Class JXG.Point

JXG.GeometryElement
↳ JXG.Point

Creates a new point object. Do not use this constructor to create a point. Use JXG.Board#create with type Point, Glider, or Intersection instead.

Defined in: point.js.
Extends JXG.GeometryElement.

Class Summary
Constructor Attributes	Constructor Name and Description
	JXG.Point(board, coordinates, attributes) A point is the basic geometric element.

Attributes Summary
Field Attributes	Field Name and Description
	attractorDistance Unit for attractorDistance and snatchDistance, used for magnetized points and for snapToPoints.
	attractors List of attractor elements.
	face There are different point styles which differ in appearance.
	showInfobox If true, the infobox is shown on mouse over, else not.
	size Determines the size of a point.
	snapToPoints If set to true, the point will snap to the nearest point in distance of JXG.Point#attractorDistance.
	snatchDistance If the distance of the point to one of its attractors is at least this number the point will be released from being a glider on the attracting element.
	style This attribute was used to determined the point layout.

Field Summary
Field Attributes	Field Name and Description
<private>	coords Coordinates of the point.
<private>	group Stores the groups of this point in an array of Group.
	needsUpdateFromParent A JXG.Point#updateGlider call is usually followed by a general JXG.Board#update which calls JXG.Point#updateGliderFromParent.
<private>	onPolygon Determines whether the point slides on a polygon if point is a glider.
<private>	position Relative position on a line if point is a glider on a line.
	slideObjects List of elements the point is bound to, i.e.
	snapSizeX Defines together with JXG.Point#snapSizeY the grid the point snaps on to.
	snapSizeY Defines together with JXG.Point#snapSizeX the grid the point snaps on to.
	snapToGrid If set to true, the point will snap to a grid defined by JXG.Point#snapSizeX and JXG.Point#snapSizeY.

Method Summary
Method Attributes	Method Name and Description
<private>	_anim(direction, stepCount) Animates a glider.
	addConstraint(terms) Convert the point to CAS point and call update().
	addTransform(el, transform) Add transformations to this point.
	Dist(point2) Getter method for the distance to a second point, this is required for CAS-elements.
	free() Converts a calculated point into a free point, i.e.
	handleAttractors() A point can change its type from free point to glider and vice versa.
	handleSnapToGrid() Move a point to its nearest grid point.
	handleSnapToPoints() Let a point snap to the nearest point in distance of JXG.Point#attractorDistance.
<private>	hasPoint(x, y) Checks whether (x,y) is near the point.
	makeGlider(glideObject) Convert the point to glider and update the construction.
	moveAlong(path, time, options) Starts an animation which moves the point along a given path in given time.
	moveTo(where, time, options) Starts an animated point movement towards the given coordinates `where`.
<deprecated>	normalizeFace(s)
	popSlideObject() Remove the last slideObject.
	remove() Remove the point from the drawing.
	setGliderPosition(x) Sets the position of a glider relative to the defining elements of the JXG.Point#slideObject.
	setPosition(method, coords) Sets coordinates and calls the point's update() method.
	setPositionByTransform(method, tv) Translates the point by `tv = (x, y)`.
	setPositionDirectly(method, coords) Sets coordinates and calls the point's update() method.
<private>	setStyle(i) Set the style of a point.
	update(fromParent) Updates the position of the point.
<private>	updateConstraint() Dummy function for unconstrained points or gliders.
<private>	updateGlider() Update of glider in case of dragging the glider or setting the postion of the glider.
<private>	updateGliderFromParent() Update of a glider in case a parent element has been updated.
<private>	updateRenderer() Calls the renderer to update the drawing.
	updateTransform() Applies the transformations of the curve to JXG.Point#baseElement.
	visit(where, time, options) Starts an animated point movement towards the given coordinates `where`.
	X() Getter method for x, this is used by for CAS-points to access point coordinates.
<private>	XEval() New evaluation of the function term.
	Y() Getter method for y, this is used by CAS-points to access point coordinates.
<private>	YEval() New evaluation of the function term.
	Z() Getter method for z, this is used by CAS-points to access point coordinates.
<private>	ZEval() New evaluation of the function term.

Events borrowed from class JXG.GeometryElement:: attribute, attribute:<attribute><attribute>, down, drag, mousedown, mousedrag, mousemove, mouseout, mouseover, mouseup, move, out, over, touchdown, touchdrag, touchup, up

Class Detail

JXG.Point(board, coordinates, attributes)

A point is the basic geometric element. Based on points lines and circles can be constructed which can be intersected which in turn are points again which can be used to construct new lines, circles, polygons, etc. This class holds methods for all kind of points like free points, gliders, and intersection points.

Parameters:
{string|JXG.Board} board: The board the new point is drawn on.
{Array} coordinates: An array with the affine user coordinates of the point.
{Object} attributes: An object containing visual properties like in JXG.Options#point and JXG.Options#elements, and optional a name and a id.

See:: JXG.Board#generateName; JXG.Board#addPoint

Attribute Detail

{string} attractorDistance

Unit for attractorDistance and snatchDistance, used for magnetized points and for snapToPoints. Possible values are 'screen' and 'user.
Defined in: options.js.

See:: JXG.Point#attractorDistance; JXG.Point#snatchDistance; JXG.Point#snapToPoints; JXG.Point#attractors

Default Value:: 'user'

{array} attractors

List of attractor elements. If the distance of the point is less than attractorDistance the point is made to glider of this element.
Defined in: options.js.

Default Value:: empty

{string} face

There are different point styles which differ in appearance. Posssible values are

Value
cross
circle
square
plus
diamond
triangleUp
triangleDown
triangleLeft
triangleRight

Defined in: options.js.

See:: JXG.Point#setStyle

Default Value:: circle

{Boolean} showInfobox

If true, the infobox is shown on mouse over, else not.
Defined in: options.js.

Default Value:: true

{number} size

Determines the size of a point. Means radius resp. half the width of a point (depending on the face).
Defined in: options.js.

See:: JXG.Point#face; JXG.Point#setStyle

Default Value:: 3

{Boolean} snapToPoints

If set to true, the point will snap to the nearest point in distance of JXG.Point#attractorDistance.
Defined in: options.js.

See:: JXG.Point#attractorDistance

Default Value:: false

{number} snatchDistance

If the distance of the point to one of its attractors is at least this number the point will be released from being a glider on the attracting element. If set to zero nothing happens.
Defined in: options.js.

Default Value:: 0

{Number} style

This attribute was used to determined the point layout. It was derived from GEONExT and was replaced by JXG.Point#face and JXG.Point#size.
Defined in: options.js.

See:: JXG.Point#face; JXG.Point#size

Default Value:: JXG.Options.point#style

Field Detail

<private> {JXG.Coords} coords

Coordinates of the point.

<private> {array} group

Stores the groups of this point in an array of Group.

See:: JXG.Group

needsUpdateFromParent

A JXG.Point#updateGlider call is usually followed by a general JXG.Board#update which calls JXG.Point#updateGliderFromParent. To prevent double updates, JXG.Point#needsUpdateFromParent is set to false in updateGlider() and reset to true in the following call to JXG.Point#updateGliderFromParent

<private> {boolean} onPolygon

Determines whether the point slides on a polygon if point is a glider.

Default Value:: false

<private> {Number} position

Relative position on a line if point is a glider on a line.

slideObjects

List of elements the point is bound to, i.e. the point glides on. Only the last entry is active. Use JXG.Point#popSlideObject to remove the currently active slideObject.

{Number} snapSizeX

Defines together with JXG.Point#snapSizeY the grid the point snaps on to. The point will only snap on values multiple to snapSizeX in x and snapSizeY in y direction. If this value is equal to or less than 0, it will use the grid displayed by the major ticks of the default ticks of the default x axes of the board.
Defined in: options.js.

See:: JXG.Point#snapToGrid; JXG.Point#snapSizeY; JXG.Board#defaultAxes

Default Value:: 1

{Number} snapSizeY

Defines together with JXG.Point#snapSizeX the grid the point snaps on to. The point will only snap on values multiple to snapSizeX in x and snapSizeY in y direction. If this value is equal to or less than 0, it will use the grid displayed by the major ticks of the default ticks of the default y axes of the board.
Defined in: options.js.

See:: JXG.Point#snapToGrid; JXG.Point#snapSizeX; JXG.Board#defaultAxes

Default Value:: 1

{Boolean} snapToGrid

If set to true, the point will snap to a grid defined by JXG.Point#snapSizeX and JXG.Point#snapSizeY.
Defined in: options.js.

See:: JXG.Point#snapSizeX; JXG.Point#snapSizeY

Default Value:: false

Method Detail

<private> _anim(direction, stepCount)

Animates a glider. Is called by the browser after startAnimation is called.

Parameters:
{Number} direction: The direction the glider is animated.
{Number} stepCount: The number of steps.

See:: #startAnimation; #stopAnimation

addConstraint(terms)

Convert the point to CAS point and call update().

Parameters:

{Array} terms

[[zterm], xterm, yterm] defining terms for the z, x and y coordinate. The z-coordinate is optional and it is used for homogeneous coordinates. The coordinates may be either

a JavaScript function,
a string containing GEONExT syntax. This string will be converted into a JavaScript function here,
a Number
a pointer to a slider object. This will be converted into a call of the Value()-method of this slider.

See:: JXG.GeonextParser#geonext2JS

{JXG.Point} addTransform(el, transform)

Add transformations to this point.

Parameters:
{JXG.GeometryElement} el
{JXG.Transformation|Array} transform: Either one JXG.Transformation or an array of JXG.Transformations.

Returns:: {JXG.Point} Reference to this point object.

{Number} Dist(point2)

Getter method for the distance to a second point, this is required for CAS-elements. Here, function inlining seems to be worthwile (for plotting).

Parameters:
{JXG.Point} point2: The point to which the distance shall be calculated.

Returns:: {Number} Distance in user coordinate to the given point

free()

Converts a calculated point into a free point, i.e. it will delete all ancestors and transformations and, if the point is currently a glider, will remove the slideObject reference.

handleAttractors()

A point can change its type from free point to glider and vice versa. If it is given an array of attractor elements (attribute attractors) and the attribute attractorDistance then the pint will be made a glider if it less than attractorDistance apart from one of its attractor elements. If attractorDistance is equal to zero, the point stays in its current form.

handleSnapToGrid()

Move a point to its nearest grid point. The function uses the coords object of the point as its actual position.

handleSnapToPoints()

Let a point snap to the nearest point in distance of JXG.Point#attractorDistance. The function uses the coords object of the point as its actual position.

<private> {Boolean} hasPoint(x, y)

Checks whether (x,y) is near the point.

Parameters:
{Number} x: Coordinate in x direction, screen coordinates.
{Number} y: Coordinate in y direction, screen coordinates.

Returns:: {Boolean} True if (x,y) is near the point, False otherwise.

makeGlider(glideObject)

Convert the point to glider and update the construction.

Parameters:
{String|Object} glideObject: The Object the point will be bound to.

{JXG.Point} moveAlong(path, time, options)

Starts an animation which moves the point along a given path in given time.

Parameters:
{Array|function} path: The path the point is moved on. This can be either an array of arrays containing x and y values of the points of the path, or function taking the amount of elapsed time since the animation has started and returns an array containing a x and a y value or NaN. In case of NaN the animation stops.
{Number} time: The time in milliseconds in which to finish the animation
{Object} options Optional: Optional settings for the animation.
{function} options.callback Optional: A function that is called as soon as the animation is finished.
{Boolean} options.interpolate Optional, Default: true: If path is an array moveAlong() will interpolate the path using JXG.Math.Numerics#Neville. Set this flag to false if you don't want to use interpolation.

Returns:: {JXG.Point} Reference to the point.

{JXG.Point} moveTo(where, time, options)

Starts an animated point movement towards the given coordinates where. The animation is done after time milliseconds. If the second parameter is not given or is equal to 0, setPosition() is called, see #setPosition.

Parameters:
{Array} where: Array containing the x and y coordinate of the target location.
{Number} time Optional: Number of milliseconds the animation should last.
{Object} options Optional: Optional settings for the animation
{function} options.callback Optional: A function that is called as soon as the animation is finished.
{String} options.effect Optional, Default: '<>': animation effects like speed fade in and out. possible values are '<>' for speed increase on start and slow down at the end (default) and '--' for constant speed during the whole animation.

Returns:: {JXG.Point} Reference to itself.

See:: #animate

{*} normalizeFace(s)

Parameters:
s

Deprecated:
Use JXG#normalizePointFace instead

Returns:: {*}

popSlideObject()

Remove the last slideObject. If there are more than one elements the point is bound to, the second last element is the new active slideObject.

remove()

Remove the point from the drawing. This only removes the SVG or VML node of the point and its label from the renderer, to remove the object completely you should use JXG.Board#removeObject.

{JXG.Point} setGliderPosition(x)

Sets the position of a glider relative to the defining elements of the JXG.Point#slideObject.

Parameters:
{Number} x

Returns:: {JXG.Point} Reference to the point element.

{JXG.Point} setPosition(method, coords)

Sets coordinates and calls the point's update() method.

Parameters:
{Number} method: The type of coordinates used here. Possible values are JXG.COORDS_BY_USER and JXG.COORDS_BY_SCREEN.
{Array} coords: coordinates in screen/user units

Returns:: {JXG.Point}

{JXG.Point} setPositionByTransform(method, tv)

Translates the point by tv = (x, y).

Parameters:
{Number} method: The type of coordinates used here. Possible values are JXG.COORDS_BY_USER and JXG.COORDS_BY_SCREEN.
{Number} tv: (x, y)

Returns:: {JXG.Point}

{JXG.Point} setPositionDirectly(method, coords)

Sets coordinates and calls the point's update() method.

Parameters:
{Number} method: The type of coordinates used here. Possible values are JXG.COORDS_BY_USER and JXG.COORDS_BY_SCREEN.
{Array} coords: coordinates (z, x, y) in screen/user units

Returns:: {JXG.Point} this element

<private> setStyle(i)

Set the style of a point. Used for GEONExT import and should not be used to set the point's face and size.

Parameters:
{Number} i: Integer to determine the style.

update(fromParent)

Updates the position of the point.

Parameters:
fromParent

<private> updateConstraint()

Dummy function for unconstrained points or gliders.

<private> updateGlider()

Update of glider in case of dragging the glider or setting the postion of the glider. The relative position of the glider has to be updated. If the second point is an ideal point, then -1 < this.position < 1, this.position==+/-1 equals point2, this.position==0 equals point1 If the first point is an ideal point, then 0 < this.position < 2 this.position==0 or 2 equals point1, this.position==1 equals point2

<private> updateGliderFromParent()

Update of a glider in case a parent element has been updated. That means the relative position of the glider stays the same.

<private> updateRenderer()

Calls the renderer to update the drawing.

{JXG.Point} updateTransform()

Applies the transformations of the curve to JXG.Point#baseElement.

Returns:: {JXG.Point} Reference to this point object.

{JXG.Point} visit(where, time, options)

Starts an animated point movement towards the given coordinates where. After arriving at where the point moves back to where it started. The animation is done after time milliseconds.

Parameters:
{Array} where: Array containing the x and y coordinate of the target location.
{Number} time: Number of milliseconds the animation should last.
{Object} options Optional: Optional settings for the animation
{function} options.callback Optional: A function that is called as soon as the animation is finished.
{String} options.effect Optional, Default: '<>': animation effects like speed fade in and out. possible values are '<>' for speed increase on start and slow down at the end (default) and '--' for constant speed during the whole animation.
{Number} options.repeat Optional, Default: 1: How often this animation should be repeated.

Returns:: {JXG.Point} Reference to itself.

See:: #animate

{Number} X()

Getter method for x, this is used by for CAS-points to access point coordinates.

Returns:: {Number} User coordinate of point in x direction.

<private> {Number} XEval()

New evaluation of the function term. This is required for CAS-points: Their XTerm() method is overwritten in #addConstraint

Returns:: {Number} User coordinate of point in x direction.

{Number} Y()

Getter method for y, this is used by CAS-points to access point coordinates.

Returns:: {Number} User coordinate of point in y direction.

<private> {Number} YEval()

New evaluation of the function term. This is required for CAS-points: Their YTerm() method is overwritten in #addConstraint

Returns:: {Number} User coordinate of point in y direction.

{Number} Z()

Getter method for z, this is used by CAS-points to access point coordinates.

Returns:: {Number} User coordinate of point in z direction.

<private> {Number} ZEval()

New evaluation of the function term. This is required for CAS-points: Their ZTerm() method is overwritten in #addConstraint

Returns:: {Number} User coordinate of point in z direction.

JSXGraph Reference

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Elements

Classes

Class JXG.Point