com.luciad.format.mbtiles

LuciadLightspeedClass TLcdMBTilesModelDecoder

java.lang.Object

com.luciad.format.mbtiles.TLcdMBTilesModelDecoder

All Implemented Interfaces:

ILcdModelDecoder

@LcdService(service=ILcdModelDecoder.class,
            priority=20000)
public class TLcdMBTilesModelDecoder
extends Object
implements ILcdModelDecoder

A model decoder for MBTiles files with either image or vector data.

Input Files

File	Required	Entry point	Description
*.mbtiles	X	X	The database file

Supported files

This model decoder supports MBTiles files with image tiles (tile data formats jpg or png) and vector tiles. WebP images are not supported, nor are files that use an IETF media type to describe their content.

Supported file transfer protocols

• This model decoder supports all transfer protocols that are supported by java.io.File.

Model structure

• This model decoder creates a model per MBTiles file.

Model descriptor

• All models returned by this model decoder have an ILcdDataSourceModelDescriptor containing a TLcdMBTilesDataSource. The getDataType() method of the data source allows you to distinguish between image and vector tiles.

Model reference

• All models returned by this model decoder have a Web Mercator reference, aligned with the MBTiles specification.

Model elements

Image tiles

The decoded model contains a single implementation of ALcdImage and ILcdEarthTileSet. The tiling structure of this tile set has world bounds defined in Web Mercator and a tile size of 256 by 256 pixels.

Vector tiles

The decoded model contains a single ILcdBounded object which represents the root node of the tile pyramid. No other information can be retrieved from this object: it is not possible to query the model for specific vector tile features or to select features using the API.

Instead, the features contained in a tile are only accessible through the layer on which they are visualized, either when they are passed to a styler or via ILcdSelection when the user selects them using the mouse. Features which are thus obtained will have the following properties:

• Each feature is represented by an ILcdDataObject. You can retrieve its data type to learn which data properties the feature has.
• The data object additionally has a property which contains the feature's geometry. This property is annotated with TLcdHasGeometryAnnotation. Hence, the geometry of a feature can be retrieved by passing the data object to ALcdShape#fromDomainObject().
• The geometry is always a shape list with one or more elements. The elements can be either points, polylines, polygons or complex polygons. Furthermore, within a given shape list, all shapes will be of the same type.

Finally, note that vector tile features should be considered temporary objects. Due to the dynamic loading of tiles and switching between detail levels, API users are strongly advised not to retain strong references to features obtained from a vector tile model.

Thread safety

• The decoded models are thread-safe for read access if you take a read lock.
• The contents of the models are not meant to be edited.

Supported versions

• MBTiles, compliant with version 1.1, 1.2 or 1.3.

Further reading

The tutorial Working with MBTiles data provides more information and code examples of how to use MBTiles image and vector data in your applications. See TLspMBTilesVectorLayerBuilder for more details on how to visualize vector tiles in a Lightspeed view.

Since:

2023.1

Field Summary

Fields

Modifier and Type	Field and Description
static String	TYPE_NAME A general and human-readable type name for the MBTiles data format

Constructor Summary

Constructors

Constructor and Description
TLcdMBTilesModelDecoder() Creates a new MBTiles model decoder.

Method Summary

Modifier and Type	Method and Description
boolean	canDecodeSource(ILcdDataSource aDataSource) Checks whether the given data source can be decoded with this model decoder.
boolean	canDecodeSource(String aSource) Checks whether the given source can be decoded with this model decoder.
ILcdModel	decode(String aSource) Decodes the single dataset in an MBTiles file.
ILcdModel	decodeSource(ILcdDataSource aDataSource) Creates a model for the given data source.
List<TLcdMBTilesDataSource>	discoverDataSources(String aPath) Returns the single data source in the given MBTiles file.
String	getDisplayName() Returns a short, displayable name for the format that is decoded by this ILcdModelDecoder.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface com.luciad.model.ILcdModelDecoder

decodeModelMetadata, decodeModelMetadata

Field Detail

TYPE_NAME

public static final String TYPE_NAME

A general and human-readable type name for the MBTiles data format

See Also:

Constant Field Values

Constructor Detail

TLcdMBTilesModelDecoder

public TLcdMBTilesModelDecoder()

Creates a new MBTiles model decoder.

Method Detail

getDisplayName

public String getDisplayName()

Description copied from interface: ILcdModelDecoder

Returns a short, displayable name for the format that is decoded by this ILcdModelDecoder.

Specified by:

getDisplayName in interface ILcdModelDecoder

Returns:

the displayable name of this ILcdModelDecoder.

canDecodeSource

public boolean canDecodeSource(ILcdDataSource aDataSource)

Checks whether the given data source can be decoded with this model decoder.

This model decoder handles TLcdMBTilesDataSource data sources and TLcdDataSource data sources. The latter case delegates the source to the canDecodeSource(String) method.

Specified by:

canDecodeSource in interface ILcdModelDecoder

Parameters:

aDataSource - the dataset to be decoded.

Returns:

true if the data source is a TLcdMBTilesDataSource or a TLcdDataSource, false otherwise.

See Also:

decodeSource(com.luciad.model.ILcdDataSource)

decodeSource

public ILcdModel decodeSource(ILcdDataSource aDataSource)
                       throws IOException

Creates a model for the given data source.

The data source must be a TLcdMBTilesDataSource, which represents one data set in the MBTiles file.

Specified by:

decodeSource in interface ILcdModelDecoder

Parameters:

aDataSource - the dataset to be decoded.

Returns:

A model with the structure described in the class javadoc.

Throws:

IOException - if the dataset cannot be loaded.

See Also:

canDecodeSource(com.luciad.model.ILcdDataSource)

canDecodeSource

public boolean canDecodeSource(String aSource)

Checks whether the given source can be decoded with this model decoder.

This model decoder handles only .mbtiles files.

Specified by:

canDecodeSource in interface ILcdModelDecoder

Parameters:

aSource - the data source to be verified; typically a file name or a URL.

Returns:

true if the source has .mbtiles extension.

See Also:

decode(String)

decode

public ILcdModel decode(String aSource)
                 throws IOException

Decodes the single dataset in an MBTiles file.

Specified by:

decode in interface ILcdModelDecoder

Parameters:

aSource - the MBTiles file to be decoded.

Returns:

A model representing the dataset in the MBTiles file.

Throws:

IOException - if the file cannot be loaded.

See Also:

canDecodeSource(String)

discoverDataSources

public List<TLcdMBTilesDataSource> discoverDataSources(String aPath)
                                                throws IOException

Returns the single data source in the given MBTiles file.

You can use decodeSource(com.luciad.model.ILcdDataSource) to create a model for an individual data source.

Specified by:

discoverDataSources in interface ILcdModelDecoder

Parameters:

aPath - A path to the data source to be decoded; typically a file name or a URL.

Returns:

the single data source in the given MBTiles file.

Throws:

IOException - if the file cannot be read