The graphics functions use pointers, which are of class graphics_handle, in
order to address the data structures which control visual display. A
graphics handle may point to any one of a number of different base object
types and these objects are the graphics data structures themselves. The
primitive graphic object types 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 the corresponding
type. In addition there are several functions which operate on properties of
the graphics objects and which also return handles: the functions
plot3 return a handle pointing to an object of type line, the
subplot returns a handle pointing to an object of type axes,
fill returns a handle pointing to an object of type patch,
stem3 each return a handle
to a complex data structure as documented in
The graphics objects are arranged in a hierarchy:
1. The root is at 0. In other words,
get (0) returns the properties of
the root object.
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, a figure or axes object may be tested using
isaxes respectively. The test functions return true only if the
argument is both a handle and of the correct type (figure or axes).
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 obj.
obj may also be an array of objects in which case res will be a logical array indicating whether each handle has the property prop.
For plotting, obj is a handle to a graphics object. Otherwise, obj should be an instance of a class.
See also: get, set, ismethod, isobject.