Put datatip stack on top of axis label and update axes label after a change was done on axes position

Question

This issue is only for unix matlabs, windows users won't be able to reproduce it.

I am having trouble while trying to create datatips in which are on top of the y axis label. The following picture illustrate the issue:

As you can see, the datatips created close to the ylabel will get bottom to the ylabel text, while the desire effect is the opposite: the datatip to be on top of the axis label.

I generated the plot with the following (not so minimal) code, which is available bellow. You may remove the lines commented with % may be removed, or even just put a datatip on −78 instead of a loop in order to achieve a faster testing script, but I leave this code if someone one day wants it to create custom datatips (in this case, consider seeing also http://undocumentedmatlab.com/blog/controlling-plot-data-tips/):

gradientStep = 1e-1;

x=-100:gradientStep:100; xSize=numel(x);
y=x.^3-x.^2;

figH=figure(42);
lineH=plot(x,y);

ylabel('YLabel (YUnits)','FontSize',16)
xlabel('XLabel (XUnits)','FontSize',16)

dcH=datacursormode(figH);

nTips = 20; % May change the loop for a datatip at x=-78.

for pos = round(linspace(2,xSize,nTips))
  datatipH=dcH.createDatatip(lineH,...
    struct('Position',[x(pos) y(pos)]));

  orientation = 'top-left';

  if pos>1
    tipText{1} = 'The grandient here is: ';
    tipText{2} = ['\Deltax:',sprintf('%d',x(pos)-x(pos-1)),' XUnits'];
    tipText{3} = ['\Deltay:',sprintf('%d',y(pos)-y(pos-1)),' YUnits'];
  else
    tipText = 'Cannot calculate gradient here.';
  end

  bkgColor = [1 1 .5]; % May be removed.
  fontSize = 12; % May be removed.

  set(datatipH,'StringFcn',(@(~,~) tipText),'Orientation',...
    orientation,'backGroundColor',bkgColor,'FontSize',...
    fontSize,'Draggable','on');            % Only set text and orientation needed.    
  datatipTextBoxH=get(datatipH,'TextBoxHandle');  % May be removed.

  uistack(datatipH,'top'); % Unfortunately makes no effect, since the ylabel handles is not at the axes children list

  datatipTextBoxH=get(datatipH,'TextBoxHandle');
  set(datatipTextBoxH,'HorizontalAlignment','left',...
    'VerticalAlignment','top','Margin',0.02,'Interpreter',...
    'tex','FontName','Courier','FontSize',fontSize); % May be removed.

end
uistack(get(gca,'YLabel'),'bottom') % Also makes no effect, for the same reason.

I have tried:

• uistack all datatips to top,
• uistack the label to bottom (both of them don't work because the ylabel handle is not in the axes children handles).

---

Update: After implementing the @horchler' solution, a new issue appeared: when zooming and panning the axes, the axes label would also move. I've found a small fix for that, I changed the following aspects:

• Set datatip z-value to 1, so that it will always be higher than ylabel axis z.
• Recreating the ylabel afterwards a pan or zoom movement occurs. For this, I implemented localAxisUpdate function that get the old ylabel properties, replace it by a new one, and them reset all settable properties but the ylabel position. For this I used this reference

The resulting code is as follows:

function test
  gradientStep = 1e-1;

  x=-100:gradientStep:100; xSize=numel(x);
  y=x.^3-x.^2;

  figH=figure(42);
  lineH=plot(x,y);

  ylabel('YLabel (YUnits)','FontSize',16)
  xlabel('XLabel (XUnits)','FontSize',16)

  dcH=datacursormode(figH);

  %nTips = 20;

  %for pos = round(linspace(2,xSize,nTips))
    pos = find(x>-78,1);
    datatipH=dcH.createDatatip(lineH,...
      struct('Position',[x(pos) y(pos) 1]));

    orientation = 'top-left';

    if pos>1
      tipText{1} = 'The grandient here is: ';
      tipText{2} = ['\Deltax:',sprintf('%d',x(pos)-x(pos-1)),' XUnits'];
      tipText{3} = ['\Deltay:',sprintf('%d',y(pos)-y(pos-1)),' YUnits'];
    else
      tipText = 'Cannot calculate gradient here.';
    end

    bkgColor = [1 1 .5]; % Light Yellow
    fontSize = 12;

    set(datatipH,'StringFcn',(@(~,~) tipText),'Orientation',...
      orientation,'backGroundColor',bkgColor,'FontSize',...
      fontSize,'Draggable','on');
    datatipTextBoxH=get(datatipH,'TextBoxHandle');

    datatipTextBoxH=get(datatipH,'TextBoxHandle');
    set(datatipTextBoxH,'HorizontalAlignment','left',...
      'VerticalAlignment','top','Margin',0.02,'Interpreter',...
  %end

  % Set changes due to zoom and pan to also use adaptativeDateTicks:         
  set(zoom(figH),'ActionPostCallback',...
    @(~,~) localAxisUpdate(gca));
  set(pan(figH),'ActionPostCallback',...
    @(~,~) localAxisUpdate(gca));

end

function localAxisUpdate(aH)    
  % Fix axis label on top of datatip:
  ylh = get(aH,'YLabel');
  % Get original YLabel properties
  ylstruct = get(ylh);
  % Get settable fields:
  yfieldnames=fieldnames(rmfield(set(ylh),'Position'))';
  % Remove old label:
  delete(ylh)
  % Create new one:
  ylh = ylabel(aH,'Dummy');
  % Send it bottom:
  ylpos = get(ylh,'Position');
  set(ylh, 'Position', [ylpos(1:2) 0]);
  % Reset new ylabel to old values:
  for field=yfieldnames
    field = field{1};
    set(ylh,field,ylstruct.(field));
  end
end

This approach creates an unwanted effect, which is the ylabel will move across the figure until the mouse button is released. How can I remove this unwanted effect ?

I think the solution may be more or less as it was done in undocummented matlab solution for updating axes ticks, but now I would need the listener to the ylabel postset property. Does anyone knows how to do that? If you are a windows user, you can also try to help, all I need is to reset the position of the ylabel after a change (pan, zoom or whatever) is made on the figure.

Answer 1

How about explicitly setting the z-position of the y-label via it's handle? If I put this after your loop it seems to work in R2012b:

ylh = get(gca,'Ylabel')
ylpos = get(ylh,'Position');
set(ylh,'Position',[ylpos(1:2) 0]);

If I adjust the z-position I can get the y-label to pop up and even interleave between the datatips. I'm not completely sure if this is a bug or a feature, but sometimes there are workarounds to rendering issues that involve tweaking the position of an element slightly to get Matlab to recalculate and redraw the figure.

Answer 2

A workaround that uses both linkaxes, so useful when zooming/panning multiple plots, and the visibilty of plots.

1. create an axes (hax_1) with the function to be plotted, without the datatips
2. create an axes (hax_2) with the function to be plotted AND the datatips but without the axes labels
3. set hax_2 visibility to 'off' (this will plot the datatips above the first axes labels)
4. link the 2 axes with linkaxes([hax_1 hax_2],'xy'); (zooming and panning on one of the axes will modify on the fly the second axes)

This gives with your first code (not the edited one):

gradientStep = 1e-1;   
x=-100:gradientStep:100; xSize=numel(x);
y=x.^3-x.^2;   
figH=figure(42);
plot(x,y);   
ylabel('YLabel (YUnits)','FontSize',16)
xlabel('XLabel (XUnits)','FontSize',16)

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% modification starts

hax_1 = gca;
hax_2 = axes('Position', get(hax_1,'Position'));
lineH = plot(x,y);
linkaxes([hax_1 hax_2],'xy');
set(hax_2,'Visible', 'off');

% modification ends
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

dcH=datacursormode(figH); 
nTips = 20; % May change the loop for a datatip at x=-78.
for pos = round(linspace(2,xSize,nTips))
  datatipH=dcH.createDatatip(lineH,struct('Position',[x(pos) y(pos)]));
  orientation = 'top-left';
  if pos>1
    tipText{1} = 'The grandient here is: ';
    tipText{2} = ['\Deltax:',sprintf('%d',x(pos)-x(pos-1)),' XUnits'];
    tipText{3} = ['\Deltay:',sprintf('%d',y(pos)-y(pos-1)),' YUnits'];
  else
    tipText = 'Cannot calculate gradient here.';
  end
  bkgColor = [1 1 .5]; % May be removed.
  fontSize = 12; % May be removed.
  set(datatipH,'StringFcn',(@(~,~) tipText),'Orientation',orientation,'backGroundColor',bkgColor,'FontSize',fontSize,'Draggable','on');  % Only set text and orientation needed.    
  datatipTextBoxH=get(datatipH,'TextBoxHandle');
  set(datatipTextBoxH,'HorizontalAlignment','left','VerticalAlignment','top','Margin',0.02,'Interpreter','tex','FontName','Courier','FontSize',fontSize); % May be removed.   
end

I am on OSX 10.8.4, R2012b, and had the same issue as yours. Here, the proposed solution plots datatips above the axis labels and allow zooming/panning without making use of undocumented features of matlab.