ConstantRegion Properties

Constant region appearance and behavior

Since R2023a

A constant region is a filled area between two x- or y-values in a 1-D plot. Use the xregion or yregion function to create a constant region. You can modify its appearance and behavior by changing ConstantRegion property values.

xr = xregion(5,10);
xr.FaceColor = "green";

Location

Value — Minimum and maximum region values

two-element vector

Minimum and maximum region values, specified as a two-element vector. The minimum and maximum region values can be defined in either element of the vector. Thus, a value of [1 5] and [5 1] produce the same result.

To create an unbounded region, specify one of the elements as Inf or -Inf. (since R2023b)

If either value is a NaN value, no region appears in the axes.

Example

Create a constant region from x=5 to x=10. Then change the upper bound to 7.

xr = xregion(5,10);
xr.Value(2) = 7;

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | categorical | datetime | duration

InterceptAxis — Intercept axis

"x" | "y"

Intercept axis, specified as "x" or "y". A constant region with an x-intercept is a filled area between two x-values. Similarly, a constant region with a y-intercept is a filled area between two y-values.

Layer — Layer position

"bottom" (default) | "top"

Since R2024a

Layer position, specified as "bottom" or "top". A value of "bottom" displays the ConstantRegion object under other items in the axes, such as lines or markers. A value of "top" displays the ConstantRegion object on top of other items.

Passing a ConstantRegion object to the uistack function has no effect on its stacking order, nor does reordering the Children property of the axes.

Color and Styling

FaceColor — Fill color

RGB triplet | hexadecimal color code | "r" | "g" | "b" | ...

Fill color, specified as an RGB triplet, a hexadecimal color code, or a color name.

For a custom color, specify an RGB triplet or a hexadecimal color code.

• An RGB triplet is a three-element row vector whose elements specify the intensities of the red, green, and blue components of the color. The intensities must be in the range [0,1], for example, [0.4 0.6 0.7].

• A hexadecimal color code is a string scalar or character vector that starts with a hash symbol (#) followed by three or six hexadecimal digits, which can range from 0 to F. The values are not case sensitive. Therefore, the color codes "#FF8800", "#ff8800", "#F80", and "#f80" are equivalent.

Alternatively, you can specify some common colors by name. This table lists the named color options, the equivalent RGB triplets, and the hexadecimal color codes.

Color Name	Short Name	RGB Triplet	Hexadecimal Color Code	Appearance
"red"	"r"	[1 0 0]	"#FF0000"
"green"	"g"	[0 1 0]	"#00FF00"
"blue"	"b"	[0 0 1]	"#0000FF"
"cyan"	"c"	[0 1 1]	"#00FFFF"
"magenta"	"m"	[1 0 1]	"#FF00FF"
"yellow"	"y"	[1 1 0]	"#FFFF00"
"black"	"k"	[0 0 0]	"#000000"
"white"	"w"	[1 1 1]	"#FFFFFF"
"none"	Not applicable	Not applicable	Not applicable	No color

This table lists the default color palettes for plots in the light and dark themes.

Palette	Palette Colors
"gem" — Light theme default Before R2025a: Most plots use these colors by default.
"glow" — Dark theme default

You can get the RGB triplets and hexadecimal color codes for these palettes using the orderedcolors and rgb2hex functions. For example, get the RGB triplets for the "gem" palette and convert them to hexadecimal color codes.

RGB = orderedcolors("gem");
H = rgb2hex(RGB);

Before R2023b: Get the RGB triplets using RGB = get(groot,"FactoryAxesColorOrder").

Before R2024a: Get the hexadecimal color codes using H = compose("#%02X%02X%02X",round(RGB*255)).

FaceColorMode — Control how FaceColor is set

"auto" (default) | "manual"

Control how the FaceColor property is set, specified as one of these values:

• "auto" — MATLAB^® controls the value of the FaceColor property by using the SeriesIndex property of the ConstantRegion object and the ColorOrder property of the axes.

• "manual" — You set the value of the FaceColor property directly, or indirectly as a function argument when you create the ConstantRegion object.

If you change the value of the FaceColor property manually, MATLAB changes the value of the FaceColorMode property to "manual".

EdgeColor — Boundary line color

"none" (default) | RGB triplet | hexadecimal color code | "r" | "g" | "b" | ...

Boundary line color, specified as an RGB triplet, a hexadecimal color code, or a color name.

For a custom color, specify an RGB triplet or a hexadecimal color code.

• An RGB triplet is a three-element row vector whose elements specify the intensities of the red, green, and blue components of the color. The intensities must be in the range [0,1], for example, [0.4 0.6 0.7].

• A hexadecimal color code is a string scalar or character vector that starts with a hash symbol (#) followed by three or six hexadecimal digits, which can range from 0 to F. The values are not case sensitive. Therefore, the color codes "#FF8800", "#ff8800", "#F80", and "#f80" are equivalent.

Alternatively, you can specify some common colors by name. This table lists the named color options, the equivalent RGB triplets, and the hexadecimal color codes.

Color Name	Short Name	RGB Triplet	Hexadecimal Color Code	Appearance
"red"	"r"	[1 0 0]	"#FF0000"
"green"	"g"	[0 1 0]	"#00FF00"
"blue"	"b"	[0 0 1]	"#0000FF"
"cyan"	"c"	[0 1 1]	"#00FFFF"
"magenta"	"m"	[1 0 1]	"#FF00FF"
"yellow"	"y"	[1 1 0]	"#FFFF00"
"black"	"k"	[0 0 0]	"#000000"
"white"	"w"	[1 1 1]	"#FFFFFF"
"none"	Not applicable	Not applicable	Not applicable	No color

This table lists the default color palettes for plots in the light and dark themes.

Palette	Palette Colors
"gem" — Light theme default Before R2025a: Most plots use these colors by default.
"glow" — Dark theme default

You can get the RGB triplets and hexadecimal color codes for these palettes using the orderedcolors and rgb2hex functions. For example, get the RGB triplets for the "gem" palette and convert them to hexadecimal color codes.

RGB = orderedcolors("gem");
H = rgb2hex(RGB);

Before R2023b: Get the RGB triplets using RGB = get(groot,"FactoryAxesColorOrder").

Before R2024a: Get the hexadecimal color codes using H = compose("#%02X%02X%02X",round(RGB*255)).

FaceAlpha — Fill color transparency

0.3 (default) | scalar in range [0,1]

Fill color transparency, specified as a scalar in the range [0,1]. A value of 1 is opaque and 0 is completely transparent. Values between 0 and 1 are partially transparent.

EdgeAlpha — Boundary line transparency

1 (default) | scalar in range [0,1]

Boundary line transparency, specified as a scalar in the range [0,1]. A value of 1 is opaque and 0 is completely transparent. Values between 0 and 1 are partially transparent.

LineStyle — Boundary line style

"-" (default) | "--" | ":" | "-." | "none"

Boundary line style, specified as one of the options listed in this table.

Line Style	Description	Resulting Line
"-"	Solid line
"--"	Dashed line
":"	Dotted line
"-."	Dash-dotted line
"none"	No line	No line

LineWidth — Boundary line thickness

0.5 (default) | positive number

Boundary line thickness, specified as a positive number.

SeriesIndex — Series index

"none" (default) | positive whole number

Series index, specified as a positive whole number or "none". This property is useful for reassigning the face colors of ConstantRegion objects so that they match the colors of other objects.

If the SeriesIndex value is a number, MATLAB uses the number to calculate an index for assigning the face color when you call xregion and yregion. The index refers to the rows of the array stored in the ColorOrder property of the axes. Any objects in the axes that have the same SeriesIndex number will have the same color.

A SeriesIndex value of "none" corresponds to a neutral color that does not participate in the indexing scheme.

How Manual Color Assignment Overrides SeriesIndex Behavior

To manually control fill color, set the FaceColor property of the ConstantRegion object to a color value, such as a color name or RGB triplet.

When you manually set the fill color of an object, MATLAB does not use automatic color selection for that object, and it allows your color to persist, regardless of the value of the SeriesIndex property. The FaceColorMode property indicates whether the colors have been set manually (by you) or automatically. A value of "manual" indicates manual selection, and a value of "auto" indicates automatic selection.

To enable automatic selection, set the SeriesIndex property to a positive whole number, and set the FaceColorMode property to "auto".

In some cases, MATLAB sets the SeriesIndex property to 0, which also disables automatic color selection.

Legend

DisplayName — Legend label

'' (default) | character vector | string scalar

Legend label, specified as a character vector or string scalar. The legend does not display until you call the legend command. If you do not specify the text, then legend sets the label using the form 'dataN'.

Annotation — Include object in legend

Annotation object

Include the object in the legend, specified as an Annotation object. Set the underlying IconDisplayStyle property of the Annotation object to one of these values:

• "on" — Include the object in the legend (default).

• "off" — Do not include the object in the legend.

For example, to exclude the ConstantRegion object named obj from the legend, set the IconDisplayStyle property to "off".

obj.Annotation.LegendInformation.IconDisplayStyle = "off";

Alternatively, you can control the items in a legend using the legend function. Specify the first input argument as a vector of the graphics objects to include. If you do not specify an existing graphics object in the first input argument, then it does not appear in the legend. However, graphics objects added to the axes after the legend is created do appear in the legend. Consider creating the legend after creating all the plots to avoid extra items.

Interactivity

Visible — State of visibility

"on" (default) | on/off logical value

State of visibility, specified as "on" or "off", or as numeric or logical 1 (true) or 0 (false). A value of "on" is equivalent to true, and "off" is equivalent to false. Thus, you can use the value of this property as a logical value. The value is stored as an on/off logical value of type matlab.lang.OnOffSwitchState.

• "on" — Display the object.

• "off" — Hide the object without deleting it. You still can access the properties of an invisible object.

ContextMenu — Context menu

empty GraphicsPlaceholder array (default) | ContextMenu object

Context menu, specified as a ContextMenu object. Use this property to display a context menu when you right-click the object. Create the context menu using the uicontextmenu function.

Note

If the PickableParts property is set to 'none' or if the HitTest property is set to 'off', then the context menu does not appear.

Selected — Selection state

'off' (default) | on/off logical value

Selection state, specified as 'on' or 'off', or as numeric or logical 1 (true) or 0 (false). A value of 'on' is equivalent to true, and 'off' is equivalent to false. Thus, you can use the value of this property as a logical value. The value is stored as an on/off logical value of type matlab.lang.OnOffSwitchState.

• 'on' — Selected. If you click the object when in plot edit mode, then MATLAB sets its Selected property to 'on'. If the SelectionHighlight property also is set to 'on', then MATLAB displays selection handles around the object.

• 'off' — Not selected.

SelectionHighlight — Display of selection handles

'on' (default) | on/off logical value

Display of selection handles when selected, specified as 'on' or 'off', or as numeric or logical 1 (true) or 0 (false). A value of 'on' is equivalent to true, and 'off' is equivalent to false. Thus, you can use the value of this property as a logical value. The value is stored as an on/off logical value of type matlab.lang.OnOffSwitchState.

• 'on' — Display selection handles when the Selected property is set to 'on'.

• 'off' — Never display selection handles, even when the Selected property is set to 'on'.

Callbacks

ButtonDownFcn — Mouse-click callback

'' (default) | function handle | cell array | character vector

Mouse-click callback, specified as one of these values:

• Function handle

• Cell array containing a function handle and additional arguments

• Character vector that is a valid MATLAB command or function, which is evaluated in the base workspace (not recommended)

Use this property to execute code when you click the object. If you specify this property using a function handle, then MATLAB passes two arguments to the callback function when executing the callback:

• Clicked object — Access properties of the clicked object from within the callback function.

• Event data — Empty argument. Replace it with the tilde character (~) in the function definition to indicate that this argument is not used.

For more information on how to use function handles to define callback functions, see Create Callbacks for Graphics Objects.

Note

If the PickableParts property is set to 'none' or if the HitTest property is set to 'off', then this callback does not execute.

CreateFcn — Creation function

'' (default) | function handle | cell array | character vector

Object creation function, specified as one of these values:

• Function handle.

• Cell array in which the first element is a function handle. Subsequent elements in the cell array are the arguments to pass to the callback function.

• Character vector containing a valid MATLAB expression (not recommended). MATLAB evaluates this expression in the base workspace.

For more information about specifying a callback as a function handle, cell array, or character vector, see Create Callbacks for Graphics Objects.

This property specifies a callback function to execute when MATLAB creates the object. MATLAB initializes all property values before executing the CreateFcn callback. If you do not specify the CreateFcn property, then MATLAB executes a default creation function.

Setting the CreateFcn property on an existing component has no effect.

If you specify this property as a function handle or cell array, you can access the object that is being created using the first argument of the callback function. Otherwise, use the gcbo function to access the object.

DeleteFcn — Deletion function

'' (default) | function handle | cell array | character vector

Object deletion function, specified as one of these values:

• Function handle.

• Cell array in which the first element is a function handle. Subsequent elements in the cell array are the arguments to pass to the callback function.

• Character vector containing a valid MATLAB expression (not recommended). MATLAB evaluates this expression in the base workspace.

For more information about specifying a callback as a function handle, cell array, or character vector, see Create Callbacks for Graphics Objects.

This property specifies a callback function to execute when MATLAB deletes the object. MATLAB executes the DeleteFcn callback before destroying the properties of the object. If you do not specify the DeleteFcn property, then MATLAB executes a default deletion function.

If you specify this property as a function handle or cell array, you can access the object that is being deleted using the first argument of the callback function. Otherwise, use the gcbo function to access the object.

Callback Execution Control

Interruptible — Callback interruption

'on' (default) | on/off logical value

Callback interruption, specified as 'on' or 'off', or as numeric or logical 1 (true) or 0 (false). A value of 'on' is equivalent to true, and 'off' is equivalent to false. Thus, you can use the value of this property as a logical value. The value is stored as an on/off logical value of type matlab.lang.OnOffSwitchState.

This property determines if a running callback can be interrupted. There are two callback states to consider:

• The running callback is the currently executing callback.

• The interrupting callback is a callback that tries to interrupt the running callback.

MATLAB determines callback interruption behavior whenever it executes a command that processes the callback queue. These commands include drawnow, figure, uifigure, getframe, waitfor, and pause.

If the running callback does not contain one of these commands, then no interruption occurs. MATLAB first finishes executing the running callback, and later executes the interrupting callback.

If the running callback does contain one of these commands, then the Interruptible property of the object that owns the running callback determines if the interruption occurs:

• If the value of Interruptible is 'off', then no interruption occurs. Instead, the BusyAction property of the object that owns the interrupting callback determines if the interrupting callback is discarded or added to the callback queue.

• If the value of Interruptible is 'on', then the interruption occurs. The next time MATLAB processes the callback queue, it stops the execution of the running callback and executes the interrupting callback. After the interrupting callback completes, MATLAB then resumes executing the running callback.

Note

Callback interruption and execution behave differently in these situations:

• If the interrupting callback is a DeleteFcn, CloseRequestFcn, or SizeChangedFcn callback, then the interruption occurs regardless of the Interruptible property value.

• If the running callback is currently executing the waitfor function, then the interruption occurs regardless of the Interruptible property value.

• If the interrupting callback is owned by a Timer object, then the callback executes according to schedule regardless of the Interruptible property value.

Note

When an interruption occurs, MATLAB does not save the state of properties or the display. For example, the object returned by the gca or gcf command might change when another callback executes.

BusyAction — Callback queuing

'queue' (default) | 'cancel'

Callback queuing, specified as 'queue' or 'cancel'. The BusyAction property determines how MATLAB handles the execution of interrupting callbacks. There are two callback states to consider:

• The running callback is the currently executing callback.

• The interrupting callback is a callback that tries to interrupt the running callback.

The BusyAction property determines callback queuing behavior only when both of these conditions are met:

• The running callback contains a command that processes the callback queue, such as drawnow, figure, uifigure, getframe, waitfor, or pause.

• The value of the Interruptible property of the object that owns the running callback is 'off'.

Under these conditions, the BusyAction property of the object that owns the interrupting callback determines how MATLAB handles the interrupting callback. These are possible values of the BusyAction property:

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

• 'cancel' — Does not execute the interrupting callback.

PickableParts — Ability to capture mouse clicks

'visible' (default) | 'all' | 'none'

Ability to capture mouse clicks, specified as one of these values:

• 'visible' — Capture mouse clicks when visible. The Visible property must be set to 'on' and you must click a part of the ConstantRegion object that has a defined color. You cannot click a part that has an associated color property set to 'none'. The HitTest property determines if the ConstantRegion object responds to the click or if an ancestor does.

• 'all' — Capture mouse clicks regardless of visibility. The Visible property can be set to 'on' or 'off' and you can click a part of the ConstantRegion object that has no color. The HitTest property determines if the ConstantRegion object responds to the click or if an ancestor does.

• 'none' — Cannot capture mouse clicks. Clicking the ConstantRegion object passes the click through it to the object below it in the current view of the figure window. The HitTest property has no effect.

HitTest — Response to captured mouse clicks

'on' (default) | on/off logical value

Response to captured mouse clicks, specified as 'on' or 'off', or as numeric or logical 1 (true) or 0 (false). A value of 'on' is equivalent to true, and 'off' is equivalent to false. Thus, you can use the value of this property as a logical value. The value is stored as an on/off logical value of type matlab.lang.OnOffSwitchState.

• 'on' — Trigger the ButtonDownFcn callback of the ConstantRegion object. If you have defined the ContextMenu property, then invoke the context menu.

• 'off' — Trigger the callbacks for the nearest ancestor of the ConstantRegion object that meets one of these conditions:

  • HitTest property is set to 'on'.

  • PickableParts property is set to a value that enables the ancestor to capture mouse clicks.

Note

The PickableParts property determines if the ConstantRegion object can capture mouse clicks. If it cannot, then the HitTest property has no effect.

BeingDeleted — Deletion status

Read-only: on/off logical value

This property is read-only.

Deletion status, returned as an on/off logical value of type matlab.lang.OnOffSwitchState.

MATLAB sets the BeingDeleted property to 'on' when the DeleteFcn callback begins execution. The BeingDeleted property remains set to 'on' until the component object no longer exists.

Check the value of the BeingDeleted property to verify that the object is not about to be deleted before querying or modifying it.

Parent/Child

Parent — Parent

Axes object (default)

Parent, specified as an Axes object.

Children — Children

empty GraphicsPlaceholder array

The object has no children. You cannot set this property.

HandleVisibility — Visibility of object handle

"on" (default) | "off" | "callback"

Visibility of the object handle in the Children property of the parent, specified as one of these values:

• "on" — Object handle is always visible.

• "off" — Object handle is invisible at all times. This option is useful for preventing unintended changes by another function. Set HandleVisibility to "off" to temporarily hide the handle during the execution of that function.

• "callback" — Object handle is visible from within callbacks or functions invoked by callbacks, but not from within functions invoked from the command line. This option blocks access to the object at the command line, but permits callback functions to access it.

If the object is not listed in the Children property of the parent, then functions that obtain object handles by searching the object hierarchy or querying handle properties cannot return it. Examples of such functions include the get, findobj, gca, gcf, gco, newplot, cla, clf, and close functions.

Hidden object handles are still valid. Set the root ShowHiddenHandles property to "on" to list all object handles regardless of their HandleVisibility property setting.

Identifiers

Type — Type of graphics object

Read-only: 'constantregion'

This property is read-only.

Type of graphics object, returned as 'constantregion'. Use this property to find all objects of a given type within a plotting hierarchy, for example, searching for the type using findobj.

Tag — Object identifier

'' (default) | character vector | string scalar

Object identifier, specified as a character vector or string scalar. You can specify a unique Tag value to serve as an identifier for an object. When you need access to the object elsewhere in your code, you can use the findobj function to search for the object based on the Tag value.

UserData — User data

[] (default) | array

User data, specified as any MATLAB array. For example, you can specify a scalar, vector, matrix, cell array, character array, table, or structure. Use this property to store arbitrary data on an object.

If you are working in App Designer, create public or private properties in the app to share data instead of using the UserData property. For more information, see Share Data Within App Designer Apps.

Version History

Introduced in R2023a

R2024a: Layer filled regions in plots

Move ConstantRegion objects above or below other elements in a plot by setting the Layer property to "top" or "bottom".

R2023b: Create unbounded regions

Create unbounded filled regions by specifying either element of the Value property as Inf or –Inf.

R2023b: Control automatic color selection with the SeriesIndex property

Control how ConstantRegion objects vary in color by setting the SeriesIndex property. This property is useful when you want to match the colors of different objects in the axes.