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images.roi.Rectangle class

Package: images.roi

Rectangular region-of-interest

Description

The images.roi.Rectangle class creates a rectangular region-of-interest (ROI) object. You call the draw method of the object to begin drawing the ROI interactively by using your mouse. You can also adjust the size and position of the ROI by using the mouse. The ROI also has a context menu that controls aspects of its appearance and behavior.

The images.roi.Rectangle class is a handle class.

Creation

Description

example

h = images.roi.Rectangle creates an instance of the images.roi.Rectangle class with default properties.

h = images.roi.Rectangle(ax) creates an ROI in the axes specified by ax.

h = images.roi.Rectangle(___,Name,Value) modifies the appearance and behavior of the ROI using one or more name-value pairs to specify properties. You can set properties using name-value pairs with or without specifying ax.

Input Arguments

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Parent of the ROI, specified as an Axes object.

Properties

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Public Properties

Aspect ratio of the rectangle, specified as a positive numeric scalar. The value of this property changes automatically when you draw or resize the rectangle. The images.roi.Rectangle object calculates this value as height/width

ROI color, specified as a MATLAB® ColorSpec (Color Specification).

Example: 'green'

Example: 'g'

Example: [0 1 0]

ROI can be interactively deleted via a context menu, specified as true or false. When the value is true (default), you can delete the ROI via the context menu. To disable this context menu item, set this property to false. When the value is set to false, you can still delete the ROI by calling the delete function, specifying the handle to the ROI as the input.

Area of the axes in which you can interactively place the ROI, specified as one of the values in this table.

ValueDescription
'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.

Transparency of the ROI face, specified as a numeric scalar value in the range [0 1]. When the value is 1, the ROI is fully opaque. When the value is 0, the ROI is completely transparent.

ROI face can capture clicks, specified as true or false. When true (default), the ROI face captures mouse clicks. When false, the ROI face does not capture mouse clicks.

Aspect ratio remains constant during interaction, specified as true or false. When the value is true, the ROI maintains the aspect ratio when you draw or resize the rectangle. When the value is false (default), you can change the aspect ratio when drawing or resizing the rectangle. You can change the state of this property using the default context menu.

Visibility of the ROI handle in the Children property of the parent, specified as one of the values in this table.

ValueDescription
'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.

Interactivity of the ROI, specified as one of the values in this table.

ValueDescription
'all'The ROI is fully interactable (default).
'none'The ROI is not interactable, and no drag points are visible.
'translate'The ROI can be translated (moved) within the drawing area but not reshaped. This value is not available for use with images.roi.Point objects.
'reshape'The ROI can be reshaped but not translated. This value is not available for use with images.roi.Point objects or images.roi.Rectangle objects.

ROI label, specified as a character vector or string. By default, the ROI has no label ('').

Width of the ROI edge, specified as a positive numeric scalar in points. The default value is three times the number of points per screen pixel.

ROI parent, specified as an Axes object. A UIAxes cannot be the parent of the ROI.

Position of the ROI, specified as a 1-by-4 numeric array 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.

Ability of the rectangle to be rotated, specified as true or false. 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.

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 Position. The Position property represents the initial position of the ROI, before rotation. To determine the location of a rotated ROI, use the Vertices property.

Selection state of the ROI, specified as the logical value true or false. You can also set this property interactively. For example, clicking on the ROI selects the ROI and sets this property to true. Similarly, if you press Ctrl and click the ROI, the ROI is deselected and the value of this property is set to false.

Color of the ROI when selected, specified as a MATLAB ColorSpec (Color Specification). The intensities must be in the range [0,1]. If 'SelectedColor' is set to 'none', then the value of Color defines the color of the ROI for all states, selected or not.

Example: 'green'

Example: 'g'

Example: [0 1 0]

Color of the ROI stripe, specified as a MATLAB ColorSpec (Color Specification) value. By default, the edge of an ROI is solid colored. If you specify StripeColor, the ROI edge is striped. The striping consists of a combination of the value specified by 'Color' and this value.

Example: 'green'

Example: 'g'

Example: [0 1 0]

Tag to associate with the ROI, specified as a character vector or string. Use the tag value to find the ROI object in a hierarchy of objects using the findobj function.

Context menu, specified as a ContextMenu object. Use this property to display a custom context menu when you right-click the ROI. You can create a custom context menu by using the uicontextmenu function and then configuring context menu properties.

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. MATLAB does not use this data.

Locations of points on the edge of the ROI, specified as an n-by-2 array.

This property is read-only.

ROI visibility, specified as one of the values in this table.

ValueDescription
'on'Display the ROI (default).
'off'Hide the ROI without deleting it. You still can access the properties of an invisible ROI.

Methods

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Events

Event NameTriggerEvent DataEvent Attributes
DeletingROIROI is about to be interactively deleted.event.EventData

NotifyAccess: private

ListenAccess: public

DrawingStartedROI is about to be interactively drawn.event.EventData

NotifyAccess: private

ListenAccess: public

DrawingFinishedROI has been interactively drawn.event.EventData

NotifyAccess: private

ListenAccess: public

MovingROIROI shape or location is being interactively changed.images.roi.RectangleMovingEventData

NotifyAccess: private

ListenAccess: public

ROIMovedROI shape or location has been interactively changed.images.roi.RectangleMovingEventData

NotifyAccess: private

ListenAccess: public

ROIClickedROI has been clicked.images.roi.ROIClickedEventData

NotifyAccess: private

ListenAccess: public

Examples

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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');

Introduced in R2018b