RecyclerView - animate change of grid layout manager columns

问题:

I want to animate the change of my RecyclerViews GridLayoutManager. I defaulty show a list of items in a grid with 3 columns and the user can select to show more or less columns.

I would like the views in the RecyclerView to move/scale to their new positions, but I have no idea how this could be done.

What I want in the end

• allow to scale the grid via an expand/contract touch gesture => I know how to do that
• animate the change of the LayoutManager

Does anyone know how I can animate the change of the LayoutManager?

回答1:

The source of inspiration here would be the Google Photos app,the stock Sony Gallery app

There are basically 2 approaches you can go with:

1. You modify the spancount of the GridLayoutManager using setSpanCount(int)

2. You set a very high span count(~100) use the SpanSizeLookUp to change the per item spanSize on the fly.

   • I have used the Gist provided by Musenkishi,for this answer to provide an animator to animate the changes in grid layout changes
   • I have used this approach in a sample GitHub project implementing the same.
   • Caveats:
     • I have currently used the click listener to keep modifying the the span size look up.This could be changed to a ItemGestureListener to capture pinch zoom events and change accordingly.
     • You need to determine a way to choose a span count so that all the items in a row occupy the entire screen width (and hence you do not see any empty space)
     • You call notifyItemRangeChanged using a runnable post delayed since you cannot call the notifyChanged methods from within bindView/createView etc.
     • After changing the span size,you need to notifyItemRangeChanged with an appropriate range so that all the items currently displayed on the screen are shifted accordingly.I have used (code at the bottom)

This is not a complete solution but a 2 hour solution for the same.You can obviously improve on all the points mentioned :). I hope to keep updating the sample since this kind of views have always fascinated me. Do not view this as the final solution but just a particular way of achieving this approach. If you were to use a StaggerredLayoutManager instead,you could easily avoid blank spaces between items.

public int calculateRange() {      int start = ((GridLayoutManager)        grv.getLayoutManager()).findFirstVisibleItemPosition();      int end = ((GridLayoutManager) grv.getLayoutManager()).findLastVisibleItemPosition();      if (start < 0)          start = 0;      if (end < 0)          end = getItemCount();      return end - start;   } 

回答2:

I deal with the same problem as you, and so far I have not found a good solution.

Simple change of columns number in GridLayoutManager seems weird so for now I use animation to fade out/in entire layout. Something like this:

private void animateRecyclerLayoutChange(final int layoutSpanCount) {     Animation fadeOut = new AlphaAnimation(1, 0);     fadeOut.setInterpolator(new DecelerateInterpolator());     fadeOut.setDuration(400);     fadeOut.setAnimationListener(new Animation.AnimationListener() {         @Override         public void onAnimationStart(Animation animation) {         }          @Override         public void onAnimationRepeat(Animation animation) {         }          @Override         public void onAnimationEnd(Animation animation) {             productsRecyclerLayoutManager.setSpanCount(layoutSpanCount);             productsRecyclerLayoutManager.requestLayout();             Animation fadeIn = new AlphaAnimation(0, 1);             fadeIn.setInterpolator(new AccelerateInterpolator());             fadeIn.setDuration(400);             productsRecycler.startAnimation(fadeIn);         }     });     productsRecycler.startAnimation(fadeOut); } 

If you combine fade out/in animation with scaling each visible item, It will be a decent animation for GridLayoutManager changes.

回答3:

You can do this with "gesture detector" see the sample tutorial here http://wiki.workassis.com/pinch-zoom-in-recycler-view/ In this tutorial we will fetch images from gallery and show them in a grid layout in recycler view. You will be able to change layout on pinch gesture. Following are the screen shots of different layouts.

mScaleGestureDetector = new ScaleGestureDetector(this, new ScaleGestureDetector.SimpleOnScaleGestureListener() {                 @Override                 public boolean onScale(ScaleGestureDetector detector) {                     if (detector.getCurrentSpan() > 200 && detector.getTimeDelta() > 200) {                         if (detector.getCurrentSpan() - detector.getPreviousSpan() < -1) {                             if (mCurrentLayoutManager == mGridLayoutManager1) {                                 mCurrentLayoutManager = mGridLayoutManager2;                                 mRvPhotos.setLayoutManager(mGridLayoutManager2);                                 return true;                             } else if (mCurrentLayoutManager == mGridLayoutManager2) {                                 mCurrentLayoutManager = mGridLayoutManager3;                                 mRvPhotos.setLayoutManager(mGridLayoutManager3);                                 return true;                             }                         } else if(detector.getCurrentSpan() - detector.getPreviousSpan() > 1) {                             if (mCurrentLayoutManager == mGridLayoutManager3) {                                 mCurrentLayoutManager = mGridLayoutManager2;                                 mRvPhotos.setLayoutManager(mGridLayoutManager2);                                 return true;                             } else if (mCurrentLayoutManager == mGridLayoutManager2) {                                 mCurrentLayoutManager = mGridLayoutManager1;                                 mRvPhotos.setLayoutManager(mGridLayoutManager1);                                 return true;                             }                         }                     }                     return false;                 }             }); 

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