Adding legend to plot window before actually plotting

I have written a timer object function which updates a plot every 10ms. The plot window is all set up before the first timerFCN iteration. It basically plots 2 sets of data (one red line and one blue line with respect to time). I need to add a legend to this plot. Is there somehow i create a custom legends (i.e. define my own linestyle and linecolour for the legend). Since it only starts plotting once the first timerFcn runs, if i try to add a legend before this, it comes up with Warning: Plot empty.

I could add the legend in the timerFcn code section, but since its running every 10ms, just running that one extra line will cause my code to run a bit slower, which i cant have.

Thanks

Answer 1

[Walter Roberson]

Create the two lines ahead of time, with the appropriate color and marker, and with [] as their XData and YData. You can then legend(). After that, as you go, update the XData and YData properties of the two lines to reflect the incoming data.

Answer 2

[Nitin]

Did you try to go in Edit-> Figure Properties in the plot window?