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| Learn more about MATLAB |
You can set and query graphics object properties in two ways:
The Property Editor is an interactive tool that enables you to see and change object property values.
The set and get commands enable you to set and query the values of properties.
To change the default values of properties, see Setting Default Property Values.
See Core Graphics Objects for general information about this type of object.
This section lists property names along with the types of values each property accepts.
m-by-n matrix of double or uint8
The transparency data. A matrix of non-NaN values specifying the transparency of each face or vertex of the object. The AlphaData can be of class double or uint8.
MATLAB software determines the transparency in one of three ways:
Using the elements of AlphaData as transparency values (AlphaDataMapping set to none)
Using the elements of AlphaData as indices into the current alphamap (AlphaDataMapping set to direct)
Scaling the elements of AlphaData to range between the minimum and maximum values of the axes ALim property (AlphaDataMapping set to scaled, the default)
{none} | direct| scaled
Transparency mapping method. This property determines how MATLAB interprets indexed alpha data. It can be any of the following:
none — The transparency values of AlphaData are between 0 and 1 or are clamped to this range (the default).
scaled — Transform the AlphaData to span the portion of the alphamap indicated by the axes ALim property, linearly mapping data values to alpha values.
direct — Use the AlphaData as indices directly into the alphamap. When not scaled, the data are usually integer values ranging from 1 to length(alphamap). MATLAB maps values less than 1 to the first alpha value in the alphamap, and values greater than length(alphamap) to the last alpha value in the alphamap. Values with a decimal portion are fixed to the nearest, lower integer. If AlphaData is an array of uint8 integers, then the indexing begins at 0 (i.e., MATLAB maps a value of 0 to the first alpha value in the alphamap).
hg.Annotation object Read Only
Control the display of image objects in legends. The Annotation property enables you to specify whether this image 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 image object is displayed in a figure legend:
| IconDisplayStyle Value | Purpose |
|---|---|
| on | Represent this image object in a legend (default) |
| off | Do not include this image object in a legend |
| children | Same as on because image objects do not have children |
Setting the IconDisplayStyle property
These commands set the IconDisplayStyle of a graphics object with handle hobj to off:
hAnnotation = get(hobj,'Annotation'); hLegendEntry = get(hAnnotation','LegendInformation'); set(hLegendEntry,'IconDisplayStyle','off')
Using the IconDisplayStyle property
See Controlling Legends for more information and examples.
on | {off} Read Only
This object is being deleted. The BeingDeleted property provides a mechanism that you can use 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 might call other functions that act on a number of different objects. These functions might not need to perform actions on objects if the objects are going to be deleted, and therefore, can check the object's BeingDeleted property before acting.
cancel | {queue}
Callback routine interruption. The BusyAction property enables you to control how MATLAB handles events that potentially interrupt executing callbacks. If there is a callback function executing, callbacks invoked subsequently always attempt to interrupt it.
If the Interruptible property of the object whose callback is executing is set to on (the default), then interruption occurs at the next point where the event queue is processed. If the Interruptible property is off, the BusyAction property (of the object owning the executing callback) determines how MATLAB handles the event. The choices are
cancel — Discard the event that attempted to execute a second callback routine.
queue — Queue the event that attempted to execute a second callback routine until the current callback finishes.
string or function handle
Button press callback function. A callback that executes whenever you press a mouse button while the pointer is over this object, but not over another graphics object.
See the figure's SelectionType property to determine if modifier keys were also pressed.
This property can be
A string that is a valid MATLAB expression
The name of an M-file
A function handle
Set this property to a function handle that references the callback. The expressions execute in the MATLAB workspace.
See Function Handle Callbacks for information on how to use function handles to define the callbacks.
matrix or m-by-n-by-3 array
The image data. A matrix or 3-D array of values specifying the color of each rectangular area defining the image. image(C) assigns the values of C to CData. MATLAB determines the coloring of the image in one of three ways:
Using the elements of CData as indices into the current colormap (the default) (CDataMapping set to direct)
Scaling the elements of CData to range between the values min(get(gca,'CLim')) and max(get(gca,'CLim')) (CDataMapping set to scaled)
Interpreting the elements of CData directly as RGB values (true color specification)
Note that the behavior of NaNs in image CData is not defined. See the image AlphaData property for information on using transparency with images.
A true color specification for CData requires an m-by-n-by-3 array of RGB values. The first page contains the red component, the second page the green component, and the third page the blue component of each element in the image. RGB values range from 0 to 1. The following picture illustrates the relative dimensions of CData for the two color models.
If CData has only one row or column, the height or width respectively is always one data unit and is centered about the first YData or XData element respectively. For example, using a 4-by-1 matrix of random data,
C = rand(4,1); image(C,'CDataMapping','scaled') axis image
produces
scaled | {direct}
Direct or scaled indexed colors. This property determines whether MATLAB interprets the values in CData as indices into the figure colormap (the default) or scales the values according to the values of the axes CLim property.
When CDataMapping is direct, the values of CData should be in the range 1 to length(get(gcf,'Colormap')). If you use true color specification for CData, this property has no effect. If CData is of type logical, 0's will index the first color of the colormap and 1's will index the second color.
handles
The empty matrix; image objects have no children.
on | off
Clipping mode. By default, MATLAB clips images to the axes rectangle. If you set Clipping to off, the image can be displayed outside the axes rectangle. For example, if you create an image, set hold to on, freeze axis scaling (with axis manual ), and then create a larger image, it extends beyond the axis limits.
string or function handle
Callback routine executed during object creation. This property defines a callback routine that executes when MATLAB creates an image object. You must define this property as a default value for images or in a call to the image function to create a new image object. For example, the statement
set(0,'DefaultImageCreateFcn','axis image')
defines a default value on the root level that sets the aspect ratio and the axis limits so the image has square pixels. MATLAB executes this routine after setting all image properties. Setting this property on an existing image object has no effect.
The handle of the object whose CreateFcn is being executed is accessible only 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.
string or function handle
Callback executed during object deletion. A callback that executes when this object is deleted (e.g., this might happen when you issue a delete command on the 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 accessible only 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 (default is empty string)
String used by legend for this image object. The legend function uses the string defined by the DisplayName property to label this image object in the legend.
If you specify string arguments with the legend function, DisplayName is set to this image object's corresponding string and that string is used 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, DisplayName is set 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 programmatically a legend that uses the DisplayName string, call legend with the toggle or show option.
See Controlling Legends for more examples.
{normal} | none | xor | background
Erase mode. This property controls the technique MATLAB uses to draw and erase objects and their children. 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 set to 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 set to none). This damages other graphics objects that are behind the erased object, but the erased object is always properly colored.
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 can mathematically combine layers of colors (e.g., 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.
Set the axes background color with the axes Color property. Set the figure background color with the figure Color property.
You can use the MATLAB 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 by command-line users and GUIs. This property 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 objects that you need to protect for some reason.
on — Handles are always visible when HandleVisibility is on.
callback — Setting HandleVisibility to callback causes handles to be 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 — Setting HandleVisibility to off makes handles invisible at all times. This might be necessary when a callback invokes a function that might potentially damage the GUI (such as evaluating a user-typed string) and so 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 this object can become the current object (as returned by the gco command and the figure CurrentObject property) as a result of a mouse click on the objects that compose the area graph. If HitTest is off, clicking this object selects the object below it (which is usually the axes containing it).
{on} | off
Callback routine interruption mode. The Interruptible property controls whether an object's callback can be interrupted by callbacks invoked subsequently.
Only callbacks defined for the ButtonDownFcn property are affected by the Interruptible property. MATLAB checks for events that can interrupt a callback only when it encounters a drawnow, figure, getframe, or pause command in the routine. See the BusyAction property for related information.
Setting Interruptible to on allows any graphics object's callback to interrupt callback routines originating from a bar property. Note that MATLAB does not save the state of variables or the display (e.g., the handle returned by the gca or gcf command) when an interruption occurs.
handle of parent axes, hggroup, or hgtransform
Parent of this object. This property contains the handle of the object's parent. The parent is normally the axes, hggroup, or hgtransform object that contains the object.
See Objects That Can Contain Other Objects for more information on parenting graphics objects.
on | {off}
Is object selected? When you set this property to on, MATLAB displays selection "handles" at the corners and midpoints if the SelectionHighlight property is also on (the default). You can, for example, define the ButtonDownFcn callback to set this property to on, thereby indicating that this particular object is selected. This property is also set to on when an object is manually selected in plot edit mode.
{on} | off
Objects are highlighted when selected. When the Selected property is on, MATLAB indicates the selected state by drawing four edge handles and four corner handles. When SelectionHighlight is off, MATLAB does not draw the handles except when in plot edit mode and objects are selected manually.
string
User-specified object label. The Tag property provides a means to identify graphics objects with a user-specified label. This is particularly useful when you are constructing interactive graphics programs that would otherwise need to define object handles as global variables or pass them as arguments between callbacks. You can define Tag as any string.
For example, you might create an areaseries object and set the Tag property.
t = area(Y,'Tag','area1')
When you want to access objects of a given type, you can use findobj to find the object's handle. The following statement changes the FaceColor property of the object whose Tag is area1.
set(findobj('Tag','area1'),'FaceColor','red')string (read only)
Type of graphics object. This property contains a string that identifies the class of graphics object. For image objects, Type is always 'image'.
handle of a uicontextmenu object
Associate a context menu with this object. Assign this property the handle of a uicontextmenu object created in the object's parent figure. Use the uicontextmenu function to create the context menu. MATLAB displays the context menu whenever you right-click over the object.
array
User-specified data. This property can be any data you want to associate with this object (including cell arrays and structures). The object does not set values for this property, but you can access it using the set and get functions.
{on} | off
Visibility of this object and its children. By default, a new object's visibility is on. This means all children of the object are visible unless the child object's Visible property is set to off. Setting an object's Visible property to off prevents the object from being displayed. However, the object still exists and you can set and query its properties.
[1 size(CData,2)] by default
Control placement of image along x-axis. A vector specifying the locations of the centers of the elements CData(1,1) and CData(m,n), where CData has a size of m-by-n. Element CData(1,1) is centered over the coordinate defined by the first elements in XData and YData. Element CData(m,n) is centered over the coordinate defined by the last elements in XData and YData. The centers of the remaining elements of CData are evenly distributed between those two points.
The width of each CData element is determined by the expression
(XData(2)-XData(1))/(size(CData,2)-1)
You can also specify a single value for XData. In this case, image centers the first element at this coordinate and centers each following element one unit apart.
[1 size(CData,1)] by default
Control placement of image along y-axis. A vector specifying the locations of the centers of the elements CData(1,1) and CData(m,n), where CData has a size of m-by-n. Element CData(1,1) is centered over the coordinate defined by the first elements in XData and YData. Element CData(m,n) is centered over the coordinate defined by the last elements in XData and YData. The centers of the remaining elements of CData are evenly distributed between those two points.
The height of each CData element is determined by the expression
(YData(2)-YData(1))/(size(CData,1)-1)
You can also specify a single value for YData. In this case, image centers the first element at this coordinate and centers each following element one unit apart.
 | image | imagesc |  |
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