CustomGlowListView

import android.content.Context;
import android.graphics.Rect;
import android.os.AsyncTask;
import android.util.AttributeSet;
import android.view.GestureDetector;
import android.view.GestureDetector.SimpleOnGestureListener;
import android.view.MotionEvent;
import android.view.ViewGroup;
import android.widget.AbsListView;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.ImageView.ScaleType;
import android.widget.ListView;
import android.widget.RelativeLayout;

public class CustomGlowListView extends RelativeLayout {

    private final ImageView underscrollEdge;
    private final ImageView underscrollGlow;
    private final ImageView overscrollGlow;
    private final ImageView overscrollEdge;
    private AbsListView listView;

    private final static float MAX_EDGE_SIZE = 11f;
    private final static float MAX_GLOW_SIZE = 93f;

    protected static final float FLING_BUMP_HEIGHT = 160;

    private float scrollDistanceSinceBoundary = 0;

    private final Rect paddingRectangle = new Rect();

    GestureDetector listViewGestureDetector;

    // Gives the option of short circuiting the overscroll glow fade (Such as by
    // scrolling away from the overscrolled edge)
    boolean interruptFade = false;

    private GlowShrinker animator;

    public CustomGlowListView(Context context, AttributeSet attrs) {
        super(context, attrs);

        listViewGestureDetector = new GestureDetector(
                new ListViewGestureDetector());

        if (getTag() == null
                || getTag().toString().equalsIgnoreCase("ListView")) {
            listView = new ListView(context) {
                @Override
                protected void onOverScrolled(int scrollX, int scrollY,
                        boolean clampedX, boolean clampedY) {
                    if (listIsAtTop()) {
                        scrollDistanceSinceBoundary += FLING_BUMP_HEIGHT;
                        scaleEdges(underscrollEdge, underscrollGlow,
                                scrollDistanceSinceBoundary);
                        reset();
                    } else if (listIsAtBottom()) {
                        scrollDistanceSinceBoundary += FLING_BUMP_HEIGHT;
                        scaleEdges(overscrollEdge, overscrollGlow,
                                scrollDistanceSinceBoundary);
                        reset();
                    }
                }
            };
        } else if (getTag().toString().equalsIgnoreCase("GridView")) {
            listView = new GridView(context, attrs);
            ((GridView) listView).getSelector().getPadding(paddingRectangle);
        }
        listView.setId(android.R.id.list);
        if (Integer.parseInt(Build.VERSION.SDK) >= 9) {
            listView.setOverScrollMode(OVER_SCROLL_NEVER);
        }
        addView(listView, new RelativeLayout.LayoutParams(
                LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));

        underscrollEdge = new ImageView(context);
        underscrollEdge.setImageResource(R.drawable.underscroll_edge);
        underscrollEdge.setScaleType(ScaleType.FIT_XY);
        underscrollGlow = new ImageView(context);
        underscrollGlow.setImageResource(R.drawable.underscroll_glow);
        underscrollGlow.setScaleType(ScaleType.FIT_XY);
        overscrollGlow = new ImageView(context);
        overscrollGlow.setImageResource(R.drawable.overscroll_glow);
        overscrollGlow.setScaleType(ScaleType.FIT_XY);
        overscrollEdge = new ImageView(context);
        overscrollEdge.setImageResource(R.drawable.overscroll_edge);
        overscrollEdge.setScaleType(ScaleType.FIT_XY);

        addView(underscrollGlow, getWideLayout(ALIGN_PARENT_TOP));
        addView(underscrollEdge, getWideLayout(ALIGN_PARENT_TOP));

        addView(overscrollGlow, getWideLayout(ALIGN_PARENT_BOTTOM));
        addView(overscrollEdge, getWideLayout(ALIGN_PARENT_BOTTOM));
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent ev) {
        if (ev.getAction() == MotionEvent.ACTION_DOWN) {
            interruptFade = true;
        }
        listViewGestureDetector.onTouchEvent(ev);

        if (ev.getAction() == MotionEvent.ACTION_UP) {
            reset();
        }
        return super.dispatchTouchEvent(ev);
    }

    private RelativeLayout.LayoutParams getWideLayout(int alignment) {
        RelativeLayout.LayoutParams returnLayout = new RelativeLayout.LayoutParams(
                LayoutParams.MATCH_PARENT, 0);
        returnLayout.addRule(alignment);
        return returnLayout;
    }

    public void reset() {
        interruptFade = false;
        if (animator != null && !animator.isFinished()) {
            animator.cancel(true);
        }
        animator = new GlowShrinker();
        animator.execute(scrollDistanceSinceBoundary);
        scrollDistanceSinceBoundary = 0;
    }

    private boolean listIsAtTop() {
        if (listView.getChildCount() == 0) {
            // No action for empty lists
            return false;
        }
        if (listView.getFirstVisiblePosition() > 0) {
            return false;
        }
        return listView.getChildAt(0).getTop() - paddingRectangle.top == 0;
    }

    private boolean listIsAtBottom() {
        if (listView.getChildCount() == 0) {
            // No action for empty lists
            return false;
        }
        int index = listView.getChildCount() - 1;
        if (listView.getLastVisiblePosition() < index) {
            return false;
        }
        return listView.getChildAt(index).getBottom()
                + paddingRectangle.bottom == listView.getHeight();
    }

    private class ListViewGestureDetector extends SimpleOnGestureListener {
        @Override
        public boolean onScroll(MotionEvent downMotionEvent,
                MotionEvent currentMotionEvent, float distanceX, float distanceY) {
            float distanceTraveled = downMotionEvent.getY()
                    - currentMotionEvent.getY();
            boolean atTop = listIsAtTop();
            boolean atBottom = listIsAtBottom();

            if (atTop && distanceTraveled < 0) {
                // At top and finger moving down
                scrollDistanceSinceBoundary -= distanceY;
                scaleEdges(underscrollEdge, underscrollGlow,
                        scrollDistanceSinceBoundary);
            } else if (atTop && distanceTraveled > 0
                    && scrollDistanceSinceBoundary > 0) {
                // At top and finger moving up while in overscroll
                scrollDistanceSinceBoundary -= distanceY;
                scaleEdges(underscrollEdge, underscrollGlow,
                        scrollDistanceSinceBoundary);
            } else if (atBottom && distanceTraveled > 0) {
                // At bottom and finger moving up
                scrollDistanceSinceBoundary += distanceY;
                scaleEdges(overscrollEdge, overscrollGlow,
                        scrollDistanceSinceBoundary);
            } else if (atBottom && distanceTraveled < 0
                    && scrollDistanceSinceBoundary > 0) {
                // At bottom and finger moving up while in overscroll
                scrollDistanceSinceBoundary += distanceY;
                scaleEdges(overscrollEdge, overscrollGlow,
                        scrollDistanceSinceBoundary);
            } else if (scrollDistanceSinceBoundary != 0) {
                // Neither over scrolling or under scrolling but was at last
                // check. Reset both graphics.
                reset();
            }

            return false;
        }

    }

    private class GlowShrinker extends AsyncTask<Float, Integer, Void> {
        ImageView glow;
        ImageView edge;

        private final int SHRINK_SPEED = 4;
        private final int SHRINK_INCREMENT = 50;

        private boolean finished;

        @Override
        protected void onPreExecute() {
            if (underscrollGlow.getHeight() > 0) {
                glow = underscrollGlow;
                edge = underscrollEdge;
            } else if (overscrollGlow.getHeight() > 0) {
                glow = overscrollGlow;
                edge = overscrollEdge;
            } else {
                return;
            }
        }

        @Override
        protected Void doInBackground(Float... scrollDistanceSinceBoundary) {
            if (glow != null && edge != null) {
                int currentSize = (int) scrollDistanceSinceBoundary[0]
                        .floatValue();
                int shrinkRate = currentSize / SHRINK_INCREMENT;

                for (int i = 0; i < SHRINK_INCREMENT; i++) {
                    if (isCancelled()) {
                        break;
                    }
                    if (interruptFade) {
                        publishProgress(0);
                        return null;
                    }
                    currentSize -= shrinkRate;
                    publishProgress(currentSize);

                    try {
                        Thread.sleep(SHRINK_SPEED);
                    } catch (InterruptedException e) {
                    }
                }
            }
            return null;
        }

        @Override
        protected void onProgressUpdate(Integer... values) {
            CustomGlowListView.scaleEdges(edge, glow, values[0]);
        }

        @Override
        protected void onPostExecute(Void result) {
            if (glow != null && edge != null) {
                CustomGlowListView.scaleEdges(edge, glow, 0);
            }
            finished = true;
        }

        public boolean isFinished() {
            return finished;
        }

    }

    private static void scaleEdges(ImageView scrollEdge, ImageView scrollGlow,
            float scrollBy) {
        float edgeSize = scrollBy / 20;
        float glowSize = scrollBy / 2;
        if (edgeSize > MAX_EDGE_SIZE) {
            edgeSize = MAX_EDGE_SIZE;
        }
        if (glowSize > MAX_GLOW_SIZE) {
            glowSize = MAX_GLOW_SIZE;
        }
        setHeight(scrollEdge, edgeSize);
        setHeight(scrollGlow, glowSize);
    }

    private static void setHeight(ImageView viewIn, float height) {
        ViewGroup.LayoutParams params = viewIn.getLayoutParams();
        params.height = (int) height;
        viewIn.setLayoutParams(params);
    }

    public AbsListView getListView() {
        return listView;
    }
}