Add custom price lines

[primozv]

Describe the solution you'd like

There is a price line added for the price matching the last price in the data. It can be removed by setting priceLineVisible to false. Is it possible to add a custom price line that would mark specific price not matching the last price. Or multiple custom price lines. If not can that feature be added. Sometimes we need to mark a specific value that the histogram needs to reach, or 20%/80% values of the price graph.

[timocov]

As workaround you can create a series on the level you want to show (something like in #116).

[odlainepre]

ref: https://github.com/tradingview/lightweight-charts/issues/194

Hi! Need custom price line. As in the private lib tvWidget.chart (). CreateOrderLine ({})

This option is very necessary for production, if possible, add in 1.2.0.

My case: need to display orders. Private library charting_library is very heavy. Only this functionality is not enough to start production version of my project.

[eugene-korobko]

I'd like suggesting following approach:

Add two methods to ISeriesApi:

createPriceLine(options: PriceLineOptions): IPriceLine;
removePriceLine(IPriceLine): void;

PriceLineOptions - is an interface with structure

{
    level: BarPrice | BarPriceProvider,
    color: string,
    lineWidth: LineWidth,
    lineStyle: LineStyle,
}

where

BarPriceProvider = (series: ISeries) => BarPrice

So we will support both push and pull approaches to get price line level value. I'm not sure about cases where pulling would be more effective. We could postpone it so far.

interface IPriceLine is very simple:

applyOptions(options: Partial<PriceLineOptions>): void;
options(): Readonly<PriceLineOptions>;

applyOptions could be used to change color/style as well as price level

[timocov]

@eugene-korobko

level: BarPrice | BarPriceProvider

By default the library doesn't repaint if nothing is changed. How in case of BarPriceProvider the library will know that it needed to be repainted?

What's about price range? Should price line extend price range or not (in autoscale mode)? Should we have option for that?

Others looks fine for me.

@nikitamarcius please note that the first version will not support drawing text for price lines (on, above or even below).

[odlainepre]

Add plz in 1.3.0 text for priceLine

[timocov]

@nikitamarcius I guess it's something like #278. Anyway, it should be separate issue :)

[odlainepre]

@timocov agree

[HighBreedTech]

please i need help on https://github.com/tradingview/lightweight-charts/issues/348