Android Wear Bitmap DataItem Asset Size

Question

I am storing Bitmaps in an Asset that gets stored in a DataItem using a DataItemMap that I sync with my wearables. If I iterate through all of my DataItems using:

DataItemBuffer list = api.getDataItems(connection.getClient()).await()
for(DataItem item : list) {
    ...
}

how can I get the size of each Asset?

EDIT: When I use

DataMapItem dataMapItem = DataMapItem.fromDataItem(item);
Asset asset = dataMapItem.getDataMap().getAsset(BITMAP_KEY);
int size = asset.getData().length;

I get an NPE that says:

Attempt to get length of null array

The Asset was put using:

PutDataMapRequest putRequest = PutDataMapRequest.create(path);
DataMap map = putRequest.getDataMap();

ByteArrayOutputStream stream = new ByteArrayOutputStream();
b.compress(Bitmap.CompressFormat.PNG, 100, stream);
stream.flush();
Asset asset = Asset.createFromBytes(stream.toByteArray());
map.putAsset(mapKey, asset);

Wearable.DataApi.putDataItem(connection.getClient(), putRequest.asPutDataRequest());

Answer 1

According to this you have to read the assets through the DataApi:

GoogleApiClient client = ...;
PendingResult<DataApi.GetFdForAssetResult> pendingResult = Wearable.DataApi.getFdForAsset(client, asset);
DataApi.GetFdForAssetResult assetResult = pendingResult.await();
InputStream assetInputStream = assetResult.getInputStream();

EDIT: If you just need the size, don't rely on the asset. On the sender side, simply write the size into the DataMap:

PutDataMapRequest putRequest = PutDataMapRequest.create(path);
DataMap map = putRequest.getDataMap();

ByteArrayOutputStream stream = new ByteArrayOutputStream();
b.compress(Bitmap.CompressFormat.PNG, 100, stream);
stream.flush();
byte[] byteArray = stream.toByteArray();
Asset asset = Asset.createFromBytes(byteArray);
map.putAsset(mapKey, asset);
map.putLong("dataSize", byteArray.length);

Wearable.DataApi.putDataItem(connection.getClient(), putRequest.asPutDataRequest());

When you want to read the size, just do the following:

DataMapItem dataMapItem = DataMapItem.fromDataItem(item);
long size = dataMapItem.getDataMap().getLong("dataSize");