org.geotools.data.util

Class ScreenMap

Object

ScreenMap

public class ScreenMap
extends Object

The screenmap is a packed bitmap of the screen, one bit per pixels. It can be used to avoid rendering a lot of very small features in the same pixel.

The screenmap can be used two ways:

• By working directly against the pixels using checkAndSet(int, int)
• By working with real world envelopes using checkAndSet(Envelope), in that case the full math transform from data to screen, and the generalization spans must be set

When checkAndSet returns false the geometry sits in a pixel that has been already populated and can be skipped.

Author:

jeichar, Andrea Aime - OpenGeo

Constructor Summary

Constructors

Constructor and Description
ScreenMap(int x, int y, int width, int height)
ScreenMap(int x, int y, int width, int height, MathTransform mt)
ScreenMap(ScreenMap original, int expandBy)

Method Summary

Modifier and Type	Method and Description
boolean	canSimplify(Envelope envelope)
boolean	checkAndSet(Envelope envelope)
boolean	checkAndSet(int x, int y) Checks if the geometry should be skipped.
boolean	get(Envelope envelope)
boolean	get(int x, int y) Returns true if the pixel at location x,y is set or out of bounds.
Geometry	getSimplifiedShape(double minx, double miny, double maxx, double maxy, GeometryFactory geometryFactory, Class geometryType) Returns geometry suitable for rendering the pixel that has just been occupied.
Geometry	getSimplifiedShape(Geometry geometry) Returns geometry suitable for rendering the pixel that has just been occupied.
void	set(int x, int y, boolean value) Sets location at position x,y to the value.
void	setSpans(double spanX, double spanY)
void	setTransform(MathTransform mt)

Methods inherited from class Object

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

Constructor Detail

ScreenMap

public ScreenMap(int x,
                 int y,
                 int width,
                 int height,
                 MathTransform mt)

ScreenMap

public ScreenMap(ScreenMap original,
                 int expandBy)

ScreenMap

public ScreenMap(int x,
                 int y,
                 int width,
                 int height)

Method Detail

setTransform

public void setTransform(MathTransform mt)

checkAndSet

public boolean checkAndSet(Envelope envelope)
                    throws TransformException

Throws:

TransformException

canSimplify

public boolean canSimplify(Envelope envelope)

setSpans

public void setSpans(double spanX,
                     double spanY)

checkAndSet

public boolean checkAndSet(int x,
                           int y)

Checks if the geometry should be skipped. If the test returns true it means the geometry sits in a pixel that has already been used

get

public boolean get(Envelope envelope)
            throws TransformException

Throws:

TransformException

get

public boolean get(int x,
                   int y)

Returns true if the pixel at location x,y is set or out of bounds.

getSimplifiedShape

public Geometry getSimplifiedShape(Geometry geometry)

Returns geometry suitable for rendering the pixel that has just been occupied. The geometry is designed to actually fill the pixel

Parameters:

minx -

miny -

maxx -

maxy -

geometryFactory -

geometryType -

Returns:

getSimplifiedShape

public Geometry getSimplifiedShape(double minx,
                                   double miny,
                                   double maxx,
                                   double maxy,
                                   GeometryFactory geometryFactory,
                                   Class geometryType)

Returns geometry suitable for rendering the pixel that has just been occupied. The geometry is designed to actually fill the pixel

Parameters:

minx -

miny -

maxx -

maxy -

geometryFactory -

geometryType -

Returns:

set

public void set(int x,
                int y,
                boolean value)

Sets location at position x,y to the value.