问题
I am implementing the bottom navigation bar of the material design https://material.io/guidelines/components/bottom-navigation.html
It suggests that while scrolling down , we should hide the bar , and show it while scrolling up.
I am a little lost in how to go about this. Should I have to manually do that , or there is some functionality built in inside the view that would do it.
Do I have some behaviour for this ? (as the bottomnavigation is a child of coord layout)
回答1:
This is work for me.
I have used "slide up" and "slide down" animation for my gridview. when grid scroll upward then hide bottomNavBar and when scroll downward then show bottomNavBar. that's it.
myGridView.setOnTouchListener(this);
int y, initialY, scrollingY, scrolledY;
boolean isVisible = true;
@Override
public boolean onTouch(View view, MotionEvent motionEvent) {
y = (int) motionEvent.getRawY();
switch (motionEvent.getAction()) {
case MotionEvent.ACTION_DOWN:
initialY = (int) motionEvent.getRawY();
Log.e("Down===", initialY+"");
break;
case MotionEvent.ACTION_MOVE:
scrollingY = (int) motionEvent.getRawY();
Log.e("Move===", scrollingY+"");
switch (view.getId()) {
case R.id.exploreGridMain:
if(isVisible && initialY > scrolledY) {
bottomNavigationView.startAnimation(slideDown);
slideDown.setAnimationListener(new Animation.AnimationListener() {
@Override
public void onAnimationStart(Animation animation) {
}
@Override
public void onAnimationEnd(Animation animation) {
bottomNavigationView.setVisibility(View.GONE);
}
@Override
public void onAnimationRepeat(Animation animation) {
}
});
isVisible = false;
} else if(!isVisible && initialY < scrolledY){
bottomNavigationView.startAnimation(slideUp);
slideUp.setAnimationListener(new Animation.AnimationListener() {
@Override
public void onAnimationStart(Animation animation) {
}
@Override
public void onAnimationEnd(Animation animation) {
bottomNavigationView.setVisibility(View.VISIBLE);
}
@Override
public void onAnimationRepeat(Animation animation) {
}
});
isVisible = true;
}
break;
}
scrolledY = scrollingY;
break;
case MotionEvent.ACTION_UP:
Log.e("Up===", scrolledY+"-"+y);
break;
}
return false;
}
来源：https://stackoverflow.com/questions/43142441/hiding-bottomnavigationview-on-scroll