datacursormode: how to permanently turn on "make new data tip"?

Hello! I want to select multiple data points on figure using data cursor (shift + click). Can this functionality be turned on programmatically in a way that there is no need for holding shift? Thank you for any advice!

[Adam]

Not that I am aware of.

doc datacursormode

gives details of what you can change programmatically on the datacursormode object, but this is not one of the things and I don't imagine it would be anywhere else. It may be possible with underlying java programming, but I wouldn't have a clue about that!

Answer 1

[Yair Altman]

Although the official documentation of the datacursormode function says explicitly that:

"You place data tips only by clicking data objects on graphs. You cannot place them programmatically (by executing code to position a data cursor)."

This is in fact WRONG AND MISLEADING, as I explained far back in 2011: https://undocumentedmatlab.com/blog/controlling-plot-data-tips

The general solution for your specific request:

1. First, set the plot line's button-down function to a custom callback function:

hLine = plot(...);
set(hLine, 'ButtonDownFcn', @lineClickedCallback);

2. Next, implement this callback function that will add the requested data-tip at the clicked location:

function lineClickedCallback(hLine, eventData)
   % Get the clicked position from the event-data
   pos = eventData.IntersectionPoint;

   % Get the line's containing figure
   hFig = ancestor(hLine,'figure');

   % Get the figure's datacursormode object
   cursorMode = datacursormode(hFig);  

   % Create a new data-tip at the clicked location
   hDatatip = cursorMode.createDatatip(hLine);
   set(hDatatip, 'Position',pos, 'MarkerSize',5, 'MarkerFaceColor','none', 'MarkerEdgeColor','r', 'Marker','o', 'HitTest','off');
end

You can modify this code to make the data-tip and/or marker look different.

[Marko Usaj]

Dear Yair, you are the best! Works like a charm! You also solved my next big wish to change this nasty black square as a data tip to something else. Empty circles are just perfect!

However, my next goal is to be able to call this function from some simple GUI, which enable switching between different functions (zoom, pan, get data, save data...) using HotKeys. I tried equivalent approach as I have it before but it seems that the function cannot be activated in the same way. If you have any more tips to give me here I would really appreciate. Here is the code:

1. GUI with some plots

function HotKeyAcc
global hLine;

% A figure
fig = figure('menubar','none');

% Add menus with Accelerators
mymenu = uimenu('Parent',fig,'Label','Hot Keys');
uimenu('Parent',mymenu,'Label','Zoom','Accelerator','w','Callback',@(src,evt)zoom(fig,'on'));
uimenu('Parent',mymenu,'Label','Pan','Accelerator','x','Callback',@(src,evt)pan(fig,'on'));
uimenu('Parent',mymenu,'Label','GetPoints','Accelerator','d','Callback',@(src,evt)getDataFromFigureNew(hLine));
%uimenu('Parent',mymenu,'Label','Data','Accelerator','a','Callback',@(src,evt)loadNextTrace(fig,totint,totintbg));
%uimenu('Parent',mymenu,'Label','Data','Accelerator','s','Callback',@(src,evt)SaveDataPoints(fig));

%some plots
a = -16; t = 0:60;
ha(1) = subplot(2,1,1);
hLine=plot(t,sin(a*t));
ha(2) = subplot(2,1,2);
plot(t,sin(5*a*t));
linkaxes(ha, 'x');
end

2. Your function I want to call to pick the data points

function getDataFromFigureNew(hLine)

set(hLine, 'ButtonDownFcn', @lineClickedCallback,'enable', 'on');

function lineClickedCallback(hLine, eventData)
   % Get the clicked position from the event-data
   pos = eventData.IntersectionPoint;

     % Get the line's containing figure
     hFig = ancestor(hLine,'figure');

     % Get the figure's datacursormode object
     cursorMode = datacursormode(hFig);
     set(cursorMode,'UpdateFcn',@myUpdateFcn);

     % Create a new data-tip at the clicked location
     hDatatip = cursorMode.createDatatip(hLine);
     set(hDatatip, 'Position',pos, 'MarkerSize',5, 'MarkerFaceColor','none', 'MarkerEdgeColor','r', 'Marker','o', 'HitTest','off');
  end

function txt = myUpdateFcn(~, ~)

        txt = {''};% I do not want any info about data points displayed on figure

end

end

3. This is my old function to get data points which worked with this approach:

    function getDataFromFigure2(fig)

    dcm_obj = datacursormode(fig);
    set(dcm_obj,'UpdateFcn',@myUpdateFcn,'enable', 'on');

    function txt = myUpdateFcn(~, event_obj)
            % no data shown on figure
            txt = {''};
    end
    end

[Yair Altman]

This is an altogether different question so you should accept the answer on this thread (if as you said it answered it), and then open a new thread for this new question (with an appropriate title and description).

In the new question, if you make your code simpler, it is more likely to be answered: People answer questions on this forum in their spare time and don't typically have time to read lengthy codes posted by others.