@Override
public boolean onDependentViewChanged(
CoordinatorLayout parent, FloatingActionButton fab, View dependency) {
if (dependency instanceof AppBarLayout) {
AppBarLayout appBarLayout = (AppBarLayout) dependency;
CoordinatorLayout.LayoutParams lp = (CoordinatorLayout.LayoutParams) fab.getLayoutParams();
int bottomMargin = lp.bottomMargin;
int distanceToScroll = fab.getHeight() + bottomMargin;
// Log.e("@@!!", ViewCompat.getY(appBarLayout) + "\t" +
// appBarLayout.getTotalScrollRange());
float ratio = ViewCompat.getY(appBarLayout) / (float) appBarLayout.getTotalScrollRange();
if (ratio < -0.9f) {
ratio = -1f;
}
ViewCompat.setTranslationY(fab, -distanceToScroll * ratio);
return true;
}
return false;
}
private float centerY(View view) {
return ViewCompat.getY(view) + view.getHeight() / 2f;
}
public void update(RecyclerView referenceList, float dx, float dy) {
if (indexList != null && indexList.getChildCount() > 2) {
show();
updatePosBasedOnReferenceList(referenceList);
View firstVisibleView = indexList.getChildAt(0);
View secondVisibleView = indexList.getChildAt(1);
TextView firstRowIndex = (TextView) firstVisibleView.findViewById(R.id.section_title);
TextView secondRowIndex = (TextView) secondVisibleView.findViewById(R.id.section_title);
int visibleRange = indexList.getChildCount();
int actual = indexList.getChildPosition(firstVisibleView);
int next = actual + 1;
int last = actual + visibleRange;
// RESET STICKY LETTER INDEX
stickyIndex.setText(String.valueOf(getIndexContext(firstRowIndex)).toUpperCase());
stickyIndex.setVisibility(TextView.VISIBLE);
ViewCompat.setAlpha(firstRowIndex, 1);
if (dy > 0) {
// USER SCROLLING DOWN THE RecyclerView
if (next <= last) {
if (isHeader(firstRowIndex, secondRowIndex)) {
stickyIndex.setVisibility(TextView.INVISIBLE);
firstRowIndex.setVisibility(TextView.VISIBLE);
ViewCompat.setAlpha(
firstRowIndex,
(1 - (Math.abs(ViewCompat.getY(firstVisibleView)) / firstRowIndex.getHeight())));
secondRowIndex.setVisibility(TextView.VISIBLE);
} else {
firstRowIndex.setVisibility(TextView.INVISIBLE);
stickyIndex.setVisibility(TextView.VISIBLE);
}
}
} else if (dy < 0) {
// USER IS SCROLLING UP THE RecyclerVIew
if (next <= last) {
// RESET FIRST ROW STATE
firstRowIndex.setVisibility(TextView.INVISIBLE);
if ((isHeader(firstRowIndex, secondRowIndex)
|| (getIndexContext(firstRowIndex) != getIndexContext(secondRowIndex)))
&& isHeader(firstRowIndex, secondRowIndex)) {
stickyIndex.setVisibility(TextView.INVISIBLE);
firstRowIndex.setVisibility(TextView.VISIBLE);
ViewCompat.setAlpha(
firstRowIndex,
1 - (Math.abs(ViewCompat.getY(firstVisibleView) / firstRowIndex.getHeight())));
secondRowIndex.setVisibility(TextView.VISIBLE);
} else {
secondRowIndex.setVisibility(TextView.INVISIBLE);
}
}
}
if (stickyIndex.getVisibility() == TextView.VISIBLE) {
firstRowIndex.setVisibility(TextView.INVISIBLE);
}
} else {
hide();
}
}