Documentation

# ConstantLine Properties

Constant line appearance and behavior

A constant line is a line that is graphed at a specified x- or y-value in Cartesian axes. The xline and yline functions create constant vertical and horizontal lines, respectively. You can modify the appearance and behavior of the constant line by changing ConstantLine property values.

xl = xline(4); xl.LineWidth = 2;

## Location

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Location of the constant line on the x- or y-axis, specified as a scalar. You can specify the value as a numeric, categorical, datetime, or duration value.

#### Example

Create a constant line at x = 5.5. Then change the value to 7.

xl = xline(5.5); xl.Value = 7;

Intercept axis, specified as 'x' or 'y' for a vertical line or horizontal line, respectively. A constant line with an x-intercept is a vertical line, whereas a constant line with a y-intercept is a horizontal line.

## Labels

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Line label, specified as a character vector, cell array of character vectors, string array, or numeric array. To create a multiline label, use a string array or a cell array of character vectors.

Example: 'cutoff frequency'

Example: {'first line','second line'}

Example: ["first line" "second line"]

To include special characters, such as superscripts, subscripts, Greek letters, or mathematical symbols, use TeX markup. For a list of supported markup, see the Interpreter property.

Horizontal alignment of the label with respect to the line, specified as one of the options in the table.

OptionDescription
'right'

Right side of the line.

'left'

Left side of the line.

'center'

Center of the line. For vertical lines, the label segments the line.

Vertical alignment of the label with respect to the line, specified as one of the options in the table.

OptionDescription
'top'

Top of the line.

'middle'

Middle of the line. For horizontal lines, the label segments the line.

'bottom'

Bottom of the line.

Label orientation, specified as 'aligned' or 'horizontal'. Examples are shown in the table.

OrientationDescription
'aligned'

Label has the same orientation as the line.

'horizontal'

Label is horizontal, regardless of the line orientation.

Interpretation of text characters, specified as one of these values:

• 'tex' — Interpret characters using a subset of TeX markup.

• 'latex' — Interpret characters using LaTeX markup.

• 'none' — Display literal characters.

#### TeX Markup

By default, MATLAB® supports a subset of TeX markup. Use TeX markup to add superscripts and subscripts, modify the font type and color, and include special characters in the text.

Modifiers remain in effect until the end of the text. Superscripts and subscripts are an exception because they modify only the next character or the characters within the curly braces. When you set the Interpreter property to 'tex', the supported modifiers are as follows.

ModifierDescriptionExample
^{ }Superscript'text^{superscript}'
_{ }Subscript'text_{subscript}'
\bfBold font'\bf text'
\itItalic font'\it text'
\slOblique font (usually the same as italic font)'\sl text'
\rmNormal font'\rm text'
\fontname{specifier}Font name — Replace specifier with the name of a font family. You can use this in combination with other modifiers.'\fontname{Courier} text'
\fontsize{specifier}Font size —Replace specifier with a numeric scalar value in point units.'\fontsize{15} text'
\color{specifier}Font color — Replace specifier with one of these colors: red, green, yellow, magenta, blue, black, white, gray, darkGreen, orange, or lightBlue.'\color{magenta} text'
\color[rgb]{specifier}Custom font color — Replace specifier with a three-element RGB triplet.'\color[rgb]{0,0.5,0.5} text'

This table lists the supported special characters with the Interpreter property set to 'tex'.

Character SequenceSymbolCharacter SequenceSymbolCharacter SequenceSymbol

\alpha

α

\upsilon

υ

\sim

~

\angle

\phi

\leq

\ast

*

\chi

χ

\infty

\beta

β

\psi

ψ

\clubsuit

\gamma

γ

\omega

ω

\diamondsuit

\delta

δ

\Gamma

Γ

\heartsuit

\epsilon

ϵ

\Delta

Δ

\spadesuit

\zeta

ζ

\Theta

Θ

\leftrightarrow

\eta

η

\Lambda

Λ

\leftarrow

\theta

θ

\Xi

Ξ

\Leftarrow

\vartheta

ϑ

\Pi

Π

\uparrow

\iota

ι

\Sigma

Σ

\rightarrow

\kappa

κ

\Upsilon

ϒ

\Rightarrow

\lambda

λ

\Phi

Φ

\downarrow

\mu

µ

\Psi

Ψ

\circ

º

\nu

ν

\Omega

Ω

\pm

±

\xi

ξ

\forall

\geq

\pi

π

\exists

\propto

\rho

ρ

\ni

\partial

\sigma

σ

\cong

\bullet

\varsigma

ς

\approx

\div

÷

\tau

τ

\Re

\neq

\equiv

\oplus

\aleph

\Im

\cup

\wp

\otimes

\subseteq

\oslash

\cap

\in

\supseteq

\supset

\lceil

\subset

\int

\cdot

·

\o

ο

\rfloor

\neg

¬

\nabla

\lfloor

\times

x

\ldots

...

\perp

\surd

\prime

´

\wedge

\varpi

ϖ

\0

\rceil

\rangle

\mid

|

\vee

\langle

\copyright

#### LaTeX Markup

To use LaTeX markup, set the Interpreter property to 'latex'. Use dollar symbols around the text, for example, use '$\int_1^{20} x^2 dx$' for inline mode or '$$\int_1^{20} x^2 dx$$' for display mode.

The displayed text uses the default LaTeX font style. The FontName, FontWeight, and FontAngle properties do not have an effect. To change the font style, use LaTeX markup.

The maximum size of the text that you can use with the LaTeX interpreter is 1200 characters. For multiline text, this reduces by about 10 characters per line.

## Color and Styling

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Line color, specified as an RGB triplet, a hexadecimal color code, a color name, or a short 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 character vector or a string scalar 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. Thus, 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 hexadecimal color codes.

Color NameShort NameRGB TripletHexadecimal Color CodeAppearance
'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 applicableNot applicableNot applicableNo color

Here are the RGB triplets and hexadecimal color codes for the default colors MATLAB uses in many types of plots.

[0 0.4470 0.7410]'#0072BD'

[0.8500 0.3250 0.0980]'#D95319'

[0.9290 0.6940 0.1250]'#EDB120'

[0.4940 0.1840 0.5560]'#7E2F8E'

[0.4660 0.6740 0.1880]'#77AC30'

[0.3010 0.7450 0.9330]'#4DBEEE'

[0.6350 0.0780 0.1840]'#A2142F'

Example: 'g'

Example: [0.6 0.2 0.5]

Example: '#D2F9A7'

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

Line StyleDescriptionResulting Line
'-'Solid line

'--'Dashed line

':'Dotted line

'-.'Dash-dotted line

'none'No lineNo line

Line width, specified as a positive value in points.

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 semitransparent.

## Font

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Font name, specified as a supported font name or 'FixedWidth'. To display and print text properly, you must choose a font that your system supports. The default font depends on your operating system and locale.

To use a fixed-width font that looks good in any locale, use 'FixedWidth'. The fixed-width font relies on the root FixedWidthFontName property. Setting the root FixedWidthFontName property causes an immediate update of the display to use the new font.

Font size, specified as a positive number. The unit of measurement is points. The default font size depends on your operating system and locale.

Character thickness, specified as 'normal' or 'bold'.

MATLAB uses the FontWeight property to select a font from those available on your system. Not all fonts have a bold weight. Therefore, specifying a bold font weight can still result in the normal font weight.

Character slant, specified as 'normal' or 'italic'.

Not all fonts have both font styles. Therefore, the italic font might look the same as the normal font.

## Legend

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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'.

Control for including or excluding the object from a legend, returned as an Annotation object. Set the underlying IconDisplayStyle property 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 a graphics object, go, from the legend set the IconDisplayStyle property to 'off'.

go.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

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State of visibility, specified as one of these values:

• 'on' — Display the object.

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

Selection state, specified as one of these values:

• '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.

Display of selection handles when selected, specified as one of these values:

• '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

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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 Callback Definition.

### Note

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

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 Callback Definition.

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.

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 Callback Definition.

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

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Callback interruption, specified as 'on' or 'off'. The Interruptible 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.

Whenever MATLAB invokes a callback, that callback attempts to interrupt the running callback (if one exists). The Interruptible property of the object owning the running callback determines if interruption is allowed. The Interruptible property has two possible values:

• 'on' — Allows other callbacks to interrupt the object's callbacks. The interruption occurs at the next point where MATLAB processes the queue, such as when there is a drawnow, figure, uifigure, getframe, waitfor, or pause command.

• If the running callback contains one of those commands, then MATLAB stops the execution of the callback at that point and executes the interrupting callback. MATLAB resumes executing the running callback when the interrupting callback completes.

• If the running callback does not contain one of those commands, then MATLAB finishes executing the callback without interruption.

• 'off' — Blocks all interruption attempts. The BusyAction property of the object owning the interrupting callback determines if the interrupting callback is discarded or put into a queue.

### 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.

• Timer objects execute according to schedule regardless of the Interruptible property value.

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.

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.

Whenever MATLAB invokes a callback, that callback attempts to interrupt a running callback. The Interruptible property of the object owning the running callback determines if interruption is permitted. If interruption is not permitted, then the BusyAction property of the object owning the interrupting callback determines if it is discarded or put in the queue. 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.

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 ConstantLine 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 ConstantLine 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 ConstantLine object that has no color. The HitTest property determines if the ConstantLine object responds to the click or if an ancestor does.

• 'none' — Cannot capture mouse clicks. Clicking the ConstantLine 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.

Response to captured mouse clicks, specified as one of these values:

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

• 'off' — Trigger the callbacks for the nearest ancestor of the ConstantLine object that has one of these:

• HitTest property set to 'on'

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

### Note

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

Deletion status, returned as 'off' or 'on'. 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

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Parent, specified as an Axes object.

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

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 the 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

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

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.

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.