Rectangle
Rectangular region of interest
Description
A Rectangle
object specifies the shape and position of a
rectangular region-of-interest (ROI). You can customize the appearance and interactive
behavior of the ROI.
For more information about using this ROI, including keyboard shortcuts, see Tips.
Creation
There are two ways to create a Rectangle
object. For more information,
see Create ROI Shapes.
Use the
drawrectangle
function. Use this function when you want to create the ROI and set the appearance in a single command. You can specify the shape and position of the ROI interactively by drawing the ROI over an image using the mouse, or programmatically by using name-value arguments.Use the
images.roi.Rectangle
function described here. Use this function when you want to specify the appearance and behavior of the ROI before you specify the shape and position of the ROI. After creating the object, you can specify the shape and position interactively by using thedraw
function or programmatically by modifying properties of the object.
Syntax
Description
creates a
roi
= images.roi.RectangleRectangle
object with default properties.
creates an ROI in the axes specified by roi
= images.roi.Rectangle(ax
)ax
.
sets properties using name-value
arguments. You can specify multiple name-value arguments.roi
= images.roi.Rectangle(___,Name,Value
)
Example: images.roi.Rectangle("Color","y")
creates a yellow colored
Rectangle
object.
Input Arguments
ax
— Parent of ROI
gca
(default) | Axes
object | UIAxes
object
Parent of ROI, specified as an Axes
object or a
UIAxes
object. For information about using an ROI in a UIAxes,
including important limitations, see Using ROIs in Apps Created with App Designer.
Properties
AspectRatio
— Aspect ratio of rectangle
1
(default) | positive number
Aspect ratio of the rectangle, specified as a positive number. The value of this
property changes automatically when you draw or resize the rectangle. The
Rectangle
object calculates this value as
height/width
.
Color
— ROI color
[0 0.4470 0.7410]
(default) | RGB triplet | color name | short color name
ROI color, specified as an RGB triplet, a color name, or a short color name.
You can specify any color using an RGB triplet. An RGB triplet is a 3-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].
You can specify some common colors by name as a string scalar or character vector. This table lists the named color options and the equivalent RGB triplets.
Color Name | Short Name | RGB Triplet | Appearance |
---|---|---|---|
"red" | "r" | [1 0 0] |
|
"green" | "g" | [0 1 0] |
|
"blue" | "b" | [0 0 1] |
|
"cyan"
| "c" | [0 1 1] |
|
"magenta" | "m" | [1 0 1] |
|
"yellow" | "y" | [1 1 0] |
|
"black" | "k" | [0 0 0] |
|
"white" | "w" | [1 1 1] |
|
Here are the RGB triplets for the default colors that MATLAB® uses in many types of plots.
RGB Triplet | Appearance |
---|---|
[0 0.4470 0.7410] |
|
[0.8500 0.3250 0.0980] |
|
[0.9290 0.6940 0.1250] |
|
[0.4940 0.1840 0.5560] |
|
[0.4660 0.6740 0.1880] |
|
[0.3010 0.7450 0.9330] |
|
[0.6350 0.0780 0.1840] |
|
Example: "Color","r"
Example: "Color","green"
Example: "Color",[0 0.4470 0.7410]
ContextMenu
— Context menu
ContextMenu
object
Context menu that displays when you right-click the ROI, specified as a
ContextMenu
object. You can create a custom context menu by using
the uicontextmenu
function and then
configuring context menu properties.
Deletable
— Context menu provides option to delete the ROI
true
or 1
(default) | false
or 0
Context menu provides an option to delete the ROI, specified as a numeric or
logical 1
(true
) or 0
(false
). When the value is true
, you can delete the ROI
interactively using the context menu. When the value is false
, the
context menu option to delete the ROI is disabled.
In both cases, you can delete the ROI outside of the context menu by using the
delete
function.
DrawingArea
— Area of axes in which you can interactively place ROI
"auto"
(default) | "unlimited"
| [x,y,w,h]
Area of the axes in which you can interactively place the ROI, specified as one of the values in this table.
Value | Description |
---|---|
"auto" | The drawing area is the current axes limits (default). |
"unlimited" | The drawing area has no boundary and ROIs can be drawn or dragged to extend beyond the axes limits. |
[x,y,w,h] | The drawing area is restricted to a rectangular region beginning at (x,y), and extending to width w and height h. |
FaceAlpha
— Transparency of ROI face
0.2
(default) | number in the range [0, 1]
Transparency of the ROI face, specified as a number in the range [0, 1]. When the value is
1
, the ROI face is completely opaque. When the value is
0
, the ROI face is completely transparent.
FaceSelectable
— ROI face can capture clicks
true
or 1
(default) | false
or 0
ROI face can capture clicks, specified as a numeric or
logical 1
(true
) or 0
(false
). When true
, the ROI face captures mouse clicks. When
false
, the ROI face does not capture mouse clicks.
FixedAspectRatio
— Aspect ratio remains constant
false
or 0
(default) | true
or 1
Aspect ratio remains constant during interaction, specified as a numeric or
logical 0
(false
) or 1
(true
). When the value is true
, the aspect ratio remains
constant when you draw or resize the ROI. When the value is false
,
you can change the aspect ratio when drawing or resizing the ROI. You can change the
state of this property using the default context menu.
HandleVisibility
— Visibility of ROI handle in Children
property of parent
"on"
(default) | "off"
| "callback"
Visibility of the ROI handle in the Children
property of the parent,
specified as one of the values in this table.
Value | Description |
---|---|
"on" | The object handle is always visible (default). |
"off" | The object handle is hidden at all times. |
"callback" | The object handle is visible from within callbacks or functions invoked by callbacks, but not from within functions invoked from the command line. |
InteractionsAllowed
— Interactivity of ROI
"all"
(default) | "none"
| "translate"
Interactivity of the ROI, specified as one of the values in this table.
Value | Description |
---|---|
"all" | The ROI is fully interactable. |
"none" | The ROI is not interactable, and no drag points are visible. |
"translate" | The ROI can be translated (moved) within the drawing area. |
Label
— ROI label
''
(default) | character vector | string scalar
ROI label, specified as a character vector or string scalar. By default, the ROI has no label
(''
).
LabelAlpha
— Transparency of text background
1
(default) | number in the range [0, 1]
Transparency of the text background, specified as a number in the range [0, 1]. When
set to 1
, the text background is completely opaque. When set to
0
, the text background is completely transparent.
LabelTextColor
— Label text color
"black"
(default) | RGB triplet | color name | short color name
Label text color, specified as an RGB triplet, a color name, or a short color name.
You can specify any color using an RGB triplet. An RGB triplet is a 3-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].
You can specify some common colors by name as a string scalar or character vector. This table lists the named color options and the equivalent RGB triplets.
Color Name | Short Name | RGB Triplet | Appearance |
---|---|---|---|
"red" | "r" | [1 0 0] |
|
"green" | "g" | [0 1 0] |
|
"blue" | "b" | [0 0 1] |
|
"cyan"
| "c" | [0 1 1] |
|
"magenta" | "m" | [1 0 1] |
|
"yellow" | "y" | [1 1 0] |
|
"black" | "k" | [0 0 0] |
|
"white" | "w" | [1 1 1] |
|
Here are the RGB triplets for the default colors that MATLAB uses in many types of plots.
RGB Triplet | Appearance |
---|---|
[0 0.4470 0.7410] |
|
[0.8500 0.3250 0.0980] |
|
[0.9290 0.6940 0.1250] |
|
[0.4940 0.1840 0.5560] |
|
[0.4660 0.6740 0.1880] |
|
[0.3010 0.7450 0.9330] |
|
[0.6350 0.0780 0.1840] |
|
Example: "LabelTextColor","r"
Example: "LabelTextColor","green"
Example: "LabelTextColor",[0 0.4470 0.7410]
LabelVisible
— Visibility of ROI label
'on'
(default) | 'off'
| 'hover'
| 'inside'
Visibility of the ROI label, specified as one of these values:
Value | Description |
---|---|
'on' | Label is visible when the ROI is visible and the Label
property is nonempty (default). |
'hover' | Label is visible only when the mouse hovers over the ROI. |
'inside' | Label is visible only when there is adequate space inside the ROI to display it. |
'off' | Label is not visible. |
LineWidth
— Width of ROI border
positive number
Width of the ROI border, specified as a positive number in points. The default value is three times the number of points per screen pixel, such that the border is three pixels wide.
MarkerSize
— Marker size
positive number
Marker size, specified as a positive number in points. The default value is eight times the number of points per screen pixel, such that markers are eight pixels in size.
Parent
— ROI parent
Axes
object | UIAxes
object
ROI parent, specified as an Axes
or UIAxes
object. For
information about using an ROI in a UIAxes, including important limitations,
see Using ROIs in Apps Created with App Designer.
Position
— Position of ROI
1-by-4 numeric vector
Position of the ROI, specified as a 1-by-4 numeric vector of the form
[xmin, ymin, width, height]
. xmin
and
ymin
specify the location of the upper left corner of the
rectangle. width
and height
specify the extent to
the rectangle in two dimensions.
Rotatable
— Rectangle can be rotated
false
or 0
(default) | true
or 1
Rectangle can be rotated, specified as a numeric or
logical 0
(false
) or 1
(true
). When the value is false
(default), the rectangle
cannot be rotated. When the value is true
, you can rotate the
rectangle by clicking near the markers at the corners.
RotationAngle
— Angle around center of rectangle
0
(default) | numeric scalar
Angle around the center of the rectangle, specified as a numeric scalar. The angle is measured in degrees in a clockwise direction. The value of this property changes automatically when you draw or move the ROI.
The value of RotationAngle
does not impact the values in the
Position
property. The Position
property
represents the initial position of the ROI, before rotation. To determine the location
of a rotated ROI, use the Vertices
property.
Selected
— Selection state of ROI
false
or 0
(default) | true
or 1
Selection state of the ROI, specified as a numeric or
logical 0
(false
) or 1
(true
). You can also set this property interactively. For example, clicking on
the ROI selects the ROI and sets this property to true
. Similarly,
pressing the Ctrl key and clicking the ROI deselects the ROI and sets
the value of this property to false
.
SelectedColor
— Color of ROI when selected
"none"
(default) | RGB triplet | color name | short color name
Color of the ROI when selected, specified as an RGB triplet, a color name, a short
color name, or "none"
. If you specify "none"
, then
the value of Color
defines the color of the ROI for all states,
selected or not.
You can specify any color using an RGB triplet. An RGB triplet is a 3-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].
You can specify some common colors by name as a string scalar or character vector. This table lists the named color options and the equivalent RGB triplets.
Color Name | Short Name | RGB Triplet | Appearance |
---|---|---|---|
"red" | "r" | [1 0 0] |
|
"green" | "g" | [0 1 0] |
|
"blue" | "b" | [0 0 1] |
|
"cyan"
| "c" | [0 1 1] |
|
"magenta" | "m" | [1 0 1] |
|
"yellow" | "y" | [1 1 0] |
|
"black" | "k" | [0 0 0] |
|
"white" | "w" | [1 1 1] |
|
Here are the RGB triplets for the default colors that MATLAB uses in many types of plots.
RGB Triplet | Appearance |
---|---|
[0 0.4470 0.7410] |
|
[0.8500 0.3250 0.0980] |
|
[0.9290 0.6940 0.1250] |
|
[0.4940 0.1840 0.5560] |
|
[0.4660 0.6740 0.1880] |
|
[0.3010 0.7450 0.9330] |
|
[0.6350 0.0780 0.1840] |
|
Example: "SelectedColor","r"
Example: "SelectedColor","green"
Example: "SelectedColor",[0 0.4470 0.7410]
StripeColor
— Color of ROI stripe
"none"
(default) | RGB triplet | color name | short color name
Color of the ROI stripe, specified as an RGB triplet, a color name, a short color
name, or "none"
. If you specify "none"
, then the
ROI edge is a solid color specified by Color
. Otherwise, the edge
of the ROI is striped, with colors alternating between the colors specified by
Color
and StripeColor
.
You can specify any color using an RGB triplet. An RGB triplet is a 3-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].
You can specify some common colors by name as a string scalar or character vector. This table lists the named color options and the equivalent RGB triplets.
Color Name | Short Name | RGB Triplet | Appearance |
---|---|---|---|
"red" | "r" | [1 0 0] |
|
"green" | "g" | [0 1 0] |
|
"blue" | "b" | [0 0 1] |
|
"cyan"
| "c" | [0 1 1] |
|
"magenta" | "m" | [1 0 1] |
|
"yellow" | "y" | [1 1 0] |
|
"black" | "k" | [0 0 0] |
|
"white" | "w" | [1 1 1] |
|
Here are the RGB triplets for the default colors that MATLAB uses in many types of plots.
RGB Triplet | Appearance |
---|---|
[0 0.4470 0.7410] |
|
[0.8500 0.3250 0.0980] |
|
[0.9290 0.6940 0.1250] |
|
[0.4940 0.1840 0.5560] |
|
[0.4660 0.6740 0.1880] |
|
[0.3010 0.7450 0.9330] |
|
[0.6350 0.0780 0.1840] |
|
Example: "StripeColor","r"
Example: "StripeColor","green"
Example: "StripeColor",[0 0.4470 0.7410]
Tag
— Tag to associate with ROI
''
(default) | character vector | string scalar
Tag to associate with the ROI, specified as a character vector or
string scalar. Use the tag value to find the ROI object in a
hierarchy of objects using the findobj
function.
UserData
— Data to associate with ROI
any MATLAB data
Data to associate with the ROI, specified as any MATLAB data. For example, you can specify a scalar, vector, matrix, cell array,
string, character array, table, or structure. The Rectangle
object
does not use this data.
Vertices
— Locations of points on edge of rectangle
4-by-2 numeric matrix
This property is read-only.
Locations of points on the corners of the ROI, returned as a 4-by-2 numeric matrix.
Visible
— ROI visibility
"on"
(default) | "off"
| on/off logical value
ROI visibility, specified as "on"
or "off"
, or as a
numeric or logical 1
(true
) or
0
(false
). A value of "on"
is equivalent to true, and "off"
is equivalent to false. The value is
stored as an on/off logical value of type OnOffSwitchState
.
Value | Description |
---|---|
"on" | Display the ROI. |
"off" | Hide the ROI without deleting it. You still can access the properties of an invisible ROI. |
Object Functions
addlistener | Create event listener bound to event source |
beginDrawingFromPoint | Begin drawing ROI from specified point |
bringToFront | Bring ROI to front of Axes stacking order |
createMask | Create binary mask image from ROI |
draw | Begin drawing ROI interactively |
inROI | Query if points are located in ROI |
wait | Block MATLAB command line until ROI operation is finished |
Examples
Create Rectangular ROI Non-interactively
Read image into the workspace and display it.
I = imread('baby.jpg');
figure
imshow(I)
Create a rectangular ROI on the image, using the Position
parameter to specify its location and size. The example also specifies that the edge of the rectangle is a striped line. For programmatically created ROIs, if you want the ROI drawn in a specific axes, you must specify that axes as an input argument. Otherwise, an instance of the images.roi.Rectangle
class is created but not displayed. In this example, specify the current axes (gca
) to draw the ROI on the image in that axes.
h = images.roi.Rectangle(gca,'Position',[500,500,1000,1000],'StripeColor','r');
Set Up Listeners for Rectangle ROI Events
Read and display image.
I = imread("cameraman.tif");
imshow(I)
Create a Rectangle ROI in the same axes as the image, then add listeners for ROI moving events.
roi = images.roi.Rectangle(gca); addlistener(roi,"MovingROI",@allevents); addlistener(roi,"ROIMoved",@allevents);
Draw the Rectangle ROI interactively. Then, invoke the allevents
callback function by moving the ROI. When you move the ROI, the listeners send notifications of these events and execute the callback function.
draw(roi)
The allevents
callback function displays at the command line the previous position and the current position of the ROI.
function allevents(src,evt) evname = evt.EventName; switch evname case "MovingROI" disp("ROI moving. Previous position: "+mat2str(evt.PreviousPosition)); disp("ROI moving. Current position: "+mat2str(evt.CurrentPosition)); case "ROIMoved" disp("ROI moved. Previous position: "+mat2str(evt.PreviousPosition)); disp("ROI moved. Current position: "+mat2str(evt.CurrentPosition)); end end
More About
Events
To receive notification from the ROI when certain events happen, set up listeners for these events. You can specify a callback function that executes when one of these events occurs. When the ROI notifies your application through the listener, it returns data specific to the event. Look at the event class for the specific event to see what is returned.
For an example, see Set Up Listeners for Rectangle ROI Events.
Event Name | Trigger | Event Data | Event Attributes |
---|---|---|---|
DeletingROI | ROI is about to be interactively deleted. | event.EventData |
|
DrawingStarted | ROI is about to be interactively drawn. | event.EventData |
|
DrawingFinished | ROI has been interactively drawn. | event.EventData |
|
MovingROI | ROI shape or location is being interactively changed. | images.roi.RectangleMovingEventData |
|
ROIMoved | ROI shape or location has been interactively changed. | images.roi.RectangleMovingEventData |
|
ROIClicked | ROI has been clicked. | images.roi.ROIClickedEventData |
|
Tips
To draw the ROI interactively using the
draw
ordrawrectangle
function, position the cursor on the axes and click and drag to create the shape. To finish the ROI, release the mouse button.The ROI supports the following interactivity, including keyboard shortcuts.
Behavior Keyboard shortcut Cancel drawing the ROI. Press Esc. The function returns a valid ROI object with an empty Position
property.Resize (reshape) the ROI. Position the cursor over a vertex and then click and drag. The rectangle has vertices at each corner and at the midpoint of each side. To preserve the aspect ratio while resizing, press the Shift key. To lock the aspect ratio, use the Fix Aspect Ratio in the right-click context menu.
Move the ROI. Position the cursor over the ROI. The cursor changes to the fleur shape. Click and drag the ROI. Delete the ROI. Position the pointer on the rectangle, right-click, and choose Delete Rectangle from the context menu. You can also delete the ROI programmatically using the delete
function.For information about using an ROI in an app created with App Designer, see Using ROIs in Apps Created with App Designer.
Version History
Introduced in R2018bR2020a: UIContextMenu
property is not recommended
Starting in R2020a, using the UIContextMenu
property to assign a
context menu to a graphics object or UI component is not recommended. Use the
ContextMenu
property instead. The property values are the
same.
There are no plans to remove support for the UIContextMenu
property at this time. However, the UIContextMenu
property no
longer appears in the list returned by calling the get
function on a
graphics object or UI component.
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