library/src/main/java/com/bumptech/glide/load/resource/transcode/TranscoderFactory.java

package com.bumptech.glide.load.resource.transcode;

import java.util.HashMap;
import java.util.Map;

public class TranscoderFactory {
    private static final MultiClassKey GET_KEY = new MultiClassKey();

    private static class MultiClassKey {
        private Class decoded;
        private Class transcoded;

        public MultiClassKey() {}

        public MultiClassKey(Class decoded, Class transcoded) {
            this.decoded = decoded;
            this.transcoded = transcoded;
        }

        public void set(Class decoded, Class transcoded) {
            this.decoded = decoded;
            this.transcoded = transcoded;
        }

        @Override
        public String toString() {
            return "MultiClassKey{" +
                    "decoded=" + decoded +
                    ", transcoded=" + transcoded +
                    '}';
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) {
                return true;
            }
            if (o == null || getClass() != o.getClass()) {
                return false;
            }

            MultiClassKey that = (MultiClassKey) o;

            if (!decoded.equals(that.decoded)) {
                return false;
            }
            if (!transcoded.equals(that.transcoded)) {
                return false;
            }

            return true;
        }

        @Override
        public int hashCode() {
            int result = decoded.hashCode();
            result = 31 * result + transcoded.hashCode();
            return result;
        }
    }

    private Map<MultiClassKey, ResourceTranscoder> factories = new HashMap<MultiClassKey, ResourceTranscoder>();

    public <Z, R> void register(Class<Z> decodedClass, Class<R> transcodedClass, ResourceTranscoder<Z, R> factory) {
        factories.put(new MultiClassKey(decodedClass, transcodedClass), factory);
    }

    @SuppressWarnings("unchecked")
    public <Z, R> ResourceTranscoder<Z, R> get(Class<Z> decodedClass, Class<R> transcodedClass) {
        if (decodedClass.equals(transcodedClass)) {
            return UnitTranscoder.get();
        }
        ResourceTranscoder<Z, R> result;
        synchronized (GET_KEY) {
            GET_KEY.set(decodedClass, transcodedClass);
            result = factories.get(GET_KEY);
        }
        if (result == null) {
            throw new IllegalArgumentException("No transcoder registered for " + decodedClass + " and "
                    + transcodedClass);
        }
        return result;
    }
}