The transformation is defined by setting the range (mathematical coordinates) and the size (pixel coordinates) of the plot. The latter is usually done by the paint() method of a Canvas or Component.
If plots with differing ranges on a single canvas have to be done, simply create two PlottingContexts and use them one after the other.
The actual plotting is done by Plottable-objects themselves by passing a PlottingContext-object to their plot()-method @see de.bablokb.plotlib.core.Plottable @version $Revision: 1.2 $ @author $Author: bablokb $ */ public class PlottingContext { /** Internal helper constant for log-transformation. */ private final static double LOG10 = Math.log(10); /** Transformation constant. */ public final static int LINEAR = 1, // use only standard mapping LOGLINEAR = 2, // transform x-values logarithmically LINEARLOG = 3, // transform y-values logarithmically LOGLOG = 4; // transform both x- and y-values logarithmically /** Type of transformation. Defaults to LINEAR. */ private int iTransType = LINEAR; /** Range (mathematical coordinates) to be plotted. */ private Rectangle2D iRange = null; /** Size (pixel coordinates) of plot. */ private Dimension2D iSize = null; /** Transformation matrix. */ private AffineTransform iAf = null; /** Graphics2D object. */ private Graphics2D iG2 = null; /** Component object. */ private Component iComponent = null; ///////////////////////////////////////////////////////////////////////////// /** Create and initialize the plot context. */ public PlottingContext() { } ///////////////////////////////////////////////////////////////////////////// /** Set transformation type. */ public void setTransformationType(int type) { iTransType = type; } ///////////////////////////////////////////////////////////////////////////// /** Query transformation type. */ public int getTransformationType() { return iTransType; } ///////////////////////////////////////////////////////////////////////////// /** Set the range. */ public void setRange(Rectangle2D range) { iRange = range; iAf = null; } ///////////////////////////////////////////////////////////////////////////// /** Query the range. */ public Rectangle2D getRange() { return iRange; } ///////////////////////////////////////////////////////////////////////////// /** Set the plot size. */ public void setSize(Dimension2D size) { iSize = size; iAf = null; } ///////////////////////////////////////////////////////////////////////////// /** Query the size. */ public Dimension2D getSize() { return iSize; } ///////////////////////////////////////////////////////////////////////////// /** Set the Graphics2D object. */ public void setG2(Graphics2D g2) { iG2 = g2; } ///////////////////////////////////////////////////////////////////////////// /** Query the Graphics2 object. */ public Graphics2D getG2() { return iG2; } ///////////////////////////////////////////////////////////////////////////// /** Set the component object. */ public void setComponent(Component c) { iComponent = c; } ///////////////////////////////////////////////////////////////////////////// /** Query the component object. */ public Component getComponent() { return iComponent; } ///////////////////////////////////////////////////////////////////////////// /** Query the x-ratio. This is the amount in mathematical coordinates which maps to a unit in device coordinates (e.g. a pixel) in the direction of the x-axis.
FIXME: do we have to take care of special devices, e.g. printers? */ public double getXratio() { if (iRange == null) throw new MissingRangeException(); else if (iSize == null) throw new MissingSizeException(); return iRange.getWidth()/iSize.getWidth(); } ///////////////////////////////////////////////////////////////////////////// /** Query the y-ratio. This is the amount in mathematical coordinates which maps to a unit in device coordinates (e.g. a pixel) in the direction of the y-axis.
FIXME: do we have to take care of special devices, e.g. printers? */ public double getYratio() { if (iRange == null) throw new MissingRangeException(); else if (iSize == null) throw new MissingSizeException(); return iRange.getHeight()/iSize.getHeight(); } ///////////////////////////////////////////////////////////////////////////// /** Set defaults from system properties. Properties can be specified on the commandline or by importing a properties file. Supported properties:
FIXME: Setting the background color for the component results in a call to paint(), thus resulting in an endless loop (if setDefaults() is called from paint()). Is this a bug or a feature?
FIXME: What about additional defaults, e.g. plotlib.symbols.size? */ public void setDefaults() { Color col = Color.getColor("plotlib.foreground.color"); if (col != null && iG2 != null) iG2.setColor(col); float width = Plotlib.THIN; try { width = Float.parseFloat(System.getProperty("plotlib.width")); } catch (Exception e) { } BasicStroke s = new BasicStroke(width); iG2.setStroke(s); } ///////////////////////////////////////////////////////////////////////////// /** Calculate the affine transformation, which transforms mathematical coordinates into Java2D coordinates. */ public AffineTransform getMatrix() { if (iRange == null) throw new MissingRangeException(); else if (iSize == null) throw new MissingSizeException(); else if (iG2 == null) throw new MissingG2Exception(); if (iAf != null) return iAf; double xmin = iRange.getMinX(), xdel = iRange.getWidth(), ydel = iRange.getHeight(), ymax = iRange.getMinY() + ydel, pxmax = iSize.getWidth(), pymax = iSize.getHeight(); iAf = new AffineTransform(pxmax/xdel,0.0,0.0,-pymax/ydel, -pxmax*xmin/xdel,pymax*ymax/ydel); return iAf; } ///////////////////////////////////////////////////////////////////////////// /** Transform a given Point2D. */ public Point2D transform(Point2D p) { AffineTransform af = getMatrix(); Point2D ptSrc = (Point2D) p.clone(), ptDst = (Point2D) p.clone(); if (iTransType == LOGLINEAR || iTransType == LOGLOG) ptSrc.setLocation(Math.log(ptSrc.getX())*LOG10,ptSrc.getY()); if (iTransType == LINEARLOG || iTransType == LOGLOG) ptSrc.setLocation(ptSrc.getX(),Math.log(ptSrc.getY())*LOG10); af.transform(ptSrc,ptDst); return ptDst; } ///////////////////////////////////////////////////////////////////////////// /** Transform a given Line2D. */ public Line2D transform(Line2D l) { Line2D lDst = (Line2D) l.clone(); lDst.setLine(transform(l.getP1()),transform(l.getP2())); return lDst; } ///////////////////////////////////////////////////////////////////////////// /** Transform a given Rectangle2D. */ public Rectangle2D transform(Rectangle2D r) { Rectangle2D rDst = (Rectangle2D) r.clone(); Point2D.Double p1 = new Point2D.Double(rDst.getMinX(),rDst.getMinY()); Point2D.Double p2 = new Point2D.Double(rDst.getMaxX(),rDst.getMaxY()); rDst.setFrameFromDiagonal(transform(p1),transform(p2)); return rDst; } }