TestEllipticalArcTo.java

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package org.apache.poi.xdgf.usermodel.section.geometry;

import com.microsoft.schemas.office.visio.x2012.main.RowType;
import org.junit.jupiter.api.Test;

import java.awt.geom.Arc2D;
import java.awt.geom.Path2D;
import java.util.HashMap;

public class TestEllipticalArcTo {

    private static final double X0 = 0.0;
    private static final double Y0 = 0.0;
    private static final double R = 100.0;
    private static final double X = R;
    private static final double Y = R;
    // Rotation angle does not affect the calculation
    private static final double C = 0.0;
    // Draw a circular arc, it does not matter for this test which type of arc we draw
    private static final double D = 1.0;

    @Test
    public void shouldAddArcToPathWhenControlPointIsNotColinearWithBeginAndEnd() {
        double a = R / 2.0;
        double b = R - Math.sqrt(R * R - a * a);
        EllipticalArcTo ellipticalArcTo = createEllipticalArcTo(a, b);

        Path2D.Double actualPath = new Path2D.Double();
        actualPath.moveTo(X0, Y0);

        // Shape isn't used while creating an elliptical arc
        ellipticalArcTo.addToPath(actualPath, null);

        Path2D.Double expectedPath = new Path2D.Double();
        expectedPath.moveTo(X0, Y0);
        Arc2D arc = new Arc2D.Double(-R, Y0, R * 2, R * 2, 90, -90, Arc2D.OPEN);
        expectedPath.append(arc, false);

        GeometryTestUtils.assertPath(expectedPath, actualPath);
    }

    @Test
    public void shouldAddLineToPathWhenControlPointIsColinearWithBeginAndEnd() {
        // We artificially set control point that is obviously colinear with begin and end.
        // However, when you draw a very small arc, it might happen that all three points are colinear to each other
        EllipticalArcTo ellipticalArcTo = createEllipticalArcTo(50.0, 50.0);

        Path2D.Double actualPath = new Path2D.Double();
        actualPath.moveTo(X0, Y0);

        // Shape isn't used while creating an elliptical arc
        ellipticalArcTo.addToPath(actualPath, null);

        Path2D.Double expectedPath = new Path2D.Double();
        expectedPath.moveTo(X0, Y0);
        expectedPath.lineTo(X, Y);

        GeometryTestUtils.assertPath(expectedPath, actualPath);
    }

    private static EllipticalArcTo createEllipticalArcTo(double a, double b) {
        RowType row = GeometryTestUtils.createRow(
                0L,
                new HashMap<String, Object>() {{
                    put("X", X);
                    put("Y", Y);
                    put("A", a);
                    put("B", b);
                    put("C", C);
                    put("D", D);
                }}
        );
        return new EllipticalArcTo(row);
    }

}