miguel ángel domínguez coloma
Sync two ScrollLayouts when scroll
If we need to scroll two ScrollLayout at the same time we can create a new View that implements the standard ScrollView in order to create a listener which allow us to know when this one is scrolling and modify the behavior of the other (or maybe because we want to know about the scroll behavior).
// IScrollListener.java
public interface IScrollListener {
void onScrollChanged(IScrollListener scrollView, int x, int y, int oldx, int oldy);
}
// ObservableScrollView.java
public class ObservableScrollView extends ScrollView {
private IScrollListener listener = null;
public ObservableScrollView(Context context) {
super(context);
}
public ObservableScrollView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public ObservableScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public void setScrollViewListener(IScrollListener listener) {
this.listener = listener;
}
@Override
protected void onScrollChanged(int x, int y, int oldx, int oldy) {
super.onScrollChanged(x, y, oldx, oldy);
if (listener != null) {
listener.onScrollChanged(this, x, y, oldx, oldy);
}
}
}
Use two ObservableScrollView in your layout: oScrollViewOne, oScrollViewTwo.
// YourActivity.java
public class YourActivity extends Activity implements ScrollViewListener {
ObservableScrollView oScrollViewOne, oScrollViewTwo;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
oScrollViewOne = (ObservableScrollView) this.findViewById(R.id.oScrollViewOne);
oScrollViewTwo = (ObservableScrollView) this.findViewById(R.id.oScrollViewTwo);
oScrollViewOne.setScrollViewListener(this);
oScrollViewTwo.setScrollViewListener(this);
}
@Override
void onScrollChanged(IScrollListener scrollView, int x, int y, int oldx, int oldy) {
if (scrollView == oScrollViewOne) {
oScrollViewTwo.scrollTo(x, y);
} else if (scrollView == oScrollViewTwo) {
oScrollViewOne.scrollTo(x, y);
}
}
}
