MATLAB: Change image after mouse over

axesguiguidemouse overwindowbuttonmotionfcn

I have a GUI set up at the moment with one component being an axes that is holding an image. What I want is when the user mouses over the axes/image the image changes to something else.

How would I go about doing something like this using the WindowButtonMotionFcn?

First I am not sure how I make this function work with an axes, and second I do not know where to place it with the code.

All the sources I have read do not use it the in the GUIDE GUI .m file, and instead in their own functions.

In the GUIDE GUI .m there doesn't seem to be any place to constantly check to see whether or not a mouse over has occurred.

Best Answer

You cannot have WindowsButtonMotionFcn for the axes, but you can have it for the figure. Just select the GUI figure, right click-> view Callbacks and choose WindowsButtonMotionFcn. This should create one for you in the MATLAB file.

I had sample code in there as:

function figure1_WindowButtonMotionFcn(hObject, eventdata, handles)
% hObject    handle to figure1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
[posx, posy ]= get(hObject,'CurrentPoint');
% Write your code to Check to see if the mouse is over the axes
if (checkoveraxes...)
  plot(handles.axes1,rand(10));  % Change image, here i'm just plotting
end

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MATLAB: How to use function handle

This should work:

set(gcf, 'windowButtonMotionFcn', @(~, ~) boop('hello world'));

A UI callback always receives two arguments (an object handle and some event data), which you need to accept. I've done that above by creating an anonymous function that accepts and ignores these two arguments (the @(~, ~)) and then simply call your handle with the correct argument.

See the doc for more details.

MATLAB: Callback of axes in figure not being called

It's because the image is "covering up" the axes. So when you click, you're clicking on the image, not the axes object which is underneath. I know, I know. It's quirky, but that's the way they do it. One workaround is to get the axes to respond by setting the hittest for the image to off. That way the click trickles down the the axes. The other work around is to setup a button down callback for the image so that it's the image's callback that actually gets called rather than the axes's callback. The drawback is that (I believe) you have to either set hittest to off or reestablish the callback whenever you display a new image array in the axes. Study this snippet

% Display in axes, storing handle of image for later quirk workaround.
hold off;  % IMPORTANT NOTE: hold needs to be off in order for the "fit" feature to work correctly.
axesChildHandle = imshow(imgOriginal, 'InitialMagnification', 'fit');
% !!!! QUIRK workaround.!!!!
% Make it so that if they click in the image axes, it will execute the
% button down callback.  Now it won't  -- unless you do this quirk workaround.
% Double click on the dialog box's (main figure's) background to bring up the property inspector.
% Change both the WindowButtonDownFcn and ButtonDownFcn properties so that they are blank.
% Also set the main figure's HitTest to off.  Then, make sure you already have the handle to the
% image living in the axes by getting it from an imshow.  Then do this:
set(axesChildHandle, 'ButtonDownFcn', @axesImage_ButtonDownFcn);
% Put everything you want to do when they click the image
% into the function called axesImage_ButtonDownFcn()
% !!!! End QUIRK workaround.!!!!

Best Answer

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MATLAB: Callback of axes in figure not being called

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