How to store ROIs?

Hello. I am writing a GUI that allows a user to plot multiple ROI's using the drawline function on an axes by interactively using the mouse. I want to be able to store each ROI as they are drawn by the user so that I can iterate over them individually. I am using GUIDE and I'm unsure how to do this. Any help would be appreciated.

Answer 1

[Image Analyst]

Try this:

imshow('peppers.png');
uiwait(helpdlg('Draw a line'));
hLine = drawline('SelectedColor','yellow');
allROIs{1} = hLine.Position;
% Draw and save the second line.
uiwait(helpdlg('Draw another line'));
hLine = drawline('SelectedColor','yellow');
allROIs{2} = hLine.Position;

% Now clear lines
hLines = findobj(gca, 'type', 'images.roi.Line');
delete(hLines);
% Now have program draw them back again.
for k = 1 : length(allROIs)
	message = sprintf('Click OK to see ROI #%d', k);
	uiwait(helpdlg(message));
	thisROI = allROIs{k}
	drawline('Position', thisROI);	
end

Adapt as needed.

[The MightySpaceQuin]

I'm trying to adapt it, but I'm having a hard time doing it and getting constant errors instead.

So far this is what my code looks like:

function plotLine_Callback(hObject, eventdata, handles)

handles.line = drawline(handles.axes1, ... 
'Type','Line',...
'LineWidth', 1.325, ... 
'InteractionsAllowed', 'none');

handles.linePosition = get(handles.line, 'Position');
handles.xln = handles.linePosition(:,1); 
handles.yln = handles.linePosition(:,2); 

handles.lineHandles = findobj('Type', 'Line');

Trying to do the following brings up errors

handles.linePosition = get(handles.line, 'Position');

[Image Analyst]

You aren't specifying the number of rows for handles.linePosition so using colon there will throw an error because it doesn't know how many rows there are. Also, you're not indexing anything so all your ROI's will jsut overwrite the same one all the time.

[The MightySpaceQuin]

I seem to have got past the overwrite issue, but I have a problem plotting intersections for all the lines. As well as clearing the array of all handle objects. This is what I have so far:

function plotLine_Callback(hObject, eventdata, handles)

handles.line = drawline(handles.axes1, ... 
'Type','Line',...
'LineWidth', 1.325, ... 
'InteractionsAllowed', 'none');

if not(isfield(handles, 'lineHandles'))
    handles.lineHandles = {};
end

handles.linePos = handles.line.Position;
handles.xln = handles.linePos(:,1); 
handles.yln = handles.linePos(:,2);

handles.lineHandles = [handles.lineHandles, handles.line];

disp(handles.lineHandles);

function intersects(hObject, eventdata, handles)

[xi,yi] = polyxpoly(handles.xC, handles.yC, handles.xln, handles.yln);
 hold on;
 plot(xi, yi, 'r*', 'MarkerSize', 15, 'LineWidth', 1.95, 'Color', '#900C3F');

This is what the command view reports from the disp function:

[Image Analyst]

Did you see the code I gave for clearing the lines:

% Now clear lines
hLines = findobj(gca, 'type', 'images.roi.Line');
delete(hLines);

It would be easier for me to debug if you just attached the complete .m and .fig files.