Class JXG.GeometryElement

↳ JXG.GeometryElement

This is the basic class for geometry elements like points, circles and lines.

Defined in: GeometryElement.js.

Class Summary
Constructor Attributes	Constructor Name and Description
	JXG.GeometryElement(board, attributes, type, oclass) Constructs a new GeometryElement object.

Attributes Summary
Field Attributes	Field Name and Description
	dash Determines the elements border-style.
	draft If true the element will be drawn in grey scale colors to visualize that it's only a draft.
	fillColor The fill color of this geometry element.
	fillOpacity Opacity for fill color.
	fixed If true the element is fixed and can not be dragged around.
	frozen If true the element is fixed and can not be dragged around.
	highlight
	highlightFillColor The fill color of the given geometry element when the mouse is pointed over it.
	highlightFillOpacity Opacity for fill color when the object is highlighted.
	highlightStrokeColor The stroke color of the given geometry element when the user moves the mouse over it.
	highlightStrokeOpacity Opacity for stroke color when the object is highlighted.
	highlightStrokeWidth Width of the element's stroke when the mouse is pointed over it.
	needsRegularUpdate If this is set to true, the element is updated in every update call of the board.
	shadow If true the element will get a shadow.
	strokeColor The stroke color of the given geometry element.
	strokeOpacity Opacity for element's stroke color.
	strokeWidth Width of the element's stroke.
	trace If true the element will be traced, i.e.
	traceAttributes Extra visual properties for traces of an element
	visible If false the element won't be visible on the board, otherwise it is shown.
	withLabel If true a label will display the element's name.

Field Summary
Field Attributes	Field Name and Description
	addEvent Alias of JXG.GeometryElement#on.
	ancestors Elements on which this elements depends on are stored here.
<private>	baseElement TODO
	board Reference to the board associated with the element.
	childElements Stores all dependent objects to be updated when this point is moved.
	descendants Elements depending on this element are stored here.
	dump The element is saved with an explicit entry in the file (`true`) or implicitly via a composition.
<constant>	elementClass The element's class.
	elType The string used with JXG.Board#create
	eventHandlers Stores the eventhandlers attached to the element.
	getAttribute Get the value of the property `key`.
	hasLabel If element has a label subelement then this property will be set to true.
	highlighted True, if the element is currently highlighted.
	id Unique identifier for the element.
	isDraggable Controls if this element can be dragged.
	isReal If element is in two dimensional real space this is true, else false.
	methodMap The methodMap determines which methods can be called from within JessieCode and under which name it can be used.
	mouseover Is the mouse over this element?
	name Not necessarily unique name for the element.
	needsUpdate Controls if updates are necessary
	notExistingParents Stores all Intersection Objects which in this moment are not real and so hide this element.
	numTraces Counts the number of objects drawn as part of the trace of the element.
	quadraticform Quadratic form representation of circles (and conics)
	removeEvent Alias of JXG.GeometryElement#off.
	stdform [c,b0,b1,a,k,r,q0,q1] See A.E.
	subs Subs contains the subelements, created during the create method.
	symbolic Stores variables for symbolic computations
	traces Keeps track of all objects drawn as part of the trace of the element.
	transformations Stores the transformations which are applied during update in an array
<constant>	type Type of the element.
	visProp An associative array containing all visual properties.

Method Summary
Method Attributes	Method Name and Description
<private>	_set(property, value) Sets the value of property `property` to `value`.
	addChild(obj) Add an element as a child to the current element.
<private>	addDescendants(obj) Adds the given object to the descendants list of this object and all its child objects.
	animate(hash, time, options) Animates properties for that object like stroke or fill color, opacity and maybe even more later.
	bounds() Dimensions of the smallest rectangle enclosing the element.
	clearTrace() Removes all objects generated by the trace function.
	cloneToBackground() Copy the element to background.
<private>	countChildren() Counts the direct children of an object without counting labels.
<private>	createGradient() Creates a gradient nodes in the renderer.
	createLabel() Creates a label element for this geometry element.
<private>	draggable() Decides whether an element can be dragged.
<private>	generatePolynomial() Array of strings containing the polynomials defining the element.
	getAttributes() Retrieve a copy of the current visProp.
	getLabelAnchor() Returns the coords object where the label of the element shall be drawn.
	getName() Returns the elements name, Used in JessieCode.
	getParents() List of the element ids resp.
<deprecated>	getProperty(key) Deprecated alias for JXG.GeometryElement#getAttribute.
	getTextAnchor() Returns the coords object where a text that is bound to the element shall be drawn.
	getType() The type of the element as used in JXG.Board#create.
	hasPoint(x, y) Checks whether (x,y) is near the element.
	hideElement() Hide the element.
	labelColor(lColor) Set the labelColor of an element
	noHighlight() Uses the "normal" properties of the element.
<private>	normalize() Normalize the element's standard form.
	off(event, handler) Unregister an event handler.
	on(event, handler) Register a new event handler
<private>	prepareUpdate() Notify all child elements for updates.
	remove() Removes the element from the construction.
	resolveShortcuts(properties) Resolves property shortcuts like `color` and expands them, e.g.
	setArrow(firstArrow, lastArrow) Determines whether the arc has arrows at start or end of the arc.
	setAttribute(attributes) Sets an arbitrary number of attributes.
<private>	setDash(dash) Set the dash style of an object.
	setLabelText(str) Updates the element's label text, strips all html.
<deprecated>	setProperty() Deprecated alias for JXG.GeometryElement#setAttribute.
<private>	setStraight(x, y) TODO Was hat das hier verloren? "Straights" gibts doch nur fuer Lines oder? Sollte das dann nicht nur in Line.js zu finden sein? --michael
	showElement() Make the element visible.
	triggerEventHandlers(event) Triggers all event handlers of this element for a given event.
	update() General update method.
<private>	updateRenderer() Provide updateRenderer method.

Class Detail

JXG.GeometryElement(board, attributes, type, oclass)

Constructs a new GeometryElement object.

Parameters:
board
attributes
type
oclass

Attribute Detail

{Number} dash

Determines the elements border-style. Possible values are:

0 for a solid line
1 for a dotted line
2 for a line with small dashes
3 for a line with medium dashes
4 for a line with big dashes
5 for a line with alternating medium and big dashes and large gaps
6 for a line with alternating medium and big dashes and small gaps

Defined in: Options.js.

Default Value:: 0

{boolean} draft

If true the element will be drawn in grey scale colors to visualize that it's only a draft.
Defined in: Options.js.

{String} fillColor

The fill color of this geometry element.
Defined in: Options.js.

See:: JXG.GeometryElement#highlightFillColor; JXG.GeometryElement#fillOpacity; JXG.GeometryElement#highlightFillOpacity

{number} fillOpacity

Opacity for fill color.
Defined in: Options.js.

See:: JXG.GeometryElement#fillColor; JXG.GeometryElement#highlightFillColor; JXG.GeometryElement#highlightFillOpacity

{Boolean} fixed

If true the element is fixed and can not be dragged around. The element will be repositioned on zoom and moveOrigin events.
Defined in: Options.js.

Default Value:: false

{Boolean} frozen

If true the element is fixed and can not be dragged around. The element will even stay at its position on zoom and moveOrigin events. Only free elements like points, texts, curves can be frozen.
Defined in: Options.js.

Default Value:: false

{Boolean} highlight

Defined in: Options.js.

Default Value:: true

{String} highlightFillColor

The fill color of the given geometry element when the mouse is pointed over it.
Defined in: Options.js.

See:: JXG.GeometryElement#fillColor; JXG.GeometryElement#fillOpacity; JXG.GeometryElement#highlightFillOpacity

{number} highlightFillOpacity

Opacity for fill color when the object is highlighted.
Defined in: Options.js.

See:: JXG.GeometryElement#fillColor; JXG.GeometryElement#highlightFillColor; JXG.GeometryElement#fillOpacity

{String} highlightStrokeColor

The stroke color of the given geometry element when the user moves the mouse over it.
Defined in: Options.js.

See:: JXG.GeometryElement#strokeColor; JXG.GeometryElement#strokeWidth; JXG.GeometryElement#strokeOpacity; JXG.GeometryElement#highlightStrokeOpacity

{number} highlightStrokeOpacity

Opacity for stroke color when the object is highlighted.
Defined in: Options.js.

See:: JXG.GeometryElement#strokeColor; JXG.GeometryElement#highlightStrokeColor; JXG.GeometryElement#strokeWidth; JXG.GeometryElement#strokeOpacity

{number} highlightStrokeWidth

Width of the element's stroke when the mouse is pointed over it.
Defined in: Options.js.

See:: JXG.GeometryElement#strokeColor; JXG.GeometryElement#highlightStrokeColor; JXG.GeometryElement#strokeOpacity; JXG.GeometryElement#highlightStrokeOpacity; JXG.GeometryElement#highlightFillColor

{Boolean} needsRegularUpdate

If this is set to true, the element is updated in every update call of the board. If set to false, the element is updated only after zoom events or more generally, when the bounding box has been changed. Examples for the latter behaviour should be axes.
Defined in: Options.js.

See:: JXG.GeometryElement#needsRegularUpdate

Default Value:: true

{boolean} shadow

If true the element will get a shadow.
Defined in: Options.js.

Default Value:: false

{String} strokeColor

The stroke color of the given geometry element.
Defined in: Options.js.

See:: JXG.GeometryElement#highlightStrokeColor; JXG.GeometryElement#strokeWidth; JXG.GeometryElement#strokeOpacity; JXG.GeometryElement#highlightStrokeOpacity

{number} strokeOpacity

Opacity for element's stroke color.
Defined in: Options.js.

See:: JXG.GeometryElement#strokeColor; JXG.GeometryElement#highlightStrokeColor; JXG.GeometryElement#strokeWidth; JXG.GeometryElement#highlightStrokeOpacity

{number} strokeWidth

Width of the element's stroke.
Defined in: Options.js.

See:: JXG.GeometryElement#strokeColor; JXG.GeometryElement#highlightStrokeColor; JXG.GeometryElement#strokeOpacity; JXG.GeometryElement#highlightStrokeOpacity

{Boolean} trace

If true the element will be traced, i.e. on every movement the element will be copied to the background. Use JXG.GeometryElement#clearTrace to delete the trace elements.
Defined in: Options.js.

See:: JXG.GeometryElement#clearTrace; JXG.GeometryElement#traces; JXG.GeometryElement#numTraces

Default Value:: false

{Object} traceAttributes

Extra visual properties for traces of an element
Defined in: Options.js.

See:: JXG.GeometryElement#trace

{boolean} visible

If false the element won't be visible on the board, otherwise it is shown.
Defined in: Options.js.

See:: JXG.GeometryElement#hideElement; JXG.GeometryElement#showElement

Default Value:: true

{Boolean} withLabel

If true a label will display the element's name.
Defined in: Options.js.

Default Value:: false

Field Detail

addEvent

Alias of JXG.GeometryElement#on.

{Object} ancestors

Elements on which this elements depends on are stored here.

<private> {JXG.GeometryElement} baseElement

TODO

Default Value:: null

{JXG.Board} board

Reference to the board associated with the element.

{Object} childElements

Stores all dependent objects to be updated when this point is moved.

{Object} descendants

Elements depending on this element are stored here.

{Boolean} dump

The element is saved with an explicit entry in the file (true) or implicitly via a composition.

Default Value:: true

<constant> {number} elementClass

The element's class.

{String} elType

The string used with JXG.Board#create

{Object} eventHandlers

Stores the eventhandlers attached to the element.

getAttribute

Get the value of the property key.

{Boolean} hasLabel

If element has a label subelement then this property will be set to true.

Default Value:: false

{Boolean} highlighted

True, if the element is currently highlighted.

Default Value:: false

{String} id

Unique identifier for the element. Equivalent to id-attribute of renderer element.

{Boolean} isDraggable

Controls if this element can be dragged. In GEONExT only free points and gliders can be dragged.

Default Value:: false

{Boolean} isReal

If element is in two dimensional real space this is true, else false.

Default Value:: true

{Object} methodMap

The methodMap determines which methods can be called from within JessieCode and under which name it can be used. The map is saved in an object, the name of a property is the name of the method used in JessieCode, the value of a property is the name of the method in JavaScript.

{Boolean} mouseover

Is the mouse over this element?

Default Value:: false

{String} name

Not necessarily unique name for the element.

See:: JXG.Board#generateName

Default Value:: Name generated by JXG.Board#generateName.

{Boolean} needsUpdate

Controls if updates are necessary

Default Value:: true

{Object} notExistingParents

Stores all Intersection Objects which in this moment are not real and so hide this element.

{Number} numTraces

Counts the number of objects drawn as part of the trace of the element.

See:: JXG.GeometryElement#traced; JXG.GeometryElement#clearTrace; JXG.GeometryElement#traces

{Array} quadraticform

Quadratic form representation of circles (and conics)

Default Value:: [[1,0,0],[0,1,0],[0,0,1]]

removeEvent

Alias of JXG.GeometryElement#off.

{Array} stdform

[c,b0,b1,a,k,r,q0,q1] See A.E. Middleditch, T.W. Stacey, and S.B. Tor: "Intersection Algorithms for Lines and Circles", ACM Transactions on Graphics, Vol. 8, 1, 1989, pp 25-40. The meaning of the parameters is: Circle: points p=[p0,p1] on the circle fulfill a<p,p> + <b,p> + c = 0 For convenience we also store r: radius k: discriminant = sqrt(<b,b>-4ac) q=[q0,q1] center Points have radius = 0. Lines have radius = infinity. b: normalized vector, representing the direction of the line. Should be put into Coords, when all elements possess Coords.

Default Value:: [1, 0, 0, 0, 1, 1, 0, 0]

{Object} subs

Subs contains the subelements, created during the create method.

{Object} symbolic

Stores variables for symbolic computations

{Object} traces

Keeps track of all objects drawn as part of the trace of the element.

See:: JXG.GeometryElement#traced; JXG.GeometryElement#clearTrace; JXG.GeometryElement#numTraces

{Array} transformations

Stores the transformations which are applied during update in an array

See:: JXG.Transformation

<constant> {number} type

Type of the element.

{Object} visProp

An associative array containing all visual properties.

Default Value:: empty object

Method Detail

<private> _set(property, value)

Sets the value of property property to value.

Parameters:
{String} property: The property's name.
{%} value: The new value

addChild(obj)

Add an element as a child to the current element. Can be used to model dependencies between geometry elements.

Parameters:
{JXG.GeometryElement} obj: The dependent object.

<private> addDescendants(obj)

Adds the given object to the descendants list of this object and all its child objects.

Parameters:
{JXG.GeometryElement} obj: The element that is to be added to the descendants list.

Returns:

{JXG.GeometryElement} animate(hash, time, options)

Animates properties for that object like stroke or fill color, opacity and maybe even more later.

Parameters:

{Object} hash

Object containing propiertes with target values for the animation.

{number} time

Number of milliseconds to complete the animation.

{Object} options Optional

Optional settings for the animation:

callback: A function that is called as soon as the animation is finished.

Returns:: A reference to the object

{Array} bounds()

Dimensions of the smallest rectangle enclosing the element.

Returns:: {Array} The coordinates of the enclosing rectangle in a format like the bounding box in JXG.Board#setBoundingBox.

clearTrace()

Removes all objects generated by the trace function.

{JXG.GeometryElement} cloneToBackground()

Copy the element to background. This is used for tracing elements.

Returns:: {JXG.GeometryElement} A reference to the element

<private> {number} countChildren()

Counts the direct children of an object without counting labels.

Returns:: {number} Number of children

<private> createGradient()

Creates a gradient nodes in the renderer.

See:: JXG.SVGRenderer#setGradient

createLabel()

Creates a label element for this geometry element.

See:: #addLabelToElement

<private> {boolean} draggable()

Decides whether an element can be dragged. This is used in setPositionDirectly methods where all parent elements are checked if they may be dragged, too.

Returns:: {boolean}

<private> {Array} generatePolynomial()

Array of strings containing the polynomials defining the element. Used for determining geometric loci the groebner way.

Returns:: An array containing polynomials describing the locus of the current object.

{Object} getAttributes()

Retrieve a copy of the current visProp.

Returns:: {Object}

{JXG.Coords} getLabelAnchor()

Returns the coords object where the label of the element shall be drawn. Differs in some cases from the values that getTextAnchor returns.

Returns:: {JXG.Coords} JXG.Coords Place where the text shall be drawn.

See:: JXG.GeometryElement#getTextAnchor

{String} getName()

Returns the elements name, Used in JessieCode.

Returns:: {String}

{Array} getParents()

List of the element ids resp. values used as parents in JXG.Board#create.

Returns:: {Array}

getProperty(key)

Deprecated alias for JXG.GeometryElement#getAttribute.

Parameters:
key

Deprecated:
Use JXG.GeometryElement#getAttribute.

{JXG.Coords} getTextAnchor()

Returns the coords object where a text that is bound to the element shall be drawn. Differs in some cases from the values that getLabelAnchor returns.

Returns:: {JXG.Coords} JXG.Coords Place where the text shall be drawn.

See:: JXG.GeometryElement#getLabelAnchor

{String} getType()

The type of the element as used in JXG.Board#create.

Returns:: {String}

{Boolean} hasPoint(x, y)

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

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 element, False otherwise.

hideElement()

Hide the element. It will still exist but not visible on the board.

labelColor(lColor)

Set the labelColor of an element

Parameters:
{String} lColor: String which determines the text color of an object's label.

See:: JXG.GeometryElement#labelColor

noHighlight()

Uses the "normal" properties of the element.

<private> normalize()

Normalize the element's standard form.

off(event, handler)

Unregister an event handler.

Parameters:
{String} event
{Function} handler: The same function used in JXG.GeometryElement#on.

on(event, handler)

Parameters:
{String} event
{Function} handler

<private> prepareUpdate()

Notify all child elements for updates.

remove()

Removes the element from the construction. This only removes the SVG or VML node of the element and its label (if available) from the renderer, to remove the element completely you should use JXG.Board#removeObject.

{Object} resolveShortcuts(properties)

Resolves property shortcuts like color and expands them, e.g. strokeColor and fillColor. Writes the expanded properties back to the given properties.

Parameters:
{Object} properties

Returns:: {Object} The given parameter with shortcuts expanded.

setArrow(firstArrow, lastArrow)

Determines whether the arc has arrows at start or end of the arc.

Parameters:
{bool} firstArrow: True if there is an arrow at the start of the arc, false otherwise.
{bool} lastArrow: True if there is an arrow at the end of the arc, false otherwise. Is stored at visProp['firstarrow'] and visProp['lastarrow']

setAttribute(attributes)

Sets an arbitrary number of attributes.

Parameters:
{Object} attributes: An object with attributes.

Examples:

<private> setDash(dash)

Set the dash style of an object. See #dash for a list of available dash styles. You should use #setProperty instead of this method.

Parameters:
{number} dash: Indicates the new dash style

setLabelText(str)

Updates the element's label text, strips all html.

Parameters:
{String} str

setProperty()

Deprecated alias for JXG.GeometryElement#setAttribute.

Deprecated:
Use JXG.GeometryElement#setAttribute.

<private> setStraight(x, y)

TODO Was hat das hier verloren? "Straights" gibts doch nur fuer Lines oder? Sollte das dann nicht nur in Line.js zu finden sein? --michael

Parameters:
x
y

showElement()

Make the element visible.

triggerEventHandlers(event)

Triggers all event handlers of this element for a given event.

Parameters:
{String} event

update()

General update method. Should be overwritten by the element itself. Can be used sometimes to commit changes to the object.

<private> updateRenderer()

Provide updateRenderer method.

JSXGraph Reference

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Elements

Classes

Class JXG.GeometryElement