package javax.media.jai;
import java.awt.geom.AffineTransform;
import java.awt.geom.Point2D;
import java.awt.geom.NoninvertibleTransformException;
import java.io.Serializable;

public final class PerspectiveTransform implements Cloneable, Serializable {

    private static final double PERSPECTIVE_DIVIDE_EPSILON = 1.0e-10;

    double m00, m01, m02, m10, m11, m12, m20, m21, m22;

    /** Constructs an identity PerspectiveTransform. */
    public PerspectiveTransform() {
        m00 = m11 = m22 = 1.0;
        m01 = m02 = m10 = m12 = m20 = m21 = 0.0;
    }

    /**
     * Constructs a new PerspectiveTransform from 9 floats.
     */
    public PerspectiveTransform(float m00, float m01, float m02,
                                float m10, float m11, float m12,
                                float m20, float m21, float m22) {
        this.m00 = m00;
        this.m01 = m01;
        this.m02 = m02;
        this.m10 = m10;
        this.m11 = m11;
        this.m12 = m12;
        this.m20 = m20;
        this.m21 = m21;
        this.m22 = m22;
    }

    /**
     * Constructs a new PerspectiveTransform from 9 doubles.
     */
    public PerspectiveTransform(double m00, double m01, double m02,
                                double m10, double m11, double m12,
                                double m20, double m21, double m22) {
        this.m00 = m00;
        this.m01 = m01;
        this.m02 = m02;
        this.m10 = m10;
        this.m11 = m11;
        this.m12 = m12;
        this.m20 = m20;
        this.m21 = m21;
        this.m22 = m22;
    }

    public PerspectiveTransform(float[] flatmatrix) {
        if ( flatmatrix == null ) {
            throw new IllegalArgumentException(JaiI18N.getString("Generic0"));
        }

        m00 = flatmatrix[0];
        m01 = flatmatrix[1];
        m02 = flatmatrix[2];
        m10 = flatmatrix[3];
        m11 = flatmatrix[4];
        m12 = flatmatrix[5];
        m20 = flatmatrix[6];
        m21 = flatmatrix[7];
        m22 = flatmatrix[8];
    }

    public PerspectiveTransform(float[][] matrix) {
        if ( matrix == null ) {
            throw new IllegalArgumentException(JaiI18N.getString("Generic0"));
        }

        m00 = matrix[0][0];
        m01 = matrix[0][1];
        m02 = matrix[0][2];
        m10 = matrix[1][0];
        m11 = matrix[1][1];
        m12 = matrix[1][2];
        m20 = matrix[2][0];
        m21 = matrix[2][1];
        m22 = matrix[2][2];
    }

    public PerspectiveTransform(double[] flatmatrix) {
        if ( flatmatrix == null ) {
            throw new IllegalArgumentException(JaiI18N.getString("Generic0"));
        }

        m00 = flatmatrix[0];
        m01 = flatmatrix[1];
        m02 = flatmatrix[2];
        m10 = flatmatrix[3];
        m11 = flatmatrix[4];
        m12 = flatmatrix[5];
        m20 = flatmatrix[6];
        m21 = flatmatrix[7];
        m22 = flatmatrix[8];
    }

    /**
     * Constructs a new PerspectiveTransform from a two-dimensional
     * array of doubles.
     */
    public PerspectiveTransform(double[][] matrix) {
        if ( matrix == null ) {
            throw new IllegalArgumentException(JaiI18N.getString("Generic0"));
        }

        m00 = matrix[0][0];
        m01 = matrix[0][1];
        m02 = matrix[0][2];
        m10 = matrix[1][0];
        m11 = matrix[1][1];
        m12 = matrix[1][2];
        m20 = matrix[2][0];
        m21 = matrix[2][1];
        m22 = matrix[2][2];
    }

    /**
     * Constructs a new PerspectiveTransform with the same effect
     * as an existing AffineTransform.
     * @throws IllegalArgumentException if transform is null
     */
    public PerspectiveTransform(AffineTransform transform) {
        if ( transform == null ) {
            throw new IllegalArgumentException(JaiI18N.getString("Generic0"));
        }

        m00 = transform.getScaleX();
        m01 = transform.getShearX();
        m02 = transform.getTranslateX();
        m10 = transform.getShearY();
        m11 = transform.getScaleY();
        m12 = transform.getTranslateY();
        m20 = 0.0;
        m21 = 0.0;
        m22 = 1.0;
    }

    /**
     * Replaces the matrix with its adjoint.
     */
    private final void makeAdjoint() {
        double m00p = m11*m22 - m12*m21;
        double m01p = m12*m20 - m10*m22; 
        double m02p = m10*m21 - m11*m20;
        double m10p = m02*m21 - m01*m22;
        double m11p = m00*m22 - m02*m20;
        double m12p = m01*m20 - m00*m21;
        double m20p = m01*m12 - m02*m11;
        double m21p = m02*m10 - m00*m12;
        double m22p = m00*m11 - m01*m10;

        m00 = m00p;
        m01 = m10p;
        m02 = m20p;
        m10 = m01p;
        m11 = m11p;
        m12 = m21p;
        m20 = m02p;
        m21 = m12p;
        m22 = m22p;
    }

     private final void normalize() {
        double invscale = 1.0/m22;
        m00 *= invscale;
        m01 *= invscale;
        m02 *= invscale;
        m10 *= invscale;
        m11 *= invscale;
        m12 *= invscale;
        m20 *= invscale;
        m21 *= invscale;
        m22 = 1.0;
    }

    private static final void getSquareToQuad(double x0, double y0,
                                              double x1, double y1,
                                              double x2, double y2,
                                              double x3, double y3,
                                              PerspectiveTransform tx) {
        double dx3 = x0 - x1 + x2 - x3;
        double dy3 = y0 - y1 + y2 - y3;

        tx.m22 = 1.0F;

        if ((dx3 == 0.0F) && (dy3 == 0.0F)) { 
            tx.m00 = x1 - x0;
            tx.m01 = x2 - x1;
            tx.m02 = x0;
            tx.m10 = y1 - y0;
            tx.m11 = y2 - y1;
            tx.m12 = y0;
            tx.m20 = 0.0F;
            tx.m21 = 0.0F;
        } else {
            double dx1 = x1 - x2;
            double dy1 = y1 - y2;
            double dx2 = x3 - x2;
            double dy2 = y3 - y2;

            double invdet = 1.0F/(dx1*dy2 - dx2*dy1);
            tx.m20 = (dx3*dy2 - dx2*dy3)*invdet;
            tx.m21 = (dx1*dy3 - dx3*dy1)*invdet;
            tx.m00 = x1 - x0 + tx.m20*x1;
            tx.m01 = x3 - x0 + tx.m21*x3;
            tx.m02 = x0;
            tx.m10 = y1 - y0 + tx.m20*y1;
            tx.m11 = y3 - y0 + tx.m21*y3;
            tx.m12 = y0;
        }
    }

    public static PerspectiveTransform getSquareToQuad(double x0, double y0,
                                                       double x1, double y1,
                                                       double x2, double y2,
                                                       double x3, double y3) {
        PerspectiveTransform tx = new PerspectiveTransform();
        getSquareToQuad(x0, y0, x1, y1, x2, y2, x3, y3, tx);
        return tx;
    }


    public static PerspectiveTransform getSquareToQuad(float x0, float y0,
                                                       float x1, float y1,
                                                       float x2, float y2,
                                                       float x3, float y3) {
        return getSquareToQuad((double)x0, (double)y0,
                               (double)x1, (double)y1,
                               (double)x2, (double)y2,
                               (double)x3, (double)y3);
    }


    /**
     * Creates a PerspectiveTransform that maps an arbitrary
     * quadrilateral onto the unit square.
     */
    public static PerspectiveTransform getQuadToSquare(double x0, double y0,
                                                       double x1, double y1,
                                                       double x2, double y2,
                                                       double x3, double y3) {
        PerspectiveTransform tx = new PerspectiveTransform();
        getSquareToQuad(x0, y0, x1, y1, x2, y2, x3, y3, tx);
        tx.makeAdjoint();
        return tx;
    }

    /**
     * Creates a PerspectiveTransform that maps an arbitrary
     * quadrilateral onto the unit square.
     */
    public static PerspectiveTransform getQuadToSquare(float x0, float y0,
                                                       float x1, float y1,
                                                       float x2, float y2,
                                                       float x3, float y3) {
        return getQuadToSquare((double)x0, (double)y0,
                               (double)x1, (double)y1,
                               (double)x2, (double)y2,
                               (double)x3, (double)y3);
    }

    /**
     * Creates a PerspectiveTransform that maps an arbitrary
     * quadrilateral onto another arbitrary quadrilateral.
     */
    public static PerspectiveTransform getQuadToQuad(double x0, double y0,
                                                     double x1, double y1,
                                                     double x2, double y2,
                                                     double x3, double y3,
                                                     double x0p, double y0p,
                                                     double x1p, double y1p,
                                                     double x2p, double y2p,
                                                     double x3p, double y3p) {
        PerspectiveTransform tx1 =
                          getQuadToSquare(x0, y0, x1, y1, x2, y2, x3, y3);

        PerspectiveTransform tx2 =
                  getSquareToQuad(x0p, y0p, x1p, y1p, x2p, y2p, x3p, y3p);

        tx1.concatenate(tx2);
        return tx1;
    }


    /**
     * Creates a PerspectiveTransform that maps an arbitrary
     * quadrilateral onto another arbitrary quadrilateral.
     */
    public static PerspectiveTransform getQuadToQuad(float x0, float y0,
                                                     float x1, float y1,
                                                     float x2, float y2,
                                                     float x3, float y3,
                                                     float x0p, float y0p,
                                                     float x1p, float y1p,
                                                     float x2p, float y2p,
                                                     float x3p, float y3p) {
        return getQuadToQuad((double)x0, (double)y0,
                              (double)x1, (double)y1,
                              (double)x2, (double)y2,
                              (double)x3, (double)y3,
                              (double)x0p, (double)y0p,
                              (double)x1p, (double)y1p,
                              (double)x2p, (double)y2p,
                              (double)x3p, (double)y3p);
    }

    /**
     * Returns the determinant of the matrix representation of the
     * transform.
     */
    public double getDeterminant() {
	return ( (m00 * ((m11 * m22) - (m12 * m21))) -
                 (m01 * ((m10 * m22) - (m12 * m20))) +
                 (m02 * ((m10 * m21) - (m11 * m20))) );

    }

    /**
     * Retrieves the 9 specifiable values in the 3x3 affine
     * transformation matrix into an array of double precision values.
     * The values are stored into the array as
     * { m00 m01 m02 m10 m11 m12 m20 m21 m22 }.
     */
    public double[] getMatrix(double[] flatmatrix) {
        if (flatmatrix == null) {
            flatmatrix = new double[9];
        }

        flatmatrix[0] = m00;
        flatmatrix[1] = m01;
        flatmatrix[2] = m02;
        flatmatrix[3] = m10;
        flatmatrix[4] = m11;
        flatmatrix[5] = m12;
        flatmatrix[6] = m20;
        flatmatrix[7] = m21;
        flatmatrix[8] = m22;

        return flatmatrix;
    }

    /**
     * Retrieves the 9 specifiable values in the 3x3 affine
     * transformation matrix into a 2-dimensional array of double
     * precision values.  The values are stored into the 2-dimensional
     * array using the row index as the first subscript and the column
     * index as the second.
     *
     */
    public double[][] getMatrix(double[][] matrix) {
        if (matrix == null) {
            matrix = new double[3][3];
        }

        matrix[0][0] = m00;
        matrix[0][1] = m01;
        matrix[0][2] = m02;
        matrix[1][0] = m10;
        matrix[1][1] = m11;
        matrix[1][2] = m12;
        matrix[2][0] = m20;
        matrix[2][1] = m21;
        matrix[2][2] = m22;

        return matrix;
    }

    /**
     * Concatenates this transform with a translation transformation.
     */
    public void translate(double tx, double ty) {
        PerspectiveTransform Tx = new PerspectiveTransform();
        Tx.setToTranslation(tx, ty);
        concatenate(Tx);
    }

    /**
     * Concatenates this transform with a rotation transformation.
     */
    public void rotate(double theta) {
        PerspectiveTransform Tx = new PerspectiveTransform();
        Tx.setToRotation(theta);
        concatenate(Tx);
    }

    /**
     * Concatenates this transform with a translated rotation transformation.
     */
    public void rotate(double theta, double x, double y) {
        PerspectiveTransform Tx = new PerspectiveTransform();
        Tx.setToRotation(theta, x, y);
        concatenate(Tx);
    }

    /**
     * Concatenates this transform with a scaling transformation.
     */
    public void scale(double sx, double sy) {
        PerspectiveTransform Tx = new PerspectiveTransform();
        Tx.setToScale(sx, sy);
        concatenate(Tx);
    }

    /**
     * Concatenates this transform with a shearing transformation.
     */
    public void shear(double shx, double shy) {
        PerspectiveTransform Tx = new PerspectiveTransform();
        Tx.setToShear(shx, shy);
        concatenate(Tx);
    }

    /**
     * Resets this transform to the Identity transform.
     */
    public void setToIdentity() {
        m00 = m11 = m22 = 1.0;
        m01 = m10 = m02 = m20 = m12 = m21 = 0.0;
    }

    /**
     * Sets this transform to a translation transformation.
     */
    public void setToTranslation(double tx, double ty) {
        m00 = 1.0;
        m01 = 0.0;
        m02 = tx;
        m10 = 0.0;
        m11 = 1.0;
        m12 = ty;
        m20 = 0.0;
        m21 = 0.0;
        m22 = 1.0;
    }

    /**
     * Sets this transform to a rotation transformation.
     */
    public void setToRotation(double theta) {
        m00 = Math.cos(theta);
        m01 = -Math.sin(theta);
        m02 = 0.0;
        m10 = - m01;
        m11 = m00;
        m12 = 0.0;
        m20 = 0.0;
        m21 = 0.0;
        m22 = 1.0;
    }

    public void setToRotation(double theta, double x, double y) {
        setToRotation(theta);
	double sin = m10;
	double oneMinusCos = 1.0 - m00;
	m02 = x * oneMinusCos + y * sin;
	m12 = y * oneMinusCos - x * sin;
    }

    public void setToScale(double sx, double sy) {
        m00 = sx;
        m01 = 0.0;
        m02 = 0.0;
        m10 = 0.0;
        m11 = sy;
        m12 = 0.0;
        m20 = 0.0;
        m21 = 0.0;
        m22 = 1.0;
    }

    /**
     * Sets this transform to a shearing transformation
     * with shear factors sx and sy.
     */
    public void setToShear(double shx, double shy) {
        m00 = 1.0;
        m01 = shx;
        m02 = 0.0;
        m10 = shy;
        m11 = 1.0;
        m12 = 0.0;
        m20 = 0.0;
        m21 = 0.0;
        m22 = 1.0;
    }

    /**
     * Sets this transform to a given AffineTransform.
     * @throws IllegalArgumentException if Tx is null
     */
    public void setTransform(AffineTransform Tx) {
        if ( Tx == null ) {
            throw new IllegalArgumentException(JaiI18N.getString("Generic0"));
        }

        m00 = Tx.getScaleX();
        m01 = Tx.getShearX();
        m02 = Tx.getTranslateX();
        m10 = Tx.getShearY();
        m11 = Tx.getScaleY();
        m12 = Tx.getTranslateY();
        m20 = 0.0;
        m21 = 0.0;
        m22 = 1.0;
    }

    /**
     * Sets this transform to a given PerspectiveTransform.
     * @throws IllegalArgumentException if Tx is null
     */
    public void setTransform(PerspectiveTransform Tx) {
        if ( Tx == null ) {
            throw new IllegalArgumentException(JaiI18N.getString("Generic0"));
        }

        m00 = Tx.m00;
        m01 = Tx.m01;
        m02 = Tx.m02;
        m10 = Tx.m10;
        m11 = Tx.m11;
        m12 = Tx.m12;
        m20 = Tx.m20;
        m21 = Tx.m21;
        m22 = Tx.m22;
    }

    public void setTransform(float m00, float m10, float m20,
                             float m01, float m11, float m21,
                             float m02, float m12, float m22) {
        this.m00 = (double)m00;
        this.m01 = (double)m01;
        this.m02 = (double)m02;
        this.m10 = (double)m10;
        this.m11 = (double)m11;
        this.m12 = (double)m12;
        this.m20 = (double)m20;
        this.m21 = (double)m21;
        this.m22 = (double)m22;
    }

    public void setTransform(double[][] matrix) {
        if ( matrix == null ) {
            throw new IllegalArgumentException(JaiI18N.getString("Generic0"));
        }

        m00 = matrix[0][0];
        m01 = matrix[0][1];
        m02 = matrix[0][2];
        m10 = matrix[1][0];
        m11 = matrix[1][1];
        m12 = matrix[1][2];
        m20 = matrix[2][0];
        m21 = matrix[2][1];
        m22 = matrix[2][2];
    }

    /**
     * Post-concatenates a given AffineTransform to this transform.
     * @throws IllegalArgumentException if Tx is null
     */
    public void concatenate(AffineTransform Tx) {
        if ( Tx == null ) {
            throw new IllegalArgumentException(JaiI18N.getString("Generic0"));
        }

        double tx_m00 = Tx.getScaleX();
        double tx_m01 = Tx.getShearX();
        double tx_m02 = Tx.getTranslateX();
        double tx_m10 = Tx.getShearY();
        double tx_m11 = Tx.getScaleY();
        double tx_m12 = Tx.getTranslateY();

        double m00p = m00*tx_m00 + m10*tx_m01 + m20*tx_m02;
        double m01p = m01*tx_m00 + m11*tx_m01 + m21*tx_m02;
        double m02p = m02*tx_m00 + m12*tx_m01 + m22*tx_m02;
        double m10p = m00*tx_m10 + m10*tx_m11 + m20*tx_m12;
        double m11p = m01*tx_m10 + m11*tx_m11 + m21*tx_m12;
        double m12p = m02*tx_m10 + m12*tx_m11 + m22*tx_m12;
        double m20p = m20;
        double m21p = m21;
        double m22p = m22;

        m00 = m00p;
        m10 = m10p;
        m20 = m20p;
        m01 = m01p;
        m11 = m11p;
        m21 = m21p;
        m02 = m02p;
        m12 = m12p;
        m22 = m22p;
    }

    /**
     * Post-concatenates a given PerspectiveTransform to this transform.
     * @throws IllegalArgumentException if Tx is null
     */
    public void concatenate(PerspectiveTransform Tx) {
        if ( Tx == null ) {
            throw new IllegalArgumentException(JaiI18N.getString("Generic0"));
        }

        double m00p = m00*Tx.m00 + m10*Tx.m01 + m20*Tx.m02;
        double m10p = m00*Tx.m10 + m10*Tx.m11 + m20*Tx.m12;
        double m20p = m00*Tx.m20 + m10*Tx.m21 + m20*Tx.m22;
        double m01p = m01*Tx.m00 + m11*Tx.m01 + m21*Tx.m02;
        double m11p = m01*Tx.m10 + m11*Tx.m11 + m21*Tx.m12;
        double m21p = m01*Tx.m20 + m11*Tx.m21 + m21*Tx.m22;
        double m02p = m02*Tx.m00 + m12*Tx.m01 + m22*Tx.m02;
        double m12p = m02*Tx.m10 + m12*Tx.m11 + m22*Tx.m12;
        double m22p = m02*Tx.m20 + m12*Tx.m21 + m22*Tx.m22;

        m00 = m00p;
        m10 = m10p;
        m20 = m20p;
        m01 = m01p;
        m11 = m11p;
        m21 = m21p;
        m02 = m02p;
        m12 = m12p;
        m22 = m22p;
    }

    /**
     * Pre-concatenates a given AffineTransform to this transform.
     * @throws IllegalArgumentException if Tx is null
     */
    public void preConcatenate(AffineTransform Tx) {
        if ( Tx == null ) {
            throw new IllegalArgumentException(JaiI18N.getString("Generic0"));
        }

        // Extend Tx: Tx.m20 = 0, Tx.m21 = 0, Tx.m22 = 1

        double tx_m00 = Tx.getScaleX();
        double tx_m01 = Tx.getShearX();
        double tx_m02 = Tx.getTranslateX();
        double tx_m10 = Tx.getShearY();
        double tx_m11 = Tx.getScaleY();
        double tx_m12 = Tx.getTranslateY();

        double m00p = tx_m00*m00 + tx_m10*m01;
        double m01p = tx_m01*m00 + tx_m11*m01;
        double m02p = tx_m02*m00 + tx_m12*m01 + m02;
        double m10p = tx_m00*m10 + tx_m10*m11;
        double m11p = tx_m01*m10 + tx_m11*m11;
        double m12p = tx_m02*m10 + tx_m12*m11 + m12;
        double m20p = tx_m00*m20 + tx_m10*m21;
        double m21p = tx_m01*m20 + tx_m11*m21;
        double m22p = tx_m02*m20 + tx_m12*m21 + m22;

        m00 = m00p;
        m10 = m10p;
        m20 = m20p;
        m01 = m01p;
        m11 = m11p;
        m21 = m21p;
        m02 = m02p;
        m12 = m12p;
        m22 = m22p;
    }

    /**
     * Pre-concatenates a given PerspectiveTransform to this transform.
     * @throws IllegalArgumentException if Tx is null
     */
    public void preConcatenate(PerspectiveTransform Tx) {
        if ( Tx == null ) {
            throw new IllegalArgumentException(JaiI18N.getString("Generic0"));
        }

        double m00p = Tx.m00*m00 + Tx.m10*m01 + Tx.m20*m02;
        double m10p = Tx.m00*m10 + Tx.m10*m11 + Tx.m20*m12;
        double m20p = Tx.m00*m20 + Tx.m10*m21 + Tx.m20*m22;
        double m01p = Tx.m01*m00 + Tx.m11*m01 + Tx.m21*m02;
        double m11p = Tx.m01*m10 + Tx.m11*m11 + Tx.m21*m12;
        double m21p = Tx.m01*m20 + Tx.m11*m21 + Tx.m21*m22;
        double m02p = Tx.m02*m00 + Tx.m12*m01 + Tx.m22*m02;
        double m12p = Tx.m02*m10 + Tx.m12*m11 + Tx.m22*m12;
        double m22p = Tx.m02*m20 + Tx.m12*m21 + Tx.m22*m22;

        m00 = m00p;
        m10 = m10p;
        m20 = m20p;
        m01 = m01p;
        m11 = m11p;
        m21 = m21p;
        m02 = m02p;
        m12 = m12p;
        m22 = m22p;
    }

    /**
     * Returns a new PerpectiveTransform that is the inverse
     * of the current transform.
     * @throws NoninvertibleTransformException if transform cannot be inverted
     */
     public PerspectiveTransform createInverse()
         throws NoninvertibleTransformException, CloneNotSupportedException {

	     PerspectiveTransform tx = (PerspectiveTransform)clone();
	     tx.makeAdjoint();
	     if (Math.abs(tx.m22) <  PERSPECTIVE_DIVIDE_EPSILON) {
  	       throw new NoninvertibleTransformException(JaiI18N.getString("PerspectiveTransform0"));
	     }
	     tx.normalize();
	     return tx;
    }

    /**
     * Returns a new PerpectiveTransform that is the adjoint,
     * of the current transform.  The adjoint is defined as
     * the matrix of cofactors, which in turn are the determinants
     * of the submatrices defined by removing the row and column
     * of each element from the original matrix in turn.
     */
    public PerspectiveTransform createAdjoint()
    throws CloneNotSupportedException{

	    PerspectiveTransform tx = (PerspectiveTransform)clone();
	    tx.makeAdjoint();
	    return tx;
    }

    /**
     * Transforms the specified ptSrc and stores the result in ptDst.
     * If ptDst is null, a new Point2D object will be allocated before
     * storing. In either case, ptDst containing the transformed point
     * is returned for convenience.
     * Note that ptSrc and ptDst can the same. In this case, the input
     * point will be overwritten with the transformed point.
     * @throws IllegalArgumentException if ptSrc is null
     */
    public Point2D transform(Point2D ptSrc, Point2D ptDst) {
        if ( ptSrc == null ) {
            throw new IllegalArgumentException(JaiI18N.getString("Generic0"));
        }

        if (ptDst == null) {
            if (ptSrc instanceof Point2D.Double) {
                ptDst = new Point2D.Double();
            } else {
                ptDst = new Point2D.Float();
            }
        }

        double x = ptSrc.getX();
        double y = ptSrc.getY();
        double w = m20 * x + m21 * y + m22;
        ptDst.setLocation((m00 * x + m01 * y + m02) / w,
                          (m10 * x + m11 * y + m12) / w);

        return ptDst;
    }

    /**
     * Transforms an array of point objects by this transform.
     * @throws IllegalArgumentException if ptSrc is null
     * @throws IllegalArgumentException if ptDst is null
     * @throws ArrayIndexOutOfBoundsException if ptSrc is too small
     */
    public void transform(Point2D[] ptSrc, int srcOff,
			  Point2D[] ptDst, int dstOff,
			  int numPts) {

        if ( ptSrc == null || ptDst == null ) {
            throw new IllegalArgumentException(JaiI18N.getString("Generic0"));
        }

        while (numPts-- > 0) {
            Point2D src = ptSrc[srcOff++];
            Point2D dst = ptDst[dstOff++];
            if (dst == null) {
                if (src instanceof Point2D.Double) {
                    dst = new Point2D.Double();
                } else {
                    dst = new Point2D.Float();
                }
                ptDst[dstOff - 1] = dst;
            }

            double x = src.getX();
            double y = src.getY();
            double w = m20 * x + m21 * y + m22;

            if (w == 0) {
                dst.setLocation(x, y);
            } else {
                dst.setLocation((m00 * x + m01 * y + m02) / w,
                                (m10 * x + m11 * y + m12) / w);
            }
        }
    }

    /**
     * Transforms an array of floating point coordinates by this transform.
     * @throws IllegalArgumentException if srcPts is null
     * @throws ArrayIndexOutOfBoundsException if srcPts is too small
     */
    public void transform(float[] srcPts, int srcOff,
			  float[] dstPts, int dstOff,
			  int numPts) {

        if ( srcPts == null ) {
            throw new IllegalArgumentException(JaiI18N.getString("Generic0"));
        }

        if (dstPts == null) {
            dstPts = new float[numPts * 2 + dstOff];
        }

        while (numPts-- > 0) {
            float x = srcPts[srcOff++];
            float y = srcPts[srcOff++];
            double w = m20 * x + m21 * y + m22;

            if (w == 0) {
                dstPts[dstOff++] = x;
                dstPts[dstOff++] = y;
            } else {
                dstPts[dstOff++] = (float)((m00 * x + m01 * y + m02) / w);
                dstPts[dstOff++] = (float)((m10 * x + m11 * y + m12) / w);
            }
        }
    }

    /**
     * Transforms an array of double precision coordinates by this transform.
     * @throws IllegalArgumentException if srcPts is null
     * @throws ArrayIndexOutOfBoundsException if srcPts is too small
     */
    public void transform(double[] srcPts, int srcOff,
			  double[] dstPts, int dstOff,
			  int numPts) {

        if ( srcPts == null ) {
            throw new IllegalArgumentException(JaiI18N.getString("Generic0"));
        }

        if (dstPts == null) {
            dstPts = new double[numPts * 2 + dstOff];
        }

        while (numPts-- > 0) {
            double x = srcPts[srcOff++];
            double y = srcPts[srcOff++];
            double w = m20 * x + m21 * y + m22;

            if (w == 0) {
                dstPts[dstOff++] = x;
                dstPts[dstOff++] = y;
            } else {
                dstPts[dstOff++] = (m00 * x + m01 * y + m02) / w;
                dstPts[dstOff++] = (m10 * x + m11 * y + m12) / w;
            }
        }
    }

    /**
     * Transforms an array of floating point coordinates by this transform,
     * storing the results into an array of doubles.
     * @throws IllegalArgumentException if srcPts is null
     * @throws ArrayIndexOutOfBoundsException if srcPts is too small
     */
    public void transform(float[] srcPts, int srcOff,
			  double[] dstPts, int dstOff,
			  int numPts) {

        if ( srcPts == null ) {
            throw new IllegalArgumentException(JaiI18N.getString("Generic0"));
        }

        if (dstPts == null) {
            dstPts = new double[numPts * 2 + dstOff];
        }

        while (numPts-- > 0) {
            float x = srcPts[srcOff++];
            float y = srcPts[srcOff++];
            double w = m20 * x + m21 * y + m22;

            if (w == 0) {
                dstPts[dstOff++] = x;
                dstPts[dstOff++] = y;
            } else {
                dstPts[dstOff++] = (m00 * x + m01 * y + m02) / w;
                dstPts[dstOff++] = (m10 * x + m11 * y + m12) / w;
            }
        }
    }

    /**
     * Transforms an array of double precision coordinates by this transform,
     * storing the results into an array of floats.
     * @throws IllegalArgumentException if srcPts is null
     * @throws ArrayIndexOutOfBoundsException if srcPts is too small
     */
    public void transform(double[] srcPts, int srcOff,
			  float[] dstPts, int dstOff,
			  int numPts) {

        if ( srcPts == null ) {
            throw new IllegalArgumentException(JaiI18N.getString("Generic0"));
        }

        if (dstPts == null) {
            dstPts = new float[numPts * 2 + dstOff];
        }

        while (numPts-- > 0) {
            double x = srcPts[srcOff++];
            double y = srcPts[srcOff++];
            double w = m20 * x + m21 * y + m22;

            if (w == 0) {
                dstPts[dstOff++] = (float)x;
                dstPts[dstOff++] = (float)y;
            } else {
                dstPts[dstOff++] = (float)((m00 * x + m01 * y + m02) / w);
                dstPts[dstOff++] = (float)((m10 * x + m11 * y + m12) / w);
            }
        }
    }

    /**
     * Inverse transforms the specified ptSrc and stores the result in ptDst.
     * If ptDst is null, a new Point2D object will be allocated before
     * storing. In either case, ptDst containing the transformed point
     * is returned for convenience.
   
     * @throws NoninvertibleTransformException  if the matrix cannot be inverted.
     * @throws IllegalArgumentException if ptSrc is null
     */
    public Point2D inverseTransform(Point2D ptSrc, Point2D ptDst)
	throws NoninvertibleTransformException
    {
        if ( ptSrc == null ) {
            throw new IllegalArgumentException(JaiI18N.getString("Generic0"));
        }

        if (ptDst == null) {
	    if (ptSrc instanceof Point2D.Double) {
		ptDst = new Point2D.Double();
	    } else {
		ptDst = new Point2D.Float();
	    }
	}
	// Copy source coords into local variables in case src == dst
	double x = ptSrc.getX();
	double y = ptSrc.getY();

        double tmp_x = (m11*m22 - m12*m21) * x +
            (m02*m21 - m01*m22) * y +
            (m01*m12 - m02*m11);
        double tmp_y = (m12*m20 - m10*m22) * x +
            (m00*m22 - m02*m20) * y +
            (m02*m10 - m00*m12);
        double w = (m10*m21 - m11*m20) * x +
            (m01*m20 - m00*m21) * y +
            (m00*m11 - m01*m10);

        double wabs = w;
        if (w < 0) {
            wabs = - w;
        }
        if (wabs < PERSPECTIVE_DIVIDE_EPSILON) {
            throw new
		NoninvertibleTransformException(
				     JaiI18N.getString("PerspectiveTransform1"));
        }

        ptDst.setLocation(tmp_x/w, tmp_y/w);

        return ptDst;
    }

    /**
     * Inverse transforms an array of double precision coordinates by
     * this transform.
     * @throws NoninvertibleTransformException  if the matrix cannot be inverted.
     * @throws IllegalArgumentException if srcPts is null
     * @throws ArrayIndexOutOfBoundsException if srcPts is too small
     * @throws NoninvertibleTransformException transform cannot be inverted
     */
    public void inverseTransform(double[] srcPts, int srcOff,
                                 double[] dstPts, int dstOff,
                                 int numPts)
        throws NoninvertibleTransformException
    {
        if ( srcPts == null ) {
            throw new IllegalArgumentException(JaiI18N.getString("Generic0"));
        }

        if (dstPts == null) {
            dstPts = new double[numPts * 2 + dstOff];
        }

        while (numPts-- > 0) {
            double x = srcPts[srcOff++];
            double y = srcPts[srcOff++];

            double tmp_x = (m11*m22 - m12*m21) * x +
                (m02*m21 - m01*m22) * y +
                (m01*m12 - m02*m11);
            double tmp_y = (m12*m20 - m10*m22) * x +
                (m00*m22 - m02*m20) * y +
                (m02*m10 - m00*m12);
            double w = (m10*m21 - m11*m20) * x +
                (m01*m20 - m00*m21) * y +
                (m00*m11 - m01*m10);

            double wabs = w;
            if (w < 0) {
                wabs = - w;
            }
            if (wabs < PERSPECTIVE_DIVIDE_EPSILON) {
                throw new NoninvertibleTransformException(
				    JaiI18N.getString("PerspectiveTransform1"));
            }

            dstPts[dstOff++] = tmp_x / w;
            dstPts[dstOff++] = tmp_y / w;
        }
    }

    /**
     * Returns a String that represents the value of this Object.
     */
    public String toString() {
        StringBuffer sb = new StringBuffer();
        sb.append("Perspective transform matrix\n");
        sb.append(this.m00);
        sb.append("\t");
        sb.append(this.m01);
        sb.append("\t");
        sb.append(this.m02);
        sb.append("\n");
        sb.append(this.m10);
        sb.append("\t");
        sb.append(this.m11);
        sb.append("\t");
        sb.append(this.m12);
        sb.append("\n");
        sb.append(this.m20);
        sb.append("\t");
        sb.append(this.m21);
        sb.append("\t");
        sb.append(this.m22);
        sb.append("\n");
        return new String(sb);
    }

    /**
     * Returns the boolean true value if this PerspectiveTransform is an
     * identity transform. Returns false otherwise.
     */
    public boolean isIdentity() {
        return m01 == 0.0 && m02 == 0.0 &&
            m10 == 0.0 && m12 == 0.0 &&
            m20 == 0.0 && m21 == 0.0 &&
            m22 != 0.0 && m00/m22 == 1.0 && m11/m22 == 1.0;
    }

    /**
     * Returns a copy of this PerspectiveTransform object.
     */
    public Object clone() {
	try {
	    return super.clone();
	} catch (CloneNotSupportedException e) {
	    // this shouldn't happen, since we are Cloneable
	    throw new InternalError();
	}
    }


    /**
     * Tests if this PerspectiveTransform equals a supplied one.
     */
    public boolean equals(Object obj) {
        if (!(obj instanceof PerspectiveTransform)) {
            return false;
        }

        PerspectiveTransform a = (PerspectiveTransform)obj;

	return ((m00 == a.m00) && (m10 == a.m10) && (m20 == a.m20) &&
		(m01 == a.m01) && (m11 == a.m11) && (m21 == a.m21) &&
		(m02 == a.m02) && (m12 == a.m12) && (m22 == a.m22));
    }
}
