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Hgtransform Properties

Hgtransform properties

Creating Hgtransform Objects

Use hgtransform to create hgtransform objects.

Modifying Properties

You can set and query graphics object properties using the set and get commands.

To change the default values of properties, see Setting Default Property Values.

See Group Objects for general information on this type of object.

Hgtransform Property Descriptions

This section provides a description of properties. Curly braces { } enclose default values.


hg.Annotation object (read-only)

Control the display of hgtransform objects in legends. Specifies whether this hgtransform object is represented in a figure legend.

Querying the Annotation property returns the handle of an hg.Annotation object. The hg.Annotation object has a property called LegendInformation, which contains an hg.LegendEntry object.

Once you have obtained the hg.LegendEntry object, you can set its IconDisplayStyle property to control whether the hgtransform object is displayed in a figure legend.

IconDisplayStyle ValuePurpose
onInclude the hgtransform object in a legend as one entry, but not its children objects
offDo not include the hgtransform or its children in a legend (default)
childrenInclude only the children of the hgtransform as separate entries in the legend

Setting the IconDisplayStyle Property

These commands set the IconDisplayStyle of a graphics object with handle hobj to children, which causes each child object to have an entry in the legend:

hAnnotation = get(hobj,'Annotation');
hLegendEntry = get(hAnnotation,'LegendInformation');

Using the IconDisplayStyle Property

See Control Legend Content for more information and examples.


on | {off} (read-only)

This object is being deleted. Mechanism to determine if objects are in the process of being deleted. MATLAB® sets the BeingDeleted property to on when the object's delete function callback is called (see the DeleteFcn property). It remains set to on while the delete function executes, after which the object no longer exists.

For example, an object's delete function calls other functions that act on a number of different objects. If a function does not need to perform an action on an about-be-deleted object, it can check the object's BeingDeleted property before acting.


cancel | {queue}

Callback queuing

Determines how MATLAB handles the execution of interrupting callbacks.

A running callback is the currently executing callback. The interrupting callback is the callback that tries to interrupt the running callback. The BusyAction property of the interrupting callback determines how MATLAB handles its execution. When the BusyAction property is set to:

  • 'queue' — Puts the interrupting callback in a queue to be processed after the running callback finishes execution.

  • 'cancel' — Discards the interrupting callback as MATLAB finishes execution.

For information about how the Interruptible property of the callback controls whether other callbacks can interrupt the running callback, see the Interruptible property description.


function handle | cell array containing function handle and additional arguments | string (not recommended)

Button press callback function. Executes whenever you press a mouse button while the pointer is within the extent of the hgtransform object, but not over another graphics object. The extent of an hgtransform object is the smallest rectangle that encloses all the children. Note that you cannot execute the hgtransform object's button down function if it has no children.

Define the ButtonDownFcn as a function handle. The function must define at least two input arguments (handle of figure associated with the mouse button press and an empty event structure).

For information on the syntax of callback functions, see Function Handle Callbacks.


array of graphics object handles

Children of the hgtransform object. An array containing the handles of all graphics objects parented to the hgtransform object (whether visible or not).

The graphics objects that can be children of an hgtransform are images, lights, lines, patches, rectangles, surfaces, and text. You can change the order of the handles and thereby change the stacking of the objects on the display.

Note that if a child object's HandleVisibility property is callback or off, its handle does not show up in the hgtransform Children property unless you set the Root ShowHiddenHandles property to on.


{on} | off

Clipping mode. This property has no effect on hgtransform objects.


function handle | cell array containing function handle and additional arguments | string (not recommended)

Callback executed during object creation. Executes when MATLAB creates an hgtransform object. You must define this property as a default value for hgtransform objects. For example, the statement:


defines a default value on the root level that applies to every hgtransform object created in a MATLAB session. Whenever you create an hgtransform object, the function associated with the function handle @myCreateFcn executes.

MATLAB executes the callback after setting all the hgtransform object's properties. Setting the CreateFcn property on an existing hgtransform object has no effect.

The handle of the object whose CreateFcn is being executed is passed by MATLAB as the first argument to the callback function and is accessible through the root CallbackObject property, which you can query using gcbo.

See Function Handle Callbacks for information on how to use function handles to define the callback function.


function handle | cell array containing function handle and additional arguments | string (not recommended)

Callback executed during object deletion. Executes when the hgtransform object is deleted (for example, this might happen when you issue a delete command on the hgtransform object, its parent axes, or the figure containing it). MATLAB executes the callback before destroying the object's properties so the callback routine can query these values.

The handle of the object whose DeleteFcn is being executed is passed by MATLAB as the first argument to the callback function and is accessible through the root CallbackObject property, which can be queried using gcbo.

See Function Handle Callbacks for information on how to use function handles to define the callback function.

See the BeingDeleted property for related information.



String used by legend. The legend function uses the DisplayName property to label the hgtransform object in the legend. The default is an empty string.

  • If you specify string arguments with the legend function, MATLAB set DisplayName to the corresponding string and uses that string for the legend.

  • If DisplayName is empty, legend creates a string of the form, ['data' n], where n is the number assigned to the object based on its location in the list of legend entries. However, legend does not set DisplayName to this string.

  • If you edit the string directly in an existing legend, MATLAB set DisplayName to the edited string.

  • If you specify a string for the DisplayName property and create the legend using the figure toolbar, then MATLAB uses the string defined by DisplayName.

  • To add a legend programmatically that uses the DisplayName string, call legend with the toggle or show option.

See Control Legend Content for more information and examples.


{normal} | none | xor | background

Erase mode. This property controls the technique MATLAB uses to draw and erase hgtransform child objects (light objects have no erase mode). Alternative erase modes are useful for creating animated sequences, where control of the way individual objects are redrawn is necessary to improve performance and obtain the desired effect.

  • normal — Redraw the affected region of the display, performing the three-dimensional analysis necessary to ensure that all objects are rendered correctly. This mode produces the most accurate picture, but is the slowest. The other modes are faster, but do not perform a complete redraw and are therefore less accurate.

  • none — Do not erase objects when they are moved or destroyed. While the objects are still visible on the screen after erasing with EraseMode none, you cannot print these objects because MATLAB stores no information about their former locations.

  • xor— Draw and erase the object by performing an exclusive OR (XOR) with each pixel index of the screen behind it. Erasing the object does not damage the color of the objects behind it. However, the color of the erased object depends on the color of the screen behind it and it is correctly colored only when it is over the axes background color (or the figure background color if the axes Color property is none). That is, it isn't erased correctly if there are objects behind it.

  • background — Erase the graphics objects by redrawing them in the axes background color, (or the figure background color if the axes Color property is none). This damages other graphics objects that are behind the erased object, but the erased object is always properly colored.

    Set the axes background color with the axes Color property. Set the figure background color with the figure Color property.

Printing with Nonnormal Erase Modes

MATLAB always prints figures as if the EraseMode of all objects is normal. This means graphics objects created with EraseMode set to none, xor, or background can look different on screen than on paper. On screen, MATLAB mathematically combines layers of colors (for example, performing an XOR on a pixel color with that of the pixel behind it) and ignore three-dimensional sorting to obtain greater rendering speed. However, these techniques are not applied to the printed output.

You can use the getframe command or other screen capture applications to create an image of a figure containing nonnormal mode objects.


{on} | callback | off

Control access to object's handle. Determines when an object's handle is visible in its parent's list of children. HandleVisibility is useful for preventing command-line users from accidentally accessing the hgtransform object.

  • on — Handles are always visible.

  • callback — Handles are visible from within callback routines or functions invoked by callback routines, but not from within functions invoked from the command line. This provides a means to protect GUIs from command-line users, while allowing callback routines to have access to object handles.

  • off — Handles are invisible at all times. Use this option when a callback invokes a function that could damage the GUI (such as evaluating a user-typed string). This option temporarily hides its own handles during the execution of that function.

Functions Affected by Handle Visibility

When a handle is not visible in its parent's list of children, it cannot be returned by functions that obtain handles by searching the object hierarchy or querying handle properties. This includes get, findobj, gca, gcf, gco, newplot, cla, clf, and close.

Properties Affected by Handle Visibility

When a handle's visibility is restricted using callback or off, the object's handle does not appear in its parent's Children property, figures do not appear in the root's CurrentFigure property, objects do not appear in the root's CallbackObject property or in the figure's CurrentObject property, and axes do not appear in their parent's CurrentAxes property.

Overriding Handle Visibility

You can set the root ShowHiddenHandles property to on to make all handles visible regardless of their HandleVisibility settings (this does not affect the values of the HandleVisibility properties). See also findall.

Handle Validity

Handles that are hidden are still valid. If you know an object's handle, you can set and get its properties and pass it to any function that operates on handles.


{on} | off

Selectable by mouse click. HitTest determines whether the hgtransform object can become the current object (as returned by the gco command and the figure CurrentObject property) as a result of a mouse click within the limits of the hgtransform object. If HitTest is off, clicking the hgtransform picks the object behind it.


off | {on}

Callback routine interruption

Controls whether MATLAB can interrupt an object's callback function when subsequent callbacks attempt to interrupt it.

For Graphics objects, the Interruptible property affects only the callbacks for theButtonDownFcn property. A running callback is the currently executing callback. The interrupting callback is the callback that tries to interrupt the running callback. MATLAB handles both the callbacks based on the Interruptible property of the object of the running callback.

When the Interruptible property is set to:

  • 'off', MATLAB finishes execution of the running callback without any interruptions

  • 'on', these conditions apply:

    • If there is a drawnow, figure, getframe, waitfor, or pause command in the running callback, then MATLAB executes the interrupting callbacks which are already in the queue and returns to finish execution of the current callback.

    • If one of the above functions is not in the running callback, then MATLAB finishes execution of the current callback without any interruption.

BusyAction property of the object of interrupting callback determines whether the callback should be ignored or should be put in the queue.

Setting Interruptible property to on (default), allows a callback from other graphics objects to interrupt callback functions originating from this object.

    Note:   MATLAB does not save the state of properties or the display when an interruption occurs. For example, the handle returned by the gca or gcf command may be changed as another callback is executed.

After the function that interrupts a callback completes, the callback resumes execution where it halted when interrupted. For more information, see Control Callback Execution and Interruption.


4-by-4 matrix

Transformation matrix applied to hgtransform object and its children. The hgtransform object applies the transformation matrix to all its children.

See Group Objects for more information and examples.


figure handle

Parent of hgtransform object. This property contains the handle of the hgtransform object's parent object. The parent of an hgtransform object is the axes, hggroup, or hgtransform object that contains it.


on | {off}

Is object selected? When you set this property to on, MATLAB displays selection handles on all child objects of the hgtransform if the SelectionHighlight property is also on (the default).


{on} | off

Objects are highlighted when selected. When the Selected property is on, MATLAB indicates the selected state by drawing selection handles on the objects parented to the hgtransform. When SelectionHighlight is off, MATLAB does not draw the handles.



User-specified object label. Provides a means to identify graphics objects with a user-specified label. The default is an empty string.

Use the Tag property and the findobj function to manipulate specific objects within a plotting hierarchy.

For example, create an hgtransform object and set the Tag property:

t = hgtransform('Tag','subgroup1')

When you want to access the hgtransform object to add another object, use findobj to find the hgtransform object's handle. The following statement adds a line to subgroup1 (assuming x and y are defined).


string (read-only)

Type of graphics object. String that identifies the class of the graphics object. Use this property to find all objects of a given type within a plotting hierarchy. For hgtransform objects, Type is 'hgtransform'. The following statement finds all the hgtransform objects in the current axes.

t = findobj(gca,'Type','hgtransform');

handle of uicontextmenu object

Associate a context menu with the hgtransform object. Assign this property the handle of a uicontextmenu object created in the hgtransform object's figure. Use the uicontextmenu function to create the context menu. MATLAB displays the context menu whenever you right-click over the extent of the hgtransform object.



User-specified data. Data you want to associate with the hgtransform object (including cell arrays and structures). The default value is an empty array. MATLAB does not use this data, but you can access it using the set and get commands.


{on} | off

Visibility of hgtransform object and its children. By default, hgtransform object visibility is on. This means all children of the hgtransform are visible unless the child object's Visible property is off. Setting an hgtransform object's Visible property to off also makes its children invisible.

See Also

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