The graphics functions use pointers, which are of class graphics_handle, in
order to address the data structures which control graphical displays. A
graphics handle may point any one of a number of different object types. The
objects are the graphics data structures. The types of objects are:
Each of these objects has a function by the same name. and, each of these
functions returns a graphics handle pointing to an object of corresponding
type. In addition there are several functions which operate on properties of
the graphics objects and which return handles: the functions
plot3 return a handle pointing to an object of type line, the function
subplot returns a handle pointing to an object of type axes, the
fill returns a handle pointing to an object of type patch, the
stem3 each return a handle
as documented in Data Sources.
The graphics objects are arranged in a hierarchy:
1. The root is at 0. i.e.,
get (0) returns the properties of the root
2. Below the root are
3. Below the
figure objects are
4. Below the
axes objects are
Graphics handles may be distinguished from function handles
(see Function Handles) by means of the function
ishandle returns true if its argument is a handle of a graphics object.
In addition, the figure object may be tested using
isfigure returns true only if its argument is a handle of a figure. The
whos function can be used to show the object type of each currently
defined graphics handle. (Note: this is not true today, but it is, I hope,
considered an error in whos. It may be better to have whos just show
graphics_handle as the class, and provide a new function which, given a
graphics handle, returns its object type. This could generalize the ishandle()
functions and, in fact, replace them.)
set commands are used to obtain and set the values of
properties of graphics objects. In addition, the
get command may be
used to obtain property names.
For example, the property
"type" of the graphics object pointed to by
the graphics handle h may be displayed by:
get (h, "type")
The properties and their current values are returned by
where h is a handle of a graphics object. If only the names of the
allowed properties are wanted they may be displayed by:
get (h, "").
Thus, for example:
h = figure (); get (h, "type") ans = figure get (h, ""); error: get: ambiguous figure property name ; possible matches: __enhanced__ hittest resize __graphics_toolkit__ integerhandle resizefcn __guidata__ interruptible selected __modified__ inverthardcopy selectionhighlight __myhandle__ keypressfcn selectiontype __plot_stream__ keyreleasefcn tag alphamap menubar toolbar beingdeleted mincolormap type busyaction name uicontextmenu buttondownfcn nextplot units children numbertitle userdata clipping outerposition visible closerequestfcn paperorientation windowbuttondownfcn color paperposition windowbuttonmotionfcn colormap paperpositionmode windowbuttonupfcn createfcn papersize windowkeypressfcn currentaxes papertype windowkeyreleasefcn currentcharacter paperunits windowscrollwheelfcn currentobject parent windowstyle currentpoint pointer wvisual deletefcn pointershapecdata wvisualmode dockcontrols pointershapehotspot xdisplay doublebuffer position xvisual filename renderer xvisualmode handlevisibility renderermode
The root figure has index 0. Its properties may be displayed by:
get (0, "").
The uses of
set are further explained in
Return true if prop is a property of the object with handle h.
h may also be an array of handles in which case res will be a logical array indicating whether each handle has the property prop.
See also: get, set.