Model- The type of the model.
Data- The type of the data that can be used by a
ResourceDecoderto decode a resource.
public interface ModelLoader<Model,Data>
DataFetcherto obtain the data for a resource represented by the model.
This interface has two objectives: 1. To translate a specific model into a data type that can be decoded into a resource. 2. To allow a model to be combined with the dimensions of the view to fetch a resource of a specific size. This not only avoids having to duplicate dimensions in xml and in your code in order to determine the size of a view on devices with different densities, but also allows you to use layout weights or otherwise programmatically put the dimensions of the view without forcing you to fetch a generic resource size. The smaller the resource you fetch, the less bandwidth and battery life you use, and the lower your memory footprint per resource.
|Modifier and Type||Interface and Description|
|Modifier and Type||Method and Description|
Returns true if the given model is a of a recognized type that this loader can probably load.
@Nullable ModelLoader.LoadData<Data> buildLoadData(Model model, int width, int height, Options options)
DataFetcherrequired to decode the resource represented by this model, as well as a set of
Keysthat identify the data loaded by the
DataFetcheras well as an optional list of alternate keys from which equivalent data can be loaded. The
DataFetcherwill not be used if the resource is already cached.
Note - If no valid data fetcher can be returned (for example if a model has a null URL), then it is acceptable to return a null data fetcher from this method.
model- The model representing the resource.
width- The width in pixels of the view or target the resource will be loaded into, or
Target.SIZE_ORIGINALto indicate that the resource should be loaded at its original width.
height- The height in pixels of the view or target the resource will be loaded into, or
Target.SIZE_ORIGINALto indicate that the resource should be loaded at its original height.
boolean handles(Model model)
For example, you may want multiple Uri -> InputStream loaders. One might handle media store Uris, another might handle asset Uris, and a third might handle file Uris etc.
This method is generally expected to do no I/O and complete quickly, so best effort
results are acceptable.
ModelLoaders that return true from this method may
buildLoadData(Object, int, int, Options)