Name: boT120536 Date: 03/23/2001


java version "1.3.1-beta"
java(tm) 2 runtime environment, standard edition (build 1.3.1-beta-b15)
java hotspot(tm) client vm (build 1.3.1beta-b15, mixed mode)

// To transform a Line2D without turning it into a GeneralPath,
// the following hack works:

private Line2D line;

void transform(AffineTransform transform) {
  double[] array = new double[4];
  array[0] = line.getX1();
  array[1] = line.getY1();
  array[2] = line.getX2();
  array[3] = line.getY2();
  transform.transform(array, 0, array, 0, 2);
  line.setLine(array[0], array[1], array[2], array[3]);
}

// But what do you do with an Ellipse? If you try the hack above, it won't
// work for a rotate transform:

private Ellipse2D ellipse;

void transform(AffineTransform transform) {
  double[] array = new double[4];
  array[0] = ellipse.getX();
  array[1] = ellipse.getY();
  array[2] = ellipse.getWidth();
  array[3] = ellipse.getHeight();
  transform.transform(array, 0, array, 0, 2);
  ellipse.setFrame(array[0], array[1], array[2], array[3]);
}

// I submitted two earlier bug reports on this issue, but now I realize it
// is really much more serious than I had first imagined.
// First of all, there is no way to use an AffineTransform to transform a shape
// without getting back a GeneralPath object. Now I understand that some classes
// (i.e. Ellipse2D) cannot represent the shape once it has been transformed.
// For example, the Ellipse2D cannot represent an Ellipse once it has been
// rotated. Therefore, once a transform has been applied, one must work with
// a GeneralPath object. This is a SERIOUS design flaw, much like cloning
// ObjectA and getting back (an unrelated) ObjectB. How can you create a
// good design in this situation?
// Furthermore, in the case (for example) of the rotated
// Ellipse2D, you can't even get the points from the GeneralPath that
// model the transformed shape. You can only get the PathIterator, which
// then gives you (say) the later 3 points of a cubic ("cube to"), but not the
// starting point!!
(Review ID: 119351)
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