Question

I’m using MapView.addView() to display a pop-up bubble on top of an OverlayItem marker when it is tapped. Sometimes the pop-up view extends beyond the edge of the display screen because of the amount of information it contains or because the marker that was tapped is close to the map’s edge. How can I determine when the pop-up view won’t fit and then adjust the map’s position so the entire pop-up view is displayed?

Answer 1

It’s been three months since I asked this question so I thought I would post the solution I came up with just in case anyone comes across this posting. This method is part of a class that extends MapView.

/**
 * Repositions the map, if necessary, in order to fully display the view passed in.  Mainly used
 * by the map bubbles displayed when tapping on an overlay item marker.  It's important that the
 * view passed in has already been laidout by the system so its measurements are available.
 *
 * @param view The being displayed on the map.
 */
private void recenter(View view) {
  Display display = windowManager.getDefaultDisplay();

  // Get the dimensions of the physical display screen.  These will differ based on the orientation
  // of the device.
  int displayWidth  = display.getWidth();
  int displayHeight = display.getHeight();

  // Get the coordinates of the top left and bottom right corners of the view.
  Point topLeft     = new Point(view.getLeft(),  view.getTop());
  Point bottomRight = new Point(view.getRight(), view.getBottom());

  // Will be used to convert between map coordinates and pixels.
  Projection projection = getProjection();

  // Get the pixel coordinates for the map's current center and use that to initialize a new point
  // object that will be used to reposition the map if necessary.
  Point mapCenter = projection.toPixels(getMapCenter(), null);
  Point newCenter = new Point(mapCenter);

  // Adjust the "x" coordinate if necessary.
  if (topLeft.x < 0) {
    newCenter.x += topLeft.x;
  }
  else if (bottomRight.x > displayWidth) {
    newCenter.x += bottomRight.x - displayWidth;
  }

  // Adjust the "y" coordinate if necessary.
  if (topLeft.y < 0) {
    newCenter.y += topLeft.y;
  }
  else if (bottomRight.y > displayHeight) {
    newCenter.y += bottomRight.y - displayHeight;
  }

  // Reposition the map only if the newly calculated center differs from the original.
  if (!newCenter.equals(mapCenter)) {
    getController().animateTo(projection.fromPixels(newCenter.x, newCenter.y));
  }
}

One thing that tripped me up was how to make sure the view passed in had its measurements available. I solved that by registering a listener to determine when the view had been laid out by the system like so:

// Add a listener to determine when the layout for the "mapBubbleMsg" view has been completed.
// This will be used to reposition the map if necessary so the newly added view is visible.
mapBubbleMsg.getViewTreeObserver().addOnGlobalLayoutListener(mapBubbleMsgLayoutListener);

And here’s the listener:

/**
 * Listen for layout changes to the "mapBubbleMsg" view.  This will be used to reposition the map
 * if necessary so the "mapBubbleMsg" view is visibile.  The first thing this listener does is
 * unregister itself in order to prevent it from being called repeatedly each time the "mapBubbleMsg"
 * view layout changes.
 */
ViewTreeObserver.OnGlobalLayoutListener mapBubbleMsgLayoutListener = new
ViewTreeObserver.OnGlobalLayoutListener() {
  public void onGlobalLayout() {
    mapBubbleMsg.getViewTreeObserver().removeGlobalOnLayoutListener(this);
    recenter(mapBubbleMsg);
  }
};

I hope this helps somebody else out there.