How to receive cursor data from axes with background image in a GUI?

Hi,

I am working with a GUIDE and want to use an axis element to enable the user selecting input data within a 2D Plane, just like this:

I used the axes create fcn to insert a background image into my axis.

function axes1_CreateFcn(hObject, eventdata, handles)
% hObject    handle to axes1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called
cbcr_plane = imread('input/cbcrplane.png');
hImage = imagesc(0:255,0:255,(flipdim(cbcr_plane,1)));
set(gca,'ydir','normal'); 
datacursormode on;

How can I access the current cursor position (X and Y) within my GUI? Thx in advance!

Answer 1

[Geoff Hayes]

Daniel - how do you wish to have access to this information? Through another callback of some GUI widget? If so, you could do something like the following - assume that you when you push a button, you want to get the information from the last (or current) cursor position. In your above axes1_CreateFcn you could save the handle to the data cursor object to the handles structure so that it will be accessible to other callbacks

 function axes1_CreateFcn(hObject, eventdata, handles)
 % hObject    handle to axes1 (see GCBO)
 % eventdata  reserved - to be defined in a future version of MATLAB
 % handles    empty - handles not created until after all CreateFcns called
 cbcr_plane = imread('input/cbcrplane.png');
 hImage = imagesc(0:255,0:255,(flipdim(cbcr_plane,1)));
 set(gca,'ydir','normal'); 

 % create the data cursor object
 handles.datacursor = datacursormode;

 % enable the data cursor object
 set(handles.datacursor,'Enable','on');

 % save the object to the handles structure
 guidata(hObject,handles);

Now suppose you have a push button (named pushbutton1) and that you want that whenever you press this button, the position of the current (or last) cursor position is printed out. In the callback to this button, do the following

 function pushbutton1_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

 if isfield(handles,'datacursor')
     cursorInfo = getCursorInfo(handles.datacursor);
     if ~isempty(cursorInfo)
        fprintf('xpos=%f  ypos=%f\n',cursorInfo.Position(1),cursorInfo.Position(2));
     end
 end

So whenever you press this button, the last/current cursor position (if it exists) will be written to the console.

Try the above and see what happens!

[Joe Pashley]

Thanks, this helped me.