Android Open Source - Android-ParallaxHeaderViewPager Main Activity

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Back to project page Android-ParallaxHeaderViewPager.

License

The source code is released under:

Apache License

Java Source Code

package com.kmshack.newsstand;
/*from   w ww .  j a  va2s  .  c o m*/
import android.annotation.TargetApi;
import android.graphics.RectF;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.util.SparseArrayCompat;
import android.support.v4.view.ViewPager;
import android.support.v7.app.ActionBarActivity;
import android.text.Spannable;
import android.text.SpannableString;
import android.util.TypedValue;
import android.view.View;
import android.view.animation.AccelerateDecelerateInterpolator;
import android.widget.AbsListView;
import android.widget.ImageView;

import com.astuetz.PagerSlidingTabStrip;
import com.flavienlaurent.notboringactionbar.AlphaForegroundColorSpan;
import com.flavienlaurent.notboringactionbar.KenBurnsSupportView;
import com.nineoldandroids.view.ViewHelper;

public class MainActivity extends ActionBarActivity implements ScrollTabHolder, ViewPager.OnPageChangeListener {

  private static AccelerateDecelerateInterpolator sSmoothInterpolator = new AccelerateDecelerateInterpolator();

  private KenBurnsSupportView mHeaderPicture;
  private View mHeader;

  private PagerSlidingTabStrip mPagerSlidingTabStrip;
  private ViewPager mViewPager;
  private PagerAdapter mPagerAdapter;

  private int mActionBarHeight;
  private int mMinHeaderHeight;
  private int mHeaderHeight;
  private int mMinHeaderTranslation;
  private ImageView mHeaderLogo;

  private RectF mRect1 = new RectF();
  private RectF mRect2 = new RectF();

  private TypedValue mTypedValue = new TypedValue();
  private SpannableString mSpannableString;
  private AlphaForegroundColorSpan mAlphaForegroundColorSpan;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    
    mMinHeaderHeight = getResources().getDimensionPixelSize(R.dimen.min_header_height);
    mHeaderHeight = getResources().getDimensionPixelSize(R.dimen.header_height);
    mMinHeaderTranslation = -mMinHeaderHeight + getActionBarHeight();

    setContentView(R.layout.activity_main);

    mHeaderPicture = (KenBurnsSupportView) findViewById(R.id.header_picture);
    mHeaderPicture.setResourceIds(R.drawable.pic0, R.drawable.pic1);
    mHeaderLogo = (ImageView) findViewById(R.id.header_logo);
    mHeader = findViewById(R.id.header);

    mPagerSlidingTabStrip = (PagerSlidingTabStrip) findViewById(R.id.tabs);
    mViewPager = (ViewPager) findViewById(R.id.pager);
    mViewPager.setOffscreenPageLimit(4);

    mPagerAdapter = new PagerAdapter(getSupportFragmentManager());
    mPagerAdapter.setTabHolderScrollingContent(this);

    mViewPager.setAdapter(mPagerAdapter);

    mPagerSlidingTabStrip.setViewPager(mViewPager);
    mPagerSlidingTabStrip.setOnPageChangeListener(this);
    mSpannableString = new SpannableString(getString(R.string.actionbar_title));
    mAlphaForegroundColorSpan = new AlphaForegroundColorSpan(0xffffffff);
    
    ViewHelper.setAlpha(getActionBarIconView(), 0f);
    
    getSupportActionBar().setBackgroundDrawable(null);
  }

  @Override
  public void onPageScrollStateChanged(int arg0) {
    // nothing
  }

  @Override
  public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
    // nothing
  }

  @Override
  public void onPageSelected(int position) {
    SparseArrayCompat<ScrollTabHolder> scrollTabHolders = mPagerAdapter.getScrollTabHolders();
    ScrollTabHolder currentHolder = scrollTabHolders.valueAt(position);

    currentHolder.adjustScroll((int) (mHeader.getHeight() + ViewHelper.getTranslationY(mHeader)));
  }

  @Override
  public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount, int pagePosition) {
    if (mViewPager.getCurrentItem() == pagePosition) {
      int scrollY = getScrollY(view);
      ViewHelper.setTranslationY(mHeader, Math.max(-scrollY, mMinHeaderTranslation));
      float ratio = clamp(ViewHelper.getTranslationY(mHeader) / mMinHeaderTranslation, 0.0f, 1.0f);
      interpolate(mHeaderLogo, getActionBarIconView(), sSmoothInterpolator.getInterpolation(ratio));
      setTitleAlpha(clamp(5.0F * ratio - 4.0F, 0.0F, 1.0F));
    }
  }

  @Override
  public void adjustScroll(int scrollHeight) {
    // nothing
  }

  public int getScrollY(AbsListView view) {
    View c = view.getChildAt(0);
    if (c == null) {
      return 0;
    }

    int firstVisiblePosition = view.getFirstVisiblePosition();
    int top = c.getTop();

    int headerHeight = 0;
    if (firstVisiblePosition >= 1) {
      headerHeight = mHeaderHeight;
    }

    return -top + firstVisiblePosition * c.getHeight() + headerHeight;
  }

  public static float clamp(float value, float max, float min) {
    return Math.max(Math.min(value, min), max);
  }

  private void interpolate(View view1, View view2, float interpolation) {
    getOnScreenRect(mRect1, view1);
    getOnScreenRect(mRect2, view2);

    float scaleX = 1.0F + interpolation * (mRect2.width() / mRect1.width() - 1.0F);
    float scaleY = 1.0F + interpolation * (mRect2.height() / mRect1.height() - 1.0F);
    float translationX = 0.5F * (interpolation * (mRect2.left + mRect2.right - mRect1.left - mRect1.right));
    float translationY = 0.5F * (interpolation * (mRect2.top + mRect2.bottom - mRect1.top - mRect1.bottom));

    ViewHelper.setTranslationX(view1, translationX);
    ViewHelper.setTranslationY(view1, translationY - ViewHelper.getTranslationY(mHeader));
    ViewHelper.setScaleX(view1, scaleX);
    ViewHelper.setScaleY(view1, scaleY);
  }

  private RectF getOnScreenRect(RectF rect, View view) {
    rect.set(view.getLeft(), view.getTop(), view.getRight(), view.getBottom());
    return rect;
  }

  @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    public int getActionBarHeight() {
    if (mActionBarHeight != 0) {
      return mActionBarHeight;
    }
    
    if(Build.VERSION.SDK_INT > Build.VERSION_CODES.HONEYCOMB){
      getTheme().resolveAttribute(android.R.attr.actionBarSize, mTypedValue, true);
    }else{
      getTheme().resolveAttribute(R.attr.actionBarSize, mTypedValue, true);
    }
    
    mActionBarHeight = TypedValue.complexToDimensionPixelSize(mTypedValue.data, getResources().getDisplayMetrics());
    
    return mActionBarHeight;
  }

  private void setTitleAlpha(float alpha) {
    mAlphaForegroundColorSpan.setAlpha(alpha);
    mSpannableString.setSpan(mAlphaForegroundColorSpan, 0, mSpannableString.length(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
    getSupportActionBar().setTitle(mSpannableString);
  }

  @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    private ImageView getActionBarIconView() {
    
    if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB){
      return (ImageView)findViewById(android.R.id.home);
    }

    return (ImageView)findViewById(android.support.v7.appcompat.R.id.home);
  }

  public class PagerAdapter extends FragmentPagerAdapter {

    private SparseArrayCompat<ScrollTabHolder> mScrollTabHolders;
    private final String[] TITLES = { "Page 1", "Page 2", "Page 3", "Page 4"};
    private ScrollTabHolder mListener;

    public PagerAdapter(FragmentManager fm) {
      super(fm);
      mScrollTabHolders = new SparseArrayCompat<ScrollTabHolder>();
    }

    public void setTabHolderScrollingContent(ScrollTabHolder listener) {
      mListener = listener;
    }

    @Override
    public CharSequence getPageTitle(int position) {
      return TITLES[position];
    }

    @Override
    public int getCount() {
      return TITLES.length;
    }

    @Override
    public Fragment getItem(int position) {
      ScrollTabHolderFragment fragment = (ScrollTabHolderFragment) SampleListFragment.newInstance(position);

      mScrollTabHolders.put(position, fragment);
      if (mListener != null) {
        fragment.setScrollTabHolder(mListener);
      }

      return fragment;
    }

    public SparseArrayCompat<ScrollTabHolder> getScrollTabHolders() {
      return mScrollTabHolders;
    }

  }
}

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