External mouse track function

Hey,

I made a function to track the cursor over certain handles, but for the sake of simplicity, i would like that to be an external function (right now its in the bottom of the GUI). I want to apply it using:

set(hObject, 'WindowButtonMotionFcn',trackCursor(uicontrol,hObject));

Where 'uicontrol' is the name of the axes that should be tracked (like handles.axes1). But when I use the set, I can't figure out, how to obtain the function output, which is x and y, both are scalars. I have also tried saving them into the handle, but this results in an

Error using trackCursor
Too many output arguments.

The functions works fine within the GUI, so it's only the syntax that seems to cause me trouble. Any help would be greatly appreciated, thank you!

- Jake

Answer 1

[Jan]

This:

 ... track the cursor over certain handles...

and

 Where 'uicontrol' is the name of the axes that should be tracked (like handles.axes1)

is not getting clear to me.

Perhaps you are looking for:

set(hObject, 'WindowButtonMotionFcn', {@trackCursor, handles.axes1});
...

And the separate function:

function trackCursor(hObj, EventData, Axes1)
handles = guidata(hObj);
P = get(Axes1, 'CurrentPoint');
handles.x = P(1, 1);
handles.y = P(1, 2);
guidata(hObj, handles);

But this contains some guessing of want you might need.

[Jakob Sørensen]

I have to say you're pretty good at guessing. The thing I had trouble with, was passing additional input into the trackCursor function. Sorry for not being very clear about that. And thanks a lot for the help, both of you.

Answer 2

[Walter Roberson]

WindowButtonMotionFcn cannot return any values. It can, however, be a function that affects shared variables.

Note that in the syntax you would like to use, trackCursor(uicontrol,hObject) would have to return a function handle to a routine that accepts a src and event object (all callbacks are passed those) and returns nothing.

[Jakob Sørensen]

But exactly how do i make the call then? And how do I make my function accept this call and save the xy-coords in the handles?