JViews 4.0 Maps Release Notes

General Changes
Library Changes
       New Classes and Interfaces

maps.IlvLookAheadFeatureIterator

maps.format.IlvMapTileLoader

maps.format.shapefile.IlvShapeFileIndex

maps.format.shapefile.IlvShapeFileTileLoader

maps.format.shapefile.IlvShapeFileSpatialIndex

• maps.format.shapefile.IlvDBFReader
• maps.format.shapefile.IlvSHPReader
• maps.format.shapefile.IlvShapeFileReader

• The ESRI Shapefile demos

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General Changes

• ilog.views.maps.format.shapefile.IlvShapeFileIndex - To read ESRI Shapefile index files (.shx extension).
• ilog.views.maps.format.shapefile.IlvShapeFileSpatialIndex - To read the newly introduced spatial index files (.idx extension).
• ilog.views.maps.format.shapefile.IlvShapeFileTileLoader - The tile loader for Shapefiles, to create load-on-demand layers when used in conjunction with IlvTiledLayer.

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Library Changes

ilog.views.maps.IlvLookAheadFeatureIterator

Defines the interface for IlvMapFeatureIterator that has the ability to fetch the ID of the next feature before reading it, allowing you to skip the next feature if it is not needed.

ilog.views.maps.format.IlvMapTileLoader

This abstract class proposes a default implementation of an IlvTileLoader. This implementation has a load() method that can take advantage of IlvLookAheadFeatureIterators. Tile loaders that use this class as the base class have only a few methods to implement.

ilog.views.maps.format.shapefile.IlvShapeFileIndex

This class brings the support of ESRI Shapefile index files (.shx extension). Shapefile index files provide file offset information for random access of geometries in a Shapefile geometry file (.shp).

ilog.views.maps.format.shapefile.IlvShapeFileTileLoader

This class is an IlvMapTileLoader specialized in reading tiles from a Shapefile. This class provides IlvLookAheadFeatureIterator to load from Shapefile tiles, and thus can be exploited by the load() method of IlvMapTileLoader.

ilog.views.maps.format.shapefile.IlvShapeFileSpatialIndex

This class stores the spatial information of Shapefiles. Basically, for each tile corresponding to the Shapefile, this class stores the IDs of the geometries, thereby enabling the load-on-demand feature.
The spatial index can be saved as an .idx file to allow load-on-demand without the need to rebuild the spatial index each time.

ilog.views.maps.format.shapefile.IlvDBFReader

• Overview of new features
• String attributes can now be trimmed so that the stored string is cleaned of leading and trailing spaces.
• It is now possible to ignore some attributes. When an attribute is ignored, it is set to null.
• Strings read from .dbf files are now decoded using a customizable character encoding.
• Retrieving of attribute sizes, that is, .dbf field size, is now possible on a field basis.
• New methods
• get/setTrimmingStringAttributes - Returns/sets the attribute trimming mode.
• is/setReadingAttribute - Returns or sets whether an attribute is being read.
• get/setStringEncoding - Returns/sets the encoding used to decode strings.
• getAttributeSize - Returns the size of the specified attribute.

• Overview of new features
• An IlvSHPReader can now be constructed for direct access to geometries contained in the Shapefile.
• This reader is now able to get the ID of the next feature before reading it. It is also able to skip the feature if the loading is not needed.
• New constructor
• A new constructor with the .shp and the .shx file names has been added.
• New methods
• getFeatureAt - Reads the feature at the specified index.
• getNextFeatureIndex - Returns the index of the next feature returned by getNextFeature.
• getNextFeatureId - Returns an Object that is the ID of the next feature returned by getNextFeature.
• skipNextFeature - Skips the next feature that should have been returned by getNextFeature.

• Overview of new features
• Constructors have been added to support Shapefile index files.
• New constructors
• A new constructor with the .shp,.shx, and .dbf file names has been added.
• A new constructor with the various readers instead of file names has been added.
• New methods
• getFeatureAt - Returns the feature at the specified index
• getNextFeatureIndex - Returns the index of the next feature returned by getNextFeature.
• getNextFeatureId - Returns an Object that is the ID of the next feature returned by getNextFeature.
• skipNextFeature - Skips the next feature that should have been returned by getNextFeature.

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Demonstration Changes

A new demo has been added in the <installdir>/demos/maps/esri directory. This demo is the LODViewer. It contains sample code to create a load-on-demand layer for Shapefiles. You can also use it to create the spatial index for Shapefiles that do not have one.
To view a Shapefile in load-on-demand:

• Select "Load a Shapefile..." in the File menu.
• Choose a Shapefile (.shp extension). If an attribute file (.dbf extension) is available in the same directory, it will be used to load the attributes for geometry. A Shapefile index (.shx) file is mandatory for load-on-demand.
• A dialog box is displayed. With this dialog box, you can either select an already-existing spatial index file, or create a new one.
• If you select an index file that does not exist, the program will propose that you create a new one.

• Select "Load a Shapefile..." in the File menu.
• Choose a Shapefile (.shp extension). If an attribute file (.dbf extension) is available in the same directory, it will be used to load the attributes for geometry. A Shapefile index (.shx) file is mandatory for load-on-demand.
• A dialog box is displayed. Select "Create spatial index". A file selector is displayed for the spatial index file name.