com.lillicoder.lib.uiwidgets.carousel.CarouselView.java Source code

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Here is the source code for com.lillicoder.lib.uiwidgets.carousel.CarouselView.java

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/**
 * Copyright 2012 Scott Weeden-Moody
 *
 * 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.lillicoder.lib.uiwidgets.carousel;

import android.content.Context;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.FrameLayout;
import android.widget.LinearLayout;

import com.lillicoder.lib.uiwidgets.R;

/**
 * {@link View} that displays a page-able set of items with item position indicators.
 */
public class CarouselView extends FrameLayout {

    private PagerAdapter _pagerAdapter;

    private LinearLayout _indicatorsContainer;
    private ViewPager _viewPager;

    /**
     * {@link OnPageChangeListener} that handles setting the correct carousel indicator
     * colors as views are paged.
     */
    private OnPageChangeListener _indicatorChangeListener = new OnPageChangeListener() {
        @Override
        public void onPageSelected(int position) {
            int currentPosition = position;
            int itemCount = CarouselView.this._pagerAdapter.getCount();

            // Get previous indicator position. If we are currently
            // looking at the first item, we should loop to the last item.
            int previousPosition;
            if (currentPosition == 0)
                previousPosition = (itemCount - 1);
            else
                previousPosition = currentPosition - 1;

            // Get next indicator position. If we are currently
            // looking at the last item, should should loop to the first item.
            int nextPosition;
            if (currentPosition == itemCount - 1)
                nextPosition = 0;
            else
                nextPosition = currentPosition + 1;

            // Update indicators states.
            CarouselIndicatorView currentIndicator = CarouselView.this.getIndicator(position);
            CarouselIndicatorView previousIndicator = CarouselView.this.getIndicator(previousPosition);
            CarouselIndicatorView nextIndicator = CarouselView.this.getIndicator(nextPosition);
            if (currentIndicator != null)
                currentIndicator.setActive(true);
            if (previousIndicator != null)
                previousIndicator.setActive(false);
            if (nextIndicator != null)
                nextIndicator.setActive(false);
        }

        @Override
        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
        }

        @Override
        public void onPageScrollStateChanged(int state) {
        }
    };

    public CarouselView(Context context) {
        this(context, null);
    }

    public CarouselView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

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

        LayoutInflater inflater = LayoutInflater.from(context);
        inflater.inflate(R.layout.view_carousel, this);

        this.initializeViewReferences();

        // Attach the page change listener to handle carousel indicators.
        this._viewPager.setOnPageChangeListener(this._indicatorChangeListener);
    }

    /**
     * Initializes child view references for this view.
     */
    private void initializeViewReferences() {
        this._indicatorsContainer = (LinearLayout) this.findViewById(R.id.CarouselView_indicatorsContainer);
        this._viewPager = (ViewPager) this.findViewById(R.id.CarouselView_viewPager);
    }

    /**
     * Populates this carousel's indicators with the given number of indicators.
     * @param count Number of item indicators to display.
     */
    private void generateIndicators(int count) {
        this._indicatorsContainer.removeAllViews();

        for (int i = 0; i < count; i++) {
            CarouselIndicatorView indicator = new CarouselIndicatorView(this.getContext());
            indicator.setActive(i == 0); // We should active the first item by default since the 
            // page change listener will not fire until paging occurs.

            this._indicatorsContainer.addView(indicator);
        }
    }

    /**
     * Gets the {@link CarouselIndicatorView} at the given position.
     * @param position Position of the indicator to get.
     * @return {@link CarouselIndicatorView} at the given position,
     *          <code>null</code> if there is no indicator at the given position.
     */
    private CarouselIndicatorView getIndicator(int position) {
        return (CarouselIndicatorView) CarouselView.this._indicatorsContainer.getChildAt(position);
    }

    /**
     * Set a PagerAdapter that will supply views for this carousel as needed.
     * @param adapter Adapter to use.
     */
    public void setPagerAdapter(PagerAdapter adapter) {
        this._pagerAdapter = adapter;

        this._viewPager.setAdapter(adapter);
        this.generateIndicators(adapter.getCount());
    }

}