How can i restrict the cross cursor in ginput function into a specific UIAxes instead of it showing in the whole appdesigner figure?

Hello, I have created an appdesigner figure where i had 2 button essentially where as the user presses the first button a graph gets shown in the UIAxes completely fine but now i want after the user presses the other button it enables the user to selct a point, I managed to get it working using ginput but the cross cursor is being displayed in the whole appdesigner figure instead of it being restricted to the UIAxes where the graph is displayed

That is how the code currently looks like

% Button pushed function: SelectButton
function SelectButtonPushed(app, event)
% Set up figure handle visibility
fhv = app.UIFigure.HandleVisibility;        % Current status
app.UIFigure.HandleVisibility = 'callback'; % Temporarily change visibility
% Set the current figure to the app's figure
set(0, 'CurrentFigure', app.UIFigure)
% Allow user to select a point on the graph in UIAxes3
[x_selected, ~] = ginput(1);
% Restore original figure handle visibility
app.UIFigure.HandleVisibility = fhv;
% Convert x-coordinate of selected point from milliseconds to seconds
selected_time = x_selected / 1000;
end

Answer 1

[Voss]

You can modify ginput to do that.

First make a copy of ginput.m, put it in your current folder and rename it to something like ginput_modified.m.

Then replace the function updateCrossHair in that file with this:

function updateCrossHair(fig, crossHair)
% update cross hair for figure.
gap = 3; % 3 pixel view port between the crosshairs
cp = hgconvertunits(fig, [fig.CurrentPoint 0 0], fig.Units, 'pixels', fig);
cp = cp(1:2);

ax = fig.CurrentAxes;
if isempty(ax)
    return_early = true;
else
    axPos = getpixelposition(ax,true);
    axX = axPos(1);
    axY = axPos(2);
    axWidth = axPos(3);
    axHeight = axPos(4);
    return_early = cp(1) < axX+gap || cp(2) < axY+gap || cp(1)>axX+axWidth-gap || cp(2)>axY+axHeight-gap;
end

% Early return if point is outside the axes or no CurrentAxes
if return_early
    set(fig,'Pointer','arrow');
    set(crossHair, 'Visible', 'off');
    return
end

cdata = NaN(16,16);
hotspot = [8,8];
set(gcf,'Pointer','custom','PointerShapeCData',cdata,'PointerShapeHotSpot',hotspot)
set(crossHair, 'Visible', 'on');

thickness = 1; % 1 Pixel thin lines. 
set(crossHair(1), 'Position', [axX cp(2) cp(1)-axX-gap thickness]);
set(crossHair(2), 'Position', [cp(1)+gap cp(2) axX+axWidth-cp(1)-gap thickness]);
set(crossHair(3), 'Position', [cp(1) axY thickness cp(2)-axY-gap]);
set(crossHair(4), 'Position', [cp(1) cp(2)+gap thickness axY+axHeight-cp(2)-gap]);
end

Then call ginput_modified (or whatever you called it) from your code.

You need to make sure the uiaxes you want the crosshairs to show up in is the CurrentAxes of the uifigure, so do

app.UIFigure.CurrentAxes = app.UIAxes; % or whatever the relevant uiaxes is called in your app

before you call ginput_modified in your code.

[Dany Majed]

Thanks for your detailed response, I tried to implement everything you mentioned earlier as well as checked that this (app.UIFigure.CurrentAxes = app.UIAxes;) is called before the ginput_modified but now what is happening the cross hair is no longer appearing at the whole UIFigure instead it is showing up at a specific region in there which is not the UIAxes as well, I discovered that by acciddent as i tried to hover with my mouse throughout the whole UIFigure.

[Voss]

Sorry about that. I forgot to take into account that the axes may not be a direct child of the figure but may in a panel or other container. To account for that, try changing this line:

axPos = hgconvertunits(fig, ax.InnerPosition, ax.Units, 'pixels', ax.Parent);

To this:

axPos = getpixelposition(ax,true);

I've changed it in my answer as well.

[Dany Majed]

It works your help is highly appreciated, Thanks for that

[Voss]

You're welcome!

Answer 2

[Walter Roberson]

You can do something using the undocumented overobj() but see https://www.mathworks.com/matlabcentral/answers/327043-change-the-mouse-pointer-while-hovering-above-the-axes#answer_256602

[Dany Majed]

Can you please try giving me more clarification on that since i have been trying different methods and unfortunately none of them seem to solve my problem where i got to a stage where i started thinking could that be a limitation from Matlab or no it can be fixed therefore if that is the case I would like additional assistance on how to achieve that. Thanks in advance any help is highly appreciated.