draw polygon continuously with mouse

לק"י

Hi guys,

I need to contour some cells. I want to use the drawpolygon command, or an equivalent of it, that will record mouse position continuously while mouse left click button is held. No such option seems to be in the drawpolygon documentation.

There are some old answers about how to do it, the problem is that most of the codes there somewhy don't work when I try to use them. Is there any other easy/quick way to obtain mouse position only when left mouse button is held?

Thanks,

Amit.

Answer 1

[Piyush Kumar]

@Amit Ifrach,

You can use "WindowButtonMotionFcn". Read more about this from "Window Callbacks" section of this documentation link.

Step 1: Create a file named "drawPolygon.m" with the following content -

function drawPolygon()
    figure('WindowButtonMotionFcn', @mouseMove);
    global isDown;
    isDown = false;
    set(gcf, 'WindowButtonDownFcn', @mouseDown);
    set(gcf, 'WindowButtonUpFcn', @mouseUp);
end

function mouseMove(src, event)
    global isDown;
    if isDown
        C = get(gca, 'CurrentPoint');
        disp(['Cursor position is (' num2str(C(1,1)) ', ' num2str(C(1,2)) ')']);
    end
end

function mouseDown(src, event)
    global isDown;
    isDown = true;
end

function mouseUp(src, event)
    global isDown;
    isDown = false;
end

Step 2: From MATLAB command line, run the file -

drawPolygon

Step 3: In the figure, you keep moving the cursor and you will get the current position of the cursor live in the MATLAB command line.

Let me know if this helps!