I think this is what you seek to move a line with the mouse in MATLAB.

http://blogs.mathworks.com/videos/2008/05/27/advanced-matlab-capture-mouse-movement/

Doug

I’m a Matlab newbie and I think your videos are fantastic – without them I would be lost!

A question: I have created a simple GUI where data can be plotted and where coordinates can be obtained by pointing and clicking the mouse on the figure. However, I’m looking to obtain the coordinates from a figure in a more dynamic way. What I would like to be able to do is create a moving point which is fixed to the trajectory of the plot, which I drag up and down the line and obtain the plot coordinates - Yahoo interactive finance graphs have something similar. Is this possible in Matlab, and if so, could you give me any hints on what I would need to do to achieve this?

Any suggestions would be very much appreciated!!

Lucy

If one subfunction has an end statement, then they all must have one. That will help with the code pasting problem.

As for handles structure:

http://blogs.mathworks.com/videos/2008/04/17/advanced-matlab-handles-and-other-inputs-to-guide-callbacks/

-Doug

The problem is solved now.. Actually I’ve used UserData property to gave the name to my ‘figure’,axis’ and ‘line’ so I could call them in the external function (draggingFcn etc.)
However, it was not so obvious at the beginning.

Everest

I just did a quick check. That version of MATLAB is about three years ago. There have been enough changes in function handles that I suspect that is the reason code written for the newer version of MATLAB does not work in an older version.

Doug

********************************************************
??? Undefined function or variable ‘f’.

Error in ==> G:\MATLAB_61\MOUSE_CAPTURE\mouse_capt.m (startDragFcn)
On line 66 ==> set(f,’WindowButtonMotionFcn’,@draggingFcn)

??? Error while evaluating line ButtonDownFcn.

??? Undefined function or variable ‘f’.

Error in ==> G:\MATLAB_61\MOUSE_CAPTURE\mouse_capt.m (stopDragFcn)
On line 128 ==> set(f, ‘WindowButtonMotionFcn’,”)

??? Error while evaluating figure WindowButtonUpFcn.
********************************************************

Why is that? What to do to make it work on the older version?

When using additional arguments for the callback function, you must set the value of the property to a cell array (i.e., enclose the function handle and arguments in curly braces). For example,
You can define the callback function to accept additional input arguments by adding them to the function definition. For example,

function startDragFcn(src,eventdata,arg1)

arg1 is an additional argument. In my case I used the handles of the GUI as an additional argument:

function startDragFcn(hObject,eventdata,handles)

So, for the callback function you have to enclose the function handle and the additional arguments in curly braces. For example,

set(hLine,’ButtonDownFcn’,{@startDragFcn,handles});
set(hFigure, ‘WindowButtonUpFcn’,{@stopDragFcn,handles});

startDragFcn(hObject, eventdata, handles)
%Inside this function handles is not availabel and I need the axes that is stored in the handles.

When I click over the line I get ??? Input argument “handles” is undefined.