Why does the font size in my Axes change spontaneously?

I have an application that has 3 axes inside of it - named 'Top', 'Middle', and 'Bottom'. They are used to compare similar sets of data.

My application uses the standard startup callback startupFcn

I have a loop in startupFcn that goes through the 3 axes and attempts to set them all to standard font sizes and colors I define. I also embed handles to the axes in the App variables for shorter paths to properties I use commonly. Here is the code excerpt from startupFcn :

numLocations = numel( app.locations );
for loc = 1:numLocations
    thisLocation = app.locations{loc};
    
    thisAxes = getDMPart(app, 'axes', thisLocation);
    %Create shortcut handles to common axes objects, and change to
    %defaults
    shortAxes                       = struct();
    shortAxes.handle                = thisAxes;
    shortAxes.title                 = title(thisAxes, [thisLocation, ' Chart']);
    shortAxes.title.Color           = app.axesTitleColor;
    shortAxes.title.FontSize        = app.axesTitleSize;
    shortAxes.X                     = thisAxes.XAxis;
    shortAxes.Y                     = thisAxes.YAxis;
    %Axes Properties Set
    shortAxes.X.FontSize            = app.axesDataSize;
    shortAxes.Y.FontSize            = app.axesDataSize;
    
    shortAxes.X.Label.String        = 'Time';
    shortAxes.X.Label.FontSize      = app.axesLabelSize;
    shortAxes.X.Label.FontWeight    = 'bold';
    
    shortAxes.Y.Label.String        = 'Variables';
    shortAxes.Y.Label.FontSize      = app.axesLabelSize;
    shortAxes.Y.Label.FontWeight    = 'bold';
    %Store in App
    app.axesApp.(thisLocation)      = shortAxes;
end

FYI, app.locations axesDataSize, and axesLabelSize are all constant properties in my app:

locations = { 'Top', 'Middle', 'Bottom' };

%Axes Properties
axesDataSize = 8;
axesLabelSize = 10;
axesTitleColor = [1 1 1];
axesTitleSize = 14;

And axesApp is a public property of my app, set to a struct as follows:

axesApp = struct(       ...
    'Top',      '',     ...
    'Middle',   '',     ...
    'Bottom',   ''      ...
    ); %Set of pointers to axes and specific axes properties

However, after I run my App, the X and Y label sizes are 7.5!

The really bizarre thing, is when I try to troubleshoot and put a breakpoint at each assignment line in startupFcn - it works perfectly. The app pops up with the label at size 10 and the axes marks at size 8, as expected. The labels only shrink to 7.5 if I run normally, without breakpoints. I don't have anything else running in parallel while staruptFcn is running. Why would this happen?

Answer 1

[Bora Eryilmaz]

axis.FontSize and axis.Label.FontSize are not independent properties. Setting axis.FontSize will not affect axis.Label.FontSize, but setting axis.Label.FontSize will affect axis.FontSize. Or, it could be the other way around. :)

clc
cla
ax = gca;

ax.XAxis.FontSize = 10;
ax.XAxis.Label.FontSize = 8;
ax.XAxis.FontSize % 10 as expected

ans = 10

ax.XAxis.Label.FontSize % 8 as expected

ans = 8

ax.XAxis.Label.FontSize = 8;
ax.XAxis.FontSize = 10;

ax.XAxis.Label.FontSize % NOT 8 as expected

ans = 11

ax.XAxis.FontSize % 10 as expected

ans = 10