Keep plotted lines on TF change?

Could some kind soul please tell me how to keep lines that are plotted with an indicator when I change the TF of the chart.
TIA

Indicators don't "keep" lines, they calculate them. So an MA on a 5M is not kept when switching to the 15M and vice versa. Perhaps you are referring to some sort of MTF (multiple time frame) indicator that you have seen which does display other TF. That is a bit more complicated and not easy to explain in a posting. The best way is find one and study the code; there are plenty to choose from.

Thanks CM.

Not explaining myself very well!

I have an indi or if you like an EA that looks for signal.
Signal received so sends alert and at the same time plots a vertical line )in this case) where the alert was triggered. This is all fine....

BUT... when I change the TF of the chart the existing vertical lines are lost. I want to be able to keep them in all TFs or regenerate them on the new TF (if that makes any sense).

Do I need to store data to a file and retrieve later or what?
Thanks

OK, so you are plotting vertical lines when a certain event happens on a chart. I don't use lines, instead I use arrows and symbols. For the sake of argument, we can use Fractals as an example. The Fractals on one TF are not the same as the Fractals on another and the indicator will recalculate them and plot them accordingly on the new TF. The Fractals from the previous TF are not retained (wouldn't make any sense)

However, if you want to keep the arrows from one TF to another, do this. Don't plot the arrows as indicator buffers, use an Object instead. ObjectCreate() has the x, y co-ordinates input as Time, Price. So the arrow will plot in the same location. Using vertical lines might work as well but... I have never done it - I always use arrows(force of habit).

I have oversimplified my explanation and made it sound easy, but there are some tricks involved when the TF change is extreme (say 1M to 4H) plus MT4 is broke when plotting objects. Give my idea a try to see if it does something like you have in mind.

No the lines are already plotted as objects.
They are deleted by the Deinit function and, therefore, I assume they are deleted every time the TF changes.

How can I keep them (and also make sure they are cleaned away when the indi is removed)

** Edit:
They are not in a for (...) loop so are not replotted

Don't refer to objects as indicators. They are two different things.

Objects will be deleted by Deinit() if it contains ObjectDelete() logic. That is fairly standard. One way I saw it done was to keep the values (price, time) as Globals, but that code was ugly and was only for a few pitchforks and would be a lot of work as a general solution.

I think the best way is keep the objects as is and have an input setting called Cleanup which is normally false. If set to true, the Deinit() would trigger the ObjectDelete() logic. Again I have made it sound easy, but you will have to overcome some quirks.

Thanks again CM.

Off to go and find some quirks to attack (I think that there are plenty in mt4 !!)

Are your vertical lines plotted across the screen? or are they like mini vertical lines?

Mini vertical lines as in they have a specific length plotted at a specific coordinate or specific X no. of bars from the current bar.

They are full vertical lines (they could be made 'mini' lines but preferred the full ones as they show in indicator sub-windows).

Does it make a difference?

If objects are being deleted, it is because the indicator is deleting them in the deinit() function. This is normal/required behavior for a well written indicator.

What you can do is use the UninitializeReason() function in deinit() to check why the indicator is being deinitialized and if the reason is REASON_CHARTCHANGE, then you would refrain from deleting the objects you want to keep between time-frames.

Oh great font of all wisdom :-))

What an excellent answer,

Thank you so very much.