Creazione, eliminazione ed esecuzione di query sugli oggetti dei grafici

Trovare, copiare ed eliminare oggetti dei grafici

Utilizzare le funzioni per creare, eliminare e copiare oggetti dei grafici, preparare figure e assi per il plottaggio e verificare la validità degli oggetti dei grafici. Esplorare il sistema grafico e rendere il codice più robusto. Ad esempio, è possibile verificare se un oggetto è un oggetto valido dei grafici prima di passarlo a una funzione.

Funzioni

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Ottenimento dell’oggetto attuale

`gca`	Assi o grafico correnti
`gcf`	Handle della figura corrente
`gcbf`	Handle of figure containing object whose callback is executing
`gcbo`	Handle of object whose callback is executing
`gco`	Handle of current object
`groot`	Graphics root object

Ricerca e identificazione degli oggetti

`ancestor`	Ancestor of graphics object
`allchild`	Find all children of specified objects
`findall`	Find all graphics objects
`findobj`	Find graphics objects with specific properties
`findfigs`	Find visible offscreen figures
`isgraphics`	True for valid graphics object handles
`ishandle`	Test for valid graphics or Java object handle
`isa`	Determine if input is instance of specified class
`ishold`	Current hold state

Creazione, copia ed eliminazione degli oggetti

`gobjects`	Initialize array for graphics objects
`copyobj`	Copy graphics objects and their children
`newplot`	Specify where to draw graphics objects
`delete`	Delete files or objects
`clf`	Clear figure
`cla`	Clear axes
`close`	Close one or more figures

Argomenti

Definizione degli assi e delle figure di destinazione

Responding to Hold State
This example shows how to test for the hold state and respond appropriately in user-defined plotting functions.
Use newplot to Control Plotting
This example shows how to prepare figures and axes for user-written plotting functions.
Control Graph Display
You can control which figures and which axes MATLAB^® uses to display the result of plotting functions.
Prepare Figures and Axes for Graphs
MATLAB plotting functions rely on the values of the figure and axes NextPlot properties to determine whether to add, clear, or clear and reset the figure and axes before drawing the new graph.
Prevent Access to Figures and Axes
In some situations it is important to prevent particular figures or axes from becoming the target for graphics output.

Creazione di oggetti

Graphics Object Handles
Use the object handle to set and query the values of the object properties.
Graphics Arrays
Graphics arrays can contain the handles of any graphics objects.
Preallocate Arrays of Graphics Objects
Use the gobjects function to preallocate arrays for graphics objects.

Identificazione, copia ed eliminazione di oggetti

Find Objects
The findobj function can scan the object hierarchy to obtain the handles of objects that have specific property values.
Delete Graphics Objects
Remove graphics objects with the delete function.
Special Object Identifiers
MATLAB provides functions that return important object handles so that you can obtain these handles whenever you require them.
Test for Valid Handle
Use isgraphics to determine if a variable is a valid graphics object handle.
Handles in Logical Expressions
Handle objects do not evaluate to logical true or false. You must use the function that tests for the state of interest and returns a logical value.