ViewGroups.java

package com.example.mrenouf.touchtest;

import android.graphics.Rect;
import android.support.v4.view.ViewCompat;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewParent;

import java.util.ArrayList;
import java.util.List;

public final class ViewGroups {
  private ViewGroups() {}

  private static final List<View> tmpViewList = new ArrayList<>();
  private static final Rect tmpRect = new Rect();


  private static ViewGroup getParentViewGroup(View view) {
    ViewParent parent = view.getParent();
    if (parent instanceof ViewGroup) {
      return (ViewGroup) parent;
    }
    return null;
  }

  public static boolean isVisiblePointWithinView(View view, float x, float y) {
    if (view.getVisibility() != View.VISIBLE) {
      return false;
    }
    // Test view is not entirely clipped by parents
    if (view.getGlobalVisibleRect(tmpRect)) {
      // transform touch point from local (view) to global (screen) coordinates
      x += tmpRect.left;
      y += tmpRect.top;

      // Verify provided point is actually within the view
      if (!tmpRect.contains((int) x, (int) y)) {
        return false;
      }

      View child = view;
      ViewGroup parent = ((ViewGroup) child.getParent());
      while (parent != null) {
        // Check this view is not covered by a sibling
        getTopSortedChildren(parent, tmpViewList);
        for (int i = 0; i < tmpViewList.size(); i++) {
          View sibling = tmpViewList.get(i);
          if (sibling == child) {
            // view is visible, not covered
            break;
          } else {
            if (sibling.getVisibility() != View.VISIBLE) {
              continue;
            }
            // Another view is on top, check if occluding.
            sibling.getGlobalVisibleRect(tmpRect);
            if (tmpRect.contains((int) x, (int) y)) {
              // The point given is covered by this view
              return false;
            }
          }
        }
        child = parent;
        parent = getParentViewGroup(child);
      }
    }
    return true;
  }


  private static void getTopSortedChildren(ViewGroup parent, List<View> out) {
    out.clear();
    final int childCount = parent.getChildCount();
    for (int i = childCount - 1; i >= 0; i--) {
      out.add(parent.getChildAt(i));
    }
    out.sort(ViewGroups::compare);
  }

  private static int compare(View lhs, View rhs) {
    final float lz = ViewCompat.getZ(lhs);
    final float rz = ViewCompat.getZ(rhs);
    if (lz > rz) {
      return -1;
    } else if (lz < rz) {
      return 1;
    }
    return 0;
  }
}