Again, thanks for the update, I've incorporated it into the latest version of the code for the next release. I added a static method to BasicGeometry that also takes a Shape object as an argument.
- Don
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Don Dietrick
_at_dfdietrick
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On Thursday, March 15, 2012 at 3:47 PM, Lecomte, J-Francois wrote:
>
> The method distanceToEdge(int x, int y) in class BasicGeometry does not handle the SEG_CLOSE properly, here is a JUnit4 test to illustrate the problem:
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>
>
>
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> public class BasicGeometryTest
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> {
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> private static final float DELTA = 0.00001f;
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>
>
>
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> /**
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> * Test method for {_at_link BasicGeometry#distanceToEdge(int, int)}.
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> *
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> * The shape tested looks like this:
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> *
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> * <pre>
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>
> * |
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> * | p2__p3
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> * | | |
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> * | |__|
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> * | p1 p4
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> * |__________________
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> *
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> * p1:(1, 1)
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> * p2:(1, 3)
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> * p3:(3, 3)
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> * p4:(3, 1)
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> * </pre>
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>
> */
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>
> _at_Test
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> public void testDistanceToEdge()
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> {
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> final Polygon shape = new Polygon();
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> shape.addPoint(1, 1);
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> shape.addPoint(1, 3);
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> shape.addPoint(3, 3);
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> shape.addPoint(3, 1);
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> final MyBasicGeometry geometry = new MyBasicGeometry(new GeneralPath(shape));
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> // Test points on line
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> assertEquals(0, geometry.distanceToEdge(1, 1), 0);
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> assertEquals(0, geometry.distanceToEdge(1, 2), 0);
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> assertEquals(0, geometry.distanceToEdge(1, 3), 0);
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> assertEquals(0, geometry.distanceToEdge(2, 1), 0); // Fails here but should not!
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> assertEquals(0, geometry.distanceToEdge(2, 3), 0);
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> assertEquals(0, geometry.distanceToEdge(3, 1), 0);
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> assertEquals(0, geometry.distanceToEdge(3, 2), 0);
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> assertEquals(0, geometry.distanceToEdge(3, 3), 0);
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>
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> // Test point inside
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> assertEquals(1, geometry.distanceToEdge(2, 2), 0);
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>
>
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> // Test distance from the left
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> assertEquals(Math.sqrt(2), geometry.distanceToEdge(0, 0), DELTA);
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> assertEquals(1, geometry.distanceToEdge(0, 1), 0);
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> assertEquals(1, geometry.distanceToEdge(0, 2), 0);
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> assertEquals(1, geometry.distanceToEdge(0, 3), 0);
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> assertEquals(Math.sqrt(2), geometry.distanceToEdge(0, 4), DELTA);
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>
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> // Test distance from the right
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> assertEquals(Math.sqrt(2), geometry.distanceToEdge(4, 0), DELTA);
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> assertEquals(1, geometry.distanceToEdge(4, 1), 0);
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> assertEquals(1, geometry.distanceToEdge(4, 2), 0);
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> assertEquals(1, geometry.distanceToEdge(4, 3), 0);
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> assertEquals(Math.sqrt(2), geometry.distanceToEdge(4, 4), DELTA);
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>
>
>
>
> // Test distance from the bottom
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> assertEquals(1, geometry.distanceToEdge(1, 0), 0);
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> assertEquals(1, geometry.distanceToEdge(2, 0), 0);
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> assertEquals(1, geometry.distanceToEdge(3, 0), 0);
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>
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> // Test distance from the top
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> assertEquals(1, geometry.distanceToEdge(1, 4), 0);
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> assertEquals(1, geometry.distanceToEdge(2, 4), 0);
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> assertEquals(1, geometry.distanceToEdge(3, 4), 0);
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> }
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>
>
>
>
> private static class MyBasicGeometry extends OMGraphic
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> {
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> public MyBasicGeometry(final GeneralPath shape)
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> {
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> super.shape = shape;
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> super.needToRegenerate = false;
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> }
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>
>
>
> _at_Override
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> public boolean generate(final Projection proj)
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> {
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> return false; // Whatever, I'm not using it...
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> }
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>
> }
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>
> }
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>
>
>
>
> Here is an implementation of the method that fixes the problem:
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>
>
>
>
> /**
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> * Return the shortest distance from the edge of a shape to an XY-point.
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> * <p>
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> * Method taken and adapted from {_at_link BasicGeometry#distanceToEdge(int, int)}
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>
> *
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> * _at_param x X coordinate of the point.
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> * _at_param y Y coordinate of the point.
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> * _at_return float distance, in pixels, from graphic to the point. Returns
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> * Float.POSITIVE_INFINITY if the graphic isn't ready (ungenerated).
>
>
> */
>
>
> _at_Override
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> public float distanceToEdge(final int x, final int y)
>
>
> {
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> float distance = Float.POSITIVE_INFINITY;
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>
>
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> if(getNeedToRegenerate() || shape == null)
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> {
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> return distance;
>
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> }
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>
>
>
>
> final PathIterator pi2 = shape.getPathIterator(null);
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> final FlatteningPathIterator pathIt = new FlatteningPathIterator(pi2, .25);
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> final double[] coords = new double[6];
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> double endPntX = Double.NaN;
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> double endPntY = Double.NaN;
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>
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> double lastMovedToPntX = Double.NaN;
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> double lastMovedToPntY = Double.NaN;
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>
>
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> while(!pathIt.isDone())
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> {
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> final int type = pathIt.currentSegment(coords);
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>
>
>
> if(type == PathIterator.SEG_LINETO)
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> {
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> final double startPntX = endPntX;
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> final double startPntY = endPntY;
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>
> endPntX = coords[0];
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> endPntY = coords[1];
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>
>
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> final float dist = (float) Line2D.ptSegDist(startPntX, startPntY, endPntX,
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> endPntY, x, y);
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>
>
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> if(dist < distance)
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> {
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> distance = dist;
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> }
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> }
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> else if(type == PathIterator.SEG_MOVETO)
>
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> {
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> endPntX = coords[0];
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> endPntY = coords[1];
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> lastMovedToPntX = coords[0];
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> lastMovedToPntY = coords[1];
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> }
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> else if(type == PathIterator.SEG_CLOSE)
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>
> {
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> final double startPntX = lastMovedToPntX;
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> final double startPntY = lastMovedToPntY;
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> endPntX = coords[0];
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> endPntY = coords[1];
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>
>
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> final float dist = (float) Line2D.ptSegDist(startPntX, startPntY, endPntX,
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> endPntY, x, y);
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>
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> if(dist < distance)
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> {
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> distance = dist;
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> }
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> }
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>
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> pathIt.next();
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> }
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> return distance;
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> }
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>
>
>
>
> I joined as attachment a bunch of JUnit4 tests to validate this method.
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>
>
>
>
> Also, I suggest this method be moved as a static public method in a Shape Utility class so it can be used without a “BasicGeometry” object (the shape object obviously should be received as parameter).
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Received on Thu Mar 15 2012 - 18:57:32 EDT