Question about how to use drawline to record line segment lengths in real time

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luo jingcheng
luo jingcheng 2023-11-3
回答： Walter Roberson 2023-11-3
When drawing line on an image, I may need to adjust multiple times to get the optimal position. The drawline example code provided by Matlab can record the line segment length in real time, but I am unable to output and save this real-time length as a variable. I am looking for a way that can tell me the real-time line segment length in the command window as I adjust the line segment, and after I confirm the final position, exit drawline, the function will output the final length value and save it as a variable in the workspace.
Thanks for the help! This is part of my code
img = imread('3.png');
imshow(img);
roi = drawline('Color','r');
addlistener(roi,'MovingROI',@allevents);
addlistener(roi,'ROIMoved',@allevents);
function allevents(src,evt)
evname = evt.EventName;
switch(evname)
case {'MovingROI', 'ROIMoved'}
linePosition = src.Position;
x1 = linePosition(1, 1);
y1 = linePosition(1, 2);
x2 = linePosition(2, 1);
y2 = linePosition(2, 2);
lineLength = sqrt((x2 - x1)^2 + (y2 - y1)^2);
disp(['length of the line: ', num2str(lineLength)]);
end
end

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回答（1 个）

Walter Roberson
Walter Roberson 2023-11-3
Use wait to wait until the user finishes with the ROI. After that you can examine roi.Position and save that to an appropriate variable or return it from the function.

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