Centered Window Android

PopupHighlightItems.java

public class PopupHighlightItems {

        private WindowManager windowManager;
        private final View contentView;
        private WeakReference<View> anchor;

        private int direction = Gravity.TOP;

        private boolean isShowing = false;
        private WindowManager.LayoutParams layoutParams;

        public PopupHighlightItems(Context context, View contentView, OnClickListener onClickListener) {
            this.windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
            this.contentView = contentView;

            createLayoutParams(contentView);
            contentView.setElevation(context.getResources().getDimension(R.dimen.elevation_medium));

            contentView.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
                @Override public void onGlobalLayout() {
                    boolean changed = calculatePosition();

                    if (isShowing && changed) {
                        windowManager.updateViewLayout(contentView, layoutParams);
                    }
                }
            });

            contentView.setOnClickListener(onClickListener);
        }

        private void createLayoutParams(View contentView) {
            this.layoutParams = new WindowManager.LayoutParams();

            LayoutParams contentViewLayoutParams = contentView.getLayoutParams();

            if (contentViewLayoutParams != null) {
                layoutParams.width = contentViewLayoutParams.width;
                layoutParams.height = contentViewLayoutParams.height;
            } else {
                layoutParams.width = LayoutParams.WRAP_CONTENT;
                layoutParams.height = LayoutParams.WRAP_CONTENT;
            }

            layoutParams.flags = (
                    WindowManager.LayoutParams.FLAG_IGNORE_CHEEK_PRESSES |
                            WindowManager.LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH |
                            WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS |
                            WindowManager.LayoutParams.FLAG_ALT_FOCUSABLE_IM |
                            WindowManager.LayoutParams.FLAG_SPLIT_TOUCH);

            layoutParams.format = PixelFormat.TRANSLUCENT;
            layoutParams.gravity = Gravity.START | Gravity.TOP;
            layoutParams.windowAnimations = 0;
            layoutParams.setTitle("PopupHighlightItems:" + Integer.toHexString(hashCode()));
            layoutParams.packageName = contentView.getContext().getPackageName();
        }

        private boolean calculatePosition() {
            int x = layoutParams.x;
            int y = layoutParams.y;

            View anchor = this.anchor.get();

            final int[] anchorLocation = new int[2];
            anchor.getLocationInWindow(anchorLocation);

            Rect displayFrame = new Rect();
            anchor.getWindowVisibleDisplayFrame(displayFrame);

            layoutParams.x = anchorLocation[0] - displayFrame.left + anchor.getWidth() / 2 - contentView.getWidth() / 2;
            layoutParams.y = anchorLocation[1] - displayFrame.top;

            if (direction == Gravity.BOTTOM) {
                layoutParams.y += anchor.getHeight() - contentView.getHeight();
            }

            return layoutParams.x != x || layoutParams.y != y;
        }

        public void show(View anchor, int direction) {
            this.anchor = new WeakReference<>(anchor);
            this.direction = direction; // TOP or BOTTOM

            calculatePosition();

            windowManager.addView(contentView, layoutParams);
            isShowing = true;
        }

        public void dismiss() {
            if (isShowing) {
                windowManager.removeView(contentView);
                isShowing = false;
            }
        }

        public boolean isShowing() {
            return isShowing;
        }
    }