Class SkySurface

java.lang.Object
uk.ac.starlink.ttools.plot2.geom.SkySurface
All Implemented Interfaces:
Surface

public class SkySurface extends Object implements Surface
Surface implementation for plotting on the celestial sphere. The data coordinates are direction cosines: 3-element arrays containing normalised X,Y,Z coordinates, where each coordinate is in the range -1..+1 and the sum of squares is 1.
Since:
20 Feb 2013
Author:
Mark Taylor
  • Constructor Summary

    Constructors
    Constructor
    Description
    SkySurface(Rectangle plotBounds, Projection projection, double[] rotmat, double zoom, double xoff, double yoff, SkySys viewSystem, SkyAxisLabeller axLabeller, Color gridColor, Color axlabelColor, Color scalebarColor, boolean sexagesimal, double crowd, Captioner captioner, boolean antialias)
    Constructor.
  • Method Summary

    Modifier and Type
    Method
    Description
    createGridder(Rotation rotation, boolean sexagesimal, double loncrowd, double latcrowd)
    Attempts to construct a GridLiner object to draw grid lines on this plot.
    Returns a labelled line corresponding to the (shorter) great circle arc between two graphics points.
    boolean
    dataToGraphics(double[] dpos, boolean visibleOnly, Point2D.Double gpos)
    Converts a data space position to a graphics position.
    boolean
    dataToGraphicsOffset(double[] dpos0, Point2D.Double gpos0, double[] dpos1, boolean visibleOnly, Point2D.Double gpos1)
    Converts an offset data space position to a graphics position.
    boolean
     
    flatPan(Point2D pos0, Point2D pos1)
    Pan gesture which just translates the entire graphics plane.
    flatZoom(Point2D pos, double factor)
    Zoom gesture which just magnifies the entire graphics plane.
    formatPosition(double[] dpos)
    Formats the given data space position as a coordinate string.
    static String
    formatPositionDec(double lonRad, double latRad, double pixRad)
    Formats a lon/lat position as decimal given the approximate size of a screen pixel.
    static String
    formatPositionSex(double lonRad, double latRad, double pixRad)
    Formats a lon/lat position as sexagesimal given the approximate size of a screen pixel.
    Returns a captioner suitable for drawing general purpose labels annotating the plot.
    int
    Returns 3.
    double
    Returns the dimensionless X offset of the plot centre from the plot bounds centre.
    double
    Returns the dimensionless Y offset of the plot centre from the plot bounds centre.
    Returns the rectangle within which all of the plot data will appear.
    getPlotInsets(boolean withScroll)
    Returns the insets that this surface would like to reserve outside the plot bounds.
    Returns the projection used by this sky surface.
    double[]
    Returns the rotation matrix corresponding to this view of the sky.
    Returns the screen position corresponding to the center of the projection used by this surface.
    Returns a shape that gives the boundary of the sky projection in graphics coordinates.
    Returns the sky system into which coordinates are projected.
    double
    Returns the zoom factor; 1 means the sky is approximately the same size as the plot bounds.
    double[]
    Attempts to turn a graphics position into a sky position.
    double[]
    Attempts to turn a graphics position into a data position.
    int
     
    boolean
    isContinuousLine(double[] dpos0, double[] dpos1)
    Indicates whether a line in graphics space between two given data space positions is continuous.
    void
    Paints the plot surface background.
    void
    Paints the plot surface foreground.
    double
    Returns the approximate solid angle covered by a screen pixel in steradians.
    double
    Returns the solid angle covered by a given graphics pixel in steradians.
    projPan(Point2D pos0, Point2D pos1)
    Pan gesture which attempts to rotate the sky while leaving the size and location of the graphics plane unchanged.
    projZoom(Point2D pos, double factor)
    Zoom gesture which attempts to zoom the sky, with the cursor staying at the same sky position, while leaving the size and location of the graphics plane unchanged.
    reframe(Point2D center, double factor)
    Returns a plot aspect giving the data region defined by a graphics position and zoom factor adjustment.
    double
    Returns the distance along a great circle in radians between two graphics positions.

    Methods inherited from class java.lang.Object

    clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait
  • Constructor Details

    • SkySurface

      public SkySurface(Rectangle plotBounds, Projection projection, double[] rotmat, double zoom, double xoff, double yoff, SkySys viewSystem, SkyAxisLabeller axLabeller, Color gridColor, Color axlabelColor, Color scalebarColor, boolean sexagesimal, double crowd, Captioner captioner, boolean antialias)
      Constructor.
      Parameters:
      plotBounds - graphics region within which the plot must fall
      projection - sky projection
      rotmat - 9-element rotation matrix
      zoom - zoom factor; 1 means the sky is approximately the same size as plot bounds
      xoff - x offset of plot centre from plot bounds centre in dimensionless units; 0 is centred
      yoff - y offset of plot centre from plot bounds centre in dimensionless units; 0 is centred
      viewSystem - sky system into which coordinates are projected
      axLabeller - sky axis labelling object
      gridColor - colour for grid drawing, or null if no grid
      axlabelColor - colour for axis labels, or null if no labels
      scalebarColor - colour for scale bar, or null if not drawn
      sexagesimal - whether to use sexagesimal coordinates
      crowd - tick mark crowding factor, 1 is normal
      captioner - text rendering object
      antialias - whether to antialias grid lines
  • Method Details

    • getDataDimCount

      public int getDataDimCount()
      Returns 3.
      Specified by:
      getDataDimCount in interface Surface
      Returns:
      number of elements in data space coordinate array
    • getPlotBounds

      public Rectangle getPlotBounds()
      Description copied from interface: Surface
      Returns the rectangle within which all of the plot data will appear. This includes anything that might get drawn by a plot layer, but does not necessarily include axis labels etc.
      Specified by:
      getPlotBounds in interface Surface
      Returns:
      plot data area bounds
    • getPlotInsets

      public Insets getPlotInsets(boolean withScroll)
      Description copied from interface: Surface
      Returns the insets that this surface would like to reserve outside the plot bounds. This is space outside the rectangle returned by Surface.getPlotBounds() to be used for axis labels etc.

      If the withScroll parameter is set, then an attempt will be made to return insets that will not alter if the current plot is scrolled around a moderate amount. For a one-time plot that's not important, but for an interactive plot it prevents the actual plot position jumping around to accommodate more or less space on the axes according to exactly where ticks happen to fall on the axes.

      This method is supposed to return only the space that may actually be touched by the plot. The calling code may wish to apply additional padding on top of this for cosmetic reasons.

      Specified by:
      getPlotInsets in interface Surface
      Parameters:
      withScroll - true to reserve space for nicer scrolling
      Returns:
      plot data area insets
    • paintBackground

      public void paintBackground(Graphics g)
      Description copied from interface: Surface
      Paints the plot surface background. Anything that appears within the plot bounds underneath the data markings must go here.
      Specified by:
      paintBackground in interface Surface
      Parameters:
      g - graphics context
    • paintForeground

      public void paintForeground(Graphics g)
      Description copied from interface: Surface
      Paints the plot surface foreground. Anything that appears on top of the data markings or outside the plot bounds must go here. This may include axes.
      Specified by:
      paintForeground in interface Surface
      Parameters:
      g - graphics context
    • getCaptioner

      public Captioner getCaptioner()
      Description copied from interface: Surface
      Returns a captioner suitable for drawing general purpose labels annotating the plot.
      Specified by:
      getCaptioner in interface Surface
      Returns:
      captioner
    • getProjection

      public Projection getProjection()
      Returns the projection used by this sky surface.
      Returns:
      projection
    • getRotation

      public double[] getRotation()
      Returns the rotation matrix corresponding to this view of the sky.
      Returns:
      9-element rotation matrix
    • getZoom

      public double getZoom()
      Returns the zoom factor; 1 means the sky is approximately the same size as the plot bounds.
      Returns:
      zoom factor
    • getOffsetX

      public double getOffsetX()
      Returns the dimensionless X offset of the plot centre from the plot bounds centre.
      Returns:
      dimensionless X offset
    • getOffsetY

      public double getOffsetY()
      Returns the dimensionless Y offset of the plot centre from the plot bounds centre.
      Returns:
      dimensionless Y offset
    • getViewSystem

      public SkySys getViewSystem()
      Returns the sky system into which coordinates are projected.
      Returns:
      view sky system
    • createGridder

      public GridLiner createGridder(Rotation rotation, boolean sexagesimal, double loncrowd, double latcrowd)
      Attempts to construct a GridLiner object to draw grid lines on this plot.

      The work is done by classes from the SkyView package.

      Parameters:
      rotation - additional rotation to apply to sky system before grid lines are plotted; may be null for no additional rotation
      sexagesimal - true for sexagesimal labels, false for decimal
      loncrowd - longitude tick mark crowding factor, 1 is normal
      latcrowd - latitude tick mark crowding factor, 1 is normal
      Returns:
      gridliner, or null on failure
    • dataToGraphics

      public boolean dataToGraphics(double[] dpos, boolean visibleOnly, Point2D.Double gpos)
      Description copied from interface: Surface
      Converts a data space position to a graphics position. If visibleOnly is true, then if the return value is true, the exit value of gPos is guaranteed to be within the plot bounds of this surface.

      If visibleOnly is false, there are no guarantees about the exit value of gPos, and its coordinates could be infinite or NaN. In this case you might want to perform additional checking, for instance with the utility methods PlotUtil.isPointFinite or isPointReal.

      Specified by:
      dataToGraphics in interface Surface
      Parameters:
      dpos - dataDimCount-element array containing data space coordinates
      visibleOnly - if true, then the conversion will only succeed when the result falls within the plot bounds of this surface
      gpos - point object into which the graphics position will be written on success
      Returns:
      true iff the conversion succeeds
    • dataToGraphicsOffset

      public boolean dataToGraphicsOffset(double[] dpos0, Point2D.Double gpos0, double[] dpos1, boolean visibleOnly, Point2D.Double gpos1)
      Description copied from interface: Surface
      Converts an offset data space position to a graphics position. Context is given in the form of an existing converted nearby point (both data and graphics positions).

      This (somewhat hacky) method is required for surfaces in which a data position may map to more than one position in graphics space, for instance sky surfaces with discontinuous longitude. The result does not need to be the same as the result of calling Surface.dataToGraphics(double[], boolean, java.awt.geom.Point2D.Double), and is not required to be a legal graphics position, but it must make visual sense, for instance when plotting error bars. The semantics of a "nearby point" is not very well defined. There are probably situations in which calling this will not give the result that's wanted, but they will probably be rare.

      Specified by:
      dataToGraphicsOffset in interface Surface
      Parameters:
      dpos0 - context position in data space
      gpos0 - context position in graphics space (result of calling dataToGraphics on dpos0)
      dpos1 - query position in data space
      visibleOnly - if true, the call only succeeds if the result is within the plot bounds of this surface
      gpos1 - point object to which the graphics position of dpos1 will be written on success
      Returns:
      true for success, false for no result
    • graphicsToData

      public double[] graphicsToData(Point2D gpos, Supplier<CoordSequence> dposSupplier)
      Description copied from interface: Surface
      Attempts to turn a graphics position into a data position. This is not always trivial, for instance in a 3D plot one graphics position maps to a line of data positions. The dposIt argument can optionally be supplied to cope with such instances. If a data pos cannot be determined, null is returned. If dposIt is absent, the method will run quickly. If it's present, it may or may not run slowly.
      Specified by:
      graphicsToData in interface Surface
      Parameters:
      gpos - graphics point
      dposSupplier - iterable over dataDimCount-element arrays representing all the data space positions plotted, or null
      Returns:
      dataDimCount-element array giving data space position for gPos, or null if it cannot be determined
    • graphicsToData

      public double[] graphicsToData(Point2D gpos)
      Attempts to turn a graphics position into a sky position. This convenience function just calls graphicsToData(gpos,null), since the iterable argument is ignored for the SkySurface.
      Parameters:
      gpos - graphics position
      Returns:
      3-element unit vector representing data position, or null if gpos out of range
    • isContinuousLine

      public boolean isContinuousLine(double[] dpos0, double[] dpos1)
      Description copied from interface: Surface
      Indicates whether a line in graphics space between two given data space positions is continuous.

      This is not very well-defined, but if drawing a line in graphics coordinates between the graphics coordinates corresponding to the two data coordinates is likely to do something badly wrong, this method should return false. It is intended to deal with the case where a short offset in data coordinates would lead to a line going the wrong way round the sky when it crosses the longitude=+/-PI boundary in an Aitoff projection.

      Specified by:
      isContinuousLine in interface Surface
      Parameters:
      dpos0 - first dataDimCount-element array containing data space coordinates
      dpos1 - second dataDimCount-element array containing data space coordinates
      Returns:
      true if drawing a graphics line between the two positions should be OK
    • formatPosition

      public String formatPosition(double[] dpos)
      Description copied from interface: Surface
      Formats the given data space position as a coordinate string. If possible the returned string should have the same length and formatting over the whole visible plot surface, so that the representation doesn't jump around when the cursor is moved.
      Specified by:
      formatPosition in interface Surface
      Parameters:
      dpos - dataDimCount-element array giving data space position
      Returns:
      human-readable string representing position
    • pixelAreaSteradians

      public double pixelAreaSteradians()
      Returns the approximate solid angle covered by a screen pixel in steradians. It tries to return a representative value for the visible area.
      Returns:
      approximate linear size of a screen pixel in radians
    • pixelAreaSteradians

      public double pixelAreaSteradians(Point2D gpos)
      Returns the solid angle covered by a given graphics pixel in steradians.
      Parameters:
      gpos - position of graphics pixel center
      Returns:
      approximate linear size of pixel in radians, or NaN if pixel is not (all) on the sky
    • screenDistanceRadians

      public double screenDistanceRadians(Point2D gp1, Point2D gp2)
      Returns the distance along a great circle in radians between two graphics positions. The evaluation should be well-conditioned for small or large angles. The given coordinates do not need to be within the graphics bounds, but if they are outside the celestial sphere, NaN will be returned.
      Parameters:
      gp1 - first position
      gp2 - second position
      Returns:
      separation between positions in radians, or NaN if one of the positions is not on the sky
    • createLine

      public LabelledLine createLine(Point2D gp1, Point2D gp2)
      Returns a labelled line corresponding to the (shorter) great circle arc between two graphics points.
      Parameters:
      gp1 - start point in graphics space
      gp2 - end point in graphics space
      Returns:
      labelled line, or null if it can't be done, for instance if not both points are on the sky
    • formatPositionSex

      public static String formatPositionSex(double lonRad, double latRad, double pixRad)
      Formats a lon/lat position as sexagesimal given the approximate size of a screen pixel. The pixel size is used to determine how much precision to give.
      Parameters:
      lonRad - longitude in radians
      latRad - latitude in radians
      pixRad - approximate size of a screen pixel in radians
    • formatPositionDec

      public static String formatPositionDec(double lonRad, double latRad, double pixRad)
      Formats a lon/lat position as decimal given the approximate size of a screen pixel. The pixel size is used to determine how much precision to give.
      Parameters:
      lonRad - longitude in radians
      latRad - latitude in radians
      pixRad - approximate size of a screen pixel in radians
    • flatPan

      public SkyAspect flatPan(Point2D pos0, Point2D pos1)
      Pan gesture which just translates the entire graphics plane.
      Parameters:
      pos0 - source graphics position
      pos1 - destination graphics position
      Returns:
      panned sky aspect
    • flatZoom

      public SkyAspect flatZoom(Point2D pos, double factor)
      Zoom gesture which just magnifies the entire graphics plane.
      Parameters:
      pos - reference graphics position
      factor - zoom factor
      Returns:
      zoomed sky aspect
    • projPan

      public SkyAspect projPan(Point2D pos0, Point2D pos1)
      Pan gesture which attempts to rotate the sky while leaving the size and location of the graphics plane unchanged. If that functionality is not supported by the projection, it will fall back to flat panning.
      Parameters:
      pos0 - source graphics position
      pos1 - destination graphics position
      Returns:
      panned sky aspect
    • projZoom

      public SkyAspect projZoom(Point2D pos, double factor)
      Zoom gesture which attempts to zoom the sky, with the cursor staying at the same sky position, while leaving the size and location of the graphics plane unchanged. If that functionality is not supported by the projection, it will fall back to flat zooming.
      Parameters:
      pos - reference graphics position
      factor - zoom factor
      Returns:
      zoomed sky aspect
    • reframe

      public SkyAspect reframe(Point2D center, double factor)
      Returns a plot aspect giving the data region defined by a graphics position and zoom factor adjustment.
      Parameters:
      center - position in current graphics coordinates of the sky position requested as the new center
      factor - zoom factor (from current)
      Returns:
      reframed sky aspect
    • getSkyCenter

      public Point getSkyCenter()
      Returns the screen position corresponding to the center of the projection used by this surface. That position will typically, but not necessarily, be the least distorted point. The returned position is not necessarily within the currently visible plot bounds.
      Returns:
      central position in graphics coordinates
    • getSkyShape

      public Shape getSkyShape()
      Returns a shape that gives the boundary of the sky projection in graphics coordinates.
      Returns:
      sky boundary shape
    • equals

      public boolean equals(Object o)
      Overrides:
      equals in class Object
    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object