Package org.apache.sis.portrayal

Class CanvasContext

java.lang.Object

org.apache.sis.referencing.operation.CoordinateOperationContext

org.apache.sis.portrayal.CanvasContext

All Implemented Interfaces:

Serializable

final class CanvasContext
extends CoordinateOperationContext

Contextual information for allowing Canvas to select the most appropriate coordinate operation for the viewed area and resolution.

Since:

1.1

Version:

1.1

Field Summary

Fields

Modifier and Type	Field	Description
private static final double	DISPLAY_RESOLUTION	Desired resolution in display units (usually pixels).
private org.opengis.metadata.extent.GeographicBoundingBox	geographicArea	The geographic area, computed when first requested and saved for reuse.
private org.opengis.referencing.operation.CoordinateOperation	objectiveToGeographic	Transformation from objective CRS to a geographic CRS, or null if none can be found.
private double	resolution	The resolution in metres, computed when first requested and saved for reuse.

Constructor Summary

Constructors

Constructor	Description
CanvasContext()	Creates a new context.

Method Summary

Modifier and Type	Method	Description
(package private) final void	clear()	Clears information that depends on Canvas.objectiveToDisplay.
(package private) final Optional<org.opengis.metadata.extent.GeographicBoundingBox>	getGeographicArea(Canvas canvas)	Returns the geographic area, or an empty value if none.
(package private) final OptionalDouble	getSpatialResolution(Canvas canvas)	Returns the spatial resolution, or an empty value if none.
(package private) final void	partialClear(boolean poi)	Clears only some information, depending on whether the modified property is point of interest or the display bounds.
private void	recompute(Canvas canvas)	Recomputes geographicArea and resolution fields that are not valid.
(package private) final void	refresh(Canvas canvas)	Sets the CoordinateOperationContext object to the desired area and accuracy of the coordinate operation to obtain.
(package private) final void	setObjectiveToGeographic(org.opengis.referencing.operation.CoordinateOperation op)	Sets the operation from Canvas.objectiveCRS to geographic CRS.

Methods inherited from class org.apache.sis.referencing.operation.CoordinateOperationContext

fromBoundingBox, getAreaOfInterest, getDesiredAccuracy, setAreaOfInterest, setAreaOfInterest, setDesiredAccuracy

Methods inherited from class java.lang.Object

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

Field Details

DISPLAY_RESOLUTION

private static final double DISPLAY_RESOLUTION

Desired resolution in display units (usually pixels). This is used for avoiding the cost of transformations having too much accuracy for the current zoom level.

See Also:

• Canvas.findTransform(CoordinateReferenceSystem, CoordinateReferenceSystem, boolean)
• Constant Field Values

objectiveToGeographic

private org.opengis.referencing.operation.CoordinateOperation objectiveToGeographic

Transformation from objective CRS to a geographic CRS, or null if none can be found. The geographic CRS (operation target) has (longitude, latitude) axes in degrees but the same geodetic datum than the objective CRS, so the prime meridian is not necessarily Greenwich. This is recomputed immediately after a change of Canvas.objectiveCRS or Canvas.pointOfInterest because it will be needed anyway for Canvas.findTransform(CoordinateReferenceSystem, CoordinateReferenceSystem, boolean).

See Also:

• Canvas.getGeographicArea()
• Canvas.objectiveToGeographic(CoordinateReferenceSystem)

geographicArea

private org.opengis.metadata.extent.GeographicBoundingBox geographicArea

The geographic area, computed when first requested and saved for reuse. This is reset to null every time that Canvas.objectiveCRS, Canvas.objectiveToDisplay or Canvas.displayBounds is modified.

See Also:

• Canvas.GEOGRAPHIC_AREA_PROPERTY
• getGeographicArea(Canvas)

resolution

private double resolution

The resolution in metres, computed when first requested and saved for reuse. This is reset to null every time Canvas.objectiveCRS, Canvas.objectiveToDisplay or Canvas.pointOfInterest is modified. Value 0 means that the value has not yet been computed.

See Also:

• Canvas.SPATIAL_RESOLUTION_PROPERTY
• getSpatialResolution(Canvas)

Constructor Details

CanvasContext

CanvasContext()

Creates a new context.

Method Details

setObjectiveToGeographic

final void setObjectiveToGeographic(org.opengis.referencing.operation.CoordinateOperation op)

Sets the operation from Canvas.objectiveCRS to geographic CRS.

Parameters:

op - the conversion from objective CRS to geographic CRS, or null if none.

clear

final void clear()

Clears information that depends on Canvas.objectiveToDisplay. This method assumes that Canvas.objectiveCRS is still valid.

partialClear

final void partialClear(boolean poi)

Clears only some information, depending on whether the modified property is point of interest or the display bounds.

Parameters:

poi - true if the modified property is the point of interest, false if the modified property is the display bounds.

getGeographicArea

final Optional<org.opengis.metadata.extent.GeographicBoundingBox> getGeographicArea(Canvas canvas)
                                                                             throws org.opengis.referencing.operation.TransformException

Returns the geographic area, or an empty value if none.

Throws:

org.opengis.referencing.operation.TransformException

See Also:

• Canvas.getGeographicArea()

getSpatialResolution

final OptionalDouble getSpatialResolution(Canvas canvas)
                                   throws org.opengis.referencing.operation.TransformException

Returns the spatial resolution, or an empty value if none.

Throws:

org.opengis.referencing.operation.TransformException

See Also:

• Canvas.getSpatialResolution()

recompute

private void recompute(Canvas canvas)
                throws org.opengis.referencing.operation.TransformException

Recomputes geographicArea and resolution fields that are not valid. This method assumes that objectiveToGeographic is null or valid.

Throws:

org.opengis.referencing.operation.TransformException

refresh

final void refresh(Canvas canvas)
            throws org.opengis.referencing.operation.TransformException

Sets the CoordinateOperationContext object to the desired area and accuracy of the coordinate operation to obtain.

Throws:

org.opengis.referencing.operation.TransformException