Sony custom listview tutorial

MainActivity

/**
 * Test activity to display the list view
 */
public class MainActivity extends Activity {

    /** The list view */
    private MyListView mListView;

    /**
     * Small class that represents a contact
     */
    private static class Contact {

        /** Name of the contact */
        String mName;

        /** Phone number of the contact */
        String mNumber;

        /**
         * Constructor
         *
         * @param name The name
         * @param number The number
         */
        public Contact(final String name, final String number) {
            mName = name;
            mNumber = number;
        }

    }

    @Override
    public void onCreate(final Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        final ArrayList<Contact> contacts = createContactList(20);
        final MyAdapter adapter = new MyAdapter(this, contacts);

        mListView = (MyListView)findViewById(R.id.my_list);
        mListView.setAdapter(adapter);

        mListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            public void onItemClick(final AdapterView<?> parent, final View view,
                                    final int position, final long id) {
                final String message = "OnClick: " + contacts.get(position).mName;
                Toast.makeText(MainActivity.this, message, Toast.LENGTH_SHORT).show();
            }
        });

        mListView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
            public boolean onItemLongClick(final AdapterView<?> parent, final View view,
                                           final int position, final long id) {
                final String message = "OnLongClick: " + contacts.get(position).mName;
                Toast.makeText(MainActivity.this, message, Toast.LENGTH_SHORT).show();
                return true;
            }
        });
    }

    /**
     * Creates a list of fake contacts
     *
     * @param size How many contacts to create
     * @return A list of fake contacts
     */
    private ArrayList<Contact> createContactList(final int size) {
        final ArrayList<Contact> contacts = new ArrayList<Contact>();
        for (int i = 0; i < size; i++) {
            contacts.add(new Contact("Contact Number " + i, "+46(0)"
                    + (int)(1000000 + 9000000 * Math.random())));
        }
        return contacts;
    }

    /**
     * Adapter class to use for the list
     */
    private static class MyAdapter extends ArrayAdapter<Contact> {

        /** Re-usable contact image drawable */
        private final Drawable contactImage;

        /**
         * Constructor
         *
         * @param context The context
         * @param contacts The list of contacts
         */
        public MyAdapter(final Context context, final ArrayList<Contact> contacts) {
            super(context, 0, contacts);
            contactImage = context.getResources().getDrawable(R.drawable.contact_image);
        }

        @Override
        public View getView(final int position, final View convertView, final ViewGroup parent) {
            View view = convertView;
            if (view == null) {
                view = LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false);
                Holder holder = new Holder();
                holder.name = (TextView)view.findViewById(R.id.contact_name);
                holder.number = (TextView)view.findViewById(R.id.contact_number);
                holder.photo = (ImageView)view.findViewById(R.id.contact_photo);
                view.setTag(holder);
            }

            Holder holder = (Holder) view.getTag();

            if (position == 14) {
                holder.name.setText("This is a long text that will make this box big. "
                        + "Really big. Bigger than all the other boxes. Biggest of them all.");
            } else {
                holder.name.setText(getItem(position).mName);
                Log.d("NAME", getItem(position).mName + " position: " + position);
            }

            holder.number.setText(getItem(position).mNumber);

            holder.photo.setImageDrawable(contactImage);

            return view;
        }

        private static class Holder {
            TextView name;
            TextView number;
            ImageView photo;
        }

    }
}

MyListView

public class MyListView extends AdapterView {

    public static final String TAG = "MyListView";

    private Adapter mAdapter;

    int mTouchStartY;
    int mListTopStart;
    int mListTop;
    int mFirstItemPosition;
    int mLastItemPosition;
    int mListTopOffset;

//    private LinkedList<View> mCachedViews = new LinkedList<View>();

    private Stack<View> mCachedViews = new Stack<View>();

    /** Children added with this layout mode will be added below the last child */
    private static final int LAYOUT_MODE_BELOW = 0;

    /** Children added with this layout mode will be added above the first child */
    private static final int LAYOUT_MODE_ABOVE = 1;

    /** User is not touching the list */
    private static final int TOUCH_STATE_RESTING = 0;

    /** User is touching the list and right now it's still a "click" */
    private static final int TOUCH_STATE_CLICK = 1;

    /** User is scrolling the list */
    private static final int TOUCH_STATE_SCROLL = 2;

    public MyListView(Context context) {
        super(context);
    }

    public MyListView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public MyListView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    private void fillList(int offset) {
        int botEdge = getChildAt(getChildCount() - 1).getBottom();
        fillListDown(botEdge, offset);

        int topEdge = getChildAt(0).getTop();
        fillListUp(topEdge, offset);
    }

    private View getCachedView() {
        if (mCachedViews.size() != 0) {
            return mCachedViews.pop();
        }
        return null;
    }

    private void fillListDown(int bottomEdge, int offset) {
        Log.d(TAG, "fillListDown");
        while (bottomEdge + offset < getHeight() && mLastItemPosition != mAdapter.getCount() - 1) {
            Log.d(TAG, "While loop: bottomEdge: " + bottomEdge + " mLastItemPosition: " + mLastItemPosition + " offset: " + offset);
            mLastItemPosition++;
            View child = mAdapter.getView(mLastItemPosition, getCachedView(), this);
            addAndMeasureChild(child, LAYOUT_MODE_BELOW);
            bottomEdge += child.getMeasuredHeight();
        }
    }

    private void fillListUp(int topEdge, int offset) {
        Log.d(TAG, "fillListUp");
        while (topEdge + offset > 0 && mFirstItemPosition != 0) {
            Log.d(TAG, "While loop: top edge: " + topEdge + " mFirstItemPosition: " + mFirstItemPosition + " offset: " + offset);
            mFirstItemPosition--;
            View child = mAdapter.getView(mFirstItemPosition, getCachedView(), this);
            addAndMeasureChild(child, LAYOUT_MODE_ABOVE);
            topEdge -= child.getMeasuredHeight();
            mListTopOffset -= child.getMeasuredHeight();
        }
    }

    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        super.onLayout(changed, left, top, right, bottom);

        if (mAdapter == null)
            return;

        if (getChildCount() == 0) {
            mFirstItemPosition = 0;
            mLastItemPosition = -1;
            fillListDown(0, 0);
        } else {
            int offset = mListTop + mListTopOffset - getChildAt(0).getTop();
            // Remove invisible views if any
            removeInvisibleViews(offset);
            fillList(offset);
        }
        Log.d(TAG, "Child count: " + getChildCount());

        invalidate();

        positionItems();

    }

    private void removeInvisibleViews(int offset) {

        int childCount = getChildCount();

        View firstChild = getChildAt(0);
        while (firstChild.getBottom() + offset < 0 && childCount > 1) {
            mFirstItemPosition++;
            mListTopOffset += firstChild.getMeasuredHeight();
            removeViewInLayout(firstChild);
            mCachedViews.push(firstChild);
            childCount--;
            firstChild = getChildAt(0);
        }

        View lastChild = getChildAt(getChildCount() - 1);
        while (lastChild.getTop() + offset > getHeight() && childCount > 1) {
            mLastItemPosition--;
            removeViewInLayout(lastChild);
            mCachedViews.push(lastChild);
            childCount--;
            lastChild = getChildAt(getChildCount() - 1);
        }

    }

    /**
     * Adds a view as a child view and takes care of measuring it
     *
     * @param child The view to add
     * @param layoutMode Either LAYOUT_MODE_ABOVE or LAYOUT_MODE_BELOW
     */
    private void addAndMeasureChild(final View child, final int layoutMode) {
        LayoutParams params = child.getLayoutParams();
        if (params == null) {
            params = new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
        }
        final int index = layoutMode == LAYOUT_MODE_ABOVE ? 0 : -1;
        addViewInLayout(child, index, params, true);

        final int itemWidth = getWidth();
        child.measure(MeasureSpec.EXACTLY | itemWidth, MeasureSpec.UNSPECIFIED);
    }

    private void positionItems() {
        int top = mListTop + mListTopOffset;
        Log.d(TAG, "mListTop: " + mListTop + " mListTopOffset: " + mListTopOffset);

        for (int index = 0; index < getChildCount(); index++) {
            View child = getChildAt(index);

            int width = child.getMeasuredWidth();
            int height = child.getMeasuredHeight();

            int left = (getWidth() - width) / 2;
            child.layout(left, top, left + width, top + height);

            top += height;

        }

    }

    private void startTouch(MotionEvent event) {

    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {

        if (getChildCount() == 0) {
            return false;
        }

        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                startTouch(event);
                mTouchStartY = (int) event.getY();
                mListTopStart = getChildAt(0).getTop() - mListTopOffset;
                break;
            case MotionEvent.ACTION_MOVE:
                int scrolledDistance = (int) event.getY() - mTouchStartY;
                mListTop = mListTopStart + scrolledDistance;
                requestLayout();
                break;
            default:
                break;
        }
        return true;
    }

    @Override
    public Adapter getAdapter() {
        return mAdapter;
    }

    @Override
    public void setAdapter(Adapter adapter) {
        this.mAdapter = adapter;

        removeAllViewsInLayout();

        requestLayout();
    }

    @Override
    public View getSelectedView() {
//        Log.d(TAG, "getSelectedView");
        return null;
    }

    @Override
    public void setSelection(int position) {
        Log.d(TAG, "setSelection");
    }
}