Riferimenti:API delle app GeoGebra

Da GeoGebra Manual.

Questo documento descrive i metodi pubblici disponibili in geogebra.GeoGebraApplet e utilizzabili in una pagina HTML con JavaScript.

Esempi

Esempio 1: il seguente frammento di codice HTML aggiunge un pulsante "Ripristina" a una pagina HTML, in modo da consentire all'utente il ripristino della costruzione allo stato iniziale: 

 <form>
   <input type="button" value="Ripristina" onclick="document.applets[0].reset();">
 </form>

Esempio 2: questo codice aggiunge i pulsanti "Nascondi A" e "Mostra A", per modificare lo stato di visibilità di un oggetto di nome "A" presente nella costruzione: 

 <form>
   <input type="button" value="Nascondi A" onclick="document.applets[0].setVisible('A', false);">
   <input type="button" value="Mostra A" onclick="document.applets[0].setVisible('A', true);">
 </form>

Esempio 3: una funzione JavaScript "unaPiccolaCostruzione()" è utilizzata per chiamare alcuni metodi di GeoGebraApplet. Nota: la lingua è impostata in Italiano ("it"), utilizzando il parametro "language" nelle tag dell'applet, per fare in modo che sia riconosciuto il comando Retta nella versione italiana. 

 <applet name="ggbApplet" code="geogebra.GeoGebraApplet"
   archive="geogebra.jar"
   width=200 height=40>
 <param name="filename" value="circonf.ggb">
 <param name="framePossible" value="false">
 <param name="language" value="it">
 Installare <a href="http://www.java.com"> Java 1.4.2 </a> (o successivi) per utilizzare questa pagina.
 </applet>
 <script type="text/javascript">
   function miaPiccolaCostruzione() {
     var applet = document.ggbApplet;
     applet.evalCommand("A = (1,1)"); 
     applet.evalCommand("B = (3,2)"); 
     applet.evalCommand("s = Retta[A, B]"); 
   }
 </script>
 <form>
   <input type="button" value="Esegui costruzione" onclick="miaPiccolaCostruzione();">
 </form>

Esempio 4: Date un'occhiata al codice sorgente del seguente foglio di lavoro, che utilizza JavaScript. 

 http://www.geogebra.org/source/program/applet/geogebra_applet_javascript_test.htm

Esempio 5: Questo foglio di lavoro utilizza un listener add in modo da verificare se è già stata completata una precedente costruzione (nel cui caso appare la scritta "Well done"). 

 http://www.geogebra.org/en/examples/javascriptAutomaticCheckingExercise.html

Metodi disponibili

Segnatura del metodo Da Descrizione
boolean evalCommand(String cmdString) 3.0 Valuta la stringa come se fosse digitata direttamente nella barra di inserimento di GeoGebra. Restituisce se la valutazione del comando ha avuto successo.
A partire da GeoGebra 3.2 è possibile passare più comandi contemporaneamente, separandoli con \n.
Nota: utilizzare il language parameter per fare in modo che siano applicati i comandi localizzati nella lingua corrente.
void setUndoPoint() 3.2 Imposta un punto di annullamento. Utile se si vuole fare in modo che l'utente possa annullare l'azione di evalCommand, ad esempio nel caso in cui sia stato creato un pulsante HTML che agisce da strumento personalizzato

Con questi metodi è possibile implementare la comunicazione da Applet a JavaScript. Utilizzando uno dei seguenti metodi, assicurarsi di avere inserito l'opzione MAYSCRIPT al termine della prima riga del tag dell'applet. Ad esempio: 

 <applet name="ggbApplet" code="geogebra.GeoGebraApplet" codebase="." archive="geogebra.jar" width="500" height="250" MAYSCRIPT>

L'opzione MAYSCRIPT è necessaria solo per le comunicazioni da GeoGebraApplet a JavaScript; non è invece richiesta affinché JavaScript possa accedere ai metodi di GeoGebraApplet.

Ad esempio, i seguenti metodi possono essere utilizzati per:

Impostare lo stato degli oggetti

Metodi generali

Segnatura del metodo Da Descrizione
void deleteObject(String objName) 2.7 Elimina l'oggetto avente il nome indicato.
void setValue(String objName, double value) 3.2 Imposta il doppio valore dell'oggetto avente il nome indicato. Nota: se l'oggetto specificato è una variabile booleana, utilizzare il valore 1 per impostarlo come true e un qualsiasi altro valore per impostarlo comefalse. Per oggetti di tipo diverso, non si ha alcun effetto.
void setCoords(String objName, double x, double y) 3.0 Imposta le coordinate dell'oggetto avente il nome indicato. Nota: se l'oggetto specificato non è un punto o un vettore, non si ha alcun effetto.
void setColor(String objName, int red, int green, int blue) 2.7 Imposta il colore dell'oggetto avente il nome indicato.
void setVisible(String objName, boolean visible) 2.7 Imposta o nasconde nella Vista Grafica l'oggetto avente il nome indicato.
void setLabelVisible(String objName, boolean visible) 3.0 Imposta o nasconde nella Vista Grafica l'etichetta dell'oggetto avente il nome indicato.
void setLabelStyle(String objName, boolean visible) 3.0 Imposta lo stile dell'etichettatura nella Vista Grafica dell'oggetto indicato. Gli stili di etichettatura disponibili sono NAME = 0, NAME_VALUE = 1, VALUE = 2 e (da GeoGebra 3.2) CAPTION = 3
void setFixed(String objName, boolean flag) 3.0 Imposta l'oggetto indicato come fissato. Nota: gli oggetti fissati non possono essere modificati.
void setTrace(String objName, boolean flag) 3.0 Attiva o disattiva la traccia dell'oggetto indicato.
boolean renameObject(String oldObjName, String newObjName) 3.2 Renames oldObjName to newObjName. Returns whether the rename was successful
void setLayer(String objName) 3.2 Sets the layer of the object
void setLayerVisible(int layer, boolean visible) 3.2 Shows or hides the all objects in the given layer
void setLineStyle(String objName, int style) 3.2 Sets the line style for the object (0 to 4)
void setLineThickness(String objName, int thickness) 3.2 sets the thickness of the object (1 to 13, -1 for default)
void setPointStyle(String objName, int style) 3.2 Sets the style of points (-1 default, 0 filled circle, 1 circle, 2 cross, 3 plus, 4 filled diamond, 5 unfilled diamond, 6 triangle (north), 7 triangle (south), 8 triangle (east), 9 triangle (west))
void setPointSize(String objName, int size) 3.2 Sets the size of a point (from 1 to 9)
void setFilling(String objName, double filling) 3.2 Sets the filling of an object (from 0 to 1)

Automatic Animation

Method Signature Since Description
void setAnimating(String objName, boolean animate) 3.2 Sets whether an object should be animated. This does not start the animation yet, use startAnimation() to do so.
void setAnimationSpeed(String objName, double speed) 3.2 Sets the animation speed of an object.
void startAnimation() 3.2 Starts automatic animation for all objects with the animating flag set, see setAnimating()
void stopAnimation() 3.2 Stops animation for all objects with the animating flag set, see setAnimating()
boolean isAnimationRunning() 3.2 Returns whether automatic animation is currently running.

Getting the state of objects

Method Signature Since Description
double getXcoord(String objName) 2.7 Returns the cartesian x-coord of the object with the given name. Note: returns 0 if the object is not a point or a vector.
double getYcoord(String objName) 2.7 Returns the cartesian y-coord of the object with the given name. Note: returns 0 if the object is not a point or a vector.
double getValue(String objName) 3.2 Returns the double value of the object with the given name (e.g. length of segment, area of polygon). Note: returns 1 for a boolean object with value true. Otherwise 0 is returned.
String getColor(String objName) 2.7 Returns the color of the object with the given name as a hex string, e.g. "#FF0000" for red. Note that the hex string always starts with # and contains no lower case letters.
boolean getVisible(String objName) 3.2 Returns true or false depending on whether the object is visible in the Graphics View. Returns false if the object does not exist.
String getValueString(String objName) 2.7 Returns the value of the object with the given name as a string.
String getDefinitionString(String objName) 2.7 Returns the definition of the object with the given name as a string.
String getCommandString(String objName) 2.7 Returns the command of the object with the given name as a string.
String getObjectType(String objName) 2.7 Returns the type of the given object as a string (like "point", "line", "circle", etc.).
boolean exists(String objName) 2.7 Returns whether an object with the given name exists in the construction.
boolean isDefined(String objName) 2.7 Returns whether the given object's value is valid at the moment.
String [] getAllObjectNames()
Deprecated since 3.0 		2.7 Returns an array with all object names in the construction. Note: using arrays in JavaScript causes problems with some browsers. Use getObjectNumber() and getObjectName() instead.
int getObjectNumber() 3.0 Returns the number of objects in the construction.
String getObjectName(int i) 3.0 Returns the name of the n-th object of the construction.
String getLayer(String objName) 3.2 Returns the layer of the object.
int getLineStyle(String objName) 3.2 Gets the line style for the object (0 to 4)
int getLineThickness(String objName) 3.2 Gets the thickness of the line (1 to 13)
int getPointStyle(String objName) 3.2 Gets the style of points (-1 default, 0 filled circle, 1 circle, 2 cross, 3 plus, 4 filled diamond, 5 unfilled diamond, 6 triangle (north), 7 triangle (south), 8 triangle (east), 9 triangle (west))
int getPointSize(String objName) 3.2 Gets the size of a point (from 1 to 9)
double getFilling(String objName) 3.2 Gets the filling of an object (from 0 to 1)

Construction / User Interface

Method Signature Since Description
void setMode(int mode) 2.7 Sets the mouse mode (i.e. tool) for the graphics window (see toolbar reference and the applet parameters "showToolBar" and  "customToolBar" )
void openFile(String strURL) 2.7 Opens a construction from a  file (given as absolute or relative URL string)
void reset() 2.7 Reloads the initial construction (given in filename parameter) of this applet.
void refreshViews() 2.7 Refreshs all views. Note: this clears all traces in the graphics window.
void setOnTheFlyPointCreationActive(boolean flag)
 3.2 Turns on the fly creation of points in graphics view on (true) or off (false). Note: this is useful if you don't want tools to have the side effect of creating points. For example, when this flag is set to false, the tool "line through two points" will not create points on the fly when you click on the background of the graphics view.
void hideCursorWhenDragging(boolean flag)
 3.2 Hides (true) or shows (false) the mouse cursor (pointer) when dragging an object to change the construction.
void setRepaintingActive(boolean flag)
 2.7 Turns the repainting of this applet on (true) or off (false). Note: use this method for efficient repainting when you invoke several methods.
void setErrorDialogsActive(boolean flag) 3.0 Turns showing of error dialogs on (true) or off (false). Note: this is especially useful together with evalCommand().
void setCoordSystem(double xmin, double xmax, double ymin, double ymax) 3.0 Sets the Cartesian coordinate system of the graphics window.
void setAxesVisible(boolean xAxis, boolean yAxis) 3.0 Shows or hides the x- and y-axis of the coordinate system in the graphics window.
void setGridVisible(boolean flag) 3.0 Shows or hides the coordinate grid in the graphics window.

GeoGebraApplet to JavaScript Communication

With these methods you can implement Applet to JavaScript communication. When you use any of the following methods, you should make sure to insert the MAYSCRIPT option add the end of the first line of your applet tag. For example:

<applet name="ggbApplet" code="geogebra.GeoGebraApplet" codebase="." archive="geogebra.jar" width="500" height="250" MAYSCRIPT>. The MAYSCRIPT option is only needed for GeoGebraApplet to JavaScript communication; it is not needed for JavaScript to access the GeoGebraApplet methods. For example, these methods can be used to:

Method Signature Since Description
void registerAddListener(String JSFunctionName) 3.0 Registers a JavaScript function as an add listener for the applet's construction. Whenever a new object is created in the GeoGebraApplet's construction, the JavaScript function JSFunctionName is called using the name of the newly created object as its single argument.

Example: First, register a listening JavaScript function:

ggbApplet.registerAddListener("myAddListenerFunction");

When an object "A" is created, the GeoGebra Applet will call the Javascript function

myAddListenerFunction("A");
void unregisterAddListener(String objName) 3.0 Removes a previously registered add listener, see registerAddListener()
void registerRemoveListener(String JSFunctionName) 3.0 Registers a JavaScript function as a remove listener for the applet's construction. Whenever an object is deleted from the GeoGebraApplet's construction, the JavaScript function JSFunctionName is called using the name of the deleted object as its single argument. Note: when a construction is cleared, remove is not called for every single object, see registerClearListener().

Example: First, register a listening JavaScript function:

ggbApplet.registerRemoveListener("myRemoveListenerFunction");

When the object "A" is deleted, the GeoGebra Applet will call the Javascript function

myRemoveListenerFunction("A");
void unregisterRemoveListener(String objName) 3.0 Removes a previously registered remove listener, see registerRemoveListener()
void registerUpdateListener(String JSFunctionName) 3.0 Registers a JavaScript function as a update listener for the applet's construction. Whenever any object is updated in the GeoGebraApplet's construction, the JavaScript function JSFunctionNameis called using the name of the updated object as its single argument. Note: when you only want to listen for the updates of a single object use registerObjectUpdateListener() instead.

Example: First, register a listening JavaScript function:

ggbApplet.registerUpdateListener("myUpdateListenerFunction");

When the object "A" is updated, the GeoGebra Applet will call the Javascript function

myUpdateListenerFunction("A");
void unregisterUpdateListener(String objName) 3.0 Removes a previously registered update listener, see registerUpdateListener()
void registerObjectUpdateListener(String objName, String JSFunctionName) 3.0 Registers a JavaScript function as an update listener for a single object. Whenever the object with the given name is updated, the JavaScript function JSFunctionNameis called using the name of the updated object as its single argument. If objName previously had a mapping JavaScript function, the old value is replaced. Note: all object updated listeners are unregistered when their object is removed or the construction is cleared, see registerRemoveListener() and registerClearListener().

Example: First, register a listening JavaScript function:

ggbApplet.registerObjectUpdateListener("A", "myAupdateListenerFunction");

Whenever the object A is updated, the GeoGebra Applet will call the Javascript function

myAupdateListenerFunction("A");

Note: an object update listener will still work after an object is renamed.

void unregisterObjectUpdateListener(String objName) 3.0 Removes a previously registered object update listener of the object with the given name, see registerObjectUpdateListener()
void registerRenameListener(String JSFunctionName) 3.0 Registers a JavaScript function as a rename listener for the applet's construction. Whenever an object is renamed in the GeoGebraApplet's construction, the JavaScript function JSFunctionName is called using the old name and the new name of the renamed object as its two arguments.

Example: First, register a listening JavaScript function:

ggbApplet.registerRenameListener("myRenameListenerFunction");

When an object "A" is renamed to "B", the GeoGebra Applet will call the Javascript function

myRenameListenerFunction("A", "B");
void unregisterRenameListener(String objName) 3.0 Removes a previously registered rename listener, see registerRenameListener()
void registerClearListener(String JSFunctionName) 3.0 Registers a JavaScript function as a clear listener for the applet's construction. Whenever the construction in the GeoGebraApplet is cleared (i.e. all objects are removed), the JavaScript function JSFunctionName is called using no arguments. Note: all update listeners are unregistered when a construction is cleared. See registerUpdateListener() and registerRemoveListener().

Example: First, register a listening JavaScript function:

ggbApplet.registerClearListener("myClearListenerFunction");

When the construction is cleared (i.e. after reseting a construction or opening a new construction file), the GeoGebra Applet will call the Javascript function

myClearListenerFunction();
void unregisterClearListener(String JSFunctionName) 3.0 Removes a previously registered clear listener, see registerClearListener()

GeoGebra's XML format

With these methods you can set everything in a construction (see XML Reference ).

Method Signature Since Description
void evalXML(String xmlString) 2.7 Evaluates the given XML string and changes the current construction. Note: the construction is NOT cleared before evaluating the XML string.
void setXML(String xmlString) 2.7 Evaluates the given XML string and changes the current construction. Note: the construction is cleared before evaluating the XML string. This method could be used to load constructions.
String getXML()
 2.7 Returns the current construction in GeoGebra's XML format. This method could be used to save constructions.
String getXML(String objName)
 3.2 Returns the GeoGebra XML string for the given object, i.e. only the <element> tag is returned.
String getAlgorithmXML(String objName)
 3.2 For a dependent GeoElement objName the XML string of the parent algorithm and all its output objects is returned. For a free GeoElement objName "" is returned.

Miscellaneous

Method Signature Since Description
String evalMathPiper(String string) 3.2 Passes the string to MathPiper and returns the result as a String.
String getIPAddress() 3.2 Returns the IP address of the local computer as a String eg "192.168.0.4"
String getHostname() 3.2 Returns the hostname of the local computer as a String
void debug(String string) 3.2 Prints the string to the Java Console
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