Is there an equivalent to imrect for uiaxes? Or any other way to get coordinates out?

I have an app I unfortunately decided to build in App Designer. Unfortunately, because I need the user to be able to drag to select an ROI on an image. And UIAxes don't take mouse events, and I can't use imrect on uiaxes. Is there any way at all to get this information? I'm willing to go to silly extremes like create an invisible button over the top of the uiaxes to catch the mouse event and then handle the dragging code manually, if needed. Is there something I can do within App Designer? Or, do I need to scrap everything and switch to GUIDE, and kludge together the rest of the tabbed interface by changing objects' visibility? Can I use non-uiaxes axes in App Designer somehow? Would they actually work?

Answer 1

[Tim Jackman]

Beginning in 18b, you can parent an axes into a uifigure. This means that it is possible to draw the new rectangle ROI in App Designer as follows:

ax = axes(app.UIFigure); drawrectangle(ax);

This page has some more info on current axes support in uifigures:

https://www.mathworks.com/help/matlab/creating_guis/graphics-support-in-app-designer.html

Specific to the rectangle ROI, context menus and mouse pointers are not supported, but the basic interactions should work.

[Luke Somers]

> Specific to the rectangle ROI, context menus and mouse pointers are not supported

I need the rectangle so as to get an ROI, but if I can get the location and dimensions out of the rectangle I can do the math on that myself.

And by mouse pointers you mean I can't change the mouse cursor, right? Not to do with a handle. If so, that's fine.

Is there an equivalent of impoint that you can put directly in a figure like this?

[Tim Jackman]

Yes, you will still be able to get the rectangle position after drawing in App Designer:

ax = axes(app.UIFigure);
h = drawrectangle(ax);
position = h.Position;

You can use the new point ROI drawpoint in App Designer:

https://www.mathworks.com/help/images/ref/drawpoint.html

You should be able to use all of the new ROIs in App Designer with the limitation that the mouse cursor won't update as you mouse over the ROI and the context menu is not supported. You can access all of the necessary information about the ROI by querying the object properties.

https://www.mathworks.com/help/images/roi-based-processing.html

[Max Nobis]

Hi Tim, I'm trying to use the code above in Matlab 2018b using programmatically created uifigure with the following code:

ax = axes(uifigure);
h = drawrectangle(ax);

However I'm encountering the following error when I try and move the mouse over the axes. Is there a way to work around this issue?

Warning: Error occurred while executing the listener callback for event WindowMouseMotion defined for class matlab.ui.Figure:
Error using matlab.ui.Figure/set
Functionality not supported with figures created with the uifigure function. For more information, see Graphics Support in App Designer.

Error in images.roi.internal.setROIPointer

Error in images.roi.internal.IPTROIPointerManager/motionCallback

Error in images.roi.internal.IPTROIPointerManager>@(src,evt)self.motionCallback(src,evt)

Error in uiwait (line 81)
    waitfor (hFigDlg, 'WaitStatus', 'inactive');

Error in images.roi.internal.ROI/draw

Error in drawrectangle (line 187)
    h.draw; 
> In uiwait (line 81)
  In images.roi.internal.ROI/draw
  In drawrectangle (line 187)

Many Thanks

[Tim Jackman]

I haven't seen this warning appear before and I can't reproduce this on my end so there isn't much I can do to resolve it at this point. I'd suggest that you try turning this warning off. To do this, reproduce the warning so it is the last warning you have encountered, then get the message ID:

[~,s] = lastwarn;

Then turn off that warning:

warning('off',s);

You may want to save the message ID and turn it off every time you open your app.

A word of caution: this warning is probably a pretty generic warning and turning it off while you are debugging or developing your app may hide potential problems.

There is some more information about this process here:

https://www.mathworks.com/help/matlab/ref/lastwarn.html

Answer 2

[Michael Mutersbaugh]

Hi Luke, I was having the same problem. What I did was create a new figure, read the image data into it, and offer the user an ROI prompt on THOSE axes instead. This method may not be what you want stylistically, but it works for the GUI.

            fig = figure;
                imshow(app.current_frame,[]);                % Image data stored in property, no axes called
                set(fig, 'Position', get(0, 'Screensize'));  % Fullscreen image
                set(fig,'CloseRequestFcn','')                % Prevent pop-up from closing
                set(fig, 'MenuBar', 'none');
                set(fig, 'ToolBar', 'none');
            % Need this while loop because mouse events will prematurely exit
            % the ROI functions, even with the CloseRequestFcn turned off
            roi = [];                                    
            while isempty(roi) 
                switch app.roi_type
                    case 'Circular'; roi = imellipse();
                    case 'Rectangle'; roi = imrect();
                    case 'Freehand'; roi = imfreehand();
                end
            end
            app.masks{end+1} = roi.createMask(); % Binary matrices stored in cell array
            delete(fig)
Once you save the masks, you can use them to manipulate your image data before offering it to the uiaxes.