Class Point

GoJS® Diagramming Components
version 3.0.0
by Northwoods Software®

A Point represents an x- and y-coordinate pair in two-dimensional space.

Use the static functions Point.parse and Point.stringify to convert to and from a standard string representation that is independent of the current locale.

When an instance of this class is the value of a property of a GraphObject class or Diagram or CommandHandler or a Tool class, you should treat the object as if it were frozen or read-only -- you cannot modify its properties. This allows the property to return a value without allocating a new instance. If you need to do your own calculations with the value, call copy to make a new instance with the same values that you can modify.

Many methods modify the object's properties and then return a reference to "this" object. The only instance method to allocate a new object is the copy method. The static Point.parse method also allocates a new object.

The "Debug" implementation of this class is significantly slower than the "Release" implementation, mostly due to additional error checking.

You cannot inherit from this class.

Constructors

constructor

new Point(x?: number, y?: number): Point
The default constructor produces the Point(0,0). This constructor may take either zero arguments or two arguments.
Parameters
- Optional x: number
  The x value.
- Optional y: number
  The y value.
Returns Point

Accessors

x
: number

Gets or sets the x value of the Point.

y
: number

Gets or sets the y value of the Point.

Methods

add

add(p: Point): Point
Modify this point so that is the sum of the current Point and the x and y co-ordinates of the given Point.
Parameters
- p: Point
  The Point to add to this Point.
Returns Point
this.
see
- offset
- subtract

compareWithLineSegmentPoint

compareWithLineSegmentPoint(p: Point, q: Point): number
Compare this point with a finite line segment given by two Points.

This method compares this point with a finite line segment determined by the given two Points. If the point is on the finite line segment, this returns zero. If the point is on the left side of the segment, this returns a positive number. If the point is on the right side of the segment, this returns a negative number. If the point is on the infinitely extended line but not within the segment, then this returns a positive number if the point is beyond the end of the segment when going from A1 to A2, or this returns a negative number if the point comes before the segment's start at A1.
Parameters
- p: Point
  the start of the finite line segment
- q: Point
  the end of the finite line segment
Returns number
<0 if this Point is on the right side of the line segment, or >0 if this Point is on the left side, or zero if exactly on the finite line segment

since
2.2

`Virtual`copy

copy(): Point
Create a copy of this Point, with the same values.

Returns Point

direction

direction(px: number, py: number): number
Compute the angle from this Point to a given (px,py) point. However, if the point is the same as this Point, the direction is zero.
Parameters
- px: number
- py: number
Returns number
the angle, in degrees, of the line from this Point to the given point.

see
directionPoint

directionPoint

directionPoint(p: Point): number
Compute the angle from this Point to a given Point. However, if the given Point is the same as this Point, the direction is zero.
Parameters
- p: Point
  the other Point to which to measure the relative angle.
Returns number
the angle, in degrees, of the line from this Point to the given point.

see
direction

distanceSquared

distanceSquared(px: number, py: number): number
Returns the square of the distance from this point to a given point (px, py).
Parameters
- px: number
- py: number
Returns number
the square of the euclidean distance.

see
distanceSquaredPoint

distanceSquaredPoint

distanceSquaredPoint(p: Point): number
Returns the square of the distance from this Point to a given Point.
Parameters
- p: Point
  the other Point to measure to.
Returns number
the square of the euclidean distance.

see
distanceSquared

equalTo

equalTo(x: number, y: number): boolean
Indicates whether the given point (x, y) is equal to this Point.
Parameters
- x: number
- y: number
Returns boolean
True if the two Points have identical X and Y values, false otherwise.

see
equals

equals

equals(p: Point): boolean
Indicates whether the given Point is equal to this Point.
Parameters
- p: Point
  The Point to compare to the current Point.
Returns boolean
True if the two Points have identical X and Y values, false otherwise.

see
equalTo

isReal

isReal(): boolean
True if this Point has X and Y values that are real numbers and not infinity.

Returns boolean

normalize

normalize(): Point
Modify this Point so that its X and Y values have been normalized to a unit length. However, if this Point is the origin (zero, zero), its length remains zero.

Returns Point
this.

offset

offset(dx: number, dy: number): Point
Modify this point by shifting its values with the given DX and DY offsets.
Parameters
- dx: number
- dy: number
Returns Point
this.
see
- add
- subtract

projectOntoLineSegment

projectOntoLineSegment(px: number, py: number, qx: number, qy: number): Point
Modify this point to be the closest point to this point that is on a finite line segment.
Parameters
- px: number
  one end of the finite line segment
- py: number
  one end of the finite line segment
- qx: number
  the other end of the finite line segment
- qy: number
  the other end of the finite line segment
Returns Point
this modified Point

projectOntoLineSegmentPoint

projectOntoLineSegmentPoint(p: Point, q: Point): Point
Modify this point to be the closest point to this point that is on a finite line segment.
Parameters
- p: Point
  one end of the finite line segment
- q: Point
  the other end of the finite line segment
Returns Point
this modified Point

rotate

rotate(angle: number): Point
Modify this Point so that has been rotated about the origin by the given angle.
Parameters
- angle: number
  an angle in degrees.
Returns Point
this.

scale

scale(sx: number, sy: number): Point
Modify this Point so that its X and Y values have been scaled by given factors along the X and Y axes.
Parameters
- sx: number
- sy: number
Returns Point
this.

set

set(p: Point): Point
Modify this Point so that its X and Y values are the same as the given Point.
Parameters
- p: Point
  the given Point.
Returns Point
this.

setRectSpot

setRectSpot(r: Rect, spot: Spot): Point
Modify this Point so that its X and Y values correspond to a particular Spot in a given Rect.

The result is meaningless if Spot.isNoSpot is true for the given Spot.
Parameters
- r: Rect
  the Rect for which we are finding the point.
- spot: Spot
  the Spot; Spot.isSpot must be true for this Spot.
Returns Point
this.

see
setSpot

setSpot

setSpot(x: number, y: number, w: number, h: number, spot: Spot): Point
Modify this Point so that its X and Y values correspond to a particular Spot in a given rectangle.

The result is meaningless if Spot.isNoSpot is true for the given Spot.
Parameters
- x: number
  The X coordinate of the Rect for which we are finding the point.
- y: number
  The Y coordinate of the Rect for which we are finding the point.
- w: number
  The Width of the Rect for which we are finding the point.
- h: number
  The Height of the Rect for which we are finding the point.
- spot: Spot
  the Spot; Spot.isSpot must be true for this Spot.
Returns Point
this the point of the spot in the rectangle.

see
setRectSpot

setTo

setTo(x: number, y: number): Point
Modify this Point with new X and Y values.
Parameters
- x: number
- y: number
Returns Point
this.

snapToGrid

snapToGrid(originx: number, originy: number, cellwidth: number, cellheight: number): Point
Modify this point to be at the nearest point on an infinite grid, given the grid's origin and size of each grid cell.
Parameters
- originx: number
  the top-left point of one of the grid cells
- originy: number
  the top-left point of one of the grid cells
- cellwidth: number
  the size of each grid cell -- must be a real number larger than zero
- cellheight: number
  the size of each grid cell -- must be a real number larger than zero
Returns Point
this modified Point

snapToGridPoint

snapToGridPoint(origin: Point, cellsize: Size): Point
Modify this point to be at the nearest point on an infinite grid, given the grid's origin and size of each grid cell.
Parameters
- origin: Point
  the top-left point of one of the grid cells
- cellsize: Size
  the size of each grid cell
Returns Point
this modified Point

subtract

subtract(p: Point): Point
Modify this point so that is the difference of this Point and the x and y co-ordinates of the given Point.
Parameters
- p: Point
  The Point to subtract from the current Point.
Returns Point
this.
see
- offset
- add

`Static` compareWithLineSegment

compareWithLineSegment(a1x: number, a1y: number, a2x: number, a2y: number, px: number, py: number): number
This static function compares a point with a finite line segment.

If the point is on the finite line segment, this returns zero. If the point is on the left side of the segment, this returns a positive number. If the point is on the right side of the segment, this returns a negative number. If the point is on the infinitely extended line but not within the segment, then this returns a positive number if the point is beyond the end of the segment when going from A1 to A2, or this returns a negative number if the point comes before the segment's start at A1.
Parameters
- a1x: number
- a1y: number
- a2x: number
- a2y: number
- px: number
- py: number
Returns number
<0 if on the right side, or >0 if on the left side, or zero if exactly on the finite line segment

since
2.2

`Static` direction

direction(px: number, py: number, qx: number, qy: number): number
This static function returns the angle in degrees of the line from point P to point Q.
Parameters
- px: number
- py: number
- qx: number
- qy: number
Returns number

`Static` distanceLineSegmentSquared

distanceLineSegmentSquared(px: number, py: number, ax: number, ay: number, bx: number, by: number): number
This static function returns the square of the distance from the point P to the finite line segment from point A to point B.
Parameters
- px: number
- py: number
- ax: number
- ay: number
- bx: number
- by: number
Returns number
the euclidean distance.

`Static` distanceSquared

distanceSquared(px: number, py: number, qx: number, qy: number): number
This static function returns the square of the distance from the point P to the point Q.
Parameters
- px: number
- py: number
- qx: number
- qy: number
Returns number

`Static` intersectingLineSegments

intersectingLineSegments(a1x: number, a1y: number, a2x: number, a2y: number, b1x: number, b1y: number, b2x: number, b2y: number): boolean
This static function is true if two finite straight line segments intersect each other.
Parameters
- a1x: number
- a1y: number
- a2x: number
- a2y: number
- b1x: number
- b1y: number
- b2x: number
- b2y: number
Returns boolean
True if the two given finite line segments intersect with each other, false otherwise.

since
2.2

`Static` parse

parse(str: string): Point
This static function can be used to read in a Point from a string that was produced by Point.stringify.

go.Point.parse("1 2") produces the Point new go.Point(1, 2).
Parameters
- str: string
Returns Point

`Static` stringify

stringify(val: Point): string
This static function can be used to write out a Point as a string that can be read by Point.parse.

go.Point.stringify(new go.Point(1, 2)) produces the string "1 2".
Parameters
- val: Point
Returns string

`Static` stringifyFixed

stringifyFixed(digits: number): ((val: Point) => string)
This static function returns a function that can be used as a back converter for a Binding to write out a Point's values as numbers with a fixed number of digits after the decimal point.

This is useful for limiting the size of JSON output and making it more legible. It might also be useful for regression testing.

Example:
```
  new go.Binding("location", "loc", go.Point.parse, go.Point.stringifyFixed(2))
```
Parameters
- digits: number
  must be a non-negative integer
Returns ((val: Point) => string)
a function that converts a Point to a string without so many decimals
- - (val: Point): string
  - This static function returns a function that can be used as a back converter for a Binding to write out a Point's values as numbers with a fixed number of digits after the decimal point.
    
    This is useful for limiting the size of JSON output and making it more legible. It might also be useful for regression testing.
    
    Example:
```
  new go.Binding("location", "loc", go.Point.parse, go.Point.stringifyFixed(2))
```
    Parameters
    - val: Point
    Returns string
    a function that converts a Point to a string without so many decimals
    
    since
    3.0
since
3.0

Class Point

Index

Constructors

Accessors

Methods

Constructors

constructor

Parameters

Optional x: number

Optional y: number

Returns Point

Accessors

x: number

y: number

Methods

add

Parameters

p: Point

Returns Point

compareWithLineSegmentPoint

Parameters

p: Point

q: Point

Returns number

Virtualcopy

Returns Point

direction

Parameters

px: number

py: number

Returns number

directionPoint

Parameters

p: Point

Returns number

distanceSquared

Parameters

px: number

py: number

Returns number

distanceSquaredPoint

Parameters

p: Point

Returns number

equalTo

Parameters

x: number

y: number

Returns boolean

equals

Parameters

p: Point

Returns boolean

isReal

Returns boolean

normalize

Returns Point

offset

Parameters

dx: number

dy: number

Returns Point

projectOntoLineSegment

Parameters

px: number

py: number

qx: number

qy: number

Returns Point

projectOntoLineSegmentPoint

Parameters

p: Point

q: Point

Returns Point

rotate

Parameters

angle: number

Returns Point

scale

Parameters

`Optional` x: number

`Optional` y: number

x
: number

y
: number

`Virtual`copy

`Static` compareWithLineSegment

`Static` direction

`Static` distanceLineSegmentSquared

`Static` distanceSquared