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how to force Draggable points to move along a line?

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Hi All. I would like to use impoint to generate a draggable point. But I want to force it to move along a line. I try to do so by setPosition, but it does not work properly. Any help?
function test()
h1 = impoint(gca,[5, 5])
addNewPositionCallback(h1,@(h1) CallThis(1,[1 2],[ 2 ]));
axis([0 10 0 10])
function CallThis(varargin)
pos = h1.getPosition()
h1.setPosition([pos(1,1), 2*pos(1,1)])
Jan on 14 May 2013
"It does not work properly" is a vague description only. Please do not let us guess, but explain the difference between your expectations and the results.
Mohsen  Davarynejad
Mohsen Davarynejad on 14 May 2013
Sure, I mean that the point moves freely. It does not move along the line. Basically the setPosition command within the CallThis function does not update the position of the point.

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Answers (1)

Roman Willi
Roman Willi on 2 Jul 2018
move along a line:
obj.dragPoint = impoint();
hp = addNewPositionCallback(obj.dragPoint,@(pos) point_move(obj,pos));
function point_move(obj, pos)
pos = [.....] % Calc Y Point of line
axilim = [.....] % X axi limit
fcn = makeConstrainToRectFcn('impoint',axilim, [pos pos]);
setPositionConstraintFcn(obj.dragPoint, fcn);


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