How to store a selected axes-point in handles

Hello fellow Matlab-Users,

This is what i want:

• User selects a point in an axes_object.
• My program stores selected point in my figure's handles_object.

My first approach was to use the datacursormode's UpdateFcn to extract the data. I couldn't find a solution to the problem, that i can't reach the handles_object from the UpdateFcn.

My second approach was to write my own datacursormode. The new problem is, that i can't catch the ButtonDownFcn_trigger of my axes_object. Now im not sure if that is because the axes_object is located inside a panel inside a figure. Or because "Some Plotting Functions Reset the ButtonDownFcn" as i read in the axes_properties_docu.

Now i really search for some advice how to get that *** Coordinates.

Best regards, Peter

This is the most useful help i found so far:

http://www.mathworks.com/matlabcentral/answers/2337-how-can-i-get-the-data-selected-by-the-user-with-the-datacursor-in-a-gui

Answer 1

[Walter Roberson]

Within your UpdateFcn callback, if you named the first parameter as hObject, then

ancestor(hObject, 'figure')

gets you the handle of the object's figure.

If by handles_object you are referring to "handles" such as is commonly passed around in GUIDE created programs, then just use

handles = guidata(hObject);

guidata() knows enough to climb the parent chain of the object it is given to find the parent figure.

Answer 2

[Peter]

Thx but i need more help.

%When i try:
function output_txt = myUpdateFcn(hObject, event_obj)
x = ancestor(hObject, 'figure')
%it returns x = []

I try to reask my question:

this is my code...

function datacursormode_Callback(hObject, eventdata, handles)
dcm_obj = datacursormode(gcf);
set(dcm_obj,'UpdateFcn',@myUpdateFcn);

funtion myUpdateFcn(obj, event_obj)
handles.selectedCoordinate = (get(event_obj, 'position'));

% This doesnt work cause myUpdateFcn doesnt know hObject
% And i dont know how to pass hObject to myUpdateFcn
guidata(hObject, handles);

Thx, Peter

[Jan]

@Peter: In your case "obj" is the same variable as "hObject" in Walter's example. It is just another *name*. Can you see the similarities:

myUpdateFcn(hObject, event_obj)

myUpdateFcn(obj, event_obj)

[Peter]

true.

but if i would write:

myUpdateFcn(Pi, event_obj)

Pi wouldnt be 3.14

as

myUpdateFcn(hObject, event_obj)

hObject isnt my figure

the value of the first parameter is actually empty

perhaps this is part of my problem

[Walter Roberson]

handles = guidata(event_obj.Target);

Question: isn't datacursormode_Callback already the UpdateFcn ? Is there any reason to reset it to myUpdateFcn? Why not use it as-is and access the handles parameter that is already passed down?

[Peter]

i don't have a datacursormode_Callback.

sorry, the name of the function was bad.

it's an ordinary button_Callback that executes datacursormode.

but i will try what u wrote and have 2 additional possible solutions to test:

- i didn't set(dcm_obj,'figure', hObject) yet

- and it seems to be possible to add aditional args with: set('UpdateFcn',{@myUpdateFcn,arg1,arg2})

i will test all that at wednesday and post if it helped.

[Peter]

i used:

set(dcm_obj,'UpdateFcn',{@myUpdateFcn,arg1,arg2})

to pass the handles to myUpdateFcn.

and it worked!

BIG thx for the help