Android Drawable Cache (Xamarin / Mono)

The code below is useful if you need to cache images in Android. Weak references are used to help protect against memory leaks.

Drawable Cache Class:

public class DrawableCache
{
 public Context Context { get; set; }
 Dictionary<object, WeakReference<Drawable.ConstantState>> _cache = new Dictionary<object, WeakReference<Drawable.ConstantState>>();

 public DrawableCache(Context context)
 {
  Context = context;
 }

 public void Put(object key, Drawable drawable)
 {
  _cache[key] = new WeakReference<Drawable.ConstantState>(drawable.GetConstantState(), false);
 }

 public Drawable Get(object key)
 {
  WeakReference<Drawable.ConstantState> value;
  if (_cache.TryGetValue(key, out value))
  {
   Drawable.ConstantState target;
   if (value.TryGetTarget(out target))
   {
    return target.NewDrawable(Context.Resources);
   }
   _cache.Remove(key);
  }
  return null;
 }
}

Optional Drawable Cache Key class

public class DrawableCacheKey
{
 public int Key { get; set; }
 public int Flags { get; set; }

 public DrawableCacheKey(int key, int flags)
 {
  Key = key;
  Flags = flags;
 }

 public override int GetHashCode()
 {
  int hash = 17;
  hash = hash * 23 + Key.GetHashCode();
  hash = hash * 23 + Flags.GetHashCode();
  return hash;
 }

 public override bool Equals(object obj)
 {
  if (this == obj)
   return true;
  if (obj == null)
   return false;
  var cast = obj as DrawableCacheKey;
  return cast != null && Key == cast.Key && Flags == cast.Flags;
 }
}