检索FAB的X和Y

Question

I have a RelativeLayout and inside this layout i have fab button:

<android.support.design.widget.FloatingActionButton
    android:id="@+id/fab"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_alignParentRight="true"
    android:layout_margin="8dp"/>

Now , in java I want to now, where is the fab position on the screen.I used this method according this post : enter link description here

private Point getPointOfView(View view) {
    int[] location = new int[2];
    view.getLocationInWindow(location);
    return new Point(location[0], location[1]);
}

and using this method like this:

fab = findViewById(R.id.fab);
for (int i = 0; i < pv.length; i++) {
    pv[i] = new Point(getPointOfView(fab).x ,getPointOfView(fab).y);
}

but getPointOfView(fab).x and getPointOfView(fab).y return 0.how could i retrieve the X & Y fab button?

Answer 1

You can make use of View#post() API, then your code would be replaced with this one:

FloatingActionButton fab = findViewById(R.id.fab);
fab.post(new Runnable() {
    @Override
    public void run() {
        // this callback will be executed after view is laid out
        for (int i = 0; i < pv.length; ++i) {
            pv[i] = new Point(getPointOfView(fab).x ,getPointOfView(fab).y);
        }
    }
})

Answer 2

use

View.getLocationOnScreen()

method to get values. Note: try to use this method in handler

new Handler ().post(...... v.getLocationOnScreen(location); .....);

onCreate method is to early to get location we should have to try this in onWindowFocusChanged() method of activity when application end all the view related tasks.

reference

Answer 3

I found, how could i get fab position:

fab.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
    @Override
    public void onGlobalLayout() {
        for (int i = 0; i < pv.length; i++) {
            pv[i] = new Point(getPointOfView(fab).x, getPointOfView(fab).y);
        }
        fab.getViewTreeObserver().removeOnGlobalLayoutListener(this);
    }
});

but if i have mistake in removing GloabalLayout place please tel me.