affinetransform.java

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    double n11 = tx.m10 * m01 + tx.m11 * m11;
    double n12 = tx.m10 * m02 + tx.m11 * m12 + tx.m12;
    m00 = n00;
    m01 = n01;
    m02 = n02;
    m10 = n10;
    m11 = n11;
    m12 = n12;
    updateType();
  }

  /**
   * Returns a transform, which if concatenated to this one, will result in
   * the identity transform. This is useful for undoing transformations, but
   * is only possible if the original transform has an inverse (ie. does not
   * map multiple points to the same line or point). A transform exists only
   * if getDeterminant() has a non-zero value.
   *
   * @return a new inverse transform
   * @throws NoninvertibleTransformException if inversion is not possible
   * @see #getDeterminant()
   */
  public AffineTransform createInverse()
    throws NoninvertibleTransformException
  {
    double det = getDeterminant();
    if (det == 0)
      throw new NoninvertibleTransformException("can't invert transform");
    return new AffineTransform(m11 / det, -m10 / det, m01 / det, -m00 / det,
                               -m02, -m12);
  }

  /**
   * Perform this transformation on the given source point, and store the
   * result in the destination (creating it if necessary). It is safe for
   * src and dst to be the same.
   *
   * @param src the source point
   * @param dst the destination, or null
   * @return the transformation of src, in dst if it was non-null
   * @throws NullPointerException if src is null
   */
  public Point2D transform(Point2D src, Point2D dst)
  {
    if (dst == null)
      dst = new Point2D.Double();
    double x = src.getX();
    double y = src.getY();
    double nx = m00 * x + m01 * y + m02;
    double ny = m10 * x + m11 * y + m12;
    dst.setLocation(nx, ny);
    return dst;
  }

  /**
   * Perform this transformation on an array of points, storing the results
   * in another (possibly same) array. This will not create a destination
   * array, but will create points for the null entries of the destination.
   * The transformation is done sequentially. While having a single source
   * and destination point be the same is safe, you should be aware that
   * duplicate references to the same point in the source, and having the
   * source overlap the destination, may result in your source points changing
   * from a previous transform before it is their turn to be evaluated.
   *
   * @param src the array of source points
   * @param srcOff the starting offset into src
   * @param dst the array of destination points (may have null entries)
   * @param dstOff the starting offset into dst
   * @param num the number of points to transform
   * @throws NullPointerException if src or dst is null, or src has null
   *         entries
   * @throws ArrayIndexOutOfBoundsException if array bounds are exceeded
   * @throws ArrayStoreException if new points are incompatible with dst
   */
  public void transform(Point2D[] src, int srcOff,
                        Point2D[] dst, int dstOff, int num)
  {
    while (--num >= 0)
      dst[dstOff] = transform(src[srcOff++], dst[dstOff++]);
  }

  /**
   * Perform this transformation on an array of points, in (x,y) pairs,
   * storing the results in another (possibly same) array. This will not
   * create a destination array. All sources are copied before the
   * transformation, so that no result will overwrite a point that has not yet
   * been evaluated.
   *
   * @param src the array of source points
   * @param srcOff the starting offset into src
   * @param dst the array of destination points
   * @param dstOff the starting offset into dst
   * @param num the number of points to transform
   * @throws NullPointerException if src or dst is null
   * @throws ArrayIndexOutOfBoundsException if array bounds are exceeded
   */
  public void transform(float[] srcPts, int srcOff,
                        float[] dstPts, int dstOff, int num)
  {
    if (srcPts == dstPts && dstOff > srcOff
        && num > 1 && srcOff + 2 * num > dstOff)
      {
        float[] f = new float[2 * num];
        System.arraycopy(srcPts, srcOff, f, 0, 2 * num);
        srcPts = f;
      }
    while (--num >= 0)
      {
        float x = srcPts[srcOff++];
        float y = srcPts[srcOff++];
        dstPts[dstOff++] = (float) (m00 * x + m01 * y + m02);
        dstPts[dstOff++] = (float) (m10 * x + m10 * y + m12);
      }
  }

  /**
   * Perform this transformation on an array of points, in (x,y) pairs,
   * storing the results in another (possibly same) array. This will not
   * create a destination array. All sources are copied before the
   * transformation, so that no result will overwrite a point that has not yet
   * been evaluated.
   *
   * @param src the array of source points
   * @param srcOff the starting offset into src
   * @param dst the array of destination points
   * @param dstOff the starting offset into dst
   * @param num the number of points to transform
   * @throws NullPointerException if src or dst is null
   * @throws ArrayIndexOutOfBoundsException if array bounds are exceeded
   */
  public void transform(double[] srcPts, int srcOff,
                        double[] dstPts, int dstOff, int num)
  {
    if (srcPts == dstPts && dstOff > srcOff
        && num > 1 && srcOff + 2 * num > dstOff)
      {
        double[] d = new double[2 * num];
        System.arraycopy(srcPts, srcOff, d, 0, 2 * num);
        srcPts = d;
      }
    while (--num >= 0)
      {
        double x = srcPts[srcOff++];
        double y = srcPts[srcOff++];
        dstPts[dstOff++] = m00 * x + m01 * y + m02;
        dstPts[dstOff++] = m10 * x + m10 * y + m12;
      }
  }

  /**
   * Perform this transformation on an array of points, in (x,y) pairs,
   * storing the results in another array. This will not create a destination
   * array.
   *
   * @param src the array of source points
   * @param srcOff the starting offset into src
   * @param dst the array of destination points
   * @param dstOff the starting offset into dst
   * @param num the number of points to transform
   * @throws NullPointerException if src or dst is null
   * @throws ArrayIndexOutOfBoundsException if array bounds are exceeded
   */
  public void transform(float[] srcPts, int srcOff,
                        double[] dstPts, int dstOff, int num)
  {
    while (--num >= 0)
      {
        float x = srcPts[srcOff++];
        float y = srcPts[srcOff++];
        dstPts[dstOff++] = m00 * x + m01 * y + m02;
        dstPts[dstOff++] = m10 * x + m10 * y + m12;
      }
  }

  /**
   * Perform this transformation on an array of points, in (x,y) pairs,
   * storing the results in another array. This will not create a destination
   * array.
   *
   * @param src the array of source points
   * @param srcOff the starting offset into src
   * @param dst the array of destination points
   * @param dstOff the starting offset into dst
   * @param num the number of points to transform
   * @throws NullPointerException if src or dst is null
   * @throws ArrayIndexOutOfBoundsException if array bounds are exceeded
   */
  public void transform(double[] srcPts, int srcOff,
                        float[] dstPts, int dstOff, int num)
  {
    while (--num >= 0)
      {
        double x = srcPts[srcOff++];
        double y = srcPts[srcOff++];
        dstPts[dstOff++] = (float) (m00 * x + m01 * y + m02);
        dstPts[dstOff++] = (float) (m10 * x + m10 * y + m12);
      }
  }

  /**
   * Perform the inverse of this transformation on the given source point,
   * and store the result in the destination (creating it if necessary). It
   * is safe for src and dst to be the same.
   *
   * @param src the source point
   * @param dst the destination, or null
   * @return the inverse transformation of src, in dst if it was non-null
   * @throws NullPointerException if src is null
   * @throws NoninvertibleTransformException if the inverse does not exist
   * @see #getDeterminant()
   */
  public Point2D inverseTransform(Point2D src, Point2D dst)
    throws NoninvertibleTransformException
  {
    double det = getDeterminant();
    if (det == 0)
      throw new NoninvertibleTransformException("couldn't invert transform");
    if (dst == null)
      dst = new Point2D.Double();
    double x = src.getX();
    double y = src.getY();
    double nx = (m11 * x + -m10 * y) / det - m02;
    double ny = (m01 * x + -m00 * y) / det - m12;
    dst.setLocation(nx, ny);
    return dst;
  }

  /**
   * Perform the inverse of this transformation on an array of points, in
   * (x,y) pairs, storing the results in another (possibly same) array. This
   * will not create a destination array. All sources are copied before the
   * transformation, so that no result will overwrite a point that has not yet
   * been evaluated.
   *
   * @param src the array of source points
   * @param srcOff the starting offset into src
   * @param dst the array of destination points
   * @param dstOff the starting offset into dst
   * @param num the number of points to transform
   * @throws NullPointerException if src or dst is null
   * @throws ArrayIndexOutOfBoundsException if array bounds are exceeded
   * @throws NoninvertibleTransformException if the inverse does not exist
   * @see #getDeterminant()
   */
  public void inverseTransform(double[] srcPts, int srcOff,
                               double[] dstPts, int dstOff, int num)
    throws NoninvertibleTransformException
  {
    double det = getDeterminant();
    if (det == 0)
      throw new NoninvertibleTransformException("couldn't invert transform");
    if (srcPts == dstPts && dstOff > srcOff
        && num > 1 && srcOff + 2 * num > dstOff)
      {
        double[] d = new double[2 * num];
        System.arraycopy(srcPts, srcOff, d, 0, 2 * num);
        srcPts = d;
      }
    while (--num >= 0)
      {
        double x = srcPts[srcOff++];
        double y = srcPts[srcOff++];
        dstPts[dstOff++] = (m11 * x + -m10 * y) / det - m02;
        dstPts[dstOff++] = (m01 * x + -m00 * y) / det - m12;
      }
  }

  /**
   * Perform this transformation, less any translation, on the given source
   * point, and store the result in the destination (creating it if
   * necessary). It is safe for src and dst to be the same. The reduced
   * transform is equivalent to:
   * <pre>
   * [ x' ] = [ m00 m01 ] [ x ] = [ m00 * x + m01 * y ]
   * [ y' ]   [ m10 m11 ] [ y ] = [ m10 * x + m11 * y ]
   * </pre>
   *
   * @param src the source point
   * @param dst the destination, or null
   * @return the delta transformation of src, in dst if it was non-null
   * @throws NullPointerException if src is null
   */
  public Point2D deltaTransform(Point2D src, Point2D dst)
  {
    if (dst == null)
      dst = new Point2D.Double();
    double x = src.getX();
    double y = src.getY();
    double nx = m00 * x + m01 * y;
    double ny = m10 * x + m11 * y;
    dst.setLocation(nx, ny);
    return dst;
  }

  /**
   * Perform this transformation, less any translation, on an array of points,
   * in (x,y) pairs, storing the results in another (possibly same) array.
   * This will not create a destination array. All sources are copied before
   * the transformation, so that no result will overwrite a point that has
   * not yet been evaluated. The reduced transform is equivalent to:
   * <pre>
   * [ x' ] = [ m00 m01 ] [ x ] = [ m00 * x + m01 * y ]
   * [ y' ]   [ m10 m11 ] [ y ] = [ m10 * x + m11 * y ]
   * </pre>
   *
   * @param src the array of source points
   * @param srcOff the starting offset into src
   * @param dst the array of destination points
   * @param dstOff the starting offset into dst
   * @param num the number of points to transform
   * @throws NullPointerException if src or dst is null
   * @throws ArrayIndexOutOfBoundsException if array bounds are exceeded
   */
  public void deltaTransform(double[] srcPts, int srcOff,
                              double[] dstPts, int dstOff,
                              int num)
  {
    if (srcPts == dstPts && dstOff > srcOff
        && num > 1 && srcOff + 2 * num > dstOff)
      {
        double[] d = new double[2 * num];
        System.arraycopy(srcPts, srcOff, d, 0, 2 * num);
        srcPts = d;
      }
    while (--num >= 0)
      {
        double x = srcPts[srcOff++];
        double y = srcPts[srcOff++];
        dstPts[dstOff++] = m00 * x + m01 * y;
        dstPts[dstOff++] = m10 * x + m11 * y;
      }
  }

  /**
   * Return a new Shape, based on the given one, where the path of the shape
   * has been transformed by this transform. Notice that this uses GeneralPath,
   * which only stores points in float precision.
   *
   * @param src the shape source to transform
   * @return the shape, transformed by this
   * @throws NullPointerException if src is null
   * @see GeneralPath#transform(AffineTransform)
   */
  public Shape createTransformedShape(Shape src)
  {
    GeneralPath p = new GeneralPath(src);
    p.transform(this);
    return p;
  }

  /**
   * Returns a string representation of the transform, in the format:
   * <code>"AffineTransform[[" + m00 + ", " + m01 + ", " + m02 + "], ["
   *   + m10 + ", " + m11 + ", " + m12 + "]]"</code>.
   *
   * @return the string representation
   */
  public String toString()
  {
    return "AffineTransform[[" + m00 + ", " + m01 + ", " + m02 + "], ["
      + m10 + ", " + m11 + ", " + m12 + "]]";
  }

  /**
   * Tests if this transformation is the identity:
   * <pre>
   * [ 1 0 0 ]
   * [ 0 1 0 ]
   * [ 0 0 1 ]
   * </pre>
   *
   * @return true if this is the identity transform
   */
  public boolean isIdentity()
  {
    // Rather than rely on type, check explicitly.
    return (m00 == 1 && m01 == 0 && m02 == 0
            && m10 == 0 && m11 == 1 && m12 == 0);
  }

  /**
   * Create a new transform of the same run-time type, with the same
   * transforming properties as this one.
   *
   * @return the clone
   */
  public Object clone()
  {
    try
      {
        return super.clone();
      }
    catch (CloneNotSupportedException e)
      {
        throw (Error) new InternalError().initCause(e); // Impossible
      }
  }

  /**
   * Return the hashcode for this transformation. The formula is not
   * documented, but appears to be the same as:
   * <pre>
   * long l = Double.doubleToLongBits(getScaleX());
   * l = l * 31 + Double.doubleToLongBits(getShearY());
   * l = l * 31 + Double.doubleToLongBits(getShearX());
   * l = l * 31 + Double.doubleToLongBits(getScaleY());
   * l = l * 31 + Double.doubleToLongBits(getTranslateX());
   * l = l * 31 + Double.doubleToLongBits(getTranslateY());
   * return (int) ((l >> 32) ^ l);
   * </pre>
   *
   * @return the hashcode
   */
  public int hashCode()
  {
    long l = Double.doubleToLongBits(m00);
    l = l * 31 + Double.doubleToLongBits(m10);
    l = l * 31 + Double.doubleToLongBits(m01);
    l = l * 31 + Double.doubleToLongBits(m11);
    l = l * 31 + Double.doubleToLongBits(m02);
    l = l * 31 + Double.doubleToLongBits(m12);
    return (int) ((l >> 32) ^ l);
  }

  /**
   * Compares two transforms for equality. This returns true if they have the
   * same matrix values.
   *
   * @param o the transform to compare
   * @return true if it is equal
   */
  public boolean equals(Object obj)
  {
    if (! (obj instanceof AffineTransform))
      return false;
    AffineTransform t = (AffineTransform) obj;
    return (m00 == t.m00 && m01 == t.m01 && m02 == t.m02
            && m10 == t.m10 && m11 == t.m11 && m12 == t.m12);
  }

  /**
   * Helper to decode the type from the matrix. This is not guaranteed
   * to find the optimal type, but at least it will be valid.
   */
  private void updateType()
  {
    double det = getDeterminant();
    if (det == 0)
      {
        type = TYPE_GENERAL_TRANSFORM;
        return;
      }
    // Scale (includes rotation by PI) or translation.
    if (m01 == 0 && m10 == 0)
      {
        if (m00 == m11)
          type = m00 == 1 ? TYPE_IDENTITY : TYPE_UNIFORM_SCALE;
        else
          type = TYPE_GENERAL_SCALE;
        if (m02 != 0 || m12 != 0)
          type |= TYPE_TRANSLATION;
      }
    // Rotation.
    else if (m00 == m11 && m01 == -m10)
      {
        type = m00 == 0 ? TYPE_QUADRANT_ROTATION : TYPE_GENERAL_ROTATION;
        if (det != 1)
          type |= TYPE_UNIFORM_SCALE;
        if (m02 != 0 || m12 != 0)
          type |= TYPE_TRANSLATION;
      }
    else
      type = TYPE_GENERAL_TRANSFORM;
  }

  /**
   * Reads a transform from an object stream.
   *
   * @param s the stream to read from
   * @throws ClassNotFoundException if there is a problem deserializing
   * @throws IOException if there is a problem deserializing
   */
  private void readObject(ObjectInputStream s)
    throws ClassNotFoundException, IOException
  {
    s.defaultReadObject();
    updateType();
  }
} // class AffineTransform