MATLAB: Problem by drawing a line on axes

guiline on axes

Hallo,
I want to draw a vertical line on an axes on GUI after selecting a point through which the line passes using a callback button.
I have 2 Problems:
1- I can choose a point that is outside the axes.
2- After clicking with the mouse to choose the point, the drawn line doesn't pass through the point and it is not vertical.
Here is my code:
% --- Executes on button press in draw.
function draw_Callback(hObject, eventdata, handles)
% hObject    handle to draw (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
%h = imline(gca);
axes(handles.axes)
[x,y] = ginput(1);
h = line ([x,y], ylim);

Best Answer

There are two errors.
First, you're getting a diagonal line because the first input of line() contains all x-values but you're entering [x,y].
Second, there's no need to use the y-coodinate of the ginput().
Here's what you want:
line([x,x], ylim)
In addition to this, I suggest using the asix handle to ylim in case a different axis is current. 
line([x,x], ylim(h))  %h is the handle to your gui axis.
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