Vertical center Themes by using a viewpager

Transitioning from a center collapsed view to an expanded view
requires a layout change. Animating children during a layout change
requires the children to be placed in a grandparent's ViewOverlay
so that they do not get clipped. A ListView cannot remove a child view,
so ViewOverlay cannot be used with ListView items, therefore a ViewPager
was used instead.

Change-Id: I665b89bf85d7466334db8a64bf37475e9e268efc

1 files changed, 104 insertions, 0 deletions

diff --git a/src/android/support/v4/view/ThemeViewPager.java b/src/android/support/v4/view/ThemeViewPager.java
new file mode 100644
index 0000000..3fb1d61
--- /dev/null
+++ b/src/android/support/v4/view/ThemeViewPager.java
@@ -0,0 +1,104 @@
+/*
+ * Copyright (C) 2014 The CyanogenMod 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 android.support.v4.view;
+
+import android.content.Context;
+import android.util.AttributeSet;
+import android.view.MotionEvent;
+import android.view.View;
+import android.view.ViewConfiguration;
+
+
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+
+public class ThemeViewPager extends ViewPager {
+    private boolean mExpanded;
+
+    private boolean mIsDragging = false;
+    private float mSlop;
+    private float mLastX;
+    private float mLastY;
+
+    public ThemeViewPager(Context context, AttributeSet attrs) {
+        super(context, attrs);
+        initView(context);
+    }
+
+    private void initView(Context context) {
+        mSlop = ViewConfiguration.get(context).getScaledTouchSlop();
+    }
+
+    public void setExpanded(boolean expanded) {
+        mExpanded = expanded;
+    }
+
+    @Override
+    public boolean onInterceptTouchEvent(MotionEvent ev) {
+        return true;
+    }
+
+    @Override
+    public boolean onTouchEvent(MotionEvent ev) {
+        switch (ev.getAction()) {
+            case MotionEvent.ACTION_DOWN:
+                mLastX = ev.getX();
+                mLastY = ev.getY();
+                break;
+            case MotionEvent.ACTION_MOVE:
+                float xDist = Math.abs(mLastX - ev.getX());
+                float yDist = Math.abs(mLastY - ev.getY());
+                if (xDist > mSlop || yDist > mSlop) {
+                    mIsDragging = true;
+                }
+                break;
+            case MotionEvent.ACTION_CANCEL:
+                mIsDragging = false;
+                break;
+            case MotionEvent.ACTION_UP:
+                if (!mIsDragging) {
+                    performClick();
+                }
+                mIsDragging = false;
+                break;
+        }
+
+        if (mExpanded) {
+            return true;
+        }
+
+        return super.onTouchEvent(ev);
+    }
+
+    /**
+     * This method will return the view associated with a given position. This is neccessary
+     * because the index value in 'getChildAt(index)' does not neccessarily associate with
+     * the viewpager's position.
+     *
+     */
+    public View getViewForPosition(int position) {
+        View view = null;
+        for(int i=0; i < getChildCount(); i++) {
+            View v = getChildAt(i);
+            ItemInfo info = infoForChild(v);
+            if (position == info.position) {
+                view = v;
+                break;
+            }
+        }
+        return view;
+    }
+}