• Placeholder transformation: Is possible to make transformation to placeholder as well? #317 (comment)
  It's also worth noting that Drawables are not Bitmaps, so you cannot transform them. Think about a VectorDrawable or PictureDrawable, how do you expect that to be blurred or round-cropped for example? For placeholder-like drawables you'll have to define a shape in XML similar to your transformation.
• Exception null: there's no error here, that's intentional. There was no exception, you passed a null, you get a null, it was handled. NPE is logically reserved to unintentional null accesses, which didn't happen inside Glide for this case.
• load(null): .load(null) can be a valid .load request #268 so you just need to do .error(R.drawable.x).fallback(R.drawable.x) if you want to treat null as error.

Btw, why did you close the issue? Accident or found a solution?

@TWiStErRob error resource would be use if for 'onException' callback return false.
But now I can see what error resource is use transform before display.

As placeholder I use shape (it's not problem). But if I use non solid drawable (vector for example) - it is'not use transformation. And this is really bad, because need preparatory work for placeholder.

Yes, you need to do some work on the placeholder, because there's no general way to do transforms.
You have two options:

• play around with XML enough to be able to round-crop any drawable, shape, mask, etc.

• programmatically render and crop it (once!) before using as a placeholder in the list.
  For full example see TWiStErRob/glide-support@1b4d9d3

  private BitmapDrawable transformDrawable(Drawable drawable, Transformation<Bitmap> transform, int size) {
      Bitmap bitmap = Bitmap.createBitmap(size, size, Config.ARGB_8888);
      Canvas canvas = new Canvas(bitmap);
      drawable.setBounds(0, 0, size, size);
      drawable.draw(canvas);
      Resource<Bitmap> original = BitmapResource.obtain(bitmap, Glide.get(getContext()).getBitmapPool());
      Resource<Bitmap> rounded = transform.transform(original, size, size);
      if (!original.equals(rounded)) {
          original.recycle();
      }
      return new BitmapDrawable(getResources(), rounded.get());
  }

Ty

it's not work for MultiTransformation?
I'm using CenterCrop and RoundedCorners to load image. and use the transformDrawable() methd to load placeholder.but it's not working. this is my code:

  MultiTransformation transformation = new MultiTransformation(new CenterCrop(), new RoundedCorners(roundingRadius));
        BitmapDrawable bitmapDrawable = transformDrawable(context, placeholder,
                transformation);
        GlideApp.with(context)
                .load(url)
                .placeholder(bitmapDrawable)
                .error(bitmapDrawable)
                .transform(transformation)
                .diskCacheStrategy(DiskCacheStrategy.ALL)
                .into(imageView);

@TWiStErRob when you say "Once!" does it mean we have to keep global reference for that BitmapDrawable, say when we load the app and later we can use same reference everywhere throughout the app? Please correct me if I am wrong. Thanks.