Buttondownfcn callback on live video data (preview)

Hello,

I am currently trying to initiate a callback routine when the user presses on an axis that contains a live video stream, i.e.

frame = getsnapshot(handles.vidObj);
axes = imshow(frame, 'Parent', handles.axes_stream); 
preview(handles.vidObj, axes); % assign vidObj to axes

However, I have not yet been able to achieve this despite looking at various discussions. I presume it is because the displayed video is stopping my mouse button being registered and the callback routine is not working.

Any help would be appreciated.

[Sam]

Anyone? I'm starting to think that maybe it's not possible.

Answer 1

[Sean de Wolski]

I am guessing that preview is nullifying your ButtonDownFcn (just an educated guess though). Thus you would need to reinstate your ButtonDownFcn on the axes after calling preview.

[Sam]

Hello, thanks for your input. I have already tried this but to no avail, i.e.

set(handles.axes_stream,'buttondownfcn',{@axes_Callback, handles});

This is set after:

preview(handles.vidObj, axes); % assign vidObj to axes

[Sean de Wolski]

Is the axes' 'Hittest' turned off?

You may want to check this.

get(ax,'hittest');

And look in the documentation for axes properties for a more thorough explanation of why.

[Sam]

Hello,

I have set hittest off:

set(handles.axes_stream,'Hittest','off');

And have checked that it is off using breakpoints in the program. I still cannot get the callback function to initiate when clicking on the axes.

[Sean de Wolski]

Well I would guess that is the issue - you want the 'HitTest' to be on :).

If the axes can't become the current object, it's ButtonDownFcn will never fire...

[Sam]

Hello,

I have tried this but the ButtonDownFcn is still not firing. :'( I guess I will have to rethink my strategy. Thanks for your input guys!

[Sean de Wolski]

Sam, if your license's SMS is current, please contact Technical Support.

[Image Analyst]

I haven't tried clicking on the live video axes. Would clicking on a button be an acceptable workaround? Because I know I can click on buttons while I have a live image in an axes, and it does the callback operations just fine.

[Sam]

I will contact Technical Support and see what they have to say and report back. For now, I will use buttons to provide the necessary functionality.

Cheers everyone!