Glide + Gravatar integration to display a user's Gravatar image in an Android ImageView.

GlideGravatarImageLoader.java

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.widget.ImageView;

import com.bumptech.glide.Glide;
import com.bumptech.glide.load.Transformation;
import com.bumptech.glide.load.engine.Resource;
import com.bumptech.glide.load.engine.bitmap_recycle.BitmapPool;
import com.bumptech.glide.load.resource.bitmap.BitmapResource;
import com.bumptech.glide.load.resource.drawable.GlideDrawable;
import com.bumptech.glide.request.RequestListener;
import com.bumptech.glide.request.target.Target;

import java.security.MessageDigest;
import java.util.Locale;

public class GlideGravatarImageLoader {
    private static final int IMAGE_SIZE = 96;
    private static final String URL_FORMAT = "http://www.gravatar.com/avatar/%1$s.jpg?s=%2$d&d=404&r=g";

    public void load(ImageView imageView, String email, Listener listener) {
        String hash = convertEmailToHash(email);
        Context context = imageView.getContext();
        Glide.with(context)
                .load(String.format(Locale.getDefault(), URL_FORMAT, hash, IMAGE_SIZE))
                .bitmapTransform(new CircularGravatarTransform(Glide.get(context).getBitmapPool()))
                .listener(new RequestListener<String, GlideDrawable>() {
                    @Override
                    public boolean onException(Exception e, String model, Target<GlideDrawable> target, boolean isFirstResource) {
                        if (listener != null) {
                            listener.failure();
                        }
                        return false;
                    }

                    @Override
                    public boolean onResourceReady(GlideDrawable resource, String model, Target<GlideDrawable> target, boolean isFromMemoryCache, boolean isFirstResource) {
                        if (listener != null) {
                            listener.success();
                        }
                        return false;
                    }
                })
                .into(imageView);
    }

    private String convertEmailToHash(String email) {
        final MessageDigest messageDigest;
        StringBuilder sb = new StringBuilder();
        try {
            messageDigest = MessageDigest.getInstance("MD5");
            messageDigest.reset();
            byte[] digest = messageDigest.digest(email.getBytes("UTF-8"));
            for (byte b : digest) {
                sb.append(Integer.toHexString((b & 0xFF) | 0x100).substring(1, 3));
            }
        } catch (Exception e) {
            sb.setLength(0);
            sb.append(email);
        }
        return sb.toString();
    }

    private class CircularGravatarTransform implements Transformation<Bitmap> {
        private BitmapPool mBitmapPool;

        CircularGravatarTransform(BitmapPool pool) {
            this.mBitmapPool = pool;
        }

        @Override
        public Resource<Bitmap> transform(Resource<Bitmap> resource, int outWidth, int outHeight) {
            Bitmap source = resource.get();
            int size = Math.min(source.getWidth(), source.getHeight());
            int width = (source.getWidth() - size) / 2;
            int height = (source.getHeight() - size) / 2;

            Bitmap bitmap = mBitmapPool.get(size, size, Bitmap.Config.ARGB_8888);
            if (bitmap == null) {
                bitmap = Bitmap.createBitmap(size, size, Bitmap.Config.ARGB_8888);
            }

            Canvas canvas = new Canvas(bitmap);
            Paint paint = new Paint();
            BitmapShader shader = new BitmapShader(source, BitmapShader.TileMode.CLAMP, BitmapShader.TileMode.CLAMP);
            if (width != 0 || height != 0) {
                Matrix matrix = new Matrix();
                matrix.setTranslate(-width, -height);
                shader.setLocalMatrix(matrix);
            }
            paint.setShader(shader);
            paint.setAntiAlias(true);

            float r = size / 2f;
            canvas.drawCircle(r, r, r, paint);

            return BitmapResource.obtain(bitmap, mBitmapPool);
        }

        @Override
        public String getId() {
            return "CircularGravatarTransform";
        }
    }

    public interface Listener {
        void success();

        void failure();
    }
}