ViewPager.PageTransformer
is your friend. I'm going to take a different approach to what you tried, but it results in what I understand to bed your desired result - swiping left/right swipes the content, but fades between two background images that don't move.
Each Fragment
in the ViewPager
will have a layout like so:
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:id="@+id/image_view"
android:layout_height="match_parent"
android:layout_width="match_parent"
android:scaleType="center" />
<LinearLayout
android:id="@+id/content_area"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<!-- content goes here -->
</LinearLayout>
</FrameLayout>
And you will create a PageTransformer
that manipulates the layout depending the position it has been swiped:
public class CustomPageTransformer implements ViewPager.PageTransformer {
public void transformPage(View view, float position) {
int pageWidth = view.getWidth();
View imageView = view.findViewById(R.id.image_view);
View contentView = view.findViewById(R.id.content_area);
if (position < -1) { // [-Infinity,-1)
// This page is way off-screen to the left
} else if (position <= 0) { // [-1,0]
// This page is moving out to the left
// Counteract the default swipe
view.setTranslationX(pageWidth * -position);
if (contentView != null) {
// But swipe the contentView
contentView.setTranslationX(pageWidth * position);
}
if (imageView != null) {
// Fade the image in
imageView.setAlpha(1 + position);
}
} else if (position <= 1) { // (0,1]
// This page is moving in from the right
// Counteract the default swipe
view.setTranslationX(pageWidth * -position);
if (contentView != null) {
// But swipe the contentView
contentView.setTranslationX(pageWidth * position);
}
if (imageView != null) {
// Fade the image out
imageView.setAlpha(1 - position);
}
} else { // (1,+Infinity]
// This page is way off-screen to the right
}
}
}
And finally hook this PageTransformer
up to your ViewPager
:
mViewPager.setPageTransformer(true, new CustomPageTransformer());
I've tested it in an existing app and it works well as long as the fragment layouts have a transparent background.