState.LOCATION_MAIN_AREA
-            | ViewState.LOCATION_BOTTOM_STACK_PEEKING;
+    private static final int VISIBLE_LOCATIONS = StackViewState.LOCATION_FIRST_CARD
+            | StackViewState.LOCATION_TOP_STACK_PEEKING
+            | StackViewState.LOCATION_MAIN_AREA
+            | StackViewState.LOCATION_BOTTOM_STACK_PEEKING;
 
     private final OnChildLocationsChangedListener mNotificationLocationsChangedListener =
             new OnChildLocationsChangedListener() {
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/stack/NotificationStackScrollLayout.java b/packages/SystemUI/src/com/android/systemui/statusbar/stack/NotificationStackScrollLayout.java
index 6dcbed6..e30ab8d 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/stack/NotificationStackScrollLayout.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/stack/NotificationStackScrollLayout.java
@@ -46,7 +46,6 @@ import com.android.systemui.statusbar.StackScrollerDecorView;
 import com.android.systemui.statusbar.StatusBarState;
 import com.android.systemui.statusbar.phone.PhoneStatusBar;
 import com.android.systemui.statusbar.policy.ScrollAdapter;
-import com.android.systemui.statusbar.stack.StackScrollState.ViewState;
 
 import java.util.ArrayList;
 import java.util.HashSet;
@@ -375,15 +374,15 @@ public class NotificationStackScrollLayout extends ViewGroup
      * Returns the location the given child is currently rendered at.
      *
      * @param child the child to get the location for
-     * @return one of {@link ViewState}'s <code>LOCATION_*</code> constants
+     * @return one of {@link StackViewState}'s <code>LOCATION_*</code> constants
      */
     public int getChildLocation(View child) {
-        ViewState childViewState = mCurrentStackScrollState.getViewStateForView(child);
+        StackViewState childViewState = mCurrentStackScrollState.getViewStateForView(child);
         if (childViewState == null) {
-            return ViewState.LOCATION_UNKNOWN;
+            return StackViewState.LOCATION_UNKNOWN;
         }
         if (childViewState.gone) {
-            return ViewState.LOCATION_GONE;
+            return StackViewState.LOCATION_GONE;
         }
         return childViewState.location;
     }
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/stack/StackScrollAlgorithm.java b/packages/SystemUI/src/com/android/systemui/statusbar/stack/StackScrollAlgorithm.java
index ddc4251..2c124d0 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/stack/StackScrollAlgorithm.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/stack/StackScrollAlgorithm.java
@@ -178,7 +178,7 @@ public class StackScrollAlgorithm {
         int childCount = algorithmState.visibleChildren.size();
         for (int i = 0; i < childCount; i++) {
             View child = algorithmState.visibleChildren.get(i);
-            StackScrollState.ViewState childViewState = resultState.getViewStateForView(child);
+            StackViewState childViewState = resultState.getViewStateForView(child);
 
             // The speed bump can also be gone, so equality needs to be taken when comparing
             // indices.
@@ -194,7 +194,7 @@ public class StackScrollAlgorithm {
         int childCount = algorithmState.visibleChildren.size();
         for (int i = 0; i < childCount; i++) {
             ExpandableView child = algorithmState.visibleChildren.get(i);
-            StackScrollState.ViewState state = resultState.getViewStateForView(child);
+            StackViewState state = resultState.getViewStateForView(child);
             float newYTranslation = state.yTranslation + state.height * (1f - state.scale) / 2f;
             float newHeight = state.height * state.scale;
             // apply clipping and shadow
@@ -242,8 +242,8 @@ public class StackScrollAlgorithm {
      * @param backgroundHeight the desired background height. The shadows of the view will be
      *                         based on this height and the content will be clipped from the top
      */
-    private void updateChildClippingAndBackground(StackScrollState.ViewState state,
-            float realHeight, float clipHeight, float backgroundHeight) {
+    private void updateChildClippingAndBackground(StackViewState state, float realHeight,
+            float clipHeight, float backgroundHeight) {
         if (realHeight > clipHeight) {
             // Rather overlap than create a hole.
             state.topOverLap = (int) Math.floor((realHeight - clipHeight) / state.scale);
@@ -270,7 +270,7 @@ public class StackScrollAlgorithm {
         int childCount = algorithmState.visibleChildren.size();
         for (int i = 0; i < childCount; i++) {
             View child = algorithmState.visibleChildren.get(i);
-            StackScrollState.ViewState childViewState = resultState.getViewStateForView(child);
+            StackViewState childViewState = resultState.getViewStateForView(child);
             childViewState.dimmed = dimmed;
             childViewState.dark = dark;
             childViewState.hideSensitive = hideSensitive;
@@ -297,14 +297,14 @@ public class StackScrollAlgorithm {
                 if (!draggedViews.contains(nextChild)) {
                     // only if the view is not dragged itself we modify its state to be fully
                     // visible
-                    StackScrollState.ViewState viewState = resultState.getViewStateForView(
+                    StackViewState viewState = resultState.getViewStateForView(
                             nextChild);
                     // The child below the dragged one must be fully visible
                     viewState.alpha = 1;
                 }
 
                 // Lets set the alpha to the one it currently has, as its currently being dragged
-                StackScrollState.ViewState viewState = resultState.getViewStateForView(draggedView);
+                StackViewState viewState = resultState.getViewStateForView(draggedView);
                 // The dragged child should keep the set alpha
                 viewState.alpha = draggedView.getAlpha();
             }
@@ -320,12 +320,14 @@ public class StackScrollAlgorithm {
         int childCount = hostView.getChildCount();
         state.visibleChildren.clear();
         state.visibleChildren.ensureCapacity(childCount);
+        int notGoneIndex = 0;
         for (int i = 0; i < childCount; i++) {
             ExpandableView v = (ExpandableView) hostView.getChildAt(i);
             if (v.getVisibility() != View.GONE) {
-                StackScrollState.ViewState viewState = resultState.getViewStateForView(v);
-                viewState.notGoneIndex = state.visibleChildren.size();
+                StackViewState viewState = resultState.getViewStateForView(v);
+                viewState.notGoneIndex = notGoneIndex;
                 state.visibleChildren.add(v);
+                notGoneIndex++;
             }
         }
     }
@@ -355,8 +357,8 @@ public class StackScrollAlgorithm {
         int numberOfElementsCompletelyIn = (int) algorithmState.itemsInTopStack;
         for (int i = 0; i < childCount; i++) {
             ExpandableView child = algorithmState.visibleChildren.get(i);
-            StackScrollState.ViewState childViewState = resultState.getViewStateForView(child);
-            childViewState.location = StackScrollState.ViewState.LOCATION_UNKNOWN;
+            StackViewState childViewState = resultState.getViewStateForView(child);
+            childViewState.location = StackViewState.LOCATION_UNKNOWN;
             int childHeight = getMaxAllowedChildHeight(child);
             float yPositionInScrollViewAfterElement = yPositionInScrollView
                     + childHeight
@@ -413,7 +415,7 @@ public class StackScrollAlgorithm {
             } else {
                 // Case 3:
                 // We are in the regular scroll area.
-                childViewState.location = StackScrollState.ViewState.LOCATION_MAIN_AREA;
+                childViewState.location = StackViewState.LOCATION_MAIN_AREA;
                 clampYTranslation(childViewState, childHeight);
             }
 
@@ -427,9 +429,9 @@ public class StackScrollAlgorithm {
                             bottomPeekStart - mCollapseSecondCardPadding
                                     - childViewState.yTranslation, mCollapsedSize);
                 }
-                childViewState.location = StackScrollState.ViewState.LOCATION_FIRST_CARD;
+                childViewState.location = StackViewState.LOCATION_FIRST_CARD;
             }
-            if (childViewState.location == StackScrollState.ViewState.LOCATION_UNKNOWN) {
+            if (childViewState.location == StackViewState.LOCATION_UNKNOWN) {
                 Log.wtf(LOG_TAG, "Failed to assign location for child " + i);
             }
             currentYPosition = childViewState.yTranslation + childHeight + mPaddingBetweenElements;
@@ -445,7 +447,7 @@ public class StackScrollAlgorithm {
      * @param childViewState the view state of the child
      * @param childHeight the height of this child
      */
-    private void clampYTranslation(StackScrollState.ViewState childViewState, int childHeight) {
+    private void clampYTranslation(StackViewState childViewState, int childHeight) {
         clampPositionToBottomStackStart(childViewState, childHeight);
         clampPositionToTopStackEnd(childViewState, childHeight);
     }
@@ -457,7 +459,7 @@ public class StackScrollAlgorithm {
      * @param childViewState the view state of the child
      * @param childHeight the height of this child
      */
-    private void clampPositionToBottomStackStart(StackScrollState.ViewState childViewState,
+    private void clampPositionToBottomStackStart(StackViewState childViewState,
             int childHeight) {
         childViewState.yTranslation = Math.min(childViewState.yTranslation,
                 mInnerHeight - mBottomStackPeekSize - mCollapseSecondCardPadding - childHeight);
@@ -470,7 +472,7 @@ public class StackScrollAlgorithm {
      * @param childViewState the view state of the child
      * @param childHeight the height of this child
      */
-    private void clampPositionToTopStackEnd(StackScrollState.ViewState childViewState,
+    private void clampPositionToTopStackEnd(StackViewState childViewState,
             int childHeight) {
         childViewState.yTranslation = Math.max(childViewState.yTranslation,
                 mCollapsedSize - childHeight);
@@ -489,7 +491,7 @@ public class StackScrollAlgorithm {
 
     private void updateStateForChildTransitioningInBottom(StackScrollAlgorithmState algorithmState,
             float transitioningPositionStart, float bottomPeakStart, float currentYPosition,
-            StackScrollState.ViewState childViewState, int childHeight) {
+            StackViewState childViewState, int childHeight) {
 
         // This is the transitioning element on top of bottom stack, calculate how far we are in.
         algorithmState.partialInBottom = 1.0f - (
@@ -510,11 +512,11 @@ public class StackScrollAlgorithm {
 
         // We want at least to be at the end of the top stack when collapsing
         clampPositionToTopStackEnd(childViewState, newHeight);
-        childViewState.location = StackScrollState.ViewState.LOCATION_MAIN_AREA;
+        childViewState.location = StackViewState.LOCATION_MAIN_AREA;
     }
 
     private void updateStateForChildFullyInBottomStack(StackScrollAlgorithmState algorithmState,
-            float transitioningPositionStart, StackScrollState.ViewState childViewState,
+            float transitioningPositionStart, StackViewState childViewState,
             int childHeight) {
 
         float currentYPosition;
@@ -524,7 +526,7 @@ public class StackScrollAlgorithm {
             currentYPosition = transitioningPositionStart
                     + mBottomStackIndentationFunctor.getValue(algorithmState.itemsInBottomStack)
                     - mPaddingBetweenElements;
-            childViewState.location = StackScrollState.ViewState.LOCATION_BOTTOM_STACK_PEEKING;
+            childViewState.location = StackViewState.LOCATION_BOTTOM_STACK_PEEKING;
         } else {
             // we are fully inside the stack
             if (algorithmState.itemsInBottomStack > MAX_ITEMS_IN_BOTTOM_STACK + 2) {
@@ -533,7 +535,7 @@ public class StackScrollAlgorithm {
                     > MAX_ITEMS_IN_BOTTOM_STACK + 1) {
                 childViewState.alpha = 1.0f - algorithmState.partialInBottom;
             }
-            childViewState.location = StackScrollState.ViewState.LOCATION_BOTTOM_STACK_HIDDEN;
+            childViewState.location = StackViewState.LOCATION_BOTTOM_STACK_HIDDEN;
             currentYPosition = mInnerHeight;
         }
         childViewState.yTranslation = currentYPosition - childHeight;
@@ -542,7 +544,7 @@ public class StackScrollAlgorithm {
 
     private void updateStateForTopStackChild(StackScrollAlgorithmState algorithmState,
             int numberOfElementsCompletelyIn, int i, int childHeight,
-            StackScrollState.ViewState childViewState, float scrollOffset) {
+            StackViewState childViewState, float scrollOffset) {
 
 
         // First we calculate the index relative to the current stack window of size at most
@@ -574,7 +576,7 @@ public class StackScrollAlgorithm {
                         - mTopStackIndentationFunctor.getValue(numItemsBefore);
                 childViewState.yTranslation = currentChildEndY - childHeight;
             }
-            childViewState.location = StackScrollState.ViewState.LOCATION_TOP_STACK_PEEKING;
+            childViewState.location = StackViewState.LOCATION_TOP_STACK_PEEKING;
         } else {
             if (paddedIndex == -1) {
                 childViewState.alpha = 1.0f - algorithmState.partialInTop;
@@ -583,7 +585,7 @@ public class StackScrollAlgorithm {
                 childViewState.alpha = 0.0f;
             }
             childViewState.yTranslation = mCollapsedSize - childHeight;
-            childViewState.location = StackScrollState.ViewState.LOCATION_TOP_STACK_HIDDEN;
+            childViewState.location = StackViewState.LOCATION_TOP_STACK_HIDDEN;
         }
 
 
@@ -605,7 +607,7 @@ public class StackScrollAlgorithm {
         // find the number of elements in the top stack.
         for (int i = 0; i < childCount; i++) {
             ExpandableView child = algorithmState.visibleChildren.get(i);
-            StackScrollState.ViewState childViewState = resultState.getViewStateForView(child);
+            StackViewState childViewState = resultState.getViewStateForView(child);
             int childHeight = getMaxAllowedChildHeight(child);
             float yPositionInScrollViewAfterElement = yPositionInScrollView
                     + childHeight
@@ -676,7 +678,7 @@ public class StackScrollAlgorithm {
         int childCount = algorithmState.visibleChildren.size();
         for (int i = 0; i < childCount; i++) {
             View child = algorithmState.visibleChildren.get(i);
-            StackScrollState.ViewState childViewState = resultState.getViewStateForView(child);
+            StackViewState childViewState = resultState.getViewStateForView(child);
             if (i < algorithmState.itemsInTopStack) {
                 float stackIndex = algorithmState.itemsInTopStack - i;
 
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/stack/StackScrollState.java b/packages/SystemUI/src/com/android/systemui/statusbar/stack/StackScrollState.java
index 0b1ce8f..adfe953 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/stack/StackScrollState.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/stack/StackScrollState.java
@@ -39,13 +39,13 @@ public class StackScrollState {
     private static final String CHILD_NOT_FOUND_TAG = "StackScrollStateNoSuchChild";
 
     private final ViewGroup mHostView;
-    private Map<ExpandableView, ViewState> mStateMap;
+    private Map<ExpandableView, StackViewState> mStateMap;
     private final Rect mClipRect = new Rect();
     private final int mClearAllTopPadding;
 
     public StackScrollState(ViewGroup hostView) {
         mHostView = hostView;
-        mStateMap = new HashMap<ExpandableView, ViewState>();
+        mStateMap = new HashMap<ExpandableView, StackViewState>();
         mClearAllTopPadding = hostView.getContext().getResources().getDimensionPixelSize(
                 R.dimen.clear_all_padding_top);
     }
@@ -58,20 +58,24 @@ public class StackScrollState {
         int numChildren = mHostView.getChildCount();
         for (int i = 0; i < numChildren; i++) {
             ExpandableView child = (ExpandableView) mHostView.getChildAt(i);
-            ViewState viewState = mStateMap.get(child);
-            if (viewState == null) {
-                viewState = new ViewState();
-                mStateMap.put(child, viewState);
-            }
-            // initialize with the default values of the view
-            viewState.height = child.getIntrinsicHeight();
-            viewState.gone = child.getVisibility() == View.GONE;
-            viewState.alpha = 1;
-            viewState.notGoneIndex = -1;
+            resetViewState(child);
         }
     }
 
-    public ViewState getViewStateForView(View requestedView) {
+    private void resetViewState(ExpandableView view) {
+        StackViewState viewState = mStateMap.get(view);
+        if (viewState == null) {
+            viewState = new StackViewState();
+            mStateMap.put(view, viewState);
+        }
+        // initialize with the default values of the view
+        viewState.height = view.getIntrinsicHeight();
+        viewState.gone = view.getVisibility() == View.GONE;
+        viewState.alpha = 1;
+        viewState.notGoneIndex = -1;
+    }
+
+    public StackViewState getViewStateForView(View requestedView) {
         return mStateMap.get(requestedView);
     }
 
@@ -87,102 +91,123 @@ public class StackScrollState {
         int numChildren = mHostView.getChildCount();
         for (int i = 0; i < numChildren; i++) {
             ExpandableView child = (ExpandableView) mHostView.getChildAt(i);
-            ViewState state = mStateMap.get(child);
-            if (state == null) {
-                Log.wtf(CHILD_NOT_FOUND_TAG, "No child state was found when applying this state " +
-                        "to the hostView");
+            StackViewState state = mStateMap.get(child);
+            if (!applyState(child, state)) {
                 continue;
             }
-            if (!state.gone) {
-                float alpha = child.getAlpha();
-                float yTranslation = child.getTranslationY();
-                float xTranslation = child.getTranslationX();
-                float zTranslation = child.getTranslationZ();
-                float scale = child.getScaleX();
-                int height = child.getActualHeight();
-                float newAlpha = state.alpha;
-                float newYTranslation = state.yTranslation;
-                float newZTranslation = state.zTranslation;
-                float newScale = state.scale;
-                int newHeight = state.height;
-                boolean becomesInvisible = newAlpha == 0.0f;
-                if (alpha != newAlpha && xTranslation == 0) {
-                    // apply layer type
-                    boolean becomesFullyVisible = newAlpha == 1.0f;
-                    boolean newLayerTypeIsHardware = !becomesInvisible && !becomesFullyVisible;
-                    int layerType = child.getLayerType();
-                    int newLayerType = newLayerTypeIsHardware
-                            ? View.LAYER_TYPE_HARDWARE
-                            : View.LAYER_TYPE_NONE;
-                    if (layerType != newLayerType) {
-                        child.setLayerType(newLayerType, null);
-                    }
-
-                    // apply alpha
-                    child.setAlpha(newAlpha);
-                }
-
-                // apply visibility
-                int oldVisibility = child.getVisibility();
-                int newVisibility = becomesInvisible ? View.INVISIBLE : View.VISIBLE;
-                if (newVisibility != oldVisibility) {
-                    child.setVisibility(newVisibility);
-                }
-
-                // apply yTranslation
-                if (yTranslation != newYTranslation) {
-                    child.setTranslationY(newYTranslation);
-                }
-
-                // apply zTranslation
-                if (zTranslation != newZTranslation) {
-                    child.setTranslationZ(newZTranslation);
-                }
-
-                // apply scale
-                if (scale != newScale) {
-                    child.setScaleX(newScale);
-                    child.setScaleY(newScale);
-                }
-
-                // apply height
-                if (height != newHeight) {
-                    child.setActualHeight(newHeight, false /* notifyListeners */);
-                }
-
-                // apply dimming
-                child.setDimmed(state.dimmed, false /* animate */);
-
-                // apply dark
-                child.setDark(state.dark, false /* animate */, 0 /* delay */);
-
-                // apply hiding sensitive
-                child.setHideSensitive(
-                        state.hideSensitive, false /* animated */, 0 /* delay */, 0 /* duration */);
-
-                // apply speed bump state
-                child.setBelowSpeedBump(state.belowSpeedBump);
-
-                // apply clipping
-                float oldClipTopAmount = child.getClipTopAmount();
-                if (oldClipTopAmount != state.clipTopAmount) {
-                    child.setClipTopAmount(state.clipTopAmount);
-                }
-                updateChildClip(child, newHeight, state.topOverLap);
-
-                if(child instanceof SpeedBumpView) {
-                    performSpeedBumpAnimation(i, (SpeedBumpView) child, state, 0);
-                } else if (child instanceof DismissView) {
-                    DismissView dismissView = (DismissView) child;
-                    boolean visible = state.topOverLap < mClearAllTopPadding;
-                    dismissView.performVisibilityAnimation(visible && !dismissView.willBeGone());
-                } else if (child instanceof EmptyShadeView) {
-                    EmptyShadeView emptyShadeView = (EmptyShadeView) child;
-                    boolean visible = state.topOverLap <= 0;
-                    emptyShadeView.performVisibilityAnimation(
-                            visible && !emptyShadeView.willBeGone());
-                }
+            if(child instanceof SpeedBumpView) {
+                performSpeedBumpAnimation(i, (SpeedBumpView) child, state, 0);
+            } else if (child instanceof DismissView) {
+                DismissView dismissView = (DismissView) child;
+                boolean visible = state.topOverLap < mClearAllTopPadding;
+                dismissView.performVisibilityAnimation(visible && !dismissView.willBeGone());
+            } else if (child instanceof EmptyShadeView) {
+                EmptyShadeView emptyShadeView = (EmptyShadeView) child;
+                boolean visible = state.topOverLap <= 0;
+                emptyShadeView.performVisibilityAnimation(
+                        visible && !emptyShadeView.willBeGone());
+            }
+        }
+    }
+
+    /**
+     * Applies a  {@link StackViewState} to an  {@link ExpandableView}.
+     *
+     * @return whether the state was applied correctly
+     */
+    public boolean applyState(ExpandableView view, StackViewState state) {
+        if (state == null) {
+            Log.wtf(CHILD_NOT_FOUND_TAG, "No child state was found when applying this state " +
+                    "to the hostView");
+            return false;
+        }
+        if (state.gone) {
+            return false;
+        }
+        applyViewState(view, state);
+
+        int height = view.getActualHeight();
+        int newHeight = state.height;
+
+        // apply height
+        if (height != newHeight) {
+            view.setActualHeight(newHeight, false /* notifyListeners */);
+        }
+
+        // apply dimming
+        view.setDimmed(state.dimmed, false /* animate */);
+
+        // apply dark
+        view.setDark(state.dark, false /* animate */, 0 /* delay */);
+
+        // apply hiding sensitive
+        view.setHideSensitive(
+                state.hideSensitive, false /* animated */, 0 /* delay */, 0 /* duration */);
+
+        // apply speed bump state
+        view.setBelowSpeedBump(state.belowSpeedBump);
+
+        // apply clipping
+        float oldClipTopAmount = view.getClipTopAmount();
+        if (oldClipTopAmount != state.clipTopAmount) {
+            view.setClipTopAmount(state.clipTopAmount);
+        }
+        updateChildClip(view, newHeight, state.topOverLap);
+        return true;
+    }
+
+    /**
+     * Applies a  {@link ViewState} to a normal view.
+     */
+    public void applyViewState(View view, ViewState state) {
+        float alpha = view.getAlpha();
+        float yTranslation = view.getTranslationY();
+        float xTranslation = view.getTranslationX();
+        float zTranslation = view.getTranslationZ();
+        float scale = view.getScaleX();
+        float newAlpha = state.alpha;
+        float newYTranslation = state.yTranslation;
+        float newZTranslation = state.zTranslation;
+        float newScale = state.scale;
+        boolean becomesInvisible = newAlpha == 0.0f;
+        if (alpha != newAlpha && xTranslation == 0) {
+            // apply layer type
+            boolean becomesFullyVisible = newAlpha == 1.0f;
+            boolean newLayerTypeIsHardware = !becomesInvisible && !becomesFullyVisible
+                    && view.hasOverlappingRendering();
+            int layerType = view.getLayerType();
+            int newLayerType = newLayerTypeIsHardware
+                    ? View.LAYER_TYPE_HARDWARE
+                    : View.LAYER_TYPE_NONE;
+            if (layerType != newLayerType) {
+                view.setLayerType(newLayerType, null);
             }
+
+            // apply alpha
+            view.setAlpha(newAlpha);
+        }
+
+        // apply visibility
+        int oldVisibility = view.getVisibility();
+        int newVisibility = becomesInvisible ? View.INVISIBLE : View.VISIBLE;
+        if (newVisibility != oldVisibility) {
+            view.setVisibility(newVisibility);
+        }
+
+        // apply yTranslation
+        if (yTranslation != newYTranslation) {
+            view.setTranslationY(newYTranslation);
+        }
+
+        // apply zTranslation
+        if (zTranslation != newZTranslation) {
+            view.setTranslationZ(newZTranslation);
+        }
+
+        // apply scale
+        if (scale != newScale) {
+            view.setScaleX(newScale);
+            view.setScaleY(newScale);
         }
     }
 
@@ -201,12 +226,12 @@ public class StackScrollState {
         child.setClipBounds(mClipRect);
     }
 
-    public void performSpeedBumpAnimation(int i, SpeedBumpView speedBump, ViewState state,
+    public void performSpeedBumpAnimation(int i, SpeedBumpView speedBump, StackViewState state,
             long delay) {
         View nextChild = getNextChildNotGone(i);
         if (nextChild != null) {
             float lineEnd = state.yTranslation + state.height / 2;
-            ViewState nextState = getViewStateForView(nextChild);
+            StackViewState nextState = getViewStateForView(nextChild);
             boolean startIsAboveNext = nextState.yTranslation > lineEnd;
             speedBump.animateDivider(startIsAboveNext, delay, null /* onFinishedRunnable */);
         }
@@ -223,53 +248,4 @@ public class StackScrollState {
         return null;
     }
 
-    public static class ViewState {
-
-        // These are flags such that we can create masks for filtering.
-
-        public static final int LOCATION_UNKNOWN = 0x00;
-        public static final int LOCATION_FIRST_CARD = 0x01;
-        public static final int LOCATION_TOP_STACK_HIDDEN = 0x02;
-        public static final int LOCATION_TOP_STACK_PEEKING = 0x04;
-        public static final int LOCATION_MAIN_AREA = 0x08;
-        public static final int LOCATION_BOTTOM_STACK_PEEKING = 0x10;
-        public static final int LOCATION_BOTTOM_STACK_HIDDEN = 0x20;
-        /** The view isn't layouted at all. */
-        public static final int LOCATION_GONE = 0x40;
-
-        float alpha;
-        float yTranslation;
-        float zTranslation;
-        int height;
-        boolean gone;
-        float scale;
-        boolean dimmed;
-        boolean dark;
-        boolean hideSensitive;
-        boolean belowSpeedBump;
-
-        /**
-         * The amount which the view should be clipped from the top. This is calculated to
-         * perceive consistent shadows.
-         */
-        int clipTopAmount;
-
-        /**
-         * How much does the child overlap with the previous view on the top? Can be used for
-         * a clipping optimization
-         */
-        int topOverLap;
-
-        /**
-         * The index of the view, only accounting for views not equal to GONE
-         */
-        int notGoneIndex;
-
-        /**
-         * The location this view is currently rendered at.
-         *
-         * <p>See <code>LOCATION_</code> flags.</p>
-         */
-        int location;
-    }
 }
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/stack/StackStateAnimator.java b/packages/SystemUI/src/com/android/systemui/statusbar/stack/StackStateAnimator.java
index b027787..215ed31 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/stack/StackStateAnimator.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/stack/StackStateAnimator.java
@@ -113,13 +113,13 @@ public class StackStateAnimator {
         for (int i = 0; i < childCount; i++) {
             final ExpandableView child = (ExpandableView) mHostLayout.getChildAt(i);
 
-            StackScrollState.ViewState viewState = finalState.getViewStateForView(child);
+            StackViewState viewState = finalState.getViewStateForView(child);
             if (viewState == null || child.getVisibility() == View.GONE) {
                 continue;
             }
 
             child.setClipBounds(null);
-            startAnimations(child, viewState, finalState, i);
+            startStackAnimations(child, viewState, finalState, i, -1 /* fixedDelay */);
         }
         if (!isRunning()) {
             // no child has preformed any animation, lets finish
@@ -134,7 +134,7 @@ public class StackStateAnimator {
         for (int i = childCount - 1; i >= 0; i--) {
             final ExpandableView child = (ExpandableView) mHostLayout.getChildAt(i);
 
-            StackScrollState.ViewState viewState = finalState.getViewStateForView(child);
+            StackViewState viewState = finalState.getViewStateForView(child);
             if (viewState == null || child.getVisibility() == View.GONE) {
                 continue;
             }
@@ -145,18 +145,29 @@ public class StackStateAnimator {
         return -1;
     }
 
+
     /**
-     * Start an animation to the given viewState
+     * Start an animation to the given  {@link StackViewState}.
+     *
+     * @param child the child to start the animation on
+     * @param viewState the {@link StackViewState} of the view to animate to
+     * @param finalState the final state after the animation
+     * @param i the index of the view; only relevant if the view is the speed bump and is
+     *          ignored otherwise
+     * @param fixedDelay a fixed delay if desired or -1 if the delay should be calculated
      */
-    private void startAnimations(final ExpandableView child, StackScrollState.ViewState viewState,
-            StackScrollState finalState, int i) {
-        int childVisibility = child.getVisibility();
-        boolean wasVisible = childVisibility == View.VISIBLE;
+    public void startStackAnimations(final ExpandableView child, StackViewState viewState,
+            StackScrollState finalState, int i, long fixedDelay) {
         final float alpha = viewState.alpha;
-        if (!wasVisible && alpha != 0 && !viewState.gone) {
-            child.setVisibility(View.VISIBLE);
+        boolean wasAdded = mNewAddChildren.contains(child);
+        long duration = mCurrentLength;
+        if (wasAdded && mAnimationFilter.hasGoToFullShadeEvent) {
+            child.setTranslationY(child.getTranslationY() + mGoToFullShadeAppearingTranslation);
+            float longerDurationFactor = viewState.notGoneIndex - mCurrentLastNotAddedIndex;
+            longerDurationFactor = (float) Math.pow(longerDurationFactor, 0.7f);
+            duration = ANIMATION_DURATION_APPEAR_DISAPPEAR + 50 +
+                    (long) (100 * longerDurationFactor);
         }
-
         boolean yTranslationChanging = child.getTranslationY() != viewState.yTranslation;
         boolean zTranslationChanging = child.getTranslationZ() != viewState.zTranslation;
         boolean scaleChanging = child.getScaleX() != viewState.scale;
@@ -164,94 +175,40 @@ public class StackStateAnimator {
         boolean heightChanging = viewState.height != child.getActualHeight();
         boolean darkChanging = viewState.dark != child.isDark();
         boolean topInsetChanging = viewState.clipTopAmount != child.getClipTopAmount();
-        boolean wasAdded = mNewAddChildren.contains(child);
         boolean hasDelays = mAnimationFilter.hasDelays;
         boolean isDelayRelevant = yTranslationChanging || zTranslationChanging || scaleChanging ||
                 alphaChanging || heightChanging || topInsetChanging || darkChanging;
-        boolean noAnimation = wasAdded;
         long delay = 0;
-        long duration = mCurrentLength;
-        if (hasDelays && isDelayRelevant || wasAdded) {
+        if (fixedDelay != -1) {
+            delay = fixedDelay;
+        } else if (hasDelays && isDelayRelevant || wasAdded) {
             delay = mCurrentAdditionalDelay + calculateChildAnimationDelay(viewState, finalState);
         }
 
-        if (wasAdded && mAnimationFilter.hasGoToFullShadeEvent) {
-            child.setTranslationY(child.getTranslationY() + mGoToFullShadeAppearingTranslation);
-            yTranslationChanging = true;
-            float longerDurationFactor = viewState.notGoneIndex - mCurrentLastNotAddedIndex;
-            longerDurationFactor = (float) Math.pow(longerDurationFactor, 0.7f);
-            duration = ANIMATION_DURATION_APPEAR_DISAPPEAR + 50 +
-                    (long) (100 * longerDurationFactor);
-        }
-
-        // start translationY animation
-        if (yTranslationChanging) {
-            if (noAnimation && !mAnimationFilter.hasGoToFullShadeEvent) {
-                child.setTranslationY(viewState.yTranslation);
-            } else {
-                startYTranslationAnimation(child, viewState, duration, delay);
-            }
-        }
-
-        // start translationZ animation
-        if (zTranslationChanging) {
-            if (noAnimation) {
-                child.setTranslationZ(viewState.zTranslation);
-            } else {
-                startZTranslationAnimation(child, viewState, duration, delay);
-            }
-        }
-
-        // start scale animation
-        if (scaleChanging) {
-            if (noAnimation) {
-                child.setScaleX(viewState.scale);
-                child.setScaleY(viewState.scale);
-            } else {
-                startScaleAnimation(child, viewState, duration);
-            }
-        }
-
-        // start alpha animation
-        if (alphaChanging && child.getTranslationX() == 0) {
-            if (noAnimation) {
-                child.setAlpha(viewState.alpha);
-            } else {
-                startAlphaAnimation(child, viewState, duration, delay);
-            }
-        }
+        startViewAnimations(child, viewState, delay, duration);
 
         // start height animation
         if (heightChanging && child.getActualHeight() != 0) {
-            if (noAnimation) {
-                child.setActualHeight(viewState.height, false);
-            } else {
-                startHeightAnimation(child, viewState, duration, delay);
-            }
+            startHeightAnimation(child, viewState, duration, delay);
         }
 
         // start top inset animation
         if (topInsetChanging) {
-            if (noAnimation) {
-                child.setClipTopAmount(viewState.clipTopAmount);
-            } else {
-                startInsetAnimation(child, viewState, duration, delay);
-            }
+            startInsetAnimation(child, viewState, duration, delay);
         }
 
         // start dimmed animation
-        child.setDimmed(viewState.dimmed, mAnimationFilter.animateDimmed && !wasAdded
-                && !noAnimation);
+        child.setDimmed(viewState.dimmed, mAnimationFilter.animateDimmed);
 
         // start dark animation
-        child.setDark(viewState.dark, mAnimationFilter.animateDark && !noAnimation, delay);
+        child.setDark(viewState.dark, mAnimationFilter.animateDark, delay);
 
         // apply speed bump state
         child.setBelowSpeedBump(viewState.belowSpeedBump);
 
         // start hiding sensitive animation
-        child.setHideSensitive(viewState.hideSensitive, mAnimationFilter.animateHideSensitive &&
-                !wasAdded && !noAnimation, delay, duration);
+        child.setHideSensitive(viewState.hideSensitive, mAnimationFilter.animateHideSensitive,
+                delay, duration);
 
         if (wasAdded) {
             child.performAddAnimation(delay, mCurrentLength);
@@ -262,7 +219,48 @@ public class StackStateAnimator {
         }
     }
 
-    private long calculateChildAnimationDelay(StackScrollState.ViewState viewState,
+    /**
+     * Start an animation to a new {@link ViewState}.
+     *
+     * @param child the child to start the animation on
+     * @param viewState the  {@link StackViewState} of the view to animate to
+     * @param delay a fixed delay
+     * @param duration the duration of the animation
+     */
+    public void startViewAnimations(View child, ViewState viewState, long delay, long duration) {
+        boolean wasVisible = child.getVisibility() == View.VISIBLE;
+        final float alpha = viewState.alpha;
+        if (!wasVisible && alpha != 0 && !viewState.gone) {
+            child.setVisibility(View.VISIBLE);
+        }
+        boolean yTranslationChanging = child.getTranslationY() != viewState.yTranslation;
+        boolean zTranslationChanging = child.getTranslationZ() != viewState.zTranslation;
+        boolean scaleChanging = child.getScaleX() != viewState.scale;
+        float childAlpha = child.getVisibility() == View.INVISIBLE ? 0.0f : child.getAlpha();
+        boolean alphaChanging = viewState.alpha != childAlpha;
+
+        // start translationY animation
+        if (yTranslationChanging) {
+            startYTranslationAnimation(child, viewState, duration, delay);
+        }
+
+        // start translationZ animation
+        if (zTranslationChanging) {
+            startZTranslationAnimation(child, viewState, duration, delay);
+        }
+
+        // start scale animation
+        if (scaleChanging) {
+            startScaleAnimation(child, viewState, duration);
+        }
+
+        // start alpha animation
+        if (alphaChanging && child.getTranslationX() == 0) {
+            startAlphaAnimation(child, viewState, duration, delay);
+        }
+    }
+
+    private long calculateChildAnimationDelay(StackViewState viewState,
             StackScrollState finalState) {
         if (mAnimationFilter.hasDarkEvent) {
             return calculateDelayDark(viewState);
@@ -314,7 +312,7 @@ public class StackStateAnimator {
         return minDelay;
     }
 
-    private long calculateDelayDark(StackScrollState.ViewState viewState) {
+    private long calculateDelayDark(StackViewState viewState) {
         int referenceIndex;
         if (mAnimationFilter.darkAnimationOriginIndex ==
                 NotificationStackScrollLayout.AnimationEvent.DARK_ANIMATION_ORIGIN_INDEX_ABOVE) {
@@ -328,14 +326,14 @@ public class StackStateAnimator {
         return Math.abs(referenceIndex - viewState.notGoneIndex) * ANIMATION_DELAY_PER_ELEMENT_DARK;
     }
 
-    private long calculateDelayGoToFullShade(StackScrollState.ViewState viewState) {
+    private long calculateDelayGoToFullShade(StackViewState viewState) {
         float index = viewState.notGoneIndex;
         index = (float) Math.pow(index, 0.7f);
         return (long) (index * ANIMATION_DELAY_PER_ELEMENT_GO_TO_FULL_SHADE);
     }
 
     private void startHeightAnimation(final ExpandableView child,
-            StackScrollState.ViewState viewState, long duration, long delay) {
+            StackViewState viewState, long duration, long delay) {
         Integer previousStartValue = getChildTag(child, TAG_START_HEIGHT);
         Integer previousEndValue = getChildTag(child, TAG_END_HEIGHT);
         int newEndValue = viewState.height;
@@ -394,7 +392,7 @@ public class StackStateAnimator {
     }
 
     private void startInsetAnimation(final ExpandableView child,
-            StackScrollState.ViewState viewState, long duration, long delay) {
+            StackViewState viewState, long duration, long delay) {
         Integer previousStartValue = getChildTag(child, TAG_START_TOP_INSET);
         Integer previousEndValue = getChildTag(child, TAG_END_TOP_INSET);
         int newEndValue = viewState.clipTopAmount;
@@ -451,8 +449,8 @@ public class StackStateAnimator {
         child.setTag(TAG_END_TOP_INSET, newEndValue);
     }
 
-    private void startAlphaAnimation(final ExpandableView child,
-            final StackScrollState.ViewState viewState, long duration, long delay) {
+    private void startAlphaAnimation(final View child,
+            final ViewState viewState, long duration, long delay) {
         Float previousStartValue = getChildTag(child,TAG_START_ALPHA);
         Float previousEndValue = getChildTag(child,TAG_END_ALPHA);
         final float newEndValue = viewState.alpha;
@@ -525,8 +523,8 @@ public class StackStateAnimator {
         child.setTag(TAG_END_ALPHA, newEndValue);
     }
 
-    private void startZTranslationAnimation(final ExpandableView child,
-            final StackScrollState.ViewState viewState, long duration, long delay) {
+    private void startZTranslationAnimation(final View child,
+            final ViewState viewState, long duration, long delay) {
         Float previousStartValue = getChildTag(child,TAG_START_TRANSLATION_Z);
         Float previousEndValue = getChildTag(child,TAG_END_TRANSLATION_Z);
         float newEndValue = viewState.zTranslation;
@@ -577,8 +575,8 @@ public class StackStateAnimator {
         child.setTag(TAG_END_TRANSLATION_Z, newEndValue);
     }
 
-    private void startYTranslationAnimation(final ExpandableView child,
-            StackScrollState.ViewState viewState, long duration, long delay) {
+    private void startYTranslationAnimation(final View child,
+            ViewState viewState, long duration, long delay) {
         Float previousStartValue = getChildTag(child,TAG_START_TRANSLATION_Y);
         Float previousEndValue = getChildTag(child,TAG_END_TRANSLATION_Y);
         float newEndValue = viewState.yTranslation;
@@ -630,8 +628,8 @@ public class StackStateAnimator {
         child.setTag(TAG_END_TRANSLATION_Y, newEndValue);
     }
 
-    private void startScaleAnimation(final ExpandableView child,
-            StackScrollState.ViewState viewState, long duration) {
+    private void startScaleAnimation(final View child,
+            ViewState viewState, long duration) {
         Float previousStartValue = getChildTag(child, TAG_START_SCALE);
         Float previousEndValue = getChildTag(child, TAG_END_SCALE);
         float newEndValue = viewState.scale;
@@ -765,7 +763,7 @@ public class StackStateAnimator {
                     NotificationStackScrollLayout.AnimationEvent.ANIMATION_TYPE_ADD) {
 
                 // This item is added, initialize it's properties.
-                StackScrollState.ViewState viewState = finalState
+                StackViewState viewState = finalState
                         .getViewStateForView(changingView);
                 if (viewState == null) {
                     // The position for this child was never generated, let's continue.
@@ -776,10 +774,7 @@ public class StackStateAnimator {
                     finalState.removeViewStateForView(changingView);
                     continue;
                 }
-                changingView.setAlpha(viewState.alpha);
-                changingView.setTranslationY(viewState.yTranslation);
-                changingView.setTranslationZ(viewState.zTranslation);
-                changingView.setActualHeight(viewState.height, false);
+                finalState.applyState(changingView, viewState);
                 mNewAddChildren.add(changingView);
 
             } else if (event.animationType ==
@@ -791,7 +786,7 @@ public class StackStateAnimator {
 
                 // Find the amount to translate up. This is needed in order to understand the
                 // direction of the remove animation (either downwards or upwards)
-                StackScrollState.ViewState viewState = finalState
+                StackViewState viewState = finalState
                         .getViewStateForView(event.viewAfterChangingView);
                 int actualHeight = changingView.getActualHeight();
                 // upwards by default
@@ -813,7 +808,7 @@ public class StackStateAnimator {
                         mHostLayout.getOverlay().remove(changingView);
                     }
                 });
-            }  else if (event.animationType ==
+            } else if (event.animationType ==
                 NotificationStackScrollLayout.AnimationEvent.ANIMATION_TYPE_REMOVE_SWIPED_OUT) {
                 // A race condition can trigger the view to be added to the overlay even though
                 // it is swiped out. So let's remove it
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/stack/StackViewState.java b/packages/SystemUI/src/com/android/systemui/statusbar/stack/StackViewState.java
new file mode 100644
index 0000000..55ef440
--- /dev/null
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/stack/StackViewState.java
@@ -0,0 +1,86 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License
+ */
+
+package com.android.systemui.statusbar.stack;
+
+import android.view.View;
+
+import com.android.systemui.statusbar.ExpandableView;
+
+/**
+* A state of an expandable view
+*/
+public class StackViewState extends ViewState {
+
+    // These are flags such that we can create masks for filtering.
+
+    public static final int LOCATION_UNKNOWN = 0x00;
+    public static final int LOCATION_FIRST_CARD = 0x01;
+    public static final int LOCATION_TOP_STACK_HIDDEN = 0x02;
+    public static final int LOCATION_TOP_STACK_PEEKING = 0x04;
+    public static final int LOCATION_MAIN_AREA = 0x08;
+    public static final int LOCATION_BOTTOM_STACK_PEEKING = 0x10;
+    public static final int LOCATION_BOTTOM_STACK_HIDDEN = 0x20;
+    /** The view isn't layouted at all. */
+    public static final int LOCATION_GONE = 0x40;
+
+    public int height;
+    public boolean dimmed;
+    public boolean dark;
+    public boolean hideSensitive;
+    public boolean belowSpeedBump;
+
+    /**
+     * The amount which the view should be clipped from the top. This is calculated to
+     * perceive consistent shadows.
+     */
+    public int clipTopAmount;
+
+    /**
+     * How much does the child overlap with the previous view on the top? Can be used for
+     * a clipping optimization
+     */
+    public int topOverLap;
+
+    /**
+     * The index of the view, only accounting for views not equal to GONE
+     */
+    public int notGoneIndex;
+
+    /**
+     * The location this view is currently rendered at.
+     *
+     * <p>See <code>LOCATION_</code> flags.</p>
+     */
+    public int location;
+
+    @Override
+    public void copyFrom(ViewState viewState) {
+        super.copyFrom(viewState);
+        if (viewState instanceof StackViewState) {
+            StackViewState svs = (StackViewState) viewState;
+            height = svs.height;
+            dimmed = svs.dimmed;
+            dark = svs.dark;
+            hideSensitive = svs.hideSensitive;
+            belowSpeedBump = svs.belowSpeedBump;
+            clipTopAmount = svs.clipTopAmount;
+            topOverLap = svs.topOverLap;
+            notGoneIndex = svs.notGoneIndex;
+            location = svs.location;
+        }
+    }
+}
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/stack/ViewState.java b/packages/SystemUI/src/com/android/systemui/statusbar/stack/ViewState.java
new file mode 100644
index 0000000..3e538df
--- /dev/null
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/stack/ViewState.java
@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License
+ */
+
+package com.android.systemui.statusbar.stack;
+
+import android.view.View;
+
+/**
+ * A state of a view. This can be used to apply a set of view properties to a view with
+ * {@link com.android.systemui.statusbar.stack.StackScrollState} or start animations with
+ * {@link com.android.systemui.statusbar.stack.StackStateAnimator}.
+*/
+public class ViewState {
+
+    public float alpha;
+    public float yTranslation;
+    public float zTranslation;
+    public boolean gone;
+    public float scale;
+
+    public void copyFrom(ViewState viewState) {
+        alpha = viewState.alpha;
+        yTranslation = viewState.yTranslation;
+        zTranslation = viewState.zTranslation;
+        gone = viewState.gone;
+        scale = viewState.scale;
+    }
+
+    public void initFrom(View view) {
+        alpha = view.getVisibility() == View.INVISIBLE ? 0.0f : view.getAlpha();
+        yTranslation = view.getTranslationY();
+        zTranslation = view.getTranslationZ();
+        gone = view.getVisibility() == View.GONE;
+        scale = view.getScaleX();
+    }
+}