com.vividsolutions.jts.awt

Class ShapeWriter


  • public class ShapeWriter
extends Object
    Writes Geometrys into Java2D Shape objects of the appropriate type. This supports rendering geometries using Java2D. The ShapeWriter allows supplying a PointTransformation class, to transform coordinates from model space into view space. This is useful if a client is providing its own transformation logic, rather than relying on Java2D AffineTransforms.

    The writer supports removing duplicate consecutive points (via the setRemoveDuplicatePoints(boolean) method) as well as true decimation (via the setDecimation(double) method. Enabling one of these strategies can substantially improve rendering speed for large geometries. It is only necessary to enable one strategy. Using decimation is preferred, but this requires determining a distance below which input geometry vertices can be considered unique (which may not always be feasible). If neither strategy is enabled, all vertices of the input Geometry will be represented in the output Shape.

    • Field Detail

      • DEFAULT_POINT_TRANSFORMATION

        public static final PointTransformation DEFAULT_POINT_TRANSFORMATION
        The point transformation used by default.

      • DEFAULT_POINT_FACTORY

        public static final PointShapeFactory DEFAULT_POINT_FACTORY
        The point shape factory used by default.

    • Constructor Detail

      • ShapeWriter

        public ShapeWriter(PointTransformation pointTransformer,
                   PointShapeFactory pointFactory)
        Creates a new ShapeWriter with a specified point transformation and point shape factory.
        Parameters:
        pointTransformer - a transformation from model to view space to use
        pointFactory - the PointShapeFactory to use

      • ShapeWriter

        public ShapeWriter(PointTransformation pointTransformer)
        Creates a new ShapeWriter with a specified point transformation and the default point shape factory.
        Parameters:
        pointTransformer - a transformation from model to view space to use

      • ShapeWriter

        public ShapeWriter()
        Creates a new ShapeWriter with the default (identity) point transformation.

    • Method Detail

      • setRemoveDuplicatePoints

        public void setRemoveDuplicatePoints(boolean doRemoveDuplicatePoints)
        Sets whether duplicate consecutive points should be eliminated. This can reduce the size of the generated Shapes and improve rendering speed, especially in situations where a transform reduces the extent of the geometry.

        The default is false.

        Parameters:
        doDecimation - whether decimation is to be used

      • setDecimation

        public void setDecimation(double decimationDistance)
        Sets the decimation distance used to determine whether vertices of the input geometry are considered to be duplicate and thus removed. The distance is axis distance, not Euclidean distance. The distance is specified in the input geometry coordinate system (NOT the transformed output coordinate system).

        When rendering to a screen image, a suitably small distance should be used to avoid obvious rendering defects. A distance equivalent to the equivalent of 1.5 pixels or less is recommended (and perhaps even smaller to avoid any chance of visible artifacts).

        The default distance is 0.0, which disables decimation.

        Parameters:
        decimationDistance - the distance below which vertices are considered to be duplicates

      • toShape

        public Shape toShape(Geometry geometry)
        Creates a Shape representing a Geometry, according to the specified PointTransformation and PointShapeFactory (if relevant).

        Note that Shapes do not preserve information about which elements in heterogeneous collections are 1D and which are 2D. For example, a GeometryCollection containing a ring and a disk will render as two disks if Graphics.fill is used, or as two rings if Graphics.draw is used. To avoid this issue use separate shapes for the components.

        Parameters:
        geometry - the geometry to convert
        Returns:
        a Shape representing the geometry