How to pause a loop of frames using toggle button?

Question

Jaroslava Orenicova 2018-1-1

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/375131-how-to-pause-a-loop-of-frames-using-toggle-button

关闭： Jaroslava Orenicova 2018-6-11

Hi, I have a problem with a toggle button. I want to display a loop of frames and pause it with toggle button. Displaying and pausing it is okay, but when I press a toggle button again, it shows a loop again from the start and not from the spot where it was paused.

This is my code:

button_state = get(hObject,'Value');

if button_state == 1; start = 1; while start <= nFrames

        ih = image(loading(:,:,start));
        colormap(gray(256));
        drawnow;
        pause(0); 
        start = start + 1;
    end
elseif button_state == 0;
pause

end

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

此问题已关闭。

Answer 1

Rik 2018-1-1

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/375131-how-to-pause-a-loop-of-frames-using-toggle-button#answer_298277

在 MATLAB Online 中打开

You are setting start = 1 before your loop.

What you might do is this:

while ( start <= nFrames ) && ( get(hObject,'Value') )

Or move the get inside the loop, so the loop actually continues (and unpauses when you toggle again):

while start <= nFrames
    if get(hObject,'Value')
        ih = image(loading(:,:,start));
        colormap(gray(256));
        start = start + 1;
    end
    drawnow;
    pause(0.01);%AFAIK pause(0) has no effect
end

5 个评论
显示 3更早的评论隐藏 3更早的评论

Jaroslava Orenicova 2018-1-1

So I have the same problem as at the beginng.

Rik 2018-1-2

It sounds like the structure of your callbacks isn't right. As I mentioned, this code sets start to 1 before the loop. If you plan on using this code as the callback for your button, it will overwrite each time. The solution is therefore to start the display loop only once. You can still include start=1, but I would suggest storing the value of start in the guidata. That way you can initialize start once (or each time you load a new file to you GUI). And if you're storing the value for start outside this function, why still continue the while-loop? Much better to use a break inside that while-loop and restart the loop with the loaded value.