CODEWITHSUNDEEP
matlab
Sultan
Sultan

Reputation: 3

making blinking rectangle in matlab

hi everyone I'm trying to write a program in matlab that does show a rectangle in gui and blink it. the speed of blinking is defined as period = 1/ freq

it is a simple but i dont know why it is not working right.

what is want to do is making that rect appear and disappear as freq specified

here is my code and it doesnt show any error 

figure
% the flashing block on frequency 
t = timer;
set(t, 'executionMode', 'fixedRate');
freq = 10;
period = 1/freq;
set(t, 'Period', 1/freq);
set(t, 'TimerFcn', 'show');
flash = true;
show = rectangle('Position',[0,0,1,1],'FaceColor','w');
hide = rectangle('Position',[0,0,1,1],'FaceColor','black');
while (true);

    % set the background to black
    set (gcf, 'Color', [0 0 0] );

    % drawing the rect box 
    n = plot(show);
    wait = period;
    m = plot(hide);

    set(gca,'xcolor',get(gcf,'color'));
    set(gca,'ycolor',get(gcf,'color'));
    set(gca,'ytick',[]);
    set(gca,'xtick',[]);
    return
end

i dont know why it is not working. so can someone explain to me

Upvotes: -1

Views: 1844

Answers (1)

Benoit_11
Benoit_11

Reputation: 13945

When you use n = plot(show) or m = plot(hide) , you are actually trying to plot the number represented by the handles to the rectangle you created, so it's not showing a rectangle but rather a point.

What you can do is define the position of the rectangles before the loop, and simply call the function rectangle each time you want to display them. However this is cumbersome as you need to delete each rectangle before displaying the new one.

As noted by @CitizenInsane, a much better way is to assign handles to rectangles before the loop (as you are actually doing) and simply toggle the Visible property of each back and forth; The result is the same but more efficient and less cumbersome.

Example:

figure

% the flashing block on frequency
t = timer;
set(t, 'executionMode', 'fixedRate');
freq = 10;
period = 1/freq;
set(t, 'Period', 1/freq);
set(t, 'TimerFcn', 'show');
flash = true;

RectPos = [0,0,1,1];

%// Set the visible property to off.
    show = rectangle('Position',RectPos,'FaceColor','w','Visible','off');
    hide = rectangle('Position',RectPos,'FaceColor','k','Visible','off');

% set the background to black
set (gcf, 'Color', [0 0 0] );

while true;

%// Play with the "Visible" property to show/hide the rectangles.
    set(show,'Visible','on')

    pause(period)

    set(show,'Visible','off')
    set(hide,'Visible','on');
    drawnow

    pause(period)

    set(hide,'Visible','off');

    set(gca,'xcolor',get(gcf,'color'));
    set(gca,'ycolor',get(gcf,'color'));
    set(gca,'ytick',[]);
    set(gca,'xtick',[]);

end

Hope that helps!

Upvotes: 1

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