How to show a picture only while pressing the button (Matlab GUIDE) - matlab

Question

I am trying to create a Matlab GUI using GUIDE. I want to insert a picture with the picture shown only while I am pressing a button (Callback function) and show the default picture once the button is released. How can I implement this? I use axes to display the picture at the mentioned location
function mc_right_Callback(hObject, eventdata, handles)
% hObject handle to mc_right (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
matlabImage2 = imread('Coor2.png');
imshow(matlabImage2, 'Parent', handles.axes7);
%Vxm_Port_Send(handles.port_handle,sprintf('F,C,I3M-%d,R',handles.x_steps)); % Move along +x (right)

Answer 1

The problem is that MATLAB uicontrols don't allow you to create separate callback functions that execute on a button press or button release. For example, a push button will execute its Callback function on a button release. It also has a ButtonDownFcn function that will execute on a button press, but this callback is only active when the Enable property is set to 'off' or 'inactive', in which case the Callback function is disabled. In other words, you can't use the ButtonDownFcn and Callback together to get responses to both button presses and releases, respectively.
However...
The figure window does have a way to specify separate callback functions for button presses, button releases, and even mouse motion or scroll wheel activity. This is how I usually overcome shortcomings in uicontrol behavior: I define figure-level callbacks that execute when they are over certain parts of the window. Here's an example:
function press_release
% Load a sample image:
imgData = imread('peppers.png');
% Create the figure and graphics objects:
hFigure = figure('WindowButtonDownFcn', #press_fcn, ...
'WindowButtonUpFcn', #release_fcn);
hImage = image(imgData, 'Visible', 'off');
hButton = uicontrol(hFigure, 'Style', 'pushbutton', ...
'Position', [10 10 30 30], ...
'Enable', 'inactive');
function press_fcn(~, ~)
if isequal(hButton, get(hFigure, 'CurrentObject'))
set(hImage, 'Visible', 'on');
set(hButton, 'Value', 1);
end
end
function release_fcn(~, ~)
set(hImage, 'Visible', 'off');
set(hButton, 'Value', 0);
end
end
When you run the above, it will create a window with an axes and a small button in the lower left corner. The button has no callbacks defined. When you click the mouse anywhere but over the button nothing happens. However, when you click the mouse over the button (making it the CurrentObject for the figure) the image will become visible and the button will depress while you are holding the button down. Releasing the button makes the image invisible again and the button appears normal. Essentially, the button is just a dummy that does nothing at all except give the user the illusion that they are pressing it to make things happen. It's really the figure callbacks doing the work.