makeConstrainToRectFcn

Create rectangularly bounded drag constraint function

makeConstrainToRectFcn is not recommended. With the new ROIs, use the DrawingArea property instead. For more information, see Version History.

Syntax

fcn = makeConstrainToRectFcn(roi,x,y)

Description

fcn = makeConstrainToRectFcn(roi,x,y) creates a position constraint function for draggable tools of a given ROI type. The position of the tool is constrained by rectangular boundaries described by position vectors x and y.

Examples

Constrain Drag of impoint to Image Limits

Display an image.

imshow("cell.tif")

Create an impoint object at the (x,y) coordinate (20,60). In an image, the positive y direction is downwards.

h = impoint(gca,20,60);

Make a function that constrains the impoint to the image limits.

x = get(gca,"XLim");
y = get(gca,"YLim");
fcn = makeConstrainToRectFcn("impoint",x,y);

Apply the constraint function to the impoint. Try dragging the point past the boundary of the image. The constraint function prevents the point from crossing the image boundary.

setPositionConstraintFcn(h,fcn);

Input Arguments

roi — ROI type

'imellipse' | 'imfreehand' | 'imline' | 'impoint' | 'impoly' | 'imrect'

ROI type, specified as 'imellipse', 'imfreehand', 'imline', 'impoint', 'impoly', or 'imrect'.

Data Types: char | string

x — Rectangular boundaries in the x direction

2-element numeric vector

Rectangular boundaries in the x direction, specified as a 2-element numeric vector of the form [xmin xmax].

y — Rectangular boundaries in the y direction

2-element numeric vector

Rectangular boundaries in the y direction, specified as a 2-element numeric vector of the form [ymin ymax].

Output Arguments

fcn — Function handle

handle

Function handle, returned as a handle. For more information, see Create Function Handle.

Version History

Introduced in R2006a

R2018b: makeConstrainToRectFcn is not recommended

Starting in R2018b, a new set of ROI objects replaces the existing set of ROI objects. The new objects provide more functional capabilities, such as face color transparency. The new classes also support events that you can use to respond to changes in your ROI such as moving or being clicked. Although there are no plans to remove the old ROI objects at this time, switch to the new ROIs to take advantage of the additional capabilities and flexibility. For more information on creating ROIs using the new ROI functions, see Create ROI Shapes.

With the new ROIs, you use the DrawingArea property of the ROI to specify the area in which you can draw or move an ROI.

Update Code

Update all instances of makeConstrainToRectFcn.

Discouraged Usage

Recommended Replacement

This example uses the makeConstrainToRectFcn function to create a function that limits the area in which you can create or move an ROI to the size of the underlying image. By default, you can move an ROI off the image area. imshow('cell.tif') h = impoint(gca,20,60); % Make a function that constrains movement of the point x = get(gca,'XLim'); y = get(gca,'YLim'); fcn = makeConstrainToRectFcn('impoint',x,y);; % Apply the constraint function to the ROI. setPositionConstraintFcn(h,fcn);

Here is equivalent code, replacing use of makeConstrainToRectFcn function with the DrawingArea property of the ROI. By default, the new ROIs limit their creation and movement to the size of the underlying image, so there is no need to recreate that part of the example. Instead, this example creates a 10-pixel margin inside the image boundary where the ROI cannot go. I = imread('cell.tif'); imshow(I) h = drawpoint(gca,'Position',[20 60]) [height width] = size(I); %Get image dimensions h.DrawingArea = [10,10,(width-20),(height-20)];