How to determine if mouse is over axes using MATLAB GUIDE

Question

I know this question has been asked before, but I can't find any good answers. I keep stumbling upon WindowButtonMotionFcn , but I don't really understand how to use it. In my program I want to be able to click and store coordinates ONLY when the user is above a certain axes, so that the normal mouse appears for the rest of the GUI and they can play with other buttons. Thanks for any insight.

Answer 1

I would recommend not using WindowButtonMotionFcn and instead use the ButtonDownFcn of your axes object. This way MATLAB takes care of your hit detection for you.

For example:

function testcode()
h.myfig = figure;
h.myaxes = axes( ...
    'Parent', h.myfig, ...
    'Units', 'Normalized', ...
    'Position', [0.5 0.1 0.4 0.8], ...
    'ButtonDownFcn', @myclick ...
    );
end

function myclick(~, eventdata)
fprintf('X: %f Y: %f Z: %f\n', eventdata.IntersectionPoint);
% Insert data capture & storage here
end

Prints your coordinate every time you click inside the axes but does nothing when you click anywhere else.

EDIT:

Since this is a GUIDE GUI the easiest approach is to utilize getappdata to pass data around the GUI. To start, you need to modify your GUI_OpeningFcn to something like the following:

function testgui_OpeningFcn(hObject, eventdata, handles, varargin)

% Choose default command line output for testgui
handles.output = hObject;

% Initialize axes click behavior and data storage
set(handles.axes1, 'ButtonDownFcn', {@clickdisplay, handles}); % Set the axes click handling to the clickdisplay function and pass the handles
mydata.clickcoordinates = []; % Initialize data array
setappdata(handles.figure1, 'mydata', mydata); % Save data array to main figure

% Update handles structure
guidata(hObject, handles);

And then add a click handling function elsewhere in your GUI:

function clickdisplay(~, eventdata, handles)
mydata = getappdata(handles.figure1, 'mydata'); % Pull data from main figure
mydata.clickcoordinates = vertcat(mydata.clickcoordinates, eventdata.IntersectionPoint); % Add coordinates onto the end of existing array
setappdata(handles.figure1, 'mydata', mydata); % Save data back to main figure

You can then pull the array into any other callback using the same getappdata call.