Refresh positions of all draw points after deleting or moving - App designer

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Ali razi
Ali razi 2021-12-30
编辑： Ali razi 2021-12-31
Following my last question (https://www.mathworks.com/matlabcentral/answers/1619365-extract-position-of-all-draw-points) I did an app designer GUI with two buttons and axes. The first one (LoadimageButton) is loading the pappers image and I can mark points until I press escape. The second button is printing out the point coordinates (PositionButton).
I have noticed that after pressing the two buttons I can move points in the axes and change their positions or delete them. The issue is that when I press the delete (in the context menu) I get this error after pressing the PositionButton:
Error using images.roi.Point/get
Invalid or deleted object.
Error in tempDrwPnt1/PositionButtonPushed (line 61)
positions = cell2mat(get(app.pointhandles, 'position'))
Error while evaluating Button PrivateButtonPushedFcn.
How can I refresh the app.pointhandles after deleting a point?
Code:
function LoadimageButtonPushed(app, event)
imshow('peppers.png','Parent',app.ImageAxes);
userStopped = false;
app.pointhandles = gobjects();
while ~userStopped
roi = drawpoint(app.ImageAxes);
if ~isvalid(roi) || isempty(roi.Position)
% End the loop
userStopped = true;
else
% store point object handle
app.pointhandles(end+1) = roi;
end
end
addlistener(roi,'MovingROI',@allevents);
addlistener(roi,'ROIMoved',@allevents);
app.pointhandles(1) = [];
function allevents(src,evt)
evname = evt.EventName;
switch(evname)
case{'MovingROI'}
disp(['ROI moving previous position: ' mat2str(evt.PreviousPosition)]);
disp(['ROI moving current position: ' mat2str(evt.CurrentPosition)]);
case{'ROIMoved'}
disp(['ROI moved previous position: ' mat2str(evt.PreviousPosition)]);
disp(['ROI moved current position: ' mat2str(evt.CurrentPosition)]);
end
end
end
% Button pushed function: PositionButton
function PositionButtonPushed(app, event)
positions = cell2mat(get(app.pointhandles, 'position'))
end

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回答（1 个）

Image Analyst
Image Analyst 2021-12-30
Not sure what's going on here:
app.pointhandles(1) = [];
positions = cell2mat(get(app.pointhandles, 'position'))
How can you get the position property of pointhandles when you just set it to null? It throws an error. Why are you setting it to null?

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