In App Designer you shouldn’t rely on ishandle(figure) or global variables for stopping the webcam loop. The reason your loop doesn’t stop is because once you enter a while loop inside a callback (EmpezarButtonPushed), MATLAB blocks the event queue, so pressing the Stop button never actually executes its callback until the loop finishes.
The correct way in App Designer is to use either:
- A timer object, or
- A flag property in your app that you can set from the Stop button.
using a property flag:
properties (Access = private)
camObj % webcam object
isRunning % flag to control capture loop
end
methods (Access = private)
% Button pushed function: EmpezarButton
function EmpezarButtonPushed(app, event)
app.camObj = webcam(1);
app.camObj.Resolution = '640x360';
app.camObj.Brightness = 10;
app.isRunning = true;
% Run loop without blocking UI
while app.isRunning
img = snapshot(app.camObj);
imshow(img, 'Parent', app.UIAxes);
drawnow limitrate % allow UI updates
end
end
% Button pushed function: StopButton
function StopButtonPushed(app, event)
app.isRunning = false;
clear app.camObj; % release webcam
end
end
For more details look into the following previous MATLAB Answer:
Hope this helps!
