Issue with imdistline() function in MATLAB?

I am trying to measure the distance two points on an image and then use that distance as an input for some other function. Here is my code:"

if true
   figure, imshow(I);
   h = imdistline(gca);

     api = iptgetapi(h);
     width = api.getDistance();
  end

When I run it, I am able to drag and get the distance I want on the image, but the distance I get from using the getDistance is some default value it started with , when it opened and it does not change , even if I change it in the image. How can the variable width have the distance i measured before I press enter or any eye and close the image.

Eric

[Brett Barnes]

Are you right clicking the line to open the context menu? There's an option there to "Export to Workspace"

Answer 1

[Roche de Guzman]

global h; h = imdistline; % activates the fx for drawing and measuring line
global xc yc; xc = 0.3; yc = 0.1; % x and y conversion factors
setLabelTextFormatter(h,'measure'); % message
addNewPositionCallback(h,@ShowDistance); % new position callback
%% Custom fx
function ShowDistance(pos)
    global h xc yc; % sets line handles and x and y conversion factors to global
    X = pos(:,1)*xc; Y = pos(:,2)*yc; % converts x and y positions from px to target unit
    d = norm(diff([X Y])); % distance in target unit
    assignin('base','d',d); % stores in Workspace
    setLabelTextFormatter(h,[num2str(d,'%.1f') ' target unit']); % updates measurement
end

[dana]

Works great!

Answer 2

[Image Analyst]

I ran your code on R21014b and it works just fine - exactly how you'd expect. I think you'll have to call tech support.