Question: How to subscribe to DataZoom value changes?

[HajiyevEl]

Hi again!
When using DataZoom, how should i get currently displayed candlesticks data?

I want to be able to set yAxis min-max values (Min-Max Type: Custom) depending on currently displayed min-max values of candlesticks on screen (from series data), and subscribe to OnDataZoomRangeChanged for further updates.
Tried using Min-Max Type: Auto, but it seems it gets min-max values from all serie data, not currently displayed (on-screen)

[HajiyevEl]

Alright, i found how to get data from DataZoom:

        // Set custom Y axis min-max values as +/- 1% of max/min values on screen candles
        private void UpdateYAxisMinMaxValues()
        {
            var serie = chart.GetSerie(0);
            chart.GetDataZoomOfSerie(serie, out DataZoom xDataZoom, out DataZoom yDataZoom);

            // Returns timestamp as max value
            //SerieHelper.GetMinMaxData(serie, out serieMinValue, out serieMaxValue, xDataZoom);

            var serieDataList = serie.GetDataList(xDataZoom);

            double serieMinValue = double.MaxValue;
            double serieMaxValue = double.MinValue;

            for (int i = 0; i < serieDataList.Count; i++)
            {
                var serieData = serieDataList[i];
                var serieDataValues = serieData.data;

                // serieDataValues[0] - Timestamp
                // serieDataValues[1] - OpenPrice
                // serieDataValues[2] - ClosePrice
                // serieDataValues[3] - LowPrice
                // serieDataValues[4] - HighPrice

                var min = serieDataValues[3];
                var max = serieDataValues[4];

                if (min < serieMinValue) serieMinValue = min;
                if (max > serieMaxValue) serieMaxValue = max;

            }

            var yAxis = chart.GetChartComponent<YAxis>(serie.yAxisIndex);
            yAxis.type = Axis.AxisType.Value;
            yAxis.minMaxType = Axis.AxisMinMaxType.Custom;
            yAxis.ceilRate = (double)ceilRate;

            serieMinValue = serieMinValue - (yAxisMinMaxOffsetInPercent / 100 * serieMinValue);
            serieMaxValue = serieMaxValue + (yAxisMinMaxOffsetInPercent / 100 * serieMaxValue);

            yAxis.min = ChartHelper.GetMinDivisibleValue(serieMinValue, ceilRate);
            yAxis.max = ChartHelper.GetMaxDivisibleValue(serieMaxValue, ceilRate);

            // Does not set min-max values, because initial values of min max is 0, AdjustMinMaxValue skips them on this line 'if (axis.min != 0 || axis.max != 0)'
            //AxisHelper.AdjustMinMaxValue(yAxis, ref serieMinValue, ref serieMaxValue, true, yAxis.ceilRate);
        }

Now how i should subscribe to OnDataZoomRangeChanged for updates when zoom changes?
For now i just check difference between previous and current values of DataZoom.start and DataZoom.end in update method, is there any other way? Delegate to subscribe for zoom updates maybe?

[monitor1394]

The startEndFunction of DataZoom is a callback for when the start and end values of a DataZoom change. You can try using this function.