java - Take a screenshot of RecyclerView in FULL length

Question

I want to get a "full page" screenshot of the activity. The view contains a RecyclerView with many items.

I can take a screenshot of the current view with this function:

public Bitmap getScreenBitmap() {
    View v= findViewById(R.id.container).getRootView();
    v.setDrawingCacheEnabled(true);
    v.buildDrawingCache(true);
    Bitmap b = Bitmap.createBitmap(v.getDrawingCache());
    v.setDrawingCacheEnabled(false); // clear drawing cache
    return b;
}

But it contains only the items I can view normally (as expected).

Is there some way to make the RecyclerView magically show in full length (display all items at once) when I take the screenshot?

If not, how should I approach this problem?

Answer 1

Inspired from Yoav's answer. This code works for recyclerview item types and probably regardless of it's size.

It was tested with a recyclerview having linearlayout manager and three item types. Yet to check it with other layout managers.

public Bitmap getScreenshotFromRecyclerView(RecyclerView view) {
        RecyclerView.Adapter adapter = view.getAdapter();
        Bitmap bigBitmap = null;
        if (adapter != null) {
            int size = adapter.getItemCount();
            int height = 0;
            Paint paint = new Paint();
            int iHeight = 0;
            final int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024);

            // Use 1/8th of the available memory for this memory cache.
            final int cacheSize = maxMemory / 8;
            LruCache<String, Bitmap> bitmaCache = new LruCache<>(cacheSize);
            for (int i = 0; i < size; i++) {
                RecyclerView.ViewHolder holder = adapter.createViewHolder(view, adapter.getItemViewType(i));
                adapter.onBindViewHolder(holder, i);
                holder.itemView.measure(View.MeasureSpec.makeMeasureSpec(view.getWidth(), View.MeasureSpec.EXACTLY),
                        View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED));
                holder.itemView.layout(0, 0, holder.itemView.getMeasuredWidth(), holder.itemView.getMeasuredHeight());
                holder.itemView.setDrawingCacheEnabled(true);
                holder.itemView.buildDrawingCache();
                Bitmap drawingCache = holder.itemView.getDrawingCache();
                if (drawingCache != null) {

                    bitmaCache.put(String.valueOf(i), drawingCache);
                }
//                holder.itemView.setDrawingCacheEnabled(false);
//                holder.itemView.destroyDrawingCache();
                height += holder.itemView.getMeasuredHeight();
            }

            bigBitmap = Bitmap.createBitmap(view.getMeasuredWidth(), height, Bitmap.Config.ARGB_8888);
            Canvas bigCanvas = new Canvas(bigBitmap);
            bigCanvas.drawColor(Color.WHITE);

            for (int i = 0; i < size; i++) {
                Bitmap bitmap = bitmaCache.get(String.valueOf(i));
                bigCanvas.drawBitmap(bitmap, 0f, iHeight, paint);
                iHeight += bitmap.getHeight();
                bitmap.recycle();
            }

        }
        return bigBitmap;
    }