Interrupting/Disabling ROI drawing functions in a GUI

Question

I am programming a GUI for the selection of regions of interest (ROIs) in an image. Several kinds of regions may be chosen using built-in MATLAB functions such as impoly/imellipse.

Below, I provide a minimal working example of a GUI where my problem may be addressed.

The question is: supposing one user misclicks one of the ROI selection buttons (i.e. chooses to select an Ellipse when the goal was to select a Polygon) how can I cancel the interactive tool for the ROI selection AVOIDING errors in the workspace?

I know that pressing the "Esc" key cancels the interactive tool but I would like to avoid errors.

One idea is to have another push button (Abort) to perform the interruption but I've been unable to come up with code to perform this operation.

function roiData = testGUI(sourceImage)

% Initialize main figure
hdl.mainfig = figure();

% Initialize roiData and roiCounter
roiData    = [];
roiCounter = 0;

% Select Elliptical ROI button
hdl.selectEllipseButton = uicontrol(hdl.mainfig, 'Units', 'normalized', 'Position',[0.05 0.7 0.2 0.1], 'String', 'Select Ellipse', 'Callback', @selectEllipse);
% Select Polygonal ROI button
hdl.selectPolygonButton = uicontrol(hdl.mainfig, 'Units', 'normalized', 'Position',[0.05 0.6 0.2 0.1], 'String', 'Select Polygon', 'Callback', @selectPolygon);
% Abort Button
hdl.abort = uicontrol(hdl.mainfig, 'Units', 'normalized', 'Position',[0.05 0.2 0.2 0.2], 'String', 'Abort', 'Callback', @abort);
% Axes
hdl.axes = axes('Parent',hdl.mainfig, 'Units', 'Normalized', 'Position', [0.35 0.2 0.6 0.6]);


    function selectEllipse(~, ~, ~)
        imshow(sourceImage, [], 'Parent', hdl.axes);
        roiCounter = roiCounter + 1;
        h = imellipse(hdl.axes);
        mask = uint16(createMask(h));
        wait(h);            
        roiData(roiCounter).mask = mask;
    end

    function selectPolygon(~, ~, ~)
        imshow(sourceImage, [], 'Parent', hdl.axes);
        roiCounter = roiCounter + 1;
        h = impoly(hdl.axes);
        mask = uint16(createMask(h));
        wait(h);
        roiData(roiCounter).mask = mask;
    end

    function abort(~, ~, ~)
        cla(hdl.axes)
        % I need something else here... (see above)
    end

% Pause until figure is closed
waitfor(hdl.mainfig);

end

Answer 1

Try this out:

function roiData = testGUI(sourceImage)
% Initialize main figure
hdl.mainfig = figure();

% Initialize roiData and roiCounter
roiData    = [];
roiCounter = 0;

% Select Elliptical ROI button
hdl.selectEllipseButton = uicontrol(hdl.mainfig, 'Units', 'normalized', 'Position',[0.05 0.7 0.2 0.1], 'String', 'Select Ellipse', 'Callback', @selectEllipse);
% Select Polygonal ROI button
hdl.selectPolygonButton = uicontrol(hdl.mainfig, 'Units', 'normalized', 'Position',[0.05 0.6 0.2 0.1], 'String', 'Select Polygon', 'Callback', @selectPolygon);
% Abort Button
hdl.abort = uicontrol(hdl.mainfig, 'Units', 'normalized', 'Position',[0.05 0.2 0.2 0.2], 'String', 'Abort', 'Callback', @abort);
% Axes
hdl.axes = axes('Parent',hdl.mainfig, 'Units', 'Normalized', 'Position', [0.35 0.2 0.6 0.6]);

% Callbackrunning parameter
callbackrunning = false;

    function selectEllipse(hObject,eventdata)   
        if(callbackrunning)
            return;
        end

        callbackrunning = true;

        imshow(sourceImage, [], 'Parent', hdl.axes);
        roiCounter = roiCounter + 1;
        h = imellipse(hdl.axes);
        if(~callbackrunning)
            return;
        end
        mask = uint16(createMask(h));
        roiData(roiCounter).mask = mask;

        callbackrunning = false;
    end

    function selectPolygon(hObject,eventdata)   
        if(callbackrunning)
            return;
        end

        callbackrunning = true;

        imshow(sourceImage, [], 'Parent', hdl.axes);
        roiCounter = roiCounter + 1;
        h = impoly(hdl.axes);
        if(~callbackrunning)
            return;
        end
        mask = uint16(createMask(h));
        roiData(roiCounter).mask = mask;

        callbackrunning = false;
    end

    function abort(hObject,eventdata)   
        if(callbackrunning)
            disp('Fire escape key to cancel previous imrect');
            % Create robot that fires an escape key
            robot = java.awt.Robot;
            robot.keyPress    (java.awt.event.KeyEvent.VK_ESCAPE);
            robot.keyRelease  (java.awt.event.KeyEvent.VK_ESCAPE);   
            callbackrunning = false;
        end
    end

% Pause until figure is closed
waitfor(hdl.mainfig);
end

The robot object fires the escape key which cancels imrect.