how to force Draggable points to move along a line?

Question

Mohsen Davarynejad 2013-5-14

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/75694-how-to-force-draggable-points-to-move-along-a-line

回答： Roman Willi 2018-7-2

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])
      setString(h1,'h1');
      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)])
      end
end

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Jan 2013-5-14

"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 2013-5-14

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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Answer 1

Roman Willi 2018-7-2

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/75694-how-to-force-draggable-points-to-move-along-a-line#answer_327132

在 MATLAB Online 中打开

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);
    end