Is it possible to program the mouse cursor selection box on figures in MATLAB?

Hello everyone,

I am basically trying to recreate the well-known property of mouse cursor selection boxes for a current MATLAB project.

When I plot a rectangle on a figure, I would like my program to be able to deform the rectangle exactly in the way those typical

selection boxes of the mouse are deformed, if I would click for example the bottom-right corner of the box with the mouse and

drag it on the figure plane.

For this, I have found a code with a similar function for lines and curves, it is found in this question:

https://de.mathworks.com/matlabcentral/answers/340393-is-there-a-way-to-click-and-drag-points-on-a-graph-to-change-it

And the fitting code for the problem is attached here as dragpoints.m .

Now, when I use the following input examples on the dragpoints-function:

x = [6 12 12 6 6];
y = [6 6 12 12 6];
dragpoints(x,y,0,20,0,20);

the plotted rectangle will not be deformed in the way a mouse cursor selection box would be when I move one corner with my mouse cursor.

So my question is: Is there a way I could change this code and make it deform rectangles like selection boxes?

Is there any way I can program this cursor selection box property in MATLAB in general?

Thanks in advance, I appreciate all your help!

[Image Analyst]

Not sure I understand what you want, but have you tried using drawrectangle to drag out a box and then using the coordinates from it to set xlim and ylim?

[Muris Spahovic]

Oh, um no actually. I didn't know this function exists, I will definitely check it out though.

Thank you very much! :)

Answer 1

[Ayush Kumar Jaiswal]

I think here is what you need:

function dragpoints(xData,yData,xLower,xUpper,yLower,yUpper)

figure;

x = xData;

y = yData;

ax = axes('xlimmode','manual','ylimmode','manual');

ax.XLim = [xLower xUpper];

ax.YLim = [yLower yUpper];

%can change the marker size or marker type to make it more visible.

%Currently is set to small points at a size of 2 so is not very visible.

line(x,y,'marker','.','markersize',2,'hittest','on','buttondownfcn',@clickmarker)

function clickmarker(src,ev)

set(ancestor(src,'figure'),'windowbuttonmotionfcn',{@dragmarker,src})

set(ancestor(src,'figure'),'windowbuttonupfcn',@stopdragging)

function dragmarker(fig,ev,src)

%get current axes and coords

h1=gca;

coords=get(h1,'currentpoint');

%get all x and y data

x=h1.Children.XData;

y=h1.Children.YData;

%check which data point has the smallest distance to the dragged point

x_diff=abs(x-coords(1,1,1));

y_diff=abs(y-coords(1,2,1));

[value index]=min(x_diff+y_diff);

%create new x and y data and exchange coords for the dragged point

x_new=x;

y_new=y;

% Ensure that x and y moves in a coordinated manner

if (index == 1)

x_new(index)=coords(1,1,1);

x_new(end)=coords(1,1,1);

x_new(4) = coords(1,1,1);

y_new(index)=coords(1,2,1);

y_new(end)=coords(1,2,1);

y_new(2)=coords(1,2,1);

elseif index == 2

x_new(index)=coords(1,1,1);

x_new(3) = coords(1,1,1);

y_new(index)=coords(1,2,1);

y_new(1)=coords(1,2,1);

y_new(end)=coords(1,2,1);

elseif index == 3

x_new(index)=coords(1,1,1);

x_new(2) = coords(1,1,1);

y_new(index)=coords(1,2,1);

y_new(4)=coords(1,2,1);

elseif index == 4

x_new(index)=coords(1,1,1);

x_new(1) = coords(1,1,1);

x_new(end) = coords(1,1,1);

y_new(index)=coords(1,2,1);

y_new(3)=coords(1,2,1);

elseif index == 5

x_new(index)=coords(1,1,1);

x_new(1)=coords(1,1,1);

x_new(4) = coords(1,1,1);

y_new(index)=coords(1,2,1);

y_new(1)=coords(1,2,1);

y_new(2)=coords(1,2,1);

end

%update plot

set(src,'xdata',x_new,'ydata',y_new);

function stopdragging(fig,ev)

set(fig,'windowbuttonmotionfcn','')

set(fig,'windowbuttonupfcn','')

[Muris Spahovic]

Just tested your function, it works very well, although the rectangle is sometimes a bit shifted when

it's deformed. But the function is definitely what I was looking for, this will definitely help me further

on my project!

Thank you very much Ayush Kumar!