org.eclipse.gmf.runtime.draw2d.ui.geometry
Class LineSeg
java.lang.Object
org.eclipse.gmf.runtime.draw2d.ui.geometry.LineSeg
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All Implemented Interfaces:
- java.io.Serializable, java.lang.Cloneable,
Translatable
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public class LineSeg
- extends java.lang.Object
- implements java.lang.Cloneable, java.io.Serializable,
Translatable
This is a geometric utility class that allows for manipulation of line segments.
A line segment is defined as a set of two points where one point is designated as the
origin and the other is the terminal.
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See Also:
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Serialized Form
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Nested Class Summary
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static class
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LineSeg.KeyPoint
Enumeration class for defining the keypoint along a line segment. |
static class
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LineSeg.Sign
Enumeration class for defining the orientations of a point relative to the line
segment. |
static class
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LineSeg.TrigValues
Structure to hold onto trig values that represent an angle |
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Constructor Summary
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LineSeg
(
LineSeg.KeyPoint start,
int fromX,
int fromY,
float slope,
long len,
int xdir)
Creates a segment using (fromX, fromY) as either the
first point of the segment (start == Origin) or the midpoint of the
segment (start == Midpoint), and using slope as its new slope and len as
the new length. |
LineSeg
(
Point ptStart,
Point ptEnd)
Constructor |
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Method Summary
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boolean
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containsPoint
(
Point aPoint,
int tolerance)
Checks if this line segment contains the given point within a tolerance value. |
float
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distanceAlong
(
Point coord)
Finds the percentage distance along this line segement where the given point
resides. |
long
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distanceToPoint
(int xCoord,
int yCoord)
Finds the perpendicular distance from a point coordinates to this line segment. |
boolean
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equals
(java.lang.Object seg)
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double[]
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getEquation
()
Returns array with 3 numbers in it, which are the coefficients of the
generalized line equation of the line corresponding to this line segment
a*x+b*y=c is the equation => result[0]=a, result[1]=b, result[2]=c |
Point
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getInfimum
()
Get a Point representing the lowest point value
for this line segment. |
static double[]
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getLineEquation
(double x1,
double y1,
double x2,
double y2)
Returns the coefficients of the generalized equation of the line passing through
points (x1,y1) and (x2,y2)
Generalized line equation: ax+by=c => a==result[0], b==result[1], c==result[2] |
PointList
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getLineIntersectionsWithEllipse
(
Rectangle ellipseBounds)
Calculates intersection points of the line of the line segment and ellipse |
PointList
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getLineIntersectionsWithLineSegs
(
PointList points)
Calculates intersection points of the line that contains this line segment with
a list of other line segments. |
PointList
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getLinesIntersections
(
LineSeg line)
Returns intersection points of two lines that contain this line segment and
the argumet line segment. |
Point
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getOrigin
()
Accesssor to retrieve the origin point of the line segement. |
LineSeg
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getParallelLineSegThroughPoint
(
Point ptLoc)
Returns a new LineSeg that is parallel to this by the given distance. |
Point
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getSupremum
()
Get points representing the highest point value
for this line segment. |
Point
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getTerminus
()
Accesssor to retrieve the terminal point of the line segement. |
LineSeg.TrigValues
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getTrigValues
(
Ray ptToVector)
Gets the trig values associated with the angle from this line segment
to the given vector. |
int
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hashCode
()
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Point
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intersect
(
LineSeg line,
int nTolerance)
Determines the intersect point between this line and the line passed
in as a parameter. |
boolean
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isHorizontal
()
Determines if this a horizontal segment |
boolean
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isVertical
()
Determines if this a vertical segment |
double
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length
()
Calculate the length of the line segment. |
Point
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locatePoint
(double pctDist,
long theHeight,
LineSeg.Sign asOriented)
Locates a point at a given height and distance along the line segment. |
void
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performScale
(double factor)
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void
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performTranslate
(int dx,
int dy)
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Point
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perpIntersect
(int startX,
int startY)
Calculates the perpendicular intersection point on
the line segment from the given point. |
float
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perpSlope
()
Calculates the perpendicular slope of this line segment. |
boolean
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pointOn
(long theDistance,
LineSeg.KeyPoint fromKeyPoint,
Point ptResult)
Gets the point on the line segment at the given distance away from the
key point. |
LineSeg.Sign
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positionRelativeTo
(
Point rel)
Returns out a positive or negative value (Positive / Negative) depending
on the orientation of the given point to the line. |
double
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projection
(int xCoord,
int yCoord)
Calculates the projection of the given point onto the line segment. |
void
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setOrigin
(
Point origin)
Sets the origin point of the line segment |
void
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setTerminus
(
Point terminus)
Sets the terminating point of the line segment. |
float
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slope
()
Calculates the slope of this line segment (y=mx+b) |
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Methods inherited from class java.lang.Object
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clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait
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LineSeg
public LineSeg(
Point ptStart,
Point ptEnd)
- Constructor
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Parameters:
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ptStart - Point indicating the start of the line segment -
ptEnd - Point indicating the end of the line segment
LineSeg
public LineSeg(
LineSeg.KeyPoint start,
int fromX,
int fromY,
float slope,
long len,
int xdir)
- Creates a segment using (fromX, fromY) as either the
first point of the segment (start == Origin) or the midpoint of the
segment (start == Midpoint), and using slope as its new slope and len as
the new length. xdir indicates which direction the segment should
go in the x-axis.
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Parameters:
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start - KeyPoint from which the other parameters are relative to -
fromX - int x value of start KeyPoint
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fromY - int y value of start KeyPoint
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slope - float slope of the line -
len - long length of the line -
xdir - direction
equals
public boolean equals(java.lang.Object seg)
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Overrides:
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equals in class java.lang.Object
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hashCode
public int hashCode()
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Overrides:
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hashCode in class java.lang.Object
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getOrigin
public
Point getOrigin()
- Accesssor to retrieve the origin point of the line segement.
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Returns:
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Point the origin of the line segment.
getTerminus
public
Point getTerminus()
- Accesssor to retrieve the terminal point of the line segement.
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Returns:
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Point the terminating point of the line segment
setOrigin
public void setOrigin(
Point origin)
- Sets the origin point of the line segment
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Parameters:
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origin - Point to set as origin
setTerminus
public void setTerminus(
Point terminus)
- Sets the terminating point of the line segment.
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Parameters:
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terminus - Point to set as terminus
getSupremum
public final
Point getSupremum()
- Get points representing the highest point value
for this line segment.
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Returns:
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Point Representing the highest point value.
getInfimum
public final
Point getInfimum()
- Get a
Point representing the lowest point value
for this line segment.
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-
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Returns:
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Point Representing the lowest point value.
isHorizontal
public final boolean isHorizontal()
- Determines if this a horizontal segment
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Returns:
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boolean true if horizontal,
false otherwise.
isVertical
public final boolean isVertical()
- Determines if this a vertical segment
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Returns:
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boolean true if vertical,
false otherwise.
slope
public final float slope()
- Calculates the slope of this line segment (y=mx+b)
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Returns:
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float the slope of this segment. If the slope
is not defined such as when the line segment is vertical, then the
constant BIGSLOPE is returned to avoid divide by zero
errors.
perpSlope
public final float perpSlope()
- Calculates the perpendicular slope of this line segment. This calculates
the slope and then inverts it. Again, to avoid divide by zero errors,
the constant
BIGSLOPE is returned if the calculated slope
before inverting it was zero.
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Returns:
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float the perpendicular slope value of the
line segment.
length
public final double length()
- Calculate the length of the line segment.
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Returns:
- the
double length of the line segment.
intersect
public
Point intersect(
LineSeg line,
int nTolerance)
- Determines the intersect point between this line and the line passed
in as a parameter. If they intersect, then true is returned and the
point reference passed in will be set to the intersect point.
If they don't intersect, then the method returns
false.
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Parameters:
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line - LineSeg to test the intersection against. -
nTolerance - int tolerance value for detecting the intersection.
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Returns:
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Point that represents the intersection with this line,
or null if the calculation is not possible.
containsPoint
public final boolean containsPoint(
Point aPoint,
int tolerance)
- Checks if this line segment contains the given point within a tolerance value.
-
-
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Parameters:
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aPoint - Point to test if contained in this line. -
tolerance - int tolerance value for detecting the intersection.
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Returns:
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boolean true if the given point lies on this
segment, false otherwise.
distanceAlong
public final float distanceAlong(
Point coord)
- Finds the percentage distance along this line segement where the given point
resides.
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Parameters:
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coord - Point to determine how far along the line segment it resides.
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Returns:
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float the distance along the line segment where the ptCoord is
in a percentage from.
distanceToPoint
public final long distanceToPoint(int xCoord,
int yCoord)
- Finds the perpendicular distance from a point coordinates to this line segment.
If point is "inside" line segment, then use distance from point to the line,
otherwise use distance to nearest endpoint of segment
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Parameters:
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xCoord - the x coordinate of the point. -
yCoord - the y coordinate of the point.
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Returns:
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long the distance from the line segment to the given point.
perpIntersect
public final
Point perpIntersect(int startX,
int startY)
- Calculates the perpendicular intersection point on
the line segment from the given point.
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Parameters:
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startX - the x coordinate of the point -
startY - the y coordinate of the point
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Returns:
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Point value containment the perpendicular intersection point.
projection
public final double projection(int xCoord,
int yCoord)
- Calculates the projection of the given point onto the line segment.
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Parameters:
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xCoord - the x coordinate of the point. -
yCoord - the y coordinate of the point.
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Returns:
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double value of the calculated projection.
positionRelativeTo
public final
LineSeg.Sign positionRelativeTo(
Point rel)
- Returns out a positive or negative value (Positive / Negative) depending
on the orientation of the given point to the line.
Point on this side: Positive.
P1------------------------------>
this segment
Point on this side: Negative.
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Parameters:
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rel - Point to test the relative position against this line.
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Returns:
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Sign value indicating the relative position of the given point.
locatePoint
public final
Point locatePoint(double pctDist,
long theHeight,
LineSeg.Sign asOriented)
- Locates a point at a given height and distance along the line segment.
B (the point we are looking for)
+
|
dist |h this segment
P1-----------+------------------->
A
get point A (on picture above)
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Parameters:
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pctDist - double distance along the line -
theHeight - long height above the line -
asOriented - Sign indicating relative position of the point to be located
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Returns:
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Point value that was located on the line.
pointOn
public final boolean pointOn(long theDistance,
LineSeg.KeyPoint fromKeyPoint,
Point ptResult)
- Gets the point on the line segment at the given distance away from the
key point.
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Parameters:
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theDistance - long distance along the line -
fromKeyPoint - KeyPoint to calculate the distance from -
ptResult - Point where the resulting calculating value is stored.
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Returns:
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boolean true if point can be calculated,
false otherwise.
getTrigValues
public
LineSeg.TrigValues getTrigValues(
Ray ptToVector)
- Gets the trig values associated with the angle from this line segment
to the given vector.
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-
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Parameters:
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ptToVector - Ray value to calculate trig values of.
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Returns:
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TrigValues object representing the trigonometry values
for the angle of the passed in Ray relative to this
or null if calculation is not possible,
getParallelLineSegThroughPoint
public final
LineSeg getParallelLineSegThroughPoint(
Point ptLoc)
- Returns a new
LineSeg that is parallel to this by the given distance.
Orientation is relative to the start and end. Negative implies to the
left and Position implies to the right.
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Parameters:
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ptLoc - Point value to constrain the line to.
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Returns:
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LineSeg line that was calculated going through the given point
getLineEquation
public static double[] getLineEquation(double x1,
double y1,
double x2,
double y2)
- Returns the coefficients of the generalized equation of the line passing through
points (x1,y1) and (x2,y2)
Generalized line equation: ax+by=c => a==result[0], b==result[1], c==result[2]
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-
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Parameters:
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x1 - - x coordinate of the 1st point -
y1 - - y coordinate of the 1st point -
x2 - - x coordinate of the 2nd point -
y2 - - y coordinate of the 2nd point
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Returns:
- the coefficients of the generalized equation of the line passing through
points (x1,y1) and (x2,y2)
getEquation
public double[] getEquation()
- Returns array with 3 numbers in it, which are the coefficients of the
generalized line equation of the line corresponding to this line segment
a*x+b*y=c is the equation => result[0]=a, result[1]=b, result[2]=c
-
-
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Returns:
- an array with 3 numbers in it, which are the coefficients of the
generalized line equation
getLinesIntersections
public
PointList getLinesIntersections(
LineSeg line)
- Returns intersection points of two lines that contain this line segment and
the argumet line segment.
The list of intersection points may contain at most two points and will contain
2 points if and only if the lines are equal. The 2 points will be the end points
of the parameter line segment
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Parameters:
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line - - the line segment
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Returns:
- intersection points of two lines that contain this line segment and
the argumet line segment.
getLineIntersectionsWithEllipse
public
PointList getLineIntersectionsWithEllipse(
Rectangle ellipseBounds)
- Calculates intersection points of the line of the line segment and ellipse
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-
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Parameters:
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ellipseBounds - - width and height of the ellipse
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Returns:
- -
PointList containing all intersection points
getLineIntersectionsWithLineSegs
public
PointList getLineIntersectionsWithLineSegs(
PointList points)
- Calculates intersection points of the line that contains this line segment with
a list of other line segments. If the list of points (line segments) form a closed
PolyLine, i.e form a closed polygon figure, then the method will
claculate intersections of a line and a figure
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-
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Parameters:
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points - - list of points that form linesegments, i.e the PolyLine
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Returns:
- the intersection points of the line that contains this line segment with
a list of other line segments.
performScale
public void performScale(double factor)
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Specified by:
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performScale
in interface
Translatable
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performTranslate
public void performTranslate(int dx,
int dy)
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Specified by:
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performTranslate
in interface
Translatable
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Guidelines for using Eclipse APIs.
Copyright (c) IBM Corp., Borland Software Corp., and others 2005,2006. All rights reserved.
