getWidth() & getHeight() returning 0 inside RecyclerView/Fragment

问题

I'm calling the populating method for the RecyclerView inside the OnCreateView method in several fragments, they are then directed to the adapter for which populates the feeds (depending on the context of the Fragment).

At the minute, I am adding tags to an uploaded image from a user on the feed. Those tags require an x and y value (position), in which is a percentage of the container (which is set and saved to a BaaS when they upload). At the moment, the pixel to percentage formula works perfectly but when I try and grab the dimensions of the container, every option I have tried returns 0 every time.

RecyclerViewHolderAllFeeds(View view) {
    ...
    this.imageContainer = (RelativeLayout) view
                .findViewById(R.id.image_container);
}

Tag Snippet: (This function is called inside the bind, to bind all the tags to the uploaded image)

  float x = containerWidth - Float.parseFloat(model.getXpoints(o)) / 100 * containerWidth;
            float y = containerHeight - Float.parseFloat(model.getYpoints(o)) / 100 * containerHeight;
            Log.e("measuredWidth", "" + containerHeight + "" + containerWidth);
            Log.e("getPointX", "" + model.getXpoints(o) + "" + model.getYpoints(o));
            Log.e("x", "x" + x + "y" + y);
            tag.setX(x);
            tag.setY(y);

I set the values for containerWidth at the moment in the OnCreateViewHolder method:

RecyclerViewHolderAllFeeds holder = null;
    LayoutInflater mInflater = LayoutInflater.from(viewGroup.getContext());
    if (viewType == 1) {
        // This method will inflate the custom layout and return as viewholde
        ViewGroup mainGroup = (ViewGroup) mInflater.inflate(R.layout.feed_and_search_feed_item_row, viewGroup, false);
        holder =  new RecyclerViewHolderAllFeeds(mainGroup);
        containerWidth = getContainerWidth(holder);
        containerHeight = getContainerHeight(holder);
    } else {
        ViewGroup mainGroup = (ViewGroup) mInflater.inflate(R.layout.progress_item, viewGroup, false);
        holder =  new ProgressViewHolder(mainGroup);
    }
    return  holder;

I have also tried this way inside the onViewAttchedToWindow method:

   @Override
   public void onViewAttachedToWindow(RecyclerViewHolderAllFeeds holder) {
       super.onViewAttachedToWindow(holder);
       containerWidth = getContainerWidth(holder);
       containerHeight = getContainerHeight(holder);
   }

But again x and y values equate to zero.

GetContainerWidth(ViewHolder holder) method:

 float getContainerWidth(final RecyclerViewHolderAllFeeds h) {
        final int[] width = new int[1];
        final ViewTreeObserver observer = h.imageContainer.getViewTreeObserver();
        observer.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
            @Override
            public void onGlobalLayout() {
                width[0] = h.imageContainer.getWidth();
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
                    h.imageContainer.getViewTreeObserver().removeOnGlobalLayoutListener(this);
                } else {
                    h.imageContainer.getViewTreeObserver().removeGlobalOnLayoutListener(this);
                }
            }
        });
        return width[0];
    }

the same logic is applied to the getContainerHeight(ViewHolder holder) method.

I have also tried it without a global listener on the tree observer and with a listener on the preDraw parameters.

observer.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
            @Override
            public boolean onPreDraw() {
                height[0] = h.imageContainer.getHeight();
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
                    h.imageContainer.getViewTreeObserver().removeOnPreDrawListener(this);
                }
                return false;
            }
        });

Log:

E/measuredWidth&Height: 0.0 0.0
E/getPointX&Y: 70.13 88.00
E/x: x 0.0 y 0.0

Could there be a work around in regards to initializing the layout somewhere else and gathering the information and storing it somewhere? I've exhausted plenty of options. I just feel I haven't seen enough around Fragments and RecyclerViews within the SO community.

Any help will be appreciated.

回答1:

As @Enzokie mentioned you have to calculate your x and y inside callback after you will know width and height of your imageContainer. So all you need is to move your OnGlobalLayoutListener to onBindViewHolder method, like this:

@Override
public void onBindViewHolder(RecyclerViewHolderAllFeeds h, int position) {
    ...
    final ViewTreeObserver observer = h.imageContainer.getViewTreeObserver();
    observer.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
        @Override
        public void onGlobalLayout() {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
                h.imageContainer.getViewTreeObserver().removeOnGlobalLayoutListener(this);
            } else {
                h.imageContainer.getViewTreeObserver().removeGlobalOnLayoutListener(this);
            }

            int containerWidth = h.imageContainer.getWidth();
            int containerHeight = h.imageContainer.getHeight();
            float x = containerWidth - Float.parseFloat(model.getXpoints(o)) / 100 * containerWidth;
            float y = containerHeight - Float.parseFloat(model.getYpoints(o)) / 100 * containerHeight;
            Log.e("measuredWidth", "" + containerHeight + "" + containerWidth);
            Log.e("getPointX", "" + model.getXpoints(o) + "" + model.getYpoints(o));
            Log.e("x", "x" + x + "y" + y);

            h.tag.setX(x);
            h.tag.setY(y);
            h.tag.requestLayout();
        }
    });
    ...
}

Hope that helps!

来源：https://stackoverflow.com/questions/40550327/getwidth-getheight-returning-0-inside-recyclerview-fragment