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Line Properties

Line properties

Creating Line Objects

Use line to create line objects.

Modifying Properties

You can set and query graphics object properties in two ways:

  • Customize Objects in Graph 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.

Line Property Descriptions

Annotation

hg.Annotation object (read-only)

Handle of Annotation object. The Annotation property enables you to specify whether this line 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 line object is displayed in a figure legend:

IconDisplayStyle ValuePurpose
onRepresent this line object in a legend (default)
offDo not include this line object in a legend
childrenSame as on because line objects do not have children

Setting the IconDisplayStyle property

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 Control Legend Content for more information and examples.

BeingDeleted

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.

BusyAction

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.

ButtonDownFcn

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 over the line object. The default is an empty array.

See the figure's SelectionType property to determine if modifier keys were also pressed.

Set this property to a function handle that references the callback. The function must define at least two input arguments (handle of line associated with the button down event and an event structure, which is empty for this property).


The following example shows how to access the callback object's handle as well as the handle of the figure that contains the object from the callback function.

function button_down(src,evnt)
% src - the object that is the source of the event
% evnt - empty for this property
   sel_typ = get(gcbf,'SelectionType')
   switch sel_typ 
      case 'normal'
         disp('User clicked left-mouse button')
         set(src,'Selected','on')
      case 'extend'
         disp('User did a shift-click')
         set(src,'Selected','on')
      case 'alt'
         disp('User did a control-click')
         set(src,'Selected','on')
         set(src,'SelectionHighlight','off')
   end
end

Suppose h is the handle of a line object and the button_down function is on your MATLAB path. The following statement assigns the button_down function to the ButtonDownFcn property:

set(h,'ButtonDownFcn',@button_down)

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

Children

vector of handles

The empty matrix; line objects have no children.

Clipping

{on} | off

Clipping mode. MATLAB clips lines to the axes plot box by default. If you set Clipping to off, lines are displayed outside the axes plot box. This occurs if you create a line, set hold to on, freeze axis scaling (set axis to manual), and then create a longer line.

Color

ColorSpec

Line color. A three-element RGB vector, or one of the MATLAB predefined names, specifying the line color. See the ColorSpec reference page for more information on specifying color.

CreateFcn

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

Callback function executed during object creation. Executes when MATLAB creates a line object. The default is an empty array.

You must specify the callback during the creation of the line or in a call to the line function to create a new line object.

For example, the statement:

set(0,'DefaultLineCreateFcn',@line_create)

defines a default value for the line CreateFcn property on the root level that sets the axes LineStyleOrder whenever you create a line object. The following callback function must be on your MATLAB path when you execute the above statement.

function line_create(src,evnt)
% src - the object that is the source of the event 
% evnt - empty for this property
	axh = get(src,'Parent'); 
	set(axh,'LineStyleOrder','-.|--')
end

MATLAB executes this function after setting all line properties. Setting this property on an existing line object has no effect.

The function must define at least two input arguments (handle of line object created and an event structure, which is empty for this property).

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

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

DeleteFcn

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

Delete line callback function. Executes when you delete the line object. This happens when you call the delete command on the object, its parent axes, or the figure containing it. The default is an empty array.

For example, the following function displays object property data before the object is deleted.

function delete_fcn(src,evnt)
% src - the object that is the source of the event 
% evnt - empty for this property
   obj_tp = get(src,'Type');
   disp([obj_tp, ' object deleted'])
   disp('Its user data is:')
   disp(get(src,'UserData'))
end

MATLAB executes the function before deleting the object's properties so these values are available to the callback function. The function must define at least two input arguments (handle of line object being deleted and an event structure, which is empty for this property).

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

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

DisplayName

string

String used by legend. The legend function uses the DisplayName property to label the line 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.

The following code shows how to use the DisplayName property from the command line or in a file.

t = 0:.1:2*pi;
a(:,1)=sin(t); a(:,2)=cos(t);
h = plot(a);
set(h,{'DisplayName'},{'Sine','Cosine'}')
legend show
EraseMode

{normal} | none | xor | background

Erase mode. Controls the technique MATLAB uses to draw and erase line objects. 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 the line when it is moved or destroyed. While the object is still visible on the screen after erasing with EraseMode none, you cannot print it, because MATLAB stores no information about its former location.

  • xor — Draw and erase the line by performing an exclusive OR (XOR) with the color of the screen beneath it. This mode does not damage the color of the objects beneath the line. However, the line's color depends on the color of whatever is beneath it on the display.

  • background — Erase the line by drawing it in the axes background Color, or the figure background Color if the axes Color is none. This damages objects that are behind the erased line, but lines are 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 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.

HandleVisibility

{on} | callback | off

Control access to object handle. Determine when an object's handle is visible in its parent's list of children. HandleVisibility is useful for preventing command-line users from accidentally drawing into or deleting a figure that contains only user interface devices (such as a dialog box).

  • 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.

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.

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.

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).

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.

For more information, see HandleVisibility Property, Functions Affected by Handle Visibility, and Properties Affected by Handle Visibility.

HitTest

{on} | off

Selectable by mouse click. Determines if the line 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 line. If HitTest is off, clicking the line selects the object below it (which might be the axes containing it).

Interruptible

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.

LineStyle

{-} | -- | : | -. | none

Line style.

 Line Style Specifiers Table

Use LineStyle none when you want to place a marker at each point but do not want the points connected with a line (see the Marker property).

LineWidth

scalar

Width of the line . Specify this value in points. The default value is 0.5 points.

Marker

character (see table)

Marker symbol. Specifies marks displayed at data points. You can set values for the Marker property independently from the LineStyle property. For a list of supported marker symbols, see the following table.

 Marker Specifiers Table

MarkerEdgeColor

ColorSpec | none | {auto}

Marker edge color. The color of the marker or the edge color for filled markers (circle, square, diamond, pentagram, hexagram, and the four triangles).

  • ColorSpec — User-defined color.

  • none — Specifies no color, which makes nonfilled markers invisible.

  • auto — Use same color as the line Color property.

MarkerFaceColor

ColorSpec | {none} | auto

Fill color for closed-shape markers. The fill color for markers that are closed shapes (circle, square, diamond, pentagram, hexagram, and the four triangles).

  • ColorSpec — User-defined color.

  • none — Makes the interior of the marker transparent, allowing the background to show through.

  • auto — Sets the fill color to the axes Color property. If the axes Color property is none, sets the fill color to the figure Color.

MarkerSize

scalar

Marker size. Size of the marker in points. The default value is 6.

    Note:   MATLAB draws the point marker (specified by the '.' symbol) at one-third the specified size.

Parent

handle of axes, hggroup, or hgtransform

Parent of line object. Handle of the line object's parent. The parent of a line object is the axes that contains it. You can reparent line objects to other axes, hggroup, or hgtransform objects.

Selected

on | off

Selection status When this property is on, MATLAB displays selection handles if the SelectionHighlight property is also on. You can, for example, define the ButtonDownFcn to set this property, allowing users to select the object with the mouse.

SelectionHighlight

{on} | off

Object highlighted when selected. When the Selected property is on, MATLAB indicates the selected state by drawing handles at each vertex. When SelectionHighlight is off, MATLAB does not draw the handles.

Tag

string

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

Use this property when 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.

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

Type

string (read-only)

Class 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 line objects, Type is always 'line'.

UIContextMenu

handle of uicontextmenu object

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

UserData

matrix

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

    Note:   Setting the UserData property more than once erases previous entries.

Visible

{on} | off

Line visibility.

  • on — All lines are visible.

  • off — Line is not visible, but still exists, and you can get and set its properties.

XData

vector

x-coordinates of line. Vector of x-coordinates defining the line. The default is [0 1].

YData and ZData, if set, must be the same length and have the same number of rows.

Create a line using the line function, then change its XData property:

mylin = line(rand(1,10),rand(1,10)); 
set(mylin,'XData',rand(1,15));
% A warning because you did not set YData
set(mylin,'XData',rand(1,15),...
   'YData',rand(1,15));
% No warning appears and the plot draws as expected.
YData

vector

y-coordinates of line. Vector of y-coordinates defining the line. The default is [0 1]. XData and ZData, if set, must be the same length and have the same number of rows.

Create a line using the line function, then change its YData property:

mylin = line(rand(1,10),rand(1,10)); 
set(mylin,'YData',rand(1,15));
% A warning because you did not set YData
set(mylin,'YData',rand(1,15),'XData',rand(1,15));
% No warning appears and the plot draws as expected.
ZData

vector

z-coordinates of line. Vector of z-coordinates defining the line. The default is [] (empty). XData and YData must have the same number of rows.

Create a line using the line function, then change its ZData property:

mylin = line(rand(1,10),rand(1,10),rand(1,10));
view(3)
set(mylin,'ZData',rand(1,15));
% A warning because you did not set YData
set(mylin,'XData',rand(1,15),...
   'YData',rand(1,15),...
   'ZData',rand(1,15));
% No warning appears and the plot draws as expected.

See Also

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