Class LineTracer


  • public class LineTracer
    extends java.lang.Object
    Draws lines composed of a sequence of points, submitted one at a time. To use it make multiple calls of addVertex, followed by a call to flush().

    Sub-sequences of the point sequence are aggregated in supplied work arrays and plotted using Graphics2D.draw(Shape). This is superior to the more obvious strategy of calling Graphics.drawLine for every pair of points. It is probably faster, it can work with non-integer coordinates, and it is necessary to get the dashing right for dashed strokes, otherwise the dash starts anew for each edge. This class does some other useful things like avoid attempts to plot lines which are extremely long or which are known to be outside the clip.

    Since:
    12 Jun 2013
    Author:
    Mark Taylor
    • Constructor Summary

      Constructors 
      Constructor Description
      LineTracer​(java.awt.Graphics g, java.awt.Rectangle bounds, java.awt.Color color, java.awt.Stroke stroke, boolean antialias, int nwork, boolean isPixel)
      Constructor.
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void addVertex​(double dx, double dy)
      Adds a point to the sequence to be plotted.
      void flush()
      Ensures that all points have been drawn.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Constructor Detail

      • LineTracer

        public LineTracer​(java.awt.Graphics g,
                          java.awt.Rectangle bounds,
                          java.awt.Color color,
                          java.awt.Stroke stroke,
                          boolean antialias,
                          int nwork,
                          boolean isPixel)
        Constructor. The nwork parameter determines the number of points aggregated into a single plotting call. There may be visual anomalies every nwork points, so it should not be too small, but arrays of this size are allocated, so it should not be too large either.
        Parameters:
        g - the base graphics context
        bounds - bounds beyond which lines should not be drawn
        color - line colour
        stroke - line stroke
        antialias - whether lines are to be antialiased
        nwork - workspace array size
        isPixel - if true, the graphics context is considered to be pixellised, allowing some optimisations to be made that should not be visible
    • Method Detail

      • addVertex

        public void addVertex​(double dx,
                              double dy)
        Adds a point to the sequence to be plotted.
        Parameters:
        dx - graphics X coordinate
        dy - graphics Y coordinate
      • flush

        public void flush()
        Ensures that all points have been drawn. Since points are plotted in bursts for reasons of aesthetics and efficiency, this must be called after all addVertex(double, double) calls to ensure that the drawing has actually been done.