PullToRefreshAdapterViewBase.java

package com.kth.baasio.helpcenter.ui.pulltorefresh;

import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.ContextMenu.ContextMenuInfo;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewParent;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.FrameLayout;
import android.widget.LinearLayout;

public abstract class PullToRefreshAdapterViewBase<T extends AbsListView> extends
        PullToRefreshBase<T> implements OnScrollListener {

    protected int mLastSavedFirstVisibleItem = -1;

    private OnScrollListener mOnScrollListener;

    protected OnLastItemVisibleListener mOnLastItemVisibleListener;

    protected OnDirectionListener mOnDirectionListener;

    protected OnFirstItemVisibleListener mOnFirstItemVisibleListener;

    private View mEmptyView;

    private FrameLayout mRefreshableViewHolder;

    public PullToRefreshAdapterViewBase(Context context) {
        super(context);
        mRefreshableView.setOnScrollListener(this);
    }

    public PullToRefreshAdapterViewBase(Context context, int mode) {
        super(context, mode);
        mRefreshableView.setOnScrollListener(this);
    }

    public PullToRefreshAdapterViewBase(Context context, AttributeSet attrs) {
        super(context, attrs);
        mRefreshableView.setOnScrollListener(this);
    }

    abstract public ContextMenuInfo getContextMenuInfo();

    public void onScroll(final AbsListView view, final int firstVisibleItem,
            final int visibleItemCount, final int totalItemCount) {

        if (null != mOnLastItemVisibleListener) {
            // detect if last item is visible
            if (visibleItemCount > 0 && (firstVisibleItem + visibleItemCount == totalItemCount)) {
                // only process first event
                if (firstVisibleItem != mLastSavedFirstVisibleItem) {
                    mLastSavedFirstVisibleItem = firstVisibleItem;
                    mOnLastItemVisibleListener.onLastItemVisible();
                }
            }
        }

        if (null != mOnScrollListener) {
            mOnScrollListener.onScroll(view, firstVisibleItem, visibleItemCount, totalItemCount);
        }
    }

    public void onScrollStateChanged(final AbsListView view, final int scrollState) {
        if (null != mOnScrollListener) {
            mOnScrollListener.onScrollStateChanged(view, scrollState);
        }
    }

    /**
     * Sets the Empty View to be used by the Adapter View. We need it handle it
     * ourselves so that we can Pull-to-Refresh when the Empty View is shown.
     * Please note, you do <strong>not</strong> usually need to call this method
     * yourself. Calling setEmptyView on the AdapterView will automatically call
     * this method and set everything up. This includes when the Android
     * Framework automatically sets the Empty View based on it's ID.
     * 
     * @param newEmptyView - Empty View to be used
     */
    public final void setEmptyView(View newEmptyView) {
        // If we already have an Empty View, remove it
        if (null != mEmptyView) {
            mRefreshableViewHolder.removeView(mEmptyView);
        }

        if (null != newEmptyView) {
            // New view needs to be clickable so that Android recognizes it as a
            // target for Touch Events
            newEmptyView.setClickable(true);

            ViewParent newEmptyViewParent = newEmptyView.getParent();
            if (null != newEmptyViewParent && newEmptyViewParent instanceof ViewGroup) {
                ((ViewGroup)newEmptyViewParent).removeView(newEmptyView);
            }

            mRefreshableViewHolder.addView(newEmptyView, ViewGroup.LayoutParams.FILL_PARENT,
                    ViewGroup.LayoutParams.FILL_PARENT);

            if (mRefreshableView instanceof EmptyViewMethodAccessor) {
                ((EmptyViewMethodAccessor)mRefreshableView).setEmptyViewInternal(newEmptyView);
            } else {
                mRefreshableView.setEmptyView(newEmptyView);
            }
        }
    }

    public final void setOnLastItemVisibleListener(OnLastItemVisibleListener listener) {
        mOnLastItemVisibleListener = listener;
    }

    public void setOnScrollListener(OnScrollListener listener) {
        mOnScrollListener = listener;
    }

    public final void setOnFirstItemVisibleListener(OnFirstItemVisibleListener listener) {
        mOnFirstItemVisibleListener = listener;
    }

    public final void setOnDirectionListener(OnDirectionListener listener) {
        mOnDirectionListener = listener;
    }

    protected void addRefreshableView(Context context, T refreshableView) {
        mRefreshableViewHolder = new FrameLayout(context);
        mRefreshableViewHolder.addView(refreshableView, ViewGroup.LayoutParams.FILL_PARENT,
                ViewGroup.LayoutParams.FILL_PARENT);
        addView(mRefreshableViewHolder, new LinearLayout.LayoutParams(LayoutParams.FILL_PARENT, 0,
                1.0f));
    };

    protected boolean isReadyForPullDown() {
        return isFirstItemVisible();
    }

    protected boolean isReadyForPullUp() {
        return isLastItemVisible();
    }

    private boolean isFirstItemVisible() {
        // if (mRefreshableView.getCount() <= getNumberInternalViews()) {
        // return true;
        // } else
        if (mRefreshableView.getFirstVisiblePosition() == 0) {

            final View firstVisibleChild = mRefreshableView.getChildAt(0);

            if (firstVisibleChild != null) {
                return firstVisibleChild.getTop() >= mRefreshableView.getTop();
            }
        }

        return false;
    }

    private boolean isLastItemVisible() {
        final int count = mRefreshableView.getCount();
        final int lastVisiblePosition = mRefreshableView.getLastVisiblePosition();

        if (DEBUG) {
            Log.d(LOG_TAG, "isLastItemVisible. Count: " + count + " Last Visible Pos: "
                    + lastVisiblePosition);
        }

        if (count <= getNumberInternalViews()) {
            return true;
        } else if (lastVisiblePosition == count - 1) {

            final int childIndex = lastVisiblePosition - mRefreshableView.getFirstVisiblePosition();
            final View lastVisibleChild = mRefreshableView.getChildAt(childIndex);

            if (lastVisibleChild != null) {
                return lastVisibleChild.getBottom() <= mRefreshableView.getBottom();
            }
        }

        return false;
    }

    protected int getNumberInternalViews() {
        return getNumberInternalHeaderViews() + getNumberInternalFooterViews();
    }

    /**
     * Returns the number of Adapter View Header Views. This will always return
     * 0 for non-ListView views.
     * 
     * @return 0 for non-ListView views, possibly 1 for ListView
     */
    protected int getNumberInternalHeaderViews() {
        return 0;
    }

    /**
     * Returns the number of Adapter View Footer Views. This will always return
     * 0 for non-ListView views.
     * 
     * @return 0 for non-ListView views, possibly 1 for ListView
     */
    protected int getNumberInternalFooterViews() {
        return 0;
    }
}