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@PPartisan
Created January 17, 2016 09:06
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Quick way of implementing a parallax effect for a ViewPager with two pages
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ViewPager viewPager = (ViewPager) findViewById(R.id.view_pager);
MyViewPagerAdapter adapter = new MyViewPagerAdapter(getSupportFragmentManager());
viewPager.setAdapter(adapter);
DisplayMetrics metrics = getDefaultDisplayMetrics(this);
//Fullscreen background ImageView, with MATCH_PARENT params for width and height.
ImageView parallaxBackground = (ImageView) findViewById(R.id.parallax_background);
parallaxBackground.getLayoutParams().width = ((int)(metrics.widthPixels * 1.1F));
final int offsetSize = ((int)(metrics.widthPixels * 1.1F) - metrics.widthPixels);
parallaxBackground.setX(-offsetSize);
ParallaxListener listener = new ParallaxListener(parallaxBackground, offsetSize);
viewPager.addOnPageChangeListener(listener);
}
private static DisplayMetrics getDefaultDisplayMetrics(Context context) {
return context.getResources().getDisplayMetrics();
}
static class ParallaxListener implements ViewPager.OnPageChangeListener {
private ImageView mImageView;
private final int offsetSize;
ParallaxListener(ImageView imageView, int offsetSize) {
mImageView = imageView;
this.offsetSize = offsetSize;
}
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
if (position == 1) {
positionOffset = 1;
}
int offset = (int) (-offsetSize + (offsetSize * positionOffset));
mImageView.setX(offset);
}
@Override
public void onPageSelected(int position) {}
@Override
public void onPageScrollStateChanged(int state) {}
}
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