Fixed-size text that zooms/scales with a plot?

When I add text to a plot using the text() command, it appears at a fixed size, and doesn't change as I zoom into the figure. For example, if I draw a rectangle with text inside it, and zoom out until the rectangle is small, the text stays the same size, and thus us now huge compared to the rectangle. I'd like text that stays put inside the rectangle. I guess this is essentially "rendering" text into a plot.

Is there a way in Matlab or something in the user community that can accomplish this? I have searched and haven't found it yet.

Many thanks. Ken

Answer 1

[Kye Taylor]

Here's a cute little function that does what you're looking for.

function textWithZoomEffect

    % plot some original data
    t = linspace(0,2*pi);
    x = sin(t);
    plot(t,x)

    % get axes size
    axis([0,2*pi,-1.5,1.5]);
    ax = axis;

    % add some text
    txt = text(pi/2,1,'Max','fontsize',40/(ax(4)-ax(3)));
    h = zoom; % get handle to zoom utility
    set(h,'ActionPostCallback',@zoomCallBack);
    set(h,'Enable','on');

    % everytime you zoom in, this function is executed
    function zoomCallBack(~, evd)      
        % Since i expect to zoom in ax(4)-ax(3) gets smaller, so fontsize
        % gets bigger.
        ax = axis(evd.Axes); % get axis size

        % change font size accordingly      
        set(txt,'FontSize',40/(ax(4)-ax(3))); 
    end
end

[Ken Purchase]

many thanks - the code is quite helpful.

I have an additional question - I'm using a different utility that does the zooming by changing axis limits, rather than going through the zoom utility. This means the zoom "ActionPostCallback" never gets invoked. Is there a similar callback for changing the axis limits? I haven't found it yet in the documentation.

[Walter Roberson]

I think I saw somewhere that you can add a listener to detect this, but I do not know how one would figure out what the event would be.

Answer 2

[Ken Purchase]

Thanks for the help above, Kye and Walter. It helped me get to a nice solution, that rescales with either axis or figure rescaling. I've uploaded it into Matlab Central File Exchange, under the name TextZoomable. It uses some (apparently undocumented?) callbacks attached to both figure rescaling and axis limit changes.

http://www.mathworks.com/matlabcentral/fileexchange/41513

Answer 3

[Walter Roberson]

zoom PostAction callback, detect the current axis xlim and ylim, decide on a scaling, and set() the text FontSize appropriately (might as well only do it for the objects that are visible.)

[Ken Purchase]

Great - thanks! (not sure I know how to detect which objects are visible - do you mean they're just within xlim, ylim?)