com.larswerkman.quickreturnlistview.DefaultFragment.java Source code

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Here is the source code for com.larswerkman.quickreturnlistview.DefaultFragment.java

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/*
 * Copyright 2012 Google Inc.
 *
 * 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.larswerkman.quickreturnlistview;

import android.annotation.SuppressLint;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.app.ListFragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewTreeObserver;
import android.view.animation.TranslateAnimation;
import android.widget.AbsListView;
import android.widget.ArrayAdapter;
import android.widget.TextView;
import android.widget.AbsListView.OnScrollListener;

public class DefaultFragment extends ListFragment {

    private QuickReturnListView mListView;
    private View mHeader;
    private TextView mQuickReturnView;
    private View mPlaceHolder;

    private int mCachedVerticalScrollRange;
    private int mQuickReturnHeight;

    private static final int STATE_ONSCREEN = 0;
    private static final int STATE_OFFSCREEN = 1;
    private static final int STATE_RETURNING = 2;
    private int mState = STATE_ONSCREEN;
    private int mScrollY;
    private int mMinRawY = 0;

    private TranslateAnimation anim;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment, null);
        mHeader = inflater.inflate(R.layout.header, null);
        mQuickReturnView = (TextView) view.findViewById(R.id.sticky);
        mPlaceHolder = mHeader.findViewById(R.id.placeholder);
        return view;
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);

        mListView = (QuickReturnListView) getListView();

        mQuickReturnView.setText("Default");
        mListView.addHeaderView(mHeader);

        String[] array = new String[] { "Android", "Android", "Android", "Android", "Android", "Android", "Android",
                "Android", "Android", "Android", "Android", "Android", "Android", "Android", "Android", "Android" };

        setListAdapter(new ArrayAdapter<String>(getActivity(), R.layout.list_item, R.id.text1, array));

        mListView.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
            @Override
            public void onGlobalLayout() {
                mQuickReturnHeight = mQuickReturnView.getHeight();
                mListView.computeScrollY();
                mCachedVerticalScrollRange = mListView.getListHeight();
            }
        });

        mListView.setOnScrollListener(new OnScrollListener() {
            @SuppressLint("NewApi")
            @Override
            public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {

                mScrollY = 0;
                int translationY = 0;

                if (mListView.scrollYIsComputed()) {
                    mScrollY = mListView.getComputedScrollY();
                }

                int rawY = mPlaceHolder.getTop()
                        - Math.min(mCachedVerticalScrollRange - mListView.getHeight(), mScrollY);

                switch (mState) {
                case STATE_OFFSCREEN:
                    if (rawY <= mMinRawY) {
                        mMinRawY = rawY;
                    } else {
                        mState = STATE_RETURNING;
                    }
                    translationY = rawY;
                    break;

                case STATE_ONSCREEN:
                    if (rawY < -mQuickReturnHeight) {
                        mState = STATE_OFFSCREEN;
                        mMinRawY = rawY;
                    }
                    translationY = rawY;
                    break;

                case STATE_RETURNING:
                    translationY = (rawY - mMinRawY) - mQuickReturnHeight;
                    if (translationY > 0) {
                        translationY = 0;
                        mMinRawY = rawY - mQuickReturnHeight;
                    }

                    if (rawY > 0) {
                        mState = STATE_ONSCREEN;
                        translationY = rawY;
                    }

                    if (translationY < -mQuickReturnHeight) {
                        mState = STATE_OFFSCREEN;
                        mMinRawY = rawY;
                    }
                    break;
                }

                /** this can be used if the build is below honeycomb **/
                if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.HONEYCOMB) {
                    anim = new TranslateAnimation(0, 0, translationY, translationY);
                    anim.setFillAfter(true);
                    anim.setDuration(0);
                    mQuickReturnView.startAnimation(anim);
                } else {
                    mQuickReturnView.setTranslationY(translationY);
                }

            }

            @Override
            public void onScrollStateChanged(AbsListView view, int scrollState) {
            }
        });
    }
}