Introduce AmbientState for StackScroller.

AmbientState is a global state for the algorithm of the
StackScroller. Dimmed and which child is activated was moved
into this state. Further, scale and dimmed is also a
StackScrollState and animated in StackStateAnimator.

Change-Id: Ia68131cee62b2e0005f55ea6dc400d149ec15278
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/stack/AmbientState.java b/packages/SystemUI/src/com/android/systemui/statusbar/stack/AmbientState.java
new file mode 100644
index 0000000..4121a40
--- /dev/null
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/stack/AmbientState.java
@@ -0,0 +1,75 @@
+/*
+ * Copyright (C) 2014 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 java.util.ArrayList;
+
+/**
+ * A global state to track all input states for the algorithm.
+ */
+public class AmbientState {
+    private ArrayList<View> mDraggedViews = new ArrayList<View>();
+    private int mScrollY;
+    private boolean mDimmed;
+    private View mActivatedChild;
+
+    public int getScrollY() {
+        return mScrollY;
+    }
+
+    public void setScrollY(int scrollY) {
+        this.mScrollY = scrollY;
+    }
+
+    public void onBeginDrag(View view) {
+        mDraggedViews.add(view);
+    }
+
+    public void onDragFinished(View view) {
+        mDraggedViews.remove(view);
+    }
+
+    public ArrayList<View> getDraggedViews() {
+        return mDraggedViews;
+    }
+
+    /**
+     * @param dimmed Whether we are in a dimmed state (on the lockscreen), where the backgrounds are
+     *               translucent and everything is scaled back a bit.
+     */
+    public void setDimmed(boolean dimmed) {
+        mDimmed = dimmed;
+    }
+
+    /**
+     * In dimmed mode, a child can be activated, which happens on the first tap of the double-tap
+     * interaction. This child is then scaled normally and its background is fully opaque.
+     */
+    public void setActivatedChild(View activatedChild) {
+        mActivatedChild = activatedChild;
+    }
+
+    public boolean isDimmed() {
+        return mDimmed;
+    }
+
+    public View getActivatedChild() {
+        return mActivatedChild;
+    }
+}