arc2d.java

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     *
     * @param a The <CODE>Arc2D</CODE> to use to set the arc's values.
     */
    public void setArc(Arc2D a) {
	setArc(a.getX(), a.getY(), a.getWidth(), a.getHeight(),
	       a.getAngleStart(), a.getAngleExtent(), a.type);
    }

    /**
     * Sets the position, bounds, angular extents, and closure type of
     * this arc to the specified values. The arc is defined by a center 
     * point and a radius rather than a bounding box for the full ellipse.
     *
     * @param x,&nbsp;y The coordinates of the center of the arc. 
     * (Specified in double precision.)
     * @param radius The radius of the arc. (Specified in double precision.)
     * @param angSt The starting angle of the arc in degrees.
     * (Specified in double precision.)
     * @param angExt The angular extent of the arc in degrees. 
     * (Specified in double precision.)
     * @param closure The closure type for the arc:
     * {@link #OPEN OPEN}, {@link #CHORD CHORD}, or {@link #PIE PIE}.     
     */
    public void setArcByCenter(double x, double y, double radius,
			       double angSt, double angExt, int closure) {
	setArc(x - radius, y - radius, radius * 2.0, radius * 2.0,
	       angSt, angExt, closure);
    }

    /**
     * Sets the position, bounds, and angular extents of this arc to the 
     * specified value. The starting angle of the arc is tangent to the 
     * line specified by points (p1, p2), the ending angle is tangent to 
     * the line specified by points (p2, p3), and the arc has the 
     * specified radius.
     *
     * @param p1 The first point that defines the arc. The starting 
     * angle of the arc is tangent to the line specified by points (p1, p2).
     * @param p2 The second point that defines the arc. The starting 
     * angle of the arc is tangent to the line specified by points (p1, p2). 
     * The ending angle of the arc is tangent to the line specified by 
     * points (p2, p3).
     * @param p3 The third point that defines the arc. The ending angle 
     * of the arc is tangent to the line specified by points (p2, p3).
     * @param radius The radius of the arc. (Specified in double precision.)
     */
    public void setArcByTangent(Point2D p1, Point2D p2, Point2D p3,
				double radius) {
	double ang1 = Math.atan2(p1.getY() - p2.getY(),
				 p1.getX() - p2.getX());
	double ang2 = Math.atan2(p3.getY() - p2.getY(),
				 p3.getX() - p2.getX());
	double diff = ang2 - ang1;
	if (diff > Math.PI) {
	    ang2 -= Math.PI * 2.0;
	} else if (diff < -Math.PI) {
	    ang2 += Math.PI * 2.0;
	}
	double bisect = (ang1 + ang2) / 2.0;
	double theta = Math.abs(ang2 - bisect);
	double dist = radius / Math.sin(theta);
	double x = p2.getX() + dist * Math.cos(bisect);
	double y = p2.getY() + dist * Math.sin(bisect);
	// REMIND: This needs some work...
	if (ang1 < ang2) {
	    ang1 -= Math.PI / 2.0;
	    ang2 += Math.PI / 2.0;
	} else {
	    ang1 += Math.PI / 2.0;
	    ang2 -= Math.PI / 2.0;
	}
	ang1 = Math.toDegrees(-ang1);
	ang2 = Math.toDegrees(-ang2);
	diff = ang2 - ang1;
	if (diff < 0) {
	    diff += 360;
	} else {
	    diff -= 360;
	}
	setArcByCenter(x, y, radius, ang1, diff, type);
    }

    /**
     * Sets the starting angle of this arc to the specified double
     * value.
     *
     * @param angSt The starting angle of the arc in degrees.
     * @see #getAngleStart
     */
    public abstract void setAngleStart(double angSt);

    /**
     * Sets the angular extent of this arc to the specified double
     * value.
     *
     * @param angExt The angular extent of the arc in degrees.
     * @see #getAngleExtent
     */
    public abstract void setAngleExtent(double angExt);

    /**
     * Sets the starting angle of this arc to the angle that the
     * specified point defines relative to the center of this arc.
     * The angular extent of the arc will remain the same.
     *
     * @param p The <CODE>Point2D</CODE> that defines the starting angle.
     * @see #getAngleStart
     */
    public void setAngleStart(Point2D p) {
	setAngleStart(-Math.toDegrees(Math.atan2(p.getY() - getCenterY(),
						 p.getX() - getCenterX())));
    }

    /**
     * Sets the starting angle and angular extent of this arc using two 
     * sets of coordinates. The first set of coordinates is used to 
     * determine the angle of the starting point relative to the arc's 
     * center. The second set of coordinates is used to determine the 
     * angle of the end point relative to the arc's center. 
     * The arc will always be non-empty and extend counterclockwise
     * from the first point around to the second point.
     *
     * @param x1,&nbsp;y1 The coordinates of the arc's starting point. 
     * @param x2,&nbsp;y2 The coordinates of the arc's ending point.
     */
    public void setAngles(double x1, double y1, double x2, double y2) {
	double x = getCenterX();
	double y = getCenterY();
	// Note: reversing the Y equations negates the angle to adjust
	// for the upside down coordinate system.
	double ang1 = Math.atan2(y - y1, x1 - x);
	double ang2 = Math.atan2(y - y2, x2 - x);
	ang2 -= ang1;
	if (ang2 <= 0.0) {
	    ang2 += Math.PI * 2.0;
	}
	setAngleStart(Math.toDegrees(ang1));
	setAngleExtent(Math.toDegrees(ang2));
    }

    /**
     * Sets the starting angle and angular extent of this arc using  
     * two points. The first point is used to determine the angle of 
     * the starting point relative to the arc's center.
     * The second point is used to determine the angle of the end point
     * relative to the arc's center. 
     * The arc will always be non-empty and extend counterclockwise
     * from the first point around to the second point.
     *
     * @param p1 The <CODE>Point2D</CODE> that defines the arc's 
     * starting point. 
     * @param p2 The <CODE>Point2D</CODE> that defines the arc's 
     * ending point.
     */
    public void setAngles(Point2D p1, Point2D p2) {
	setAngles(p1.getX(), p1.getY(), p2.getX(), p2.getY());
    }

    /**
     * Sets the closure type of this arc to the specified value: 
     * <CODE>OPEN</CODE>, <CODE>CHORD</CODE>, or <CODE>PIE</CODE>.
     *
     * @param type The integer constant that represents the closure 
     * type of this arc: {@link #OPEN}, {@link #CHORD}, or 
     * {@link #PIE}.
     *
     * @throws IllegalArgumentException if <code>type</code> is not
     * 0, 1, or 2.+
     * @see #getArcType
     */
    public void setArcType(int type) {
	if (type < OPEN || type > PIE) {
	    throw new IllegalArgumentException("invalid type for Arc: "+type);
	}
	this.type = type;
    }

    /**
     * Sets the location and size of the outer bounds of this arc
     * to the specified values.
     *
     * @param x,&nbsp;y The coordinates of the upper left corner of the 
     * arc's bounding box. (Specified in double precision.)
     * @param w The width of the arc's bounding box. (Specified in 
     * double precision.)
     * @param h The height of the arc's bounding box. (Specified in 
     * double precision.)
     */
    public void setFrame(double x, double y, double w, double h) {
	setArc(x, y, w, h, getAngleStart(), getAngleExtent(), type);
    }

    /**
     * Returns the high-precision bounding box of the arc.  The bounding  
     * box contains only the part of this <code>Arc2D</code> that is 
     * in between the starting and ending angles and contains the pie
     * wedge, if this <code>Arc2D</code> has a <code>PIE</code> closure type.
     * <p>
     * This method differs from the 
     * {@link RectangularShape#getBounds() getBounds} in that the 
     * <code>getBounds</code> method only returns the bounds of the 
     * enclosing ellipse of this <code>Arc2D</code> without considering
     * the starting and ending angles of this <code>Arc2D</code>.
     * 
     * @return the <CODE>Rectangle2D</CODE> that represents the arc's 
     * bounding box.
     */
    public Rectangle2D getBounds2D() {
	if (isEmpty()) {
	    return makeBounds(getX(), getY(), getWidth(), getHeight());
	}
	double x1, y1, x2, y2;
	if (getArcType() == PIE) {
	    x1 = y1 = x2 = y2 = 0.0;
	} else {
	    x1 = y1 = 1.0;
	    x2 = y2 = -1.0;
	}
	double angle = 0.0;
	for (int i = 0; i < 6; i++) {
	    if (i < 4) {
		// 0-3 are the four quadrants
		angle += 90.0;
		if (!containsAngle(angle)) {
		    continue;
		}
	    } else if (i == 4) {
		// 4 is start angle
		angle = getAngleStart();
	    } else {
		// 5 is end angle
		angle += getAngleExtent();
	    }
	    double rads = Math.toRadians(-angle);
	    double xe = Math.cos(rads);
	    double ye = Math.sin(rads);
	    x1 = Math.min(x1, xe);
	    y1 = Math.min(y1, ye);
	    x2 = Math.max(x2, xe);
	    y2 = Math.max(y2, ye);
	}
	double w = getWidth();
	double h = getHeight();
	x2 = (x2 - x1) * 0.5 * w;
	y2 = (y2 - y1) * 0.5 * h;
	x1 = getX() + (x1 * 0.5 + 0.5) * w;
	y1 = getY() + (y1 * 0.5 + 0.5) * h;
	return makeBounds(x1, y1, x2, y2);
    }

    /**
     * Constructs a <code>Rectangle2D</code> of the appropriate precision
     * to hold the parameters calculated to be the bounding box
     * of this arc.
     * 
     * @param x,&nbsp;y The coordinates of the upper left corner of the 
     * bounding box. (Specified in double precision.)
     * @param w The width of the bounding box. (Specified in 
     * double precision.)
     * @param h The height of the bounding box. (Specified in 
     * double precision.)
     * @return a <code>Rectangle2D</code> that is the bounding box
     *     of this arc.
     */
    protected abstract Rectangle2D makeBounds(double x, double y,
					      double w, double h);

    /*
     * Normalizes the specified angle into the range -180 to 180.
     */
    static double normalizeDegrees(double angle) {
	if (angle > 180.0) {
	    if (angle <= (180.0 + 360.0)) {
		angle = angle - 360.0;
	    } else {
		angle = Math.IEEEremainder(angle, 360.0);
		// IEEEremainder can return -180 here for some input values...
		if (angle == -180.0) {
		    angle = 180.0;
		}
	    }
	} else if (angle <= -180.0) {
	    if (angle > (-180.0 - 360.0)) {
		angle = angle + 360.0;
	    } else {
		angle = Math.IEEEremainder(angle, 360.0);
		// IEEEremainder can return -180 here for some input values...
		if (angle == -180.0) {
		    angle = 180.0;
		}
	    }
	}
	return angle;
    }

    /**
     * Determines whether or not the specified angle is within the  
     * angular extents of the arc.
     *
     * @param angle The angle to test. (Specified in double precision.)
     *
     * @return <CODE>true</CODE> if the arc contains the angle, 
     * <CODE>false</CODE> if the arc doesn't contain the angle.
     */
    public boolean containsAngle(double angle) {
	double angExt = getAngleExtent();
	boolean backwards = (angExt < 0.0);
	if (backwards) {
	    angExt = -angExt;
	}
	if (angExt >= 360.0) {
	    return true;
	}
	angle = normalizeDegrees(angle) - normalizeDegrees(getAngleStart());
	if (backwards) {
	    angle = -angle;
	}
	if (angle < 0.0) {
	    angle += 360.0;
	}

      
	return (angle >= 0.0) && (angle < angExt);
    }

    /**
     * Determines whether or not the specified point is inside the boundary 
     * of the arc.
     *
     * @param x,&nbsp;y The coordinates of the point to test. (Specified in 
     * double precision.)
     *
     * @return <CODE>true</CODE> if the point lies within the bound of 
     * the arc, <CODE>false</CODE> if the point lies outside of the 
     * arc's bounds.
     */
    public boolean contains(double x, double y) {
	// Normalize the coordinates compared to the ellipse
	// having a center at 0,0 and a radius of 0.5.
	double ellw = getWidth();
	if (ellw <= 0.0) {
	    return false;
	}
	double normx = (x - getX()) / ellw - 0.5;
	double ellh = getHeight();
	if (ellh <= 0.0) {
	    return false;