I tried searching for “Indicator” before posting this question, but did not find it... I think I remember CD has the ability to utilize a (custom developed) “Indicator” that can be selected/dragged to the Chart (am I correct?)
I’d like to create a simple set of horizontal lines (per Forex trading session) that show the high/low of that session... for both historic data (applied when I drag it to the chart) and then going forward as data is incrementally added - without any further programming.
Could you point me to a VB.NET example if one exists?
First, you need to compute your custom indicator. Your custom indicator should be like all other financial indicators (moving averages, RSI, MACD, ....). It should be an array of values, with one value per trading session. That means the array size should be the same as the array size for the closeData.
You can then write code to add the indicator to the chart using the representation you like (such as as bars, as an area, lines, etc), and with the color, style, legend entry, axis type, etc...
You can write your custom indicator computation code so that it applies to both both historical and realtime data. In this way, it can "automatically" work with incremental data without any further programming.
You can certainly write code to implement your user interface. For example, you can add a checkbox to "select" the indicator, or you can handle mouse events and use them to "select" the indicator.