getWidth() returns 0 in onCreateView()

Question

I start the intent to pick an image from gallery, then scale the image and dinamically add ImageView to the layout.

I want this image to be reloaded on orientation change. I set setRetainInstance(true) in onCreate. However, after orientation change, when I try to get appropriate width for bitmap to be scaled to by calling getWidth() on FrameLayout which is supposed to be its container, I get 0.

public class NewWallpaper extends Fragment {
    private static final int PICK_BACKGROUND = 1;

    private BitmapFactory.Options bitmapFactoryOptions;

    // Data
    private Uri backgroundURI = null;
    private WeakReference<Bitmap> backgroundBitmap = null;

    // Views
    FrameLayout backgroundContainer;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.layout_new_wallpaper, container, false);

        // BitmapFactory options
        bitmapFactoryOptions = new BitmapFactory.Options();
        bitmapFactoryOptions.inPurgeable = true;

        Button pickBackground = (Button) view.findViewById(R.id.buttonPickBackground);
        pickBackground.setOnClickListener(pickBackgroundListener);

        backgroundContainer = (FrameLayout) view.findViewById(R.id.frameLayoutbackgroundContainer);

        if (backgroundURI != null)
            setBackgroundPreview();

        return view;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setRetainInstance(true);
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
    }


    private Button.OnClickListener pickBackgroundListener = new Button.OnClickListener() {

        @Override
        public void onClick(View view) {
            Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
            intent.addCategory(Intent.CATEGORY_OPENABLE);
            intent.setType("image/*");

            startActivityForResult(intent, PICK_BACKGROUND);
        }
    };

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        if(requestCode == PICK_BACKGROUND && resultCode == getActivity().RESULT_OK && data != null && data.getData() != null) {
            backgroundURI = data.getData();
            setBackgroundPreview();
        }

        super.onActivityResult(requestCode, resultCode, data);
    }

    private void setBackgroundPreview() {
        try {
            backgroundContainer.removeAllViews();

            Bitmap background = BitmapHelper.loadScaledBitmap(getActivity(), backgroundURI, backgroundContainer.getWidth());

            backgroundBitmap = new WeakReference<Bitmap>(background);

            // returns 0
            int containerWidth = backgroundContainer.getWidth();

            ImageView backgroundView = new ImageView(getActivity());
            backgroundView.setLayoutParams(new LinearLayout.LayoutParams(
                    backgroundContainer.getWidth(),
                    BitmapHelper.calculateHeight(
                            background.getWidth(),
                            background.getHeight(),
                            backgroundContainer.getWidth())
            ));
            backgroundView.setAdjustViewBounds(true);
            backgroundView.setScaleType(ImageView.ScaleType.FIT_XY);
            backgroundView.setImageBitmap(background);

            backgroundContainer.addView(backgroundView);

        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

I can't seem to find a way to repopulate views after orientation change. Could someone tell me what I'm doing wrong?

Answer 1

Don't call setBackgroundPreview() from onCreateView. You can't measure the view if it hasn't finished being created.

Call setBackgroundPreview() in onActivityCreated instead.

Answer 2

If you want pixel width you should call view.getMeasuredWidth() instead. getWidth() and getHeight() will give you

LayoutParams.WRAP_CONTENT | LayoutParams.MATCH_PARENT  //constants (1 or 0).

Still, to make sure you are getting the right value, call that method after @onDraw() callback of your view ( so override it) , or get viewTreeObserver and wait for onGlobalLayout() callback to call the methods.

<<<<< EDIT: >>>>>

Found one example with ViewTreeObserver:

ViewTreeObserver viewTreeObserver = view.getViewTreeObserver();
if (viewTreeObserver.isAlive()) {
  viewTreeObserver.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
    @Override
    public void onGlobalLayout() {
      view.getViewTreeObserver().removeGlobalOnLayoutListener(this);
      viewWidth = mediaGallery.getMeasuredWidth();
      viewHeight = mediaGallery.getMeasuredHeight();
    }
  });
}

Removing the listener after the first callback makes sure to free up lot of process since we only need the measured params once.

Answer 3

The width and height are not defined until the view is actually rendered to the screen. Collected from getWidth and getHeight are returning a zero. Also you check this post How do you to retrieve dimensions of a view? Getheight() and Getwidth() always return zero